TW201406927A - Nitride-based red-emitting phosphor - Google Patents

Abstract

The present invention relates to a red-emitting phosphor comprising a nitride-based composition represented by the chemical formula M(x/v)M'2Si5-xAlxN8:RE, wherein: M is at least one unit price having a valence v, a valence or a trivalent metal; M' is at least one of Mg, Ca, Sr, Ba, and Zn; and RE is at least one of Eu, Ce, Tb, Pr, and Mn; wherein x satisfies 0.1 ≦ x < 0.4 And wherein the phosphor has a general crystalline structure M'2Si5N8:RE, Al replaces Si in the crystalline structure, and M is substantially located at the interstitial site. In addition, the phosphorescent system is configured such that the deviations CIE Δx and Δy of the chromaticity coordinates produced by aging for 1,000 hours at 85 ° C and 85% humidity are less than about 0.03. In addition, the phosphor absorbs UV and blue radiation and emits light having a photoluminescence peak wavelength in the range of about 620 nm to 650 nm.

Description

Nitride-based red-emitting phosphor

Embodiments of the invention relate to a nitride-based red-emitting phosphor composition.

Many red-emitting phosphorescent systems are derived from tantalum nitride (Si ₃ N ₄ ). The structure of tantalum nitride includes a Si layer and an N layer bonded in a slightly twisted SiN ₄ tetrahedral skeleton. The SiN ₄ tetrahedral system is joined by sharing the nitrogen angle so that each nitrogen is shared by three tetrahedra. See, for example, S. Hampshire, "Silicon nitride ceramics-review of structure, processing, and properties," Journal of Achievements in Materials and Manufacturing Engineering , Vol. 24, No. 1, September (2007), pp. 43-50. . The composition of a red light-emitting phosphor based on tantalum nitride generally involves substitution of Si at the center of the SiN ₄ tetrahedron by an element such as Al; this is mainly used to improve the optical properties of the phosphor, such as emission intensity and peak emission. wavelength.

However, as a result of the substitution of aluminum, since the Si ⁴⁺ is replaced by Al ³⁺ , the substituted compound loses a positive charge. There are generally two ways to achieve charge balance: in one scheme, Al ³⁺ replaces Si ⁴⁺ with O ^{2 -} instead of N ³ - such that the lost positive charge is counterbalanced with the lost negative charge. This causes the tetrahedral network to have Al ³⁺ or Si ⁴⁺ as the cation of the tetrahedral center, and the O ^{2 -} or N ^{3 -} anion in the structure is located at the corner of the tetrahedron. Since it has not been accurately known which type of tetrahedron is substituted, the name used to describe this case is (Al,Si) ₃ -(N,O) ₄ . Specifically, to achieve charge balance, there is an O-substituted N for each Al-substituted Si.

In addition, these substitution mechanisms for charge balancing (O-substituted N) can be used in conjunction with interstitial insertion of cations. In other words, the modified cation is inserted between existing atoms on the lattice site and inserted into the "naturally occurring" pores, gaps or channels. This mechanism does not require changing the anion structure (in other words, O is substituted for N), but this does not mean that O substitutions N cannot occur simultaneously. The substitution mechanism for charge balancing can occur in conjunction with gap insertion of the modifier cation.

K. Shioi et al., "Synthesis, crystal structure, and photoluminescence of Sr-α-SiAlON:Eu ²⁺ ," J. Am. Ceram Soc. , 93 [2] 465-469 (2010) A modified cation is used in the nitride phosphor of α-SiAlON. Shioi et al. give the general composition of such a phosphor: M _m/v Si _12-mn Al _m+n O _n N _16-n :Eu ²⁺ , where M is such as Li, Mg, Ca, Y and "Modified cation" such as rare earth (excluding La, Ce, Pr, and Eu), and the valence of v-based M cation. As taught by Shioi et al., the crystal structure of α-SiAlON is derived from the compound α-Si ₃ N ₄ . To generate α-SiAlON from α-Si ₃ N ₄ , partially replace Si ⁴⁺ ions by Al ³⁺ ions, and compensate for the charge imbalance caused by Al ³⁺ substitution of Si ⁴⁺ , replace some N with O and borrow Some positive charges are added by trapping M cations into the gaps in the (Si,Al)-(O,N) ₄ tetrahedral network (Shioi et al. refer to this as "stabilization").

Alkaline earth metal tantalum nitride phosphors having a general formula of M ₂ Si ₅ N ₈ (wherein M is Ca, Sr or Ba) have been extensively studied in the industry, for example, see JWH van Krevel at Technical University Eindhoven, January 2000 PhD paper, U.S. Patent 6,649,946 and HA Hoppe et al, J. Phys. Chem. Solids. 2000, 61: 2001-2006. This phosphor family emits at high quantum efficiency at wavelengths from 600 nm to 650 nm. Among them, pure Sr ₂ Si ₅ N ₈ has the highest quantum efficiency and emits at a peak wavelength of about 620 nm. It is well known in the art that this red photonitride phosphor has poor stability under LED operating conditions ranging from 60 ° C to 120 ° C and ambient relative humidity ranging from 40% to 90%.

Several groups have used experiments based on materials containing oxygen M ₂ Si ₅ N ₈ , which may also contain other metals. See, for example, U.S. Patent Nos. 7,671,529 and 6,956,247, and U.S. Published Application Nos. 2010/0288972, 2008/0081011 and 2008/0001126. However, such oxygen-containing materials are known to exhibit poor stability under combination of high temperature and high relative humidity (RH) (e.g., 85 ° C and 85% RH).

It is believed that the form of charge compensation reported in the industry does not diminish the effect of heat/humidity aging on the phosphor, as it does not appear to produce beneficial results that increase the peak emission wavelength with little or no change in light emission intensity.

The industry needs a nitride-based stable bismuth phosphor and a stable phosphor based on M ₂ Si ₅ N ₈ , in which the peak emission wavelength is in a wide range of red and other colors; and the physical properties of the phosphor (eg temperature and humidity stability) enhanced.

Embodiments of the present invention provide a nitride-based phosphor having a chemical composition based on M ₂ Si ₅ N ₈ in which Si is replaced by a third row element (particularly Al) and the cation is substantially substituted Incorporating into the phosphor crystal structure for charge balance. The phosphor materials can be configured to extend the peak emission wavelength to longer wavelengths of red and enhance the physical properties of the phosphor, particularly significantly improving temperature and humidity stability.

At least one embodiment of the present invention relates to a nitride-based phosphor composition represented by the general formula M' _x M" ₂ A _5-y D _y E ₈ : RE. Here, M' is 1+ cation, At least one of a 2+ cation and a 3+ cation, and M" is at least one of Mg, Ca, Sr, Ba, and Zn. A is at least one of Si, C, and Ge. Element D replaces component A in a substituted manner, wherein D is selected from the group consisting of elements of row IIIB of the periodic table. In one embodiment, D is at least one of B, Al, and Ga. In order to charge-compensate with D-substituted A, a modifier cation M' is added to the phosphor. M' is at least one of Li ¹⁺ , Na ¹⁺ , K ¹⁺ , Sc ³⁺ , Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ^{2+ ,} and Y ³⁺ , and substantially The cation of the plasmant is inserted into the gap of the phosphor. E is at least one of a 3-anion, a 2-anion, and a 1-anion, and may be at least one of O ^{2 -} , N ^{3 -} , F ^{1 -} , Cl ^1- , Br ^1-, and I ^1- . The rare earth activator RE is at least one of Eu, Ce, Tb, Pr and Mn; and the given y is 0.01 y<4, and the valence of x multiplied by M' is equal to y.

Herein, RE denotes a phosphor activator and the symbol ":RE" denotes doping with a rare earth, which is usually doped in a substitution manner, but may also be contained at a grain boundary in the crystal structure of the phosphor material, on the surface of the particle. Doping in the upper and interstitial sites. In general, the crystalline structure of the nitride-based 2-5-8 compound as set forth herein may have a space group selected from the group consisting of Pmn2 ₁ , Cc , derivatives thereof, or mixtures thereof. In some examples, the space group is Pmn2 ₁ . In addition, it should be noted that in the material science theory, the vacancy density of the pure crystalline material can be hundreds of parts per million of the existing lattice sites. Thus, a smaller percentage of charge balancing ions may actually terminate in the empty metal ion sites rather than in the interstitial sites, ie, the charge balancing ions fill the gaps first and then fill the gap sites.

In an alternative embodiment, the modifier cation M' residing in the intercrystalline space is selected from the group consisting of alkaline earths including Ca ²⁺ and elements Li ¹⁺ , Y ³⁺ , Mn ²⁺ , Zn ^{2 +} and one or more rare earths (RE), each of the modifier cations placed in the gap may be used individually or in combination, provided that the sum of the valences of the modifier cations is equal to the charge caused by the substitution of the element A of the IIIB row unbalanced.

Since the stoichiometric subscript of the cation will be greater than 2, it can be immediately seen that the inspected phosphor has modifier cations that are substantially added to the phosphor gap of the present invention. The conventional M ₂ Si ₅ N ₈ red-emitting phosphor has a subscript equal to two. When the value is greater than 2, it can be inferred that the excess cation does not reside at the occupied lattice site; instead, the added modifier cation is inserted into the gap which is "naturally" present in the crystal structure of the host phosphor, In a hole or channel. The gaps can be unoccupied lattice sites.

The charge balancing of Si ⁴⁺ substitutions by incorporating modifier cations placed substantially in the gap according to the present invention has the unexpected benefit of increasing the peak emission wavelength towards the red end of the spectrum. According to some embodiments, this increase is equal to or greater than about 6 nm. The unexpected result associated with an increase in emission wavelength is the substantial maintenance of light emission intensity. According to some embodiments, the intensity visible with the substitution modification and the gap modification is less than 10% relative to the pre-modification strength.

According to the present invention, charge balancing of Si ⁴⁺ substitutions by incorporating modifier cations substantially placed in the gap produces an unexpected benefit in that the stability of the phosphor under aging conditions of high temperature and high humidity is enhanced. The composition of the phosphor is configured such that the deviation of the photoluminescence intensity after aging for 1,000 hours at 85 ° C and 85% humidity is no more than about 30%. The composition of the phosphor is further configured such that after aging for 1,000 hours at 85 ° C and 85% humidity, the coordinate deviations CIE Δx and CIE Δy for each chromaticity coordinate are less than or equal to about 0.03.

In another embodiment of the invention, the charge balance of the gap modifier cation to Si ⁴⁺ substitution is accompanied by a degree of O ^{2 -} substitution N ^{3 -} . In other words, in this embodiment, the charge balancing mechanism of the modifier cations placed substantially in the gap only partially balances the charge imbalance, and the remainder is completed by O2 ^- substituted ^N3- . The reason for the "incomplete" charge balance may be that the valence of the modifier cation is lower than the valence that would otherwise have, such as when Li ⁺ and Ca ^{2+ are used} instead of Ca ²⁺ and Y ³⁺ . Alternatively, the modifier cation should be selected such that the valence is higher (2+, 3+ or even 5+ cations) and the charge balance is incomplete due to the lower number of modified cations placed.

In accordance with an embodiment of the present invention, the phosphorescent system is configured to emit light having a wavelength greater than about 600 nm under blue light excitation, wherein the blue light can be defined as light having a wavelength in the range of from about 420 nm to about 470 nm. The phosphor of the present invention can also be excited by radiation having a relatively short wavelength (e.g., from about 250 nm to about 420 nm), but when the excitation radiation is in x-ray or UV form, providing a separate blue-emitting phosphor to the desired white light to the white light source Contribute to the blue component. A common blue excitation source emits InGaN LEDs or GaN LEDs having a peak at about 460 nm.

Embodiments of the invention also include a white light illumination source comprising a blue light emitting InGaN light emitting diode (LED) and any of the red light emitting phosphors described herein. It may also contain a yellow-emitting phosphor and/or a green-emitting phosphor. In one embodiment, the green-emitting phosphor has the formula Ce:Lu ₃ Al ₅ O ₁₂ . Two exemplary red-emitting phosphors of the examples of the present invention are Eu _0.05 Ca _0.1 Sr _1.95 Si _4.8 Al _0.2 N ₈ and Eu _0.05 Ca _0.1 Sr _1.95 Si _4.8 B _0.2 N ₈ .

At least one embodiment of the invention is based on a modified form of M ₂ Si ₅ N ₈ (the so-called "258" compound), wherein M is an alkaline earth. Modification of the 258 compound comprises substituting Si with elements B, Al, Ga and/or In, especially Al, in column IIIB of the periodic table, wherein charge compensation can be achieved by inserting a so-called modifier cation substantial gap into the phosphor body crystal The structure is completed. The modifier cation has a plurality of valences and includes Li ⁺ , Ca ^{2+ ,} and Y ³⁺ . The advantages of 258 modification include increasing the peak emission wavelength towards the deep red end of the spectrum and enhancing stability in high temperature and high humidity conditions.

The phosphor may include a nitride-based composition represented by the chemical formula M _(x/v) M ' ₂ A _5-y D _y N _8-z E _p :RE, wherein: M is at least one unit price having a valence v a divalent or trivalent metal; M ' is at least one of Mg, Ca, Sr, Ba, and Zn; A is at least one of Si, C, and Ge; and D is at least one of B, Al, and Ga E is at least one of a pentavalent, hexavalent or heptavalent nonmetal having a valence w; and RE is at least one of Eu, Ce, Tb, Pr and Mn; wherein x = y-3z + p (8- w), where y satisfies 0.1 y<1.1, and wherein the phosphor has a general crystal structure of M ' ₂ A ₅ N ₈ :RE, D replaces A in the general crystal structure, and E replaces N in the general crystal structure, and M is substantially in the general At the interstitial sites within the crystalline structure. Further, the red-emitting phosphor may be selected from the group consisting of: Eu _0.05 Ca _0.1 Sr _1.95 B _0.2 Si _4.8 N ₈ ; Eu _0.05 Ca _0.1 Sr _1.95 Al _0.2 Si _4.8 N ₈ ; Eu _0.05 Ca _0.1 Sr _1.95 Ga _0.2 Si _4.8 N ₈ ; Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 N ₈ ; Eu _0.05 Sr _1.95 B _0.2 Si _4.8 N _7.93 ; Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 N _7.93 ; Eu _0.05 Sr _1.95 Ga _0.2 Si _4.8 N _7.93 ; there Ca ₃ N Eu ₂ of _0.05 Sr _1.95 Si ₅ N _8; added BN of _{Eu 0.05 Sr 1.95 Si 5 N 8} ; addition of AlN of _{Eu 0.05 Sr 1.95 Si 5 N 8} ; and added with GaN of Eu _0.05 Sr _1.95 Si ₅ N ₈ .

The red-emitting phosphor may include a nitride-based composition represented by the chemical formula M ' ₂ Si _5-y D _y N _8-z :RE, wherein M ' is at least one of Mg, Ca, Sr, Ba, and Zn One; D is at least one of B, Al, and Ga; and RE is at least one of Eu, Ce, Tb, Pr, and Mn; wherein y=3z, the phosphor has M ' ₂ Si ₅ N ₈ : The general crystalline structure of RE, and Al replaces Si in the general crystalline structure. In addition, the red-emitting phosphor can be configured, where M ' is Sr, D is Si, and RE is Eu. The red-emitting phosphor can be configured, wherein the red-emitting phosphor system consists of Sr, Si, Al, N and Eu. Red-emitting phosphors can be configured, where y satisfies 0.1 y<0.4. Red light phosphor can be configured, where z satisfies 0.05 z<0.09. The red-emitting phosphor can be configured wherein the phosphor absorbs radiation having a wavelength in the range of from about 200 nm to about 470 nm and emits light having a photoluminescence peak emission wavelength greater than 623 nm. The phosphor may be configured, wherein the phosphorescent system is selected from the group consisting of: Eu _0.05 Sr _1.95 B _0.2 Si _4.8 N _7.93 ; Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 N _7.93 ; and Eu _0.05 Sr _1.95 Ga _0.2 Si _4.8 N _7.93 .

The red-emitting phosphor having a nitride-based composition may include: an element M, wherein M is at least one of Li, Na, K, Sc, Ca, Mg, Sr, Ba, and Y; the element M ' , Wherein M ' is at least one of Mg, Ca, Sr, Ba, and Zn; lanthanum; aluminum; nitrogen; and element RE, wherein RE is at least one of Eu, Ce, Tb, Pr, and Mn; The red phosphor has a general crystalline structure of M ' ₂ Si ₅ N ₈ :RE and M and Al are incorporated therein, and wherein the red-emitting phosphor is configured to age at about 85 ° C and about 85% relative humidity After 1,000 hours, the coordinate changes CIE Δx and CIE Δy of each chromaticity coordinate are less than or equal to about 0.03.

The red-emitting phosphor may include a nitride-based composition represented by the chemical formula M _(x/v) M ' ₂ Si _5-x Al _x N ₈ :RE, wherein: M is at least one unit price having a valence v, a divalent or trivalent metal; M ' is at least one of Mg, Ca, Sr, Ba, and Zn; and RE is at least one of Eu, Ce, Tb, Pr, and Mn; wherein x satisfies 0.1 x<0.4, and wherein the red-emitting phosphor has a general crystal structure of M ' ₂ Si ₅ N ₈ :RE, Al replaces Si in the general crystal structure, and M is substantially located in the gap position in the general crystal structure Point.

10‧‧‧Lighting device

12‧‧‧LED chip

16‧‧‧Upper body parts

18‧‧‧ Lower body parts

20‧‧‧ recessed

22‧‧‧Electrical connector

24‧‧‧Electrical connector

30‧‧‧bonding line

32‧‧‧bonding line

34‧‧‧Transparent polymer materials

100‧‧‧Lighting device

102‧‧‧ hollow cylindrical body

104‧‧‧Disc-shaped base

106‧‧‧ hollow cylindrical wall section

108‧‧‧Removable ring top

112‧‧‧Blue LED

114‧‧‧Circular metal core printed circuit board

116‧‧‧Light reflecting surface

118‧‧‧Light reflecting surface

120‧‧‧Photoluminescence wavelength conversion components

After reviewing the drawings in conjunction with the description of certain embodiments of the present invention, the following Examples, their will be apparent to those skilled in the art and such other aspects and features of the present invention, wherein: Figure 1 shows, according to some embodiments of the present invention, a sample Emission spectrum of phosphors 1 to 4; Figure 2 shows an x-ray diffraction pattern of phosphors of samples 1 to 4 according to some embodiments of the present invention; and Figure 3 shows compound Eu _0.05 Ca according to some embodiments of the present invention _0.1 Sr _1.95 Si _4.8 Al _0.2 N ₈ (Sample 2) excitation spectrum illustrating that the phosphor can be effectively excited by radiation between the UV and blue regions of the electromagnetic spectrum; Figure 4 shows some implementations in accordance with the present invention Example compound _{Eu 0.05 Ca 0.1 Sr 1.95 Si 4.8} B 0.2 N 8 ( sample 3) of the excitation spectrum, which is illustrated by the phosphor may be interposed to UV radiation of the electromagnetic spectrum between the effectively excited by blue regions; FIG. 5 shows Example emission spectrum of the phosphor of the samples 5-8 in accordance with some embodiments of the present invention; FIG. 6 shows the embodiment in accordance with some embodiments of the present invention, x-ray diffraction patterns of the phosphors of samples 5-8; Figure 7 shows according to the present invention It Embodiment, the emission spectrum of the phosphor sample of some 9-12 embodiment; FIG. 8 shows the embodiment in accordance with some embodiments of the present invention, x-ray diffraction pattern of the phosphor samples of 9-12; FIG. 9 shows an embodiment of the present invention in accordance with some , an emission spectrum of the phosphors of samples 13 to 16; FIG. 10 shows an x-ray diffraction pattern of the phosphors of samples 13 to 16 according to some embodiments of the present invention; and FIG. 11 shows a sample 17 according to some embodiments of the present invention. The emission spectrum of the phosphor to 21; FIG. 12 shows an x-ray diffraction pattern of the phosphors of samples 17 to 21 according to some embodiments of the present invention; and FIG. 13 shows samples 22 to 27 according to some embodiments of the present invention. The emission spectrum of the phosphor; Figure 14 shows an x-ray diffraction pattern of the phosphors of samples 22 to 27 in accordance with some embodiments of the present invention; and Figure 15 shows the emission spectrum of a white LED (3000K) in accordance with some embodiments of the present invention. The white LED (3000K) includes a blue InGaN LED, a red phosphor having the formula Eu _0.05 Ca _0.1 Sr _1.95 Si _4.8 Al _0.2 N ₈ (sample 2), and a green phosphor having the formula Ce:Lu ₃ Al ₅ O ₁₂ body; FIG. 16 shows the embodiment in accordance with some embodiments of the present invention, Light LED (3000K) of the emission spectrum of the white LED (3000K) comprises a blue InGaN LED, having the formula Eu _0.05 Ca _0.1 Sr _1.95 Si _4.8 B _0.2 N ₈ of the red phosphor (Sample 3) and having the formula Ce: Lu ₃ Green light phosphor of Al ₅ O ₁₂ ; Figures 17A-17C show the results of reliability tests of the phosphors of samples 1 to 3 and 6 at 85 ° C and 85% relative humidity, according to some embodiments of the present invention, wherein Figure 17A is a photoluminescence intensity (brightness) as a function of time, Figure 17B is a CIE x chromaticity coordinate as a function of time, and Figure 17C is a CIE y chromaticity coordinate as a function of time; Figures 18A-18C are shown in accordance with the present invention For some embodiments, the reliability test of the uncoated and Al ₂ O ₃ /SiO ₂ coated sample 33 (which has the same composition as sample 2) at 85 ° C and 85% relative humidity The result is shown in Figure 18A as a function of photoluminescence intensity (brightness) over time, Figure 18B as a change in CIE x chromaticity coordinates over time, and Figure 18C as a change in CIE y chromaticity coordinates over time; Figure 19 shows previous Technically doped Ce yellow YAG phosphor, prior art doped Eu (650 nm) red phosphor CaAlSiN ₃ and the invention An emission spectrum of a 630 nm doped Eu red phosphor Ca _0.1 Sr ₂ Si _4.8 Al _0.2 N ₈ of the embodiment; FIG. 20 shows an emission spectrum of the phosphors of samples 28 to 32 according to some embodiments of the present invention; 21 shows an x-ray diffraction pattern of phosphors of samples 28 to 32 according to some embodiments of the present invention; FIG. 22 shows a light-emitting device of some embodiments of the present invention; and FIGS. 23A and 23B show some embodiments of the present invention Solid state lighting device.

The embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is noted that the following figures and examples are not intended to limit the scope of the invention to the single embodiment, and other embodiments may be possible by the exchange of some or all of the elements illustrated or illustrated. In addition, if some of the elements of the present invention can be practiced in part or in whole, using known components, only those parts of the known components necessary for understanding the invention are set forth and will be omitted. A detailed description of other parts of the components is provided to avoid obscuring the invention. In the present specification, an embodiment showing a single component is not to be considered as limiting; rather, the invention is intended to cover other embodiments including a plurality of the same components, and vice versa, unless otherwise explicitly stated herein. In addition, the applicant does not intend to classify any of the terms of the specification or patent application as unusual or special meaning unless explicitly stated. Further, the present invention encompasses present and future equivalents of the known components referred to herein by way of illustration.

Some embodiments of the invention relate to a nitride-based phosphor composition represented by the general formula M' _x M" ₂ A _5-y D _y E ₈ : RE. Here, M' is 1+ cation, At least one of 2+ cation and 3+ cation, and M" is at least one of Mg, Ca, Sr, Ba, and Zn, which are used individually or in combination. A is at least one of C, Si, and Ge used individually or in combination. Element D replaces component A in a substitutional manner, wherein D is selected from the group consisting of elements of row IIIB of the periodic table. The markings of the various rows of the periodic table of the present invention are used by the users in the cover page of the book " Optical Properties of Solids " by Mark Fox (Oxford University Press, New York, 2001), which follows the old IUPAC (International Pure Chemistry). The International Union of Pure and Applied Chemistry system. See http://en.wikipedia.org/wiki/Group_(periodic_table), the latest review on January 15, 2013. In one embodiment, D is at least one of B, Al, and Ga used individually or in combination.

A modifier cation M' is added to the phosphor to charge compensate for D-substituted A. Specifically, M' is at least one of Li ¹⁺ , Na ¹⁺ , K ¹⁺ , Sc ³⁺ , Ca ^{2+ ,} and Y ³⁺ used singly or in combination. M' is an additional cation used in addition to the stoichiometric amount "2" of the divalent metal M in the formula M ₂ Si ₅ N ₈ , and thus the modifier cation has been said to have been substantially inserted into the phosphor gap. The nature of this site will be further elaborated in the Nomenclature section below.

In the general formula of the phosphor of the present invention, E is at least one of a 3-anion, a 2-anion and a 1-anion. In particular, E may be at least one of O ² , N ³ , F ¹ , Cl ¹ , Br ⁻ and I ⁻ used individually or in combination. The rare earth RE is at least one of Eu, Ce, Tb, Pr, and Mn; and the given y is 0.01 y 1.0. The value of the parameter y can be defined as the value of x multiplied by the valence of M'; this is the condition for achieving charge balance.

As discussed above, the M' cation "modifier" cation is used to refer to a terminology that is introduced into the gap rather than introduced by a substitution mechanism to achieve charge balance and/or stabilization of the crystal structure. . The interstitial sites are cavities, holes or channels present in the crystal lattice by means of the arrangement of the atoms (stacked or stacked) of the constituent atoms. The dopant atoms occupying the interstitial space are to be distinguished from the atoms introduced by the substitution mode; in the latter mechanism, the dopant atoms replace the host atoms residing at the lattice sites. The difference between the manner in which the two mechanisms achieve charge balance in the phosphor will be represented by the stoichiometry of the subject.

In the following disclosure, the known (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ composition will be discussed, and then a brief commentary on the nature of the interstitial sites of the embodiments of the present invention will be made. Subsequently, the disclosure will present a phosphor based on the M' _x M" ₂ A _5-y D _y E ₈ :RE embodiment of the invention, giving its advantages and characteristics and the difference between the phosphors and the prior art. A specific example will be given, including a phosphor in which the element IIIB of the substitution Si ⁴⁺ is Al ³⁺ and in which the modified cation is Ca ²⁺ . Finally, the invention for forming a white LED will be discussed. Red-emitting nitride phosphors, as well as accelerated aging results showing the thermal and chemical stability of the phosphors of the present invention.

Known (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ Composition

Piao et al., paper entitled "Preparation of (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ solid solutions and their luminescence properties," J. of the Electrochem. Soc. 153 (12) The composition based on (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ is discussed in H232-H235 (2006) ("Preparation Paper"). As taught by Piao et al. in the preparation paper, the solution of "...(Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ in Ca ²⁺ is limited to the composition of x=0.5 The first [Ca ₂ Si ₅ N ₈ ] phase occurs when the composition is (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ in x=0.6. The two phases coexist in the range of 0.5<x<0.75. , in which a transition from a rhombic structure to a monoclinic structure occurs." Piao et al. clarify the position of the Ca ²⁺ modifier cation in the red nitride phosphor: "The doped Eu ²⁺ ions occupying the Sr ²⁺ /Ca ²⁺ ion position are arranged along the Si ₆ N ₆ ring respectively In the channel formed by the [100] and [010] directions of the two phases. When the Ca ²⁺ content is increased to x = 0.5 in the [Sr ₂ Si ₅ N ₈ ] phase, SrCaSi ₅ N _{8 is} formed, "the crystal grain is more preferable, and the [grain] size is increased". This will enhance the optical properties. When x is increased to 0.6 (60 atom%), the "SEM image indicates the presence of two phases having different morphology". See Piao et al., Preparing the paper, page H233.

In the paper, Piao et al. explain to some extent the properties of the modifier cation gap sites in the red photonitride phosphors of the present invention. In M ₂ Si ₅ N ₈ (where M = Sr and Ca) each unit cell has two crystalline M sites; this is why these compounds have two emission bands. However, in the (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ series, only one broadband emission was seen. This indicates that the two sites have a very similar crystal environment, or that the Eu ²⁺ ions in the N ^3- rich network have different coordination sites for the two sites (N ³ around each M site and in combination with it) The fact that the number of anions is) is not particularly sensitive. See Piao et al., Preparing the paper, page H234.

Piao et al. teach that when Ca ²⁺ is added to replace Sr in the [Sr ₂ Si ₅ N ₈ ] phase, the emission migrates to a longer wavelength until (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ² The point of x = 0.5 (having 2 atom% Eu) in the ⁺ series. The Eu ²⁺ emission band is red shifted from 617 nm of Sr ₂ Si ₅ N ₈ :Eu ²⁺ to 632 nm of SrCaSi ₅ N ₈ :Eu ²⁺ , wherein the Eu concentration is 2 atom% in both cases. In both cases, the ionic radii of the Ca ²⁺ and Sr ²⁺ ions with a coordination number of 10 are 1.23 Å and 1.36 Å, respectively. Therefore, when the Ca ²⁺ ion replaces the Sr ²⁺ site in the [Sr ₂ Si ₅ N ₈ ] phase, the MN bond length and the lattice parameter decrease can be seen in the x-ray diffraction (XRD) experiment. The shorter average distance of the Ca-N bond relative to Sr-N causes the Eu ²⁺ ion to experience a stronger crystal field strength, which is inversely proportional to the 5th power of the chemical bond length. See Piao et al., Preparing the paper, page H234.

According to Piao et al., the emission intensity decreases with increasing Ca ²⁺ content in the (Sr _1-x Ca _x ) ₂ Si ₅ N ₈ :Eu ²⁺ phosphor. This is explained by Piao et al. on page 235; although the details are too complex to be detailed here, the reduction in intensity is necessarily related to the coordination mode of the Eu ²⁺ ions and the energy level diagram associated with the transition of the excited state. See Piao et al., Preparing the paper, page H235.

The nature of the gap sites in the embodiments of the present invention

While it is not desired to be bound by any particular theory regarding the nature of the modified cation gap sites of embodiments of the present invention, the discussion of known theory may be helpful or may be derived therefrom. This is primarily concerned with nomenclature, as the term "gap site" is used in the present invention to describe the site at which the charge balance modifier cation is inserted. (Readers will recall that modifier cations such as Ca ²⁺ can be used to charge balance the charge imbalance resulting from Al ³⁺ substituted Si ⁴⁺ ). The term "gap" is chosen to emphasize the fact that the modifier cation typically does not replace or replace an existing ion at the lattice site. As previously emphasized, the modifier cation is added to the cations in the existing crystalline host structure.

That is, there does not appear to be much information in the literature regarding the nature of the interstitial sites, including their position or number in the modified M ₂ Si ₅ N ₈ :Eu ²⁺ unit cell. There may be some data indicating that it does not occupy the M site. For example, in Xie et al., entitled "A simple, efficient synthetic route to Sr ₂ Si ₅ N ₈ Eu ²⁺ -based red phosphors for white light-emitting diodes," in Chem. Mater. 2006, 18 , 5576-5583 It is taught that in at least one experiment of synthesizing Sr ₂ Si ₅ N ₈ , the site occupancy fraction is 90.7% for the Sr1 site and 88.9% for the Sr2 site, thereby reminding the reader that each cell has two M Site. Xie et al. describe this as "a slight defect in Sr at two sites." In the material science theory, the vacancy density of pure crystalline materials depends on the thermal equilibrium conditions of the crystals produced, which should be hundreds of parts per million of the existing lattice sites. Thus, a smaller percentage of charge balancing ions may actually terminate in an empty metal ion site such as the Sr/Ca/Eu lattice site, ie, the charge balancing ions fill the gap first and then fill the gap sites.

M’ _x M" ₂ A _5-y D _y E ₈ :RE-based discussion of the phosphor of the invention

Embodiments of the present invention relate to a nitride-based phosphor composition represented by the general formula M' _x M" ₂ A _5-y D _y E ₈ : RE. Here, M' is 1+ cation, 2+ At least one of a cation and a 3+ cation, and M" is at least one of Mg, Ca, Sr, Ba, and Zn. A is at least one of Si and Ge. Element D replaces component A in a substituted manner, wherein D is selected from the group consisting of elements of row IIIB of the periodic table. In one embodiment, D is at least one of B, Al, and Ga.

To charge-compensate D-substituted A, a modifier cation M' is added to the phosphor. M' is at least one of Li ¹⁺ , Na ¹⁺ , K ¹⁺ , Sc ³⁺ , Ca ^{2+ ,} and Y ³⁺ , and the modifier cation is substantially inserted into the phosphor gap, and E is 3 At least one of an anion, a 2-anion and a 1-anion, and may be at least one of O ²⁻ , N ³⁻ , F ⁻ , Cl ⁻ , Br ⁻ and I ⁻ . The rare earth RE is at least one of Eu, Ce, Tb, Pr, and Mn; and the given y is 0.01 y < 1.0, and the valence of x multiplied by M' is equal to y.

In an alternative embodiment, the modifier cation M' that resides substantially in the intercrystalline space is selected from the group consisting of alkaline earths including Ca ²⁺ and elements Li ⁺ , Zn ²⁺ , Y ^{3+ ,} and Or a plurality of rare earths (RE), each of the modifier cations placed in the gap being used individually or in combination.

The substitution mechanism discussed above occurs when a rare earth activator ion is inserted into the host instead of the alkaline earth atom at the lattice site, thereby converting "ordinary ceramic" into a phosphor. However, the substitution event can be carried out in other ways: for example, when Si at the center of the SiN ₄ tetrahedron is replaced by Al, it can also be substituted. This improves the optical properties. However, those skilled in the art will note that the Al/Si substitution is different from the Eu/alkaline earth substitution: in the latter case the substitution is a charge neutral substitution because the divalent alkaline earth cation is via a divalent rare earth cation. Instead, Al ³⁺ replaces Si ^{4+ to} cause the body to lose a positive charge. This lost positive charge can be balanced by further modification of the phosphor material. In an alternative mechanism, the doping of the rare earth activator may also be located at the interstitial sites; for example, Eu is known to reside at the interstitial sites of the β-SiAlON phosphor.

Two methods have been reported in the literature that are commonly used to charge balance lost positive charges. In one version, Al ³⁺ replaces Si ⁴⁺ with O ^{2 -} instead of N ³ - such that the lost positive charge is counterbalanced with the lost negative charge. This allows the network of tetrahedrons to variably have Al ³⁺ or Si ⁴⁺ cations at their centers and a combination of O ^{2 -} to N ^{3 -} anions at their corners. Since it has not been accurately known which type of tetrahedron is substituted, the name used to describe this case is (Al,Si)-(N,O) ₄ . Specifically, to achieve charge balance, there is an O substitution N for each Al substitution Si. However, embodiments of the present invention do not utilize O2 ^- substituted ^N3- as the primary charge balancing mode, but rather tend to provide modifier cations that are substantially located in the gap, but this does not mean that the modifier cannot be combined. The cation uses O ^{2 -} instead of N ^{3 -} .

The second way of charge balancing the loss of positive charge, i.e., the primary method utilized by the inventors in the present invention, supplies substantially additional positive charge into the interstitial space. The inventors conducted a series of experiments in which Si was replaced by a material of the IIIB row, and Ca ²⁺ and/or Sr ^{2+ was} used as a modifier cation.

A general representation of a phosphor comprising a substitution for N and an additional cation to achieve a charge balance for the replacement of Si or an equivalent element by a Group IIIB element in some embodiments of the invention may include the chemical formula M _(x/v) M ' ₂ A _5-y D _y N _8-z E _p : RE represents a nitride-based composition, wherein: M is at least one monovalent, divalent or trivalent metal having a valence v; M ' is Mg, Ca, Sr At least one of Ba, Zn, and Zn; A is at least one of Si, C, and Ge; D is at least one of B, Al, and Ga; and E is at least one of five or six valences having a valence w a heptavalent non-metal; and RE is at least one of Eu, Ce, Tb, Pr, and Mn; wherein x = y - 3z + p (8 - w), wherein y satisfies 0.1 y<1.1, and wherein the phosphor has a general crystal structure of M ' ₂ A ₅ N ₈ :RE, D replaces A in the general crystal structure, and E replaces N in the general crystal structure, and M is substantially in the general At the interstitial sites within the crystalline structure.

In the first series of experiments (denoted as samples 1-4), element IIIB of the periodic table as a potential replacement for Si was evaluated. The starting materials for synthesizing the "base compound" (ie, the phosphor without the contents of the IIIB line) are EuCl ₃ , Sr ₃ N ₂ , Ca ₃ N as the source of germanium, germanium, calcium, and germanium, respectively. ₂ and Si ₃ N ₄ powder. Of course, any nitride salt can provide nitrogen. The three elements from the third row of the periodic table used to replace Si are Al, B, and Ga. Experimental details regarding this series of compounds are provided in Tables 2A and 2B . The stoichiometric composition of the compound containing Samples 1-4 of the IIIB row element replacing the ruthenium is in the order of increasing atomic weight of B, Al and Ga: Eu _0.05 Ca _0.1 Sr _1.95 B _0.2 Si _4.8 N ₈ for the boron-containing compound; The Al-containing compound was Eu _0.05 Ca _0.1 Sr _1.95 Al _0.2 Si _4.8 N ₈ , and for the Ga-containing compound, it was Eu _0.05 Ca _0.1 Sr _1.95 Ga _0.2 Si _4.8 N ₈ .

Referring to Figure 1 , the phosphorescent system of the series 1-4 having the highest photoluminescence intensity contains a boron compound; this sample also exhibits a phosphor having the shortest peak emission wavelength (emitted at about 623 nm). The aluminum-containing phosphors of this group exhibited the lowest photoluminescence intensity of the control containing this group of compounds (ie, the 2-5-8 phosphor (Eu _0.05 Sr _1.95 Si ₅ N ₈ ) without the substituent of the IIIB row). Photoluminescence intensity. In other words, even the control compound Eu _0.05 Sr _1.95 Si ₅ N ₈ exhibited higher photoluminescence intensity than the aluminum-containing compound. In a separate experiment, the photoluminescence intensity of the aluminum-containing sample can be further increased by sintering at higher temperatures. It should also be noted that samples containing B and Ga do not exhibit significant 2θ degree shifts in the XRD data, which may indicate that substitution of Si may not occur in such samples. For example, B may have evaporated or may have formed an impurity phase with other elements such as Sr, and 2-5-8 material (rare or no B substituted Si) is still the main phase.

In the second series of experiments (denoted as samples 5-8), element IIIB of the periodic table as a potential replacement for Si was evaluated, but calcium was not included in this second group. Instead, to achieve charge balance, replace the nitrogen with oxygen. The oxygen is supplied in the form of raw material powders SiO ₂ and Al ₂ O ₃ . Of course, in such cases, the raw material powders SiO ₂ and Al ₂ O _{3 are} also used as a source or potential source of bismuth and aluminum and as a source of oxygen. Experimental details regarding this series of compounds utilizing oxygen to charge balance are provided in Tables 3A and 3B . The stoichiometric composition of the sample 5-8 compound which is charge-balanced by B, Al and/or Ga substituted Si via oxygen-substituted nitrogen is in this order: Eu _0.05 Sr _1.95 B _0.2 Si _4.8 O _0.2 N _7.8 for the boron-containing compound For the Al-containing compound, it is Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 O _0.2 N _7.8 , and for the Ga-containing compound, it is Eu _0.05 Sr _1.95 Ga _0.2 Si _4.8 O _0.2 N _7.8 .

Referring to Figure 5 , the phosphor having the highest photoluminescence intensity in this series (samples 5-8) was the control compound Eu _0.05 Sr _1.95 Si ₅ N ₈ . This may seem to indicate that at least for this series of experiments, the addition of oxygen attenuates the photoluminescence intensity.

In a third series of experiments (denoted as samples 9-12), compounds that are charge-balanced by gap Ca are compared for compounds that are charge-balanced by replacing oxygen, both of which are necessary for Al to replace Si. The compounds are further compared to phosphors containing Al but not causing an intentional charge balance mechanism. Experimental details regarding this series of compounds are provided in Tables 4A and 4B . The stoichiometric composition of the compound of sample 9-12 is: Eu _0.05 Ca _0.1 Sr _1.95 Al _0.2 Si _4.8 N ₈ , in which Si has been replaced by element IIIB Al, and charge balance is achieved by gap Ca; Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 O _0.2 N _7.8 , Si has also been substituted with element IIIB element Al, but this time the charge balance is achieved by replacing nitrogen with oxygen; Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 N _7.93 , In this compound, nitrogen deficiency was used to charge balance the Al-substituted Si; and finally, the control was Eu _0.05 Sr _1.95 Si ₅ N ₈ .

Referring to Figure 7 , the phosphor having the highest photoluminescence intensity in this series (samples 9-12) is also the control compound Eu _0.05 Sr _1.95 Si ₅ N ₈ , but the Al-substituted compound exhibiting charge balance using the gap Ca is exhibited. Almost as high a photoluminescence intensity. The data further shows that the substitution of this compound and the subsequent charge balance shifts the peak emission intensity to longer wavelengths. This is the opposite of the wavelength shift seen in the "practical" Sr ₂ Si ₅ N ₈ compound when Ca is substituted for Sr. This latter observation has several advantages for color reproduction when white light illumination is produced from white LEDs. From the experiments carried out by the inventors, it can be inferred that it is necessary for the substantially interstitial charge balance system in which Al is substituted by Si to be completed by Ca.

In the fourth series of experiments (denoted as samples 13-16), element IIIB of the periodic table as a potential replacement for Si was evaluated, but no intentional charge balance was achieved in this series. The latter statement means that no interstitial cation such as Ca is added; nitrogen is not replaced with oxygen (so the equation shows a stoichiometric content of nitrogen of 8). Experimental details regarding this series of compounds are provided in Tables 5A and 5B . In this series of experiments, the inventors believe that some nitrogen sites can be vacancies to balance charge. Based on the assumption that nitrogen deficiency is used to achieve charge balance, the stoichiometric composition of the compound of sample 13-16 is expected to be: Eu _0.05 Sr _1.95 B _0.2 Si _4.8 N _7.93 , in which element B of element IIIB has replaced Si, And no further attempt was made to charge balance; Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 N _7.93 , in which the element IIIB element Al has also replaced Si, and no charge balance has been attempted; and Eu _0.05 Sr _1.95 Ga _0.2 Si _4.8 N _7.93 , In the compound, element IIIB element Ga has replaced Si, and no further charge balance has been attempted. The control for this series is also Eu _0.05 Sr _1.95 Si ₅ N ₈ .

A general representative of some embodiments of the present invention comprising N-deficient to achieve a charge balance of a Group IIIB element in place of Si or an equivalent element may include the chemical formula M ' ₂ Si _5-y D _y N _{8- z} : RE represents a nitride-based composition, wherein M ' is at least one of Mg, Ca, Sr, Ba, and Zn; D is at least one of B, Al, and Ga; and RE is Eu, At least one of Ce, Tb, Pr, and Mn; wherein y = 3z, the phosphor has a general crystal structure of M ' ₂ Si ₅ N ₈ : RE, and Al replaces Si in the general crystal structure. In addition, the red-emitting phosphor can be configured, where M ' is Sr, D is Si, and RE is Eu. The red-emitting phosphor can be configured, wherein the red-emitting phosphor system consists of Sr, Si, Al, N and Eu. Red-emitting phosphors can be configured, where y satisfies 0.1 y<0.4. Red light phosphor can be configured, where z satisfies 0.05 z<0.09.

Referring to Figure 9 , the phosphor having the highest photoluminescence intensity in this series (samples 13-16) is a boron-containing compound. The second highest strength is two compounds having substantially the same strength: a gallium-containing compound and a control. Aluminum-containing compounds have significantly lower photoluminescence intensity. Interestingly, it was noted that in this series, the control, B-containing and Ga-containing samples (samples 15 and 16) exhibited peak emission wavelengths of about 624 nm. According to some embodiments, B and Ga may not replace Si, but act as a flux. This statement was made experimentally, in which the x-ray diffraction peak did not migrate by substitution; in addition, the peak emission wavelength did not migrate in these experiments. Interestingly, it was noted that this N-substituted charge-balanced Al-substituted sample had less wavelength shift and lower photoluminescence intensity than the Ca-charge-balanced sample (Sample 2). This may indicate that Ca placed in the gap for charge balancing causes the wavelength to migrate further and increase the photoluminescence intensity.

In the fifth series of experiments (denoted as samples 17-21), elements of row IIIB of the periodic table were evaluated as elements other than the stoichiometric formula Sr ₂ Si ₅ N ₈ . The amount of element IIIB added to the raw material powder mixture is about twice the amount in sample 13-16 (i.e., 50% lower than the sample of the IIIB substituted hydrazine). The amount of Ca added to the sample 21 was the same as that of the sample to which IIIB was added. Since it is difficult to accurately determine the composition of the sintered compound, especially if the single crystal x-ray diffraction method is not used, the stoichiometric formula of this series is represented by the additive of Ca, B, Al and Ga cations as their respective raw material powder salts. To show. Thus, the compounds of the stoichiometric formula of 17-21 samples may be expressed as: addition of Eu Ca ₃ N ₂ of _0.05 Sr _1.95 Si ₅ N _8; BN of added _{Eu 0.05 Sr 1.95 Si 5 N 8} ; AlN of added Eu _0.05 Sr _1.95 Si ₅ N ₈ ; Eu _0.05 Sr _1.95 Si ₅ N ₈ with GaN added; and control Eu _0.05 Sr _1.95 Si ₅ N ₈ . Experimental details regarding this series of compounds are provided in Tables 6A and 6B .

Referring to Figure 11 , each of the phosphors in this series (samples 17-21) exhibited substantially the same photoluminescence intensity and a substantially similar peak emission wavelength (about 624 nm), indicating a simple addition of the IIIB line element. May not replace 矽.

In the sixth series of experiments (denoted as samples 22-27), boron was selected from row IIIB of the periodic table for further study. See, for example, Figure 1 and the boron-containing samples of the set of samples 1-4. In this set of experiments, the boron content is expressed stoichiometrically as the parameter "y", which has the following values: y = 0; y = 0.2; y = 0.3; y = 0.4; y = 0.5 and y = 1.0. Charge compensation is accomplished by adding interstitial calcium in incremental amounts, respectively. Experimental details regarding this series of compounds are provided in Tables 7A and 7B . Samples 22-27 of the emission spectrum of the phosphor 13 shown in FIG.

In the seventh series of experiments (denoted as samples 28-32), aluminum was selected from line IIIB of the periodic table for further study. See, for example, Figure 1 and the aluminum-containing samples of the set of samples 1-4. In this set of experiments, the boron content is expressed stoichiometrically as the parameter "y", which has the following values: y = 0.15; y = 0.2; y = 0.25; y = 0.3 and y = 0.4. Charge compensation is accomplished by adding interstitial calcium in incremental amounts, respectively. Experimental details regarding this series of compounds are provided in Tables 8A and 8B . Samples 28-32 of the emission spectrum of the phosphor 20 shown in FIG.

Overview of experimental concepts

The experimental results set forth above indicate that for these experiments (which may indicate a general trend), it was found that the combination of element IIIB, Al, and Si, as a modified cation, maximized migration to longer emission wavelengths with photoluminescence intensity. At least weakened. The amounts of starting materials used, peak wavelength emission, stoichiometry of the phosphor, and an overview of the substituted/additives are shown in Table 1 below.

In the first experiment highlighted in Table 1 , Al ³⁺ substitution of Si ⁴⁺ resulted in a charge imbalance. The phosphor of sample 2 solves the charge imbalance by substantially adding the Ca ²⁺ modifier cation in the gap; this causes the peak emission wavelength of the sample 2 phosphor to increase relative to the control without the Al or modifier cation. 6nm. The sample 2 phosphor had the formula Eu _0.05 Ca _0.1 Sr _1.95 Al _0.2 Si _4.8 N ₈ and the control was Eu _0.05 Sr _1.95 Si ₅ N ₈ .

In the second experiment highlighted in Table 1 , the substitution of Al ³⁺ for Si ⁴⁺ also resulted in a charge imbalance. However, in this experiment, a larger amount of Al was used, and some Al was in the form of Al ₂ O ₃ (source of oxygen). Here, O ² -substituted N ^{3 -} is a charge balance mechanism, and thus there is no additional or no calcium added. The result is also that the peak emission wavelength of the sample 6 phosphor is increased by 6 nm relative to the sample 5 control. The compound of the sample 6 was of the formula Eu _0.05 Sr _1.95 Al _0.2 Si _4.8 N _7.8 O _0.2 , and the control was also Eu _0.05 Sr _1.95 Si ₅ N ₈ .

However, as discussed below, the reliability test data shows that the phosphor of the present invention that is charge balanced by calcium provides or is very close to the degree of stability to humidity and temperature required by the lighting industry, while the phosphor that balances the charge by oxygen Has relatively poor stability.

Figure 19 shows a comparison of the emission spectra of the following phosphors: the Ce-doped yellow YAG phosphor of the prior art; the Eu-doped (650 nm) red phosphor CaAlSiN ₃ and the 630 nm doped Eu of the present invention. Red phosphor Ca _0.1 Sr ₂ Si _4.8 Al _0.2 N ₈ (Sample 2). Each spectrum was measured at a 450 nm blue LED excitation source.

Red photonitride of the invention as part of a white LED

Figure 15 shows the spectrum of a white LED (3000K) comprising a blue InGaN LED, a red phosphor having the formula Eu _0.05 Ca _0.1 Sr _1.95 Si _4.8 Al _0.2 N ₈ (from sample 2) and having the formula Ce : Lu ₃ Al ₅ O ₁₂ green phosphor; and Figure 16 shows the spectrum of a white LED (3000K) comprising a blue InGaN LED having the formula Eu _0.05 Ca _0.1 Sr _1.95 Si _4.8 B _0.2 N ₈ The red phosphor (from sample 3) and the green phosphor having the formula Ce:Lu ₃ Al ₅ O ₁₂ .

Reliability test

In many regions, including the United States, regulators set performance standards for replacing LED lights. For example, the US Environmental Protection Agency (EPA) and the US Department of Energy (DOE) publish performance specifications, according to which the lamp can be referred to as an "ENERGY STAR ^® " qualified product, such as identifying power usage. Requirements, minimum light output requirements, luminous intensity distribution requirements, luminous efficacy requirements, life expectancy, etc. ENERGY STAR ^® "Planning Requirements for Monolithic LED Lights" requires that all LED lights "within the minimum lumen maintenance test period (6000 hours), the chromaticity change should be 0.007 on the CIE 1976 (u', v') chart. Inside, and depending on the type of lamp, the lamp must have "have 15,000 or 25,000 hours of operation" 70% lumen maintenance (L70). ENERGY STAR ^® requirements are for lamp performance and include all components of the lamp, such as LEDs, phosphors, electronic drive circuits, optical components and mechanical components. In principle, the brightness of white LEDs decreases with aging, not only because of the phosphor, but also because of the blue LED chip. Other sources of attenuation may come from packaging materials (eg, substrates), bond wires, and other components that are encapsulated by polyoxygenated oxygen. In contrast, the main factor affecting color coordinate changes is phosphor degradation. On phosphor performance it is believed to meet the requirements ENERGY STAR ^®, a relatively lower humidity accelerated test, the change in chromaticity coordinates of the phosphors in each of the 1000 hours (CIE △ x, CIE △ y ) and 85% at 85 ℃ 0.01. The phosphor coated LEDs prepared as follows were subjected to accelerated testing by combining phosphor particles with a binder such as epoxy or polyoxymethylene and then applying them to the LED wafer. The coated LEDs were placed in an oven at the specified temperature and humidity and operated continuously during the test period.

17A-17C show the results of reliability tests of the phosphors of samples 1 to 3 and 6 at 85 ° C and 85% relative humidity. Figures 17A-17C show the photoluminescence intensity (brightness) versus time and CIE chromaticity of a 3000K white LED (shown in the spectra of Figures 15 and 16 ) at 85 ° C and 85% relative humidity. The coordinates change over time. Both the Sr ₂ Si ₅ N ₈ control sample with LED conversion and the phosphor of sample 6 (Eu _0.05 Sr _1.95 Si _4.8 Al _0.2 N _7.8 O _0.2 ) showed generally unacceptable results in the industry. The most significant improvement in stability as defined by maintaining intensity and chromaticity is unexpectedly achieved by Ca gap charge balance as exemplified in Sample 2 and Al substitution of Si (see Table 2A ). Sample 3 showed a relatively small improvement in stability; Sample 3 was a sample containing B.

For further improved performance to meet the requirements ENERGY STAR ^®, may be used (e.g.) one or more of SiO _2, Al ₂ O ₃ and / or TiO ₂ coated with a coating composition of the phosphor particles of Sample 2, as described in co-pending The patent application is taught in US Application No. 13/671,501 to COATINGS FOR PHOTOLUMINESCENT MATERIALS and US Application No. 13/273,166 to HIGHLY RELIABLE PHOTOLUMINESCENT MATERIALS HAVING A THICK AND UNIFORM TITANIUM DIOXIDE COATING. The content of one is incorporated by reference in its entirety. 18A-18C show a phosphor of sample 33 having an Al ₂ O ₃ /SiO ₂ coating (which has the same composition as sample 2). As seen from these figures, the coated phosphor satisfy the criteria for establishing accelerated test of conformity ^® ENERGY STAR.

Synthesis of phosphor of the invention

For each of the examples and comparative examples set forth herein, the starting material comprises at least one of the following compounds: Si ₃ N ₄ , AlN, Ca ₃ N ₂ , Sr ₃ N ₂ , BN, GaN, SiO ₂ , Al ₂ O ₃ and EuCl ₃ .

Sample 1 to 4

To obtain the desired composition of the phosphors exemplified in Samples 1 to 4, the solid powder was weighed according to the composition shown in Table 2A . This raw material mixture was then loaded into the plastic grinding bottle together with the grinding beads, sealed in a glove box, and then subjected to a ball milling process for about 2 hours. The mixed powder was then loaded into a molybdenum crucible having an inner diameter of 30 mm and a height of 30 mm; the loaded crucible was covered with a molybdenum lid and placed in a gas sintering furnace equipped with a graphite heater.

After the crucible was loaded, the furnace was evacuated to 10 ^-2 Pa and the sample was heated to 150 ° C under these vacuum conditions. High purity N ₂ gas was introduced into the chamber at a temperature of 150 ° C; then the temperature of the furnace was raised to a temperature of about 1700 ° C at a substantially constant heating rate of 4 ° C/min. The sample was maintained at 1700 ° C for about 7 hours.

After calcination, the power was turned off and the sample was allowed to cool in the furnace. The sintered phosphor is gently ground, ball-milled to a certain particle size, and then subjected to washing, drying and screening procedures. The photoluminescence intensity (PL) and chromaticity (CIE coordinates x and y) of the final product were tested using an Ocean Optics USB4000 spectrometer. The x-ray diffraction (XRD) pattern of the phosphors of samples 1 to 4 was measured using the K _? line of the Cu target.

The test results of the phosphors of Samples 1 to 4 are shown in Table 2B . Figure 1 shows the results of the emission spectra. Figure 2 shows the XRD pattern. It should be noted that the phosphor sample 33 was produced using the same method as the sample 2.

Samples 5 to 8

To obtain the design composition of the phosphor, the solid powder was weighed according to the mixture composition shown in Table 3A , using the same synthetic procedure as described in Samples 1 to 4. The test results are listed in Table 3B .

Figure 5 is an emission spectrum of the phosphors of Samples 5 to 8. The powder x-ray diffraction measurement of the phosphors of samples 5 to 8 using the K _? line of the Cu target is shown in Fig. 6 .

Samples 9 to 12

To obtain the design composition of the phosphor, the solid powder was weighed according to the mixture composition shown in Table 4A , using the same synthetic procedure as described in Samples 1 to 4. The test results are shown in Table 4B .

Figure 7 is an emission spectrum of the phosphors of Samples 9 to 12. Powder x-ray diffraction measurements using Cu _K α line of the target of the phosphor samples of 9-12 for the 8 shown in FIG.

Samples 13 to 16

To obtain the design composition of the phosphor, the solid powder was weighed according to the mixture composition shown in Table 5A , using the same synthetic procedure as described in Samples 1 to 4. The test results are shown in Table 5B .

Figure 9 is an emission spectrum of the phosphors of Samples 13 to 16. Powder x-ray diffraction measurements using Cu _K α line of the target of the phosphor sample of 13 to 16 for the display 10 in FIG.

Samples 17 to 21

To obtain the desired composition of this group of phosphors, the solid powders were weighed according to the mixture composition shown in Table 6A , using the same synthetic procedure as described in Samples 1 through 4. The test results are shown in Table 6B .

Figure 11 is an emission spectrum of the phosphors of Samples 17 to 21. Powder x-ray diffraction measurements using Cu _K α line of the target of the phosphor sample of 17 to 21 for the display 12 in FIG.

Samples 22 to 27

To obtain the desired composition of the phosphors of samples 22 through 27, the solid powder was weighed according to the composition listed in Table 7A. The same synthetic procedure as used in samples 1 to 4 was used. The test results are shown in Table 7B.

Figure 13 is an emission spectrum of the phosphors of Samples 22 to 27. The X-ray diffraction measurement was obtained using the K _? line of the Cu target, and the XRD patterns of the samples 22 to 27 are shown in Fig. 14 .

Sample 28 to 32

To obtain the desired composition of the phosphors of samples 28 through 32, the solid powder was weighed according to the composition listed in Table 8A . The same synthetic procedure as used in samples 1 to 4 was used. The test results are shown in Table 8B. It should be noted that the intensity measurements in Table 8B are performed using equipment different from those used for the strength measurements of the samples listed in the other tables; the absolute strength measured using this different equipment is lower than the equipment used in the other samples.

Figure 20 is an emission spectrum of the phosphors of Samples 28 to 32. Using Cu _K α line of the target to obtain an X-ray diffraction measurement, and samples 28 to 32 of the XRD pattern shown in FIG. 21.

Those skilled in the art will appreciate that the compositions described above may be made using a number of different choices of elements using the methods set forth above. For example, a composition represented by the chemical formula M _(x/v) M ' ₂ A _5-y D _y N _8-z E _p :RE can be prepared, wherein: M is at least one unit price, divalent or trivalent having a valence v a metal such as Li, Na, K, Sc, Ca, Mg, Sr, Ba, and Y; M ' is at least one of Mg, Ca, Sr, Ba, and Zn; and A is at least one of Si, C, and Ge D is at least one of B, Al, and Ga; E is at least one of a pentavalent, hexavalent or heptavalent nonmetal having a valence w, such as O, N, F, Cl, Br, and I; At least one of Eu, Ce, Tb, Pr, and Mn; wherein x = y - 3z + p (8 - w), and wherein the phosphor has a general crystal structure of M ' ₂ A ₅ N ₈ : RE.

Figure 22 illustrates a lighting device in accordance with some embodiments. Device 10 can include a blue (450 nm to 470 nm) GaN (gallium nitride) LED wafer 12 housed in, for example, a package. Packages that may include, for example, low temperature co-fired ceramic (LTCC) or high temperature polymers include upper and lower body components 16 , 18 . Upper body member 16 defines a generally circular recess 20 that is configured to receive LED wafer 12 . The package further includes electrical connectors 22 and 24 that also define respective electrode contact pads 26 and 28 on the bottom plate of recess 20 . The LED wafer 12 can be mounted to the thermal pad on the bottom plate of the recess 20 using an adhesive or solder. The electrode pads of the LED wafer are electrically connected to the respective electrode contact pads 26 and 28 on the package substrate using bond wires 30 and 32 , and the recess 20 is completely filled with a transparent polymer material 34 (typically polyoxymethylene), which The transparent polymeric material 34 is loaded with a mixture of yellow and/or green phosphors and the red phosphor material of the present invention such that the exposed surface of the LED wafer 12 is covered by the phosphor/polymer material mixture. To enhance the emission brightness of the device, the walls of the recess are inclined and have a light reflecting surface.

23A and 23B illustrate a solid state lighting device in accordance with some embodiments. Device 100 is configured to produce warm white light having a CCT (correlated color temperature) of about 3000 K and a luminous flux of about 1000 lumens, and can be used as part of a downlight or other lighting fixture. The device 100 includes a hollow cylindrical body 102 that is comprised of a disc shaped base 104 , a hollow cylindrical wall portion 106, and a detachable annular top portion 108 . To aid in heat dissipation, the substrate 104 is preferably fabricated from aluminum, aluminum alloy, or any material having a high thermal conductivity. The substrate 104 can be attached to the wall portion 106 by screws or bolts or by other fasteners or by means of an adhesive.

Apparatus 100 further includes a plurality of (in the example illustrated as the 4) blue-emitting LED 112 (blue LED), such blue-emitting LED 112 is in communication with the circular mounting an MCPCB (metal core printed circuit board) 114 heat. The blue LED 112 can include 12 0.4 W GaN-based (gallium nitride-based) ceramic package arrays of blue LED chips that are configured in a rectangular array of 3 columns by 4 rows.

To maximize light emission, device 100 can further include light reflecting surfaces 116 and 118 that respectively cover the face of MCPCB 114 and the inner curved surface of top portion 108 . The apparatus 100 further includes a photoluminescence wavelength conversion component 120 comprising a mixture of yellow and/or green phosphors and a red phosphor material of the present invention operative to absorb a portion of the blue light produced by the LEDs 112 and to utilize the light The luminescence process converts it into light of different wavelengths. The emission product of device 100 includes the combined light produced by LED 112 and photoluminescent wavelength conversion component 120 . The wavelength conversion component is positioned away from the LED 112 and spatially separated from the LED. In this patent specification, "distant" and "distant" mean in a spaced or separate relationship. The wavelength conversion component 120 is configured to completely cover the housing opening such that all of the light emitted by the lamp passes through the assembly 120 . As shown, the wavelength conversion component 120 can be removably mounted to the top of the wall portion 106 using the top portion 108 to make it easier to change the emission color of the assembly and the lamp.

While the invention has been described with respect to the embodiments of the embodiments of the present invention, it will be understood that

Claims (28)

A red-emitting phosphor having a nitride-based composition, comprising: an element M, wherein M is at least one of Li, Na, K, Sc, Ca, Mg, Sr, Ba, and Y; ' , wherein M ' is at least one of Mg, Ca, Sr, Ba, and Zn; lanthanum; aluminum; nitrogen; and element RE, wherein RE is at least one of Eu, Ce, Tb, Pr, and Mn; The red-emitting phosphor has a general crystalline structure of M ' ₂ Si ₅ N ₈ :RE and M and Al are incorporated therein, and wherein the red-emitting phosphorescent system is configured such that it is at about 85 ° C and about 85% relative humidity After 1,000 hours of aging, the coordinate changes CIE Δx and CIE Δy of each chromaticity coordinate are less than or equal to about 0.03. A red light phosphor as claimed in claim 1, wherein M is Ca. A red light phosphor as claimed in claim 1 or claim 2, wherein M ' is Sr. The red-emitting phosphor of claim 1, wherein the red-emitting phosphor system is composed of Ca, Sr, Si, Al, N, and Eu. A red-emitting phosphor according to claim 1, wherein M is substantially located at a gap site within the general crystalline structure and Al replaces Si in the general crystalline structure. The red-emitting phosphor of claim 1, wherein the red-emitting phosphorescent system is configured such that, under excitation of the blue LED, the photoluminescence intensity is aged after aging at about 85 ° C and about 85% relative humidity for 1,000 hours. The attenuation is no more than about 30%. The red-emitting phosphor of claim 1, wherein the red-emitting phosphor absorbs radiation having a wavelength in the range of from about 200 nm to about 420 nm and emits light having a photoluminescence peak emission wavelength greater than 623 nm. The red-emitting phosphor of claim 1, wherein the red-emitting phosphor is Ca _0.1 Sr _2.0 Al _0.20 Si _4.80 N ₈ :Eu. The red-emitting phosphor of claim 1, wherein the red-emitting phosphor is Eu _0.05 Ca _0.1 Sr _1.95 Al _0.20 Si _4.80 N ₈ . A red-emitting phosphor comprising a nitride-based composition represented by the chemical formula M _(x/v) M ' ₂ Si _5-x Al _x N ₈ :RE, wherein: M is at least one having a valence v a monovalent, divalent or trivalent metal; M ' is at least one of Mg, Ca, Sr, Ba and Zn; and RE is at least one of Eu, Ce, Tb, Pr and Mn; wherein x satisfies 0.1 x<0.4, and wherein the red-emitting phosphor has a general crystal structure of M ' ₂ Si ₅ N ₈ :RE, Al replaces Si in the general crystal structure, and M is substantially located in the gap position in the general crystal structure Point. The red light phosphor of claim 10, wherein M is at least one of Li, Na, K, Sc, Ca, Mg, Sr, Ba, and Y. The red light phosphor of claim 10, wherein M is Ca, M ' is Sr and RE is Eu. The red light phosphor of claim 10, wherein the red light phosphorescent system is composed of Ca, Sr, Si, Al, N, and Eu. The red light phosphor of claim 10, wherein x satisfies 0.10 x<0.25. The red light phosphor of claim 10, wherein the red light phosphorescent system is configured such that upon excitation by the blue LED, the photoluminescence intensity is attenuated after aging at about 85 ° C and about 85% humidity for 1,000 hours. Not more than about 30%. The red light phosphor of claim 10, wherein the red light phosphorescent system is configured such that after aging at about 85 ° C and about 85% relative humidity for 1,000 hours, the coordinate deviation CIE Δx of each chromaticity coordinate is CIE Δy is less than or equal to about 0.03. The red-emitting phosphor of claim 10, wherein the red-emitting phosphor absorbs radiation having a wavelength in the range of from about 200 nm to about 420 nm and emits a photoluminescence peak emission Light with a wavelength greater than 623 nm. The phosphor of claim 10, wherein the red-emitting phosphorescent system is selected from the group consisting of Eu _0.05 Ca _0.075 Sr _1.95 Al _0.15 Si _4.85 N ₈ ; Eu _0.05 Ca _0.1 Sr _1.95 Al _0.20 Si _4.80 N ₈ ; Eu _0.05 Ca _0.125 Sr _1.95 Al _0.25 Si _4.75 N ₈ ; Eu _0.05 Ca _0.15 Sr _1.95 Al _0.30 Si _4.70 N ₈ ; and Eu _0.05 Ca _0.2 Sr _1.95 Al _0.40 Si _4.60 N ₈ . A white light illumination source comprising: an excitation source having an emission wavelength in the range of 200 nm to 480 nm; and a red-emitting phosphor according to claim 1, the red-emitting phosphorescent system configured to absorb excitation from the excitation source Radiating and emitting light having a peak emission wavelength ranging from about 620 nm to about 650 nm; and a yellow-emitting green phosphor. The white light illumination source of claim 19, wherein the red-emitting phosphor has the formula Eu:Ca _0.1 Sr _2.0 Al _0.20 Si _4.80 N ₈ . The white light illumination source of claim 19, wherein the yellow-emitting green phosphor has the formula Ce:Lu ₃ Al ₅ O ₁₂ . The white light illumination source of claim 19, wherein the excitation source has an emission wavelength in the range of 420 nm to 470 nm. The white light illumination source of claim 19, wherein the red-emitting phosphor system is configured to absorb excitation radiation from the excitation source and emit light having a peak emission wavelength in a range from about 628 nm to about 634 nm. A white light illumination source comprising: an excitation source having an emission wavelength in the range of 200 nm to 480 nm; and a red-emitting phosphor according to claim 12, the red-emitting phosphorescent system configured to suck The excitation radiation from the excitation source is received and emits light having a peak emission wavelength ranging from about 620 nm to about 650 nm; and a yellow-emitting green phosphor. The white light illumination source of claim 24, wherein the red-emitting phosphor system is configured to absorb excitation radiation from the excitation source and emit light having a peak emission wavelength in a range from about 628 nm to about 634 nm. A white light illumination source according to claim 24, wherein the red-emitting phosphor has the formula Eu:Ca _0.1 Sr _2.0 Al _0.20 Si _4.80 N ₈ . A white light illumination source according to claim 24, wherein the yellow-emitting green phosphor has the formula Ce:Lu ₃ Al ₅ O ₁₂ . The white light illumination source of claim 24, wherein the excitation source has an emission wavelength in the range of 420 nm to 470 nm.