DE1771974C - Ferrite material - Google Patents

Description

calls. .

Another object of the present invention is the development a ferrite material that works at frequencies

_{can be operated from} 100 to 400 MHz when applying two different fields to the material, namely a high-frequency field with alternating

The invention relates to ferrite material on the amplitude and constant field Based on iron oxide and nickel oxide with a The ferrite is said to have a magnetic permeability of

Addition of cobalt oxide. Such materials are, / = 3 to 7G / Oe and losses of μ <0.3 be! that are used in broadcast technology and have a frequency of 200 MHz, in particular in a frequency range from 100 to. The object of the invention is furthermore the expansion

400 MHz operated. a »of the working frequency range for remote nickel,

There are low-loss ferromagnetic substances from the loss of both weak and metal oxides for high-frequency purposes known, which in strong high-frequency fields without significant from a mixture of iron oxide with a lowering of the magnetic permeability , as well as one or more metal oxides or metal salts possible cyclic magnetic reversal through standing. Iron oxide is magnetic iron ore, the constant field without significant change of the approximately formula FeO-Fe "O, ₍ i.e. Fe ₃ O., corresponds to the size of the loss and the magnetic permeability. Nickel oxide is used as additional metal oxides Remote data

Contains traces of cobalt, specifically in on the basis of iron oxide and nickel oxide with a weight ratio ν η 1: 6 to 1:12, or an addition of cobalt oxide according to the specification of chromium oxide in a weight ratio of 1:10 40 characterized in that it consists of iron oxide JS bis until 1:30. If for these known ferromagnetic 48 mol percent, nickel oxide 50 to 62 mol percent, table substances statements about the electromagnetic cobalt oxide 0.7 to 2 mol percent and lead oxide 0.5 to Properties are included, these apply to a 3 mole percent.

Material that contains not only nickel oxide but also chromium oxide. Preferred compositions are 46 molar pro-

holds. In this context, it is also stated that 45 _{percent Fe 2} O ₃ , 51 mol percent NiO, 1 mol percent CoO that lead oxide increases the losses and _{that ferrites are unfavorable for these and 2 mol percent PbO and 38 mol percent J ^ e 2} O _{3 are} known to be unfavorable. However, since ferrite is 58.75 mol percent NiO, 1.25 mol percent CoO and materials, the proportions of grains are 2 mol percent PbO. ....

The most important characteristic of the

especially with regard to the effect of the invention is that the expansion of the ArbeitsfreZusätze plays, is the statement about lead oxide itself in the frequency range and the reduction in losses in only for these known ferromagnetic substances to weak and strong high-frequency fields wenen (see German patent specification 756 383). the introduction of a cobalt additive in a quantity

From a compositional standpoint, from 0.7 to 2 mole percent achieved in the nickel ferrite represents a 55 ferrite material according to the present invention. However, the magnetic permeability is basically a different material, in which lead oxide did significantly to μ = 2 to 3 G / Oe. In a complex with the oxide of cobalt - The introduction of an additional addition of

is performed, whereby the effect of this compound lead oxide in an amount of 0.5 to 4 mol percent, Adjusting yourself to the action of lead oxide, which acts as a flux, increases the magnetic permeability the well-known ferromagnetic substance under- 60 meability, offsets the effect of cobalt without part. to increase the loss level. The deviation from

Furthermore, nickel ferrites with a stoichiometric composition of stoichiometric iron oxide content, ie a composition are known which contain 50 · / »Fe ₈ O and 50 · /» NiO iron oxide content of 38 to 48 mol percent and have a cubic structure. The 50 mole percent, guaranteed the ability of the mentioned materials can be operated at frequencies of up to 65 material, the initial losses at cyclical Um-20 MHi, show a magnetization by constant field, the final permeability of μ '= 10 to 12 G / Oe and rites that contain 50 mol percent iron oxide and cobalt with a loss of u " = 6 on the addition of oxide are missing.

It can be used in the manufacture of the ferrite material Instead of lead oxide and cobalt oxide, various compounds are used which are heated up decompose to form lead or cobalt oxide.

Products made of nickel ferrite with additions of lead and cobalt oxide are manufactured using conventional ceramic technology. The substances mentioned are mixed in the required mugs by dry mixing in vibratory mills. The mixture obtained is burned at 900 ° C., then ground again in vibratory mills. The comminuted product is pressed using a 10% aqueous solution of polyvinyl alcohol as a binder at a specific pressure of 2000 kp / cm ² . After drying, the product is fired at a temperature of 900 to 980 ° C.

The invention is illustrated by working examples and measurement data explained in more detail.

example 1

Iron, nickel, cobalt and lead oxides, taken in a ratio that corresponds to the following composition in mol percent: 46 Fe ₂ O ₃ , 51 NiO, 1 CoO, 2 PbO, are mixed in a _{5 of} a vibrating mill during 1 Hour and burns in air at 900 ° C. for 4 hours. After cooling, the product obtained is treated again in the vibrating mill for 1 hour.

After the introduction of the binder, samples are pressed from the powder obtained, which have a ring shape have, after which they are burned in the air at a temperature of 960 ° C.

The measurement results of μ and μ ″ are given in the table

Example 2

The mixture given in Example 1 is treated similarly to Example 1 with one exception, that the temperature of the repeated firing is 900 ° C.

The measurement results μ ' and μ "are given in the table.

Example 3

ao A mixture which corresponds to the following composition in mol percent: 38 Fe., O ₃ , 58.75 NiO, 2PbO, 1.25 CoO, is treated similarly as described in Example 1, with the exception that the temperature of the repeated firing is 950 ° C.

The measurement results μ ' and μ " are given in the table.

example

for execution of the material

F-equenz200MHz

at H = 0.2 Oe

μ ' Ι μ " (G / Oe)

Frequency 3 ~ 0 MHz

at
H <0.2 Oe

μ ' I. · <■ " (G / Oe)

Frequency 400 MHz

at
H <0.2 Oe

/ «'I f"

(G / Oe)

number 1

No. 2

No. 3

Ferroxplan

7.0
3.0
6.0
8.5

0.03
0.03
0.03
0.17

0.035
0.03

7.0
3.0
5.9

0.03
0.03
0.03

7.0
3.0
6.0
9.2

0.5
0.03
0.03
0.73 *)

*) Information for the frequency 500 MHz.

On the Ferroxplan samples with a high-frequency field strength ff = 5 Oe, significantly increasing Losses no measurements are made.

Claims (3)

At higher frequencies the use of η. ♦ ■ · u Nickel ferrite as a result of rapidly increasing losses μ Patent claims: SffiSr magnetic permeability / difficult. 1. Ferritxuaterial based on iron- Die Nlckdfcnite nut totaftoA ^ J ^ genn, oxide and nickel oxide with an addition of cores losses μ "<. OA" but also «™ S ^ * Baltic oxide, characterized in that magnetic penr.eabil.tat /, -1.5 hsJW i, it consists of iron oxide 30 to 48 mole percent, nickel- whereby their ^ V " ^end ^^ Z Fe ^ nSc VeJ ' oxide 50 to 62 mole percent, cobalt oxide 0.7 to Beyond M ^!? * ^^ ™ ^ ** ^: 2 mole percent and lead oxide 0.5 to 3 mole percent losses in the Ummagnet.serung through em constant consists. ι »Magnetic field strong. stands g 2. Ferrite material according to claim 1, marked- Therefore ^^^ iSÄiSnTr characterized by 46 mole percent Fe ^ O ₃ . 51MoIzes from 100 to ⁴⁰ »^^. ^" ^ L ^ WeSe percent NiO, 1 mol percent CoO, 2 mol percent structure of the type. Ferroxplan «recommended. Less PhO» f ff favorable with »Ferroxplan«, however, higher losses are 3. 'ferrite material according to claim 1, marked 15 W first level of ^ toja ^ rfeWrtto and characterized by 38 mol percent Fe ₂ O ,, 58.75 mol a complicated production process, the .ohe percent NiO, 1.25 mol percent CoO, 2 Molpro firing temperatures, use of Oxygen CentPbO. atmosphere, multiple grinding and burning