CN1081016A - Composition and preparation technology of lead-based low-temperature sintered relaxor ferroelectric ceramics - Google Patents

Abstract

The invention relates to the composition and preparation process of a lead-based low-temperature sintered relaxor ferroelectric ceramic X7R capacitor porcelain material, which belongs to the field of ferroelectric ceramics and its manufacture. The ceramic material is a low-temperature sintered tungsten magnesium zirconate lead titanate relaxor ferroelectric ceramic modified by doping with ZnO, MnO ₂ , Nb ₂ O ₅ , AiO ₂ , Fe ₂ O ₃ , Al ₂ O ₃ , CeO ₂ and the like. The preparation process is to mix common chemical raw materials such as tungsten trioxide, trilead tetroxide, basic magnesium carbonate, titanium dioxide, zinc oxide, manganese oxide, niobium pentoxide, silicon dioxide, iron oxide, lead oxide, etc. After fine, pass through a 60-80 mesh sieve. Pre-fire at 700°-850°C, keep warm for 1-2 hours, grind and pass through 120 mesh or 200 sieve to obtain the desired porcelain material.

Description

Lead is that low-temperature sintering relaxation ferroelectric ceramic porcelain is formed and preparation technology

The present invention relates to a kind of lead is the composition and the preparation technology of low-temperature sintering relaxation ferroelectric ceramic X7R capacitor data, belongs to ferroelectric ceramic and manufacturing field thereof.

Multilayer (solely stone) capacitor (Multilayer Ceramic Capacitor is called for short MLC) has high specific volume, highly reliable, advantages such as frequency characteristic is good, along with electronic equipment and components and parts towards miniature, mix the needs that direction such as integrated develops, particularly the development of integrated circuit (IC) and surface installation technique (SMT) grows with each passing day to quantity and the quality requirement of MLC, X7R type MLC is a class bigger among the MLC, accounts for 40% of the total consumption of MLC.For a long time with BaTiO ₃Form for basic porcelain, its firing temperature is about 1300 ℃, must adopt precious metal palladium as interior electrode.Although people were doing some researchs aspect raising dielectric constant and the reduction sintering temperature in recent years, because system self will have certain difficulty further towards high-performance/price ratio development.

The lead that develops rapidly in recent years is that the composite perofskite type relaxation ferroelectric has high dielectric constant, and bias characteristic and the low good characteristic such as temperature that burns till preferably are considered to the main flow dielectric material of MLC of future generation.A series of Z5U of meeting have been developed at present, this type of of Y5V specification requirement formed the MLC of dielectric material, but to X7R type MLC because to holding very strictness of temperature variation requirement, the MLC of so-called X7R standard is promptly-55 ℃ →+125 ℃ scope, require electric capacity with variation of temperature rate △ C/C≤± 15%, temperature coefficient of capacitance is general bigger because relaxation ferroelectric has high dielectric constant in the Curie temperature scope, therefore development is a base-material with relaxation ferroelectric, meeting X7R and hold temperature variation requirement, is a brand-new problem in the world.Yukio Sakabe, Goro Nishioka etc. adopt Pb(Mg 1/2 W 1/2) O ₃-Pb(Ti ₁-xZr _x) O ₃The report of-ZnO system, the dielectric constant maximum can reach 5500 under suitably forming, but only meets the y5p standard, M.Yonezawa, M.Miyauchi etc. also adopt the PMW-PZT system to participate in an amount of Pb(Mn 1/3 Nb 2/3) O ₃The MLC of preparation low fever X7R, but adopted the raw material of high pure and ultra-fine, i.e. PbO, WO ₃Purity be more than 99.9%, MgO, TiO ₂, ZrO ₂Purity reach 99.5%, powder fineness≤0.2-0.45um.

The objective of the invention is research general chemical raw material, preparation lead-based relaxor ferroelectric ceramics and firing temperature thereof are 900 ℃-1000 ℃, percentage of capacitance variation with temperature meets the material composition and the technology of X7R standard in-55 ℃ → → 125 ℃ scopes, reduce sintering temperature, reduce cost, reduce noble metal dosage.Owing to adopt the raw material of general purity and fineness, therefore be more convenient for producing in batches and promoting, the selection aspect of additive is also characteristic in addition.

Content of the present invention is: a kind of with ZnO, and MnO ₂, Nb ₂O ₅, SiO ₂, Fe ₂O ₃, Al ₂O ₃, CeO ₂Deng the low-temperature sintering tungsten magnesium lead zirconate titanate relaxation ferroelectric ceramic (being called for short PMW-PZ-PT) of doping vario-property, its base-material consists of:

Pb（Mg _xW _yZr _zTi _w）O _s+a ₁mol% ZnO+a ₂mol%MnO ₂+a ₃mol%Nb ₂O ₅+a ₄mol% SiO ₂+a ₅mol% Fe ₂O ₃+a ₆mol%CeO ₂+a ₇mol% Li ₂CO ₃

0.20≤x≤0.30 0.20≤y≤0.30 wherein

0.02≤z≤0.20 0.20≤w≤0.46

x+y+z+w＝1

0≤a ₁≤10 0≤a ₂≤2

0≤a ₃≤2 0≤a ₄≤1.5

0≤a ₅≤3 0≤a ₆≤1

0≤a ₇≤2

This with Zn, Mn, Nb, the manufacturing process of the tungsten magnesium lead zirconate titanate X7R condenser ceramics of doping vario-properties such as Si is with general chemical primary industry (pure chemistry is pure or analyze pure) lead orthoplumbate (Pb ₃O ₄), tungstic acid (WO ₃), basic magnesium carbonate (Mg(OH) ₂4MgCO ₃6H ₂O), zirconium dioxide (ZnO ₂), titanium dioxide (TiO ₂), zinc oxide (ZnO), manganese oxide (MnO ₂), niobium pentoxide (Nb ₂O ₅), silicon dioxide (SiO ₂), iron oxide (Fe ₂O ₃), cerium oxide (CeO ₂), aluminium oxide (Al ₂O ₃) wait by above-mentioned chemical formula batching, mix, cross the 60-80 mesh sieve, give through 700 °～850 ℃ and burning and insulation 1-2 hour, pulverize levigate mistake 120 orders in back or 200 mesh sieves, can obtain needed raw material.

Become sheet closed cover in crucible in garden to burn through dry-pressing formed (pressure is approximately 100MPa) in this porcelain powder, firing temperature is 900 ℃-1000 ℃ insulations 2-4 hour, also can obtain good performance in 930 ℃-1000 ℃.Ceramics after burning till, its DIELECTRIC CONSTANT of test after being placed 48 hours by silver-colored silver ink firing electrode, dielectric loss value tan δ, and measure ε-T curve of-55 ℃～+ 125 ℃ with high-low temperature chamber and LRC electric bridge, can calculate △ C/C rate of change numerical value, the present invention has obtained expected results.

The present invention mainly by selecting suitable firing temperature, adopts suitable Zr/Ti ratio, and an amount of ZnO, other additives, the composition rational Match realizes that tungsten magnesium lead plumbate is being an antiferroelectric below 39 ℃, when room temperature the composite perofskite of tool quadrature distortion structure, PbZrO ₃Be that Curie temperature is 230 ℃ a antiferroelectric, it can will contain PbTiO ₃The Curie temperature of measuring lower PMW-PT component moves near the room temperature to satisfy the X7R requirement.

Be embodiments of the invention below

Pb（Mg _xW _yZr _zTi _w）O ₃+a ₁mol% ZnO+a ₂mol% MnO ₂+a ₃mol% Nb ₂O ₅+a ₄mol% SiO ₂+a ₅mol% Fe ₂O ₃+a ₆mol% CeO ₂+a ₇mol%Li ₂CO ₃

1 performance of filling a prescription

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Claims (3)

1. A lead-based low-temperature sintered relaxor ferroelectric ceramic porcelain material, characterized in that the porcelain material consists of: Pb(Mg _x W _y Zr _z Ti _w )O ₃ +a ₁ mol% ZnO+a ₂ mol% MnO ₂ +a ₃ mol%Nb ₂ O ₅ +a ₄ mol% SiO ₂ +a ₅ mol%Fe ₂ O ₃ +a ₆ mol%CeO ₂ +a ₇ mol% Li ₂ CO ₃ Where 0.20≤X≤0.30, 0.20≤y≤0.30 0.20≤z≤0.20, 0.20≤w≤0.46       x+y+z+w=1 0≤a ₁ ≤1.5, 0≤a ₂ ≤2, 0≤a ₃ ≤2 0≤a ₄ ≤1.5, 0≤a ₅ ≤3, 0≤a ₆ ≤1 _0≤a7≤2 . 2. A process for preparing the lead-based low-temperature sintered relaxor ferroelectric ceramic material as claimed in claim 1, characterized in that common chemical raw materials (industrial pure chemical pure analytical pure) trilead tetroxide (Pb ₃ O ₄ ), tungsten trioxide (WO ₃ ), basic magnesium carbonate (Mg(OH) ₂ 4MgCO ₃ 6H ₂ O), zirconium dioxide (ZrO ₂ ), titanium dioxide (TiO ₂ ), zinc oxide (ZnO), oxide Manganese (MnO ₂ , Niobium pentoxide (Nb ₂ O ₅ ), Silicon dioxide (SiO ₂ ), Iron oxide (Fe ₂ O ₃ ), Aluminum oxide (Al ₂ O ₃ ), Cerium oxide (CeO ₂ ), by rights The ingredients of the chemical formula described in Requirement 1 are mixed and ground through a 60-80 mesh sieve, pre-fired at 700°C to 850°C, kept for 1-2 hours, pulverized and ground, and passed through a 120-mesh or 200-mesh sieve to obtain porcelain material; This kind of porcelain material is dry-pressed (100MPa pressure) into discs, and fired in a high-temperature furnace with a closed cover at a firing temperature of 900°C-1000°C and heat preservation for 2-4 hours. 3. The preparation process according to claim 2, characterized in that the firing temperature is 930°C-1000°C.