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Doped BKT-BT series lead-free PTCR ceramic material and preparation method thereof

A technology of BKT-BT and ceramic materials, which is applied in the direction of instruments, measuring heat, measuring devices, etc., can solve the problems of poor comprehensive performance, unseen, lost application value, etc.

Inactive Publication Date: 2013-01-02
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the ρ in the leaded BT-PT system RT Generally higher, in order to reduce ρ RT , reported that ceramics are mixed with graphite or metal powder to make composite materials, although it can make ρ RT It drops to about 10Ω.cm, but the resistance jump is only dozens of times, and it loses its application value
Composition ρ of BT-BNT system RT Can be as low as 20Ωcm, but its comprehensive performance is not good
At present, the α of BT-PT series is less than 35% / ℃, while that of BT-BNT is even smaller, and there is no report of >25% / ℃

Method used

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  • Doped BKT-BT series lead-free PTCR ceramic material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] take x 1 =0.03,x 2 =0.5%, A is La, y=0.2%, M is Ta, z=0. Then the molecular formula of the ceramic material is (Bi 0.5 K 0.5 ) 0.03 (Ba 0.965 La 0.005 ) Ti 0.998 Ta 0.002 o 3 , which uses CP or AR grade chemical reagent Bi with extremely low PbO impurity content 2 o 3 、K 2 CO 3 、BaCO 3 , La 2 o 3 、TiO 2 and Ta 2 o 5 As the raw material, after fully drying, weigh according to the stoichiometry of the above formula.

[0023] Use absolute ethanol as the medium, and mix by ball milling for 3 hours. Dry, sieve, put the powder in a corundum crucible, and synthesize at 900°C / 1 hour and 950°C / 2 hours. Then pulverize and sieve, ball mill for 4 hours, dry, add binder, dry press molding, after 800°C / 2 hours of plastic ejection, heat at 1260-1310°C for 2-4 hours and burn. Grinding, ultrasonic cleaning, and ohmic electrodes, that is, doped lead-free PTCR ceramic components. Its main properties are: Tc: 175°C, resistance jump: 2.5×10 3 , α is 32% / °C, ρ RT 6.3×...

Embodiment 2

[0026] take x 1 =0.20,x 2 =0.3%, A is Y and Bi, wherein the mass percentage of Y and Bi is 1:1, y=0.1%, M is Sb, Z=0.5, D is MnO 2 . Raw material is except identical with embodiment 1, adds AR grade CeO in addition 2 , Y 2 o 3 , CP grade Sb 2 o 3 and MnO 2 . The process is the same as in Example 1, the synthesis temperature is 800°C / 1 hour, and 850°C / 2 hours; the firing conditions are 1200-1250°C, heat preservation for 1-3 hours. The properties of the obtained ceramics are: Tc is 182°C, resistance jump: 8.5×10 3 , α: 16% / °C, ρ RT : 1.2×10 2 Ω·Cm.

Embodiment 3

[0028] take x 1 =0.35,x 2 =0.6%, A is La, Ce mass ratio is 1:1, y=0.1%, M is Sb, Z=0.5%, D is MnO 2 . Raw material is except identical with embodiment 1, adds AR grade CeO in addition 2 , Y 2 o 3 , CP grade Sb 2 o 3 and MnO 2 . The process is the same as in Example 1, but the synthesis temperature is changed to 800°C / 1 hour and 850°C / 2 hours; the firing conditions are changed to 1200-1250°C and kept for 1-3 hours in a nitrogen flow with low oxygen concentration. become. The properties of the obtained ceramics are: Tc is 205°C, resistance jump: 4.0×10 2 , α: 12% / °C, ρ RT : 8.0×10 2 Ω·Cm.

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Abstract

The invention relates to a doped BKT-BT series lead-free positive temperature coefficient resistance ceramic material and a prepration method thereof, the general formula of the composition of the material is (Bi0.5K0.5)*1(Ba1-*1-*2)AX2)Ti1-yMyO3+Zmol%D, wherein, x1 is more than 0 and not more than 0.7, x2 is more than 0 and not more than 0.6%, y is more than 0 and less than 0.2%, Z is not less than 0 and less than 1, A is one or more of Ce, Y, La and Bi, M is one or more of Nb, Sb, Ta and Mo, and D is one or more of MnO2, TiO2, SiO2 and B2O3. For a series of the lead-free ceramic materials, TC, alpha, betaRT and resistance sudden jump Rmax / Rmin are respectively changed between 140 and 250 DEG C, between 10 and 45% / DEG C, between 20 and 60 omega.Cm and between 10<2> and 10<5> along with the change of x1, x2, y and Z.

Description

technical field [0001] The present invention relates to a range of high Curie temperature (T C ), high temperature coefficient of resistance (α), and low room temperature resistivity (ρ RT ) doped Bi 0.5 K 0.5 TiO 3 -BaTiO 3 (BkT-BT) is a lead-free positive temperature coefficient resistance (PTCR) ceramic material and its preparation method, which belongs to ABO 3 The field of perovskite-type lead-free ferroelectric semiconductor materials. Background technique [0002] Most of the PTCR ceramic materials widely used so far are BaTiO 3 based ferroelectric semiconductors. BaTiO 3 The Curie temperature is 120°C, so to obtain a PTCR ceramic material with a high working temperature with a Tc higher than 120°C, BaTiO is usually used. 3 -PbTiO 3 (BT-PT) is a solid solution, people often use PbO or Pb 3 o 4 As raw material to prepare high Tc PTCR ceramics. During the process, the flying of lead oxide dust, the volatilization of lead oxide during firing, and the waste o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/462C04B35/622G01K7/16
Inventor 李国荣郑嘹赢冷森林王天宝曾江涛殷庆瑞
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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