Phase development in ZnO varistors
Phase development in ZnO varistors
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DOI：
10.1179/1743676114y.0000000179
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发表时间：
2015-01-01
影响因子：
2.2
通讯作者：
Freer, R.
中科院分区：
文献类型：
--
作者：
Fan, J.;Poosimma, P.;Freer, R.
基于典型的氧化锌压敏电阻组分(97.0mol.-%氧化锌，1.0mol.-%Bi2O3，1.0mol.-%Sb_2O_3，0.5mol.-%MnO和0.5mol.-%Co3O4)，利用900℃以下的原位高温X射线衍射仪和900℃~1250℃烧结样品的常规环境X射线衍射仪研究了氧化锌压敏电阻在烧结过程中的相变化。在700℃和1250℃热处理的样品中可以检测到焦绿石相；尖晶石相存在于和-gt；900℃，而压敏电阻的主相是在950℃形成的，在这个温度下，形成了基本的微结构特征，并且压敏材料表现出非线性电学性能，其非线性系数α为35，击穿电场为8000 V cm(-1)。随着烧结温度的升高，α值和击穿电场均减小。
Based on a typical ZnO varistor composition (97.0 mol.-% ZnO, 1.0 mol.-% Bi2O3, 1.0 mol.-% Sb2O3, 0.5 mol.-% MnO and 0? 5 mol.-% Co3O4), phase development of the ZnO varistor during sintering has been investigated using in situ high temperature X-ray diffraction up to 900 degrees C, and conventional ambient X-ray diffraction for samples sintered at 900 degrees C to 1250 degrees C. The results indicate that alpha-Bi2O3 can be detected until 700 degrees C; the pyrochlore phase can be detected in the samples heat treated at 700 degrees C and up to 1250 degrees C; the spinel phase is present at and >900 degrees C. However, the main phases in the varistor are established by 950 degrees C. By this temperature, the essential microstructure features are formed, and the varistors exhibit non-linear electrical properties, with a non-linear coefficient alpha of 35 and breakdown field of 8000 V cm(-1). With increasing sintering temperature, both the alpha value and breakdown field decrease.