摘要
在MgCr_2O_4-TiO_2系湿敏陶瓷的基体中掺入V_2O_3杂质,改进了系统的电性能。通过大量实验,确定最佳工艺条件:1200℃还原气氛中烧结1h,采用RuO_2电极浆料,在70Hz、1V的交流电下测试湿度电阻特性;确定最佳组成为MgO:Cr_2O_3:TiO_2:V_2O_3=80:80:20:2(摩尔比)。研制的MgCr_2O_4-TiO_2系湿敏陶瓷具有阻值范围适中(10~3～10~7Ω)、响应快(小于10s)、滞后效应小(<±1%)和灵敏度高等优点。用SEM、XRD、EPMA等手段分析了典型的MgCr_2O_4-TiO_2湿敏陶瓷的显微结构、晶相和成分分布。用XPS、EPR和IR论证了该材料的导电机理。用NMR和IR初步探讨了半导体湿敏陶瓷的湿敏机理。
The electrical property of the system was improved by introducing V_2O_5 as additive to the matrix of the MgCr_2O_4-TiO_2 humidity-sensitive ceramics. Through a great deal of experiments, the optimum technological conditions were confirmed as: the sample is sintered one hour in reducing atmosphere at 1 200℃; the electrode is coated by RuO_2 paste; the humidity-sensitive characteristics of the specimens are measured at 1 V and 70Hz alternating current. The optimum composition was recognized as MgO: Cr_2O_3: TiO_2: V_2O_5 = 80: 80: 20: 2(mole ratio). The studied MgCr_2O_4-TiO_2 humidity-sensitive ceramics have the advantages of suitable resistance range(10~3-10~7 Ω), fast response(less than 10 s), small hysteresis loop(less than 1%) and high sensitivity.The microstructure, crystalline phases and distribution of chemical composition of the typical MgCr_2O_4-TiO_2 humidity-sensitive ceramics were analyzed by SEM, XRD and EPMA methods. The mechanism of the electrical conduction of this material was investigated by XPS, EPR and IR methods. By NMR and IR, the sensing mechanism of the semiconductive humidity-sensitive ceramics was preliminarily studied.
关键词
掺杂
湿敏电阻器
半导体陶瓷
doped ceramic
chrome spinel
titanium dioxide
humidity-dependent resistors
semiconductive ceramics
