ZnO压敏陶瓷的导纳谱研究

A STUDY ON ADMITTANCE SPECTROSCOPY OF ZnO VARISTOR CERAMICS

该文用导纳谱方法探讨ZnO压敏陶瓷中电子陷阶的种类和起因，研究某些微量添加剂对它们的影响．结果表明，本征缺陷二次电离填隙锌Zni2+能否探测到不但与其相对浓度大小有关，还与测量温度有关；某些添加剂例如Ba对Zni2+缺陷的形成有抑制作用．除常见的对应于本征缺陷一次电离氧空位Vo+及Zni2+的电导峰1及2以外，在低温（-170℃左右）也出现电导峰3，其对应的陷阱能级Et=0．163eV，陷阱俘获截面σn=7．71×10-12cm2，弛豫时间τ=1．11×10-6μs，该电导峰可能来源于晶界与杂质的相互作用所致的非本征缺陷．

Kinds and causes of deep electron traps in the depletion region of ZnO varistors and effects of some additives on the traps have been studied by using admittance spectroscopy method. The results show that some additives such as Ba have a restraint effect on the formation of intrinsic defect Zni2+. The detection of Zni2+ depends not only on the defect density, but also on the measurement temperature. Besides the normal conductance peaks 1 and 2, that are considered to associate with the intrinsic defects Vo+ and Zni2+, peak 3 has been observed at lowwtemperature (about - 170℃) and the corresponding trapping level is Et=0. 163eV, the capture cross section is σn = 7.71×10-12cm2and the room temperature (300K) thermal emission time constant is τ= 1. 11 × 10-6μs.The conductance peak might be caused by extrinsic defects resulting from the interaction between grain boundary and the additives.