Influence of Dopants on Electrical Properties of ZnO-V2O5 Varistors Deduced from AC Impedance and Variable-Temperature Dielectric Spectroscopy

• Published in: Journal of electronic materials Vol. 41; no. 7; pp. 1970 - 1977
• Main Authors: Wu, Jun, Li, Taotao, Qi, Ting, Qin, Qingwei, Li, Guangqiang, Zhu, Bailin, Wu, Run, Xie, Changsheng
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.07.2012; Springer
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Materials; Materials Science; Optical and Electronic Materials; Solid State Physics; Varistors; ZnO-V; Schottky barrier height; grain boundary; characteristic dielectric relaxation; O; Lead oxide; Electrical conductivity; Boron oxide; Diode; Property composition relationship; Doping; Crystal defect; Dielectric ceramics; Grain boundary; Energy relaxation; Vanadium oxide; Zinc oxide; Current density; Activation energy; Boundary layer; Alternating current; Electrical properties; Vacancy; Dielectric properties; Varistance; Manganese oxides; Leakage current; Barrier height; Non linear effect; Schottky barrier
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-012-1935-7

The influence of MnO 2 , PbO, and a mixture of MnO 2 , PbO, and B 2 O 3 on the electrical and dielectric properties of ZnO-V 2 O 5 ceramics was studied by alternating-current (AC) impedance and variable-temperature dielectric spectroscopy. The results show that, compared with the resistivity of the intervening layer at the grain boundary, the Schottky barrier present at the grain boundary is much more important for varistor performance, which can be significantly improved by using a mixture of MnO 2 , PbO, and B 2 O 3 . Consequently, better varistor performance is achieved for 94.5 mol.% ZnO + 0.5 mol.% V 2 O 5  + 1.0 mol.% MnO 2  + 2.0 mol.% PbO + 2.0 mol.% B 2 O 3 (ZVMPB), i.e., nonlinear coefficient α  = 35.3 and leakage current density I l  = 2.72  μ A/cm 2 . The activation energy for the characteristic dielectric relaxation process is in the range of 0.339 eV to 0.365 eV, indicating that it is only associated with oxygen vacancy V O · .