Effect of Bi_2O_3 addition on the microstructure and electrical properties of the SnO_2·CoO·Nb_2O_5 varistor system

摘要

Tin dioxide (SnO2) is an n type semiconductor with crystalline structure of rutile type and has low densification rate due to its high surface diffusion at low temperatures and high S11O2 partial pressure at high temperatures [1]. Dense SnO2 based ceramics can be achieved by introducing dopants [2-5] or by hot isostatic pressure processing [6, 7]. Dopants with valence +2 can promote densification of SnO2 ceramics due to the formation of solid solution with the creation of oxygen vacancies.