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Microstructure and Nonlinear Properties of Microwave‐Sintered ZnO‐V 2 O 5 Varistors: II, Effect of Mn 3 O 4 Doping
Author(s) -
Kuo ChengTzu,
Chen ChangShun,
Lin INan
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02718.x
Subject(s) - microstructure , materials science , varistor , doping , grain boundary , scanning electron microscope , analytical chemistry (journal) , schottky barrier , ceramic , microwave , schottky diode , current density , mineralogy , composite material , voltage , chemistry , optoelectronics , chromatography , quantum mechanics , diode , physics
The microstructure and nonlinear current‐voltage characteristics of Mn 3 O 4 ‐doped ZnO‐V 2 O 5 ceramics, microwave‐sintered at 800°‐1200°C for 10 min, have been investigated. A high density (96% of the theoretical density) has been achieved. The incorporation of Mn 3 O 4 additives does not significantly alter the densification behavior of the ZnO‐V 2 O 5 materials, but rather pronouncedly increases the nonlinear coefficient (α= 23.5) and markedly suppresses their leakage current density ( J L = 2.4 10 ‐6 A/cm 2 ). On the other hand, the intrinsic properties of the materials, including the Schottky barrier height (Phi b ) and the donor density ( N d ), are only moderately modified; that is, Phi b = 1.16 eV and N d = 5.4 10 17 /cm 3 . X‐ray diffractometry analyses and energy‐dispersive X‐ray microanalyses (via scanning electron microscopy) indicate that the V 2 O 5 species facilitate the densification and the development of microstructure via the formation of a liquid phase (Zn 3 (VO 4 ) 2 ) along the grain boundaries, whereas the Mn 3 O 4 species markedly enhance the nonohmic behavior of the ZnO‐V 2 O 5 materials by forming the surface states along the grain boundaries.