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Relationship between grain boundaries and electrical degradation of ZnO varistors
Author(s) -
Takada Masayuki,
Yoshino Hiroyuki,
Yoshikado Shinzo
Publication year - 2007
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.20493
Subject(s) - varistor , materials science , microstructure , scanning electron microscope , schottky diode , energy dispersive x ray spectroscopy , diffraction , dispersion (optics) , schottky barrier , degradation (telecommunications) , crystallography , composite material , optoelectronics , optics , electrical engineering , voltage , chemistry , physics , diode , engineering
The effects of the electrical degradation characteristics and microstructure of Sb 2 O 3 ‐added ZnO varistors were investigated by field emission scanning electron microscopy (FE‐SEM), energy dispersion X‐ray spectroscopy (EDX), optical microscopy, X‐ray diffraction (XRD), and voltage– current ( V − I ) characteristic measurement. The nonlinearity index α of the V − I characteristic for Bi‐Mn‐Co‐Sb 2 O 3 ‐added ZnO varistors decreased with increasing amount of Sb 2 O 3 after electrical degradation. Twin crystals of ZnO were formed by the addition of Sb 2 O 3 . The number of twin crystals with two c ‐axes perpendicular to the twin plane increased and the number of twin crystals with two c ‐axes parallel to the twin plane decreased with increasing addition of Sb 2 O 3 . It is suggested that electrical degradation is affected by a combination of orientations of ZnO grains containing twin planes and that a double Schottky barrier may not be formed in the twin plane. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 1– 9, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20493