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Microstructure and Electrical Properties of Sodium‐Diffused and Potassium‐Diffused SrTiO 3 Barrier‐Layer Capacitors Exhibiting Varistor Behavior
Author(s) -
Fujimoto Masayuki,
Chiang YetMing,
Roshko Alexana,
Kingery W. David
Publication year - 1985
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.1151-2916.1985.tb16150.x
Subject(s) - materials science , grain boundary , microstructure , varistor , transmission electron microscopy , strontium titanate , capacitor , barrier layer , scanning electron microscope , composite material , layer (electronics) , mineralogy , optoelectronics , nanotechnology , chemistry , voltage , dielectric , electrical engineering , engineering
In sodium‐diffused strontium titanate internal‐boundary‐layer capacitors exhibiting good varistor properties, high‐resolution transmission electron microscopy and scanning transmission electron microscopy revealed sodium segregation at grain boundaries in the absence of intergranular phases. The segregation layer is narrow (≅10 nm), unlike much broader diffused boundary layers which have also been observed. The nonohmic behavior in these and in potassium‐diffused specimens suggests that segregated acceptor alkali ions act as grain‐boundary electron traps leading to varistor electrical barriers.