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Interfacial Segregation in Perovskites: III, Microstructure and Electrical Properties
Author(s) -
Desu Seshu B.,
Payne David A.
Publication year - 1990
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.1151-2916.1990.tb06468.x
Subject(s) - dopant , materials science , grain boundary , doping , microstructure , crystallite , chemical physics , ceramic , grain growth , mineralogy , chemical engineering , condensed matter physics , composite material , metallurgy , chemistry , optoelectronics , physics , engineering
A model is proposed to relate segregation of dopants with the development of fine ceramic microstructures and electrical properties in polycrystalline donor‐doped BaTiO 3 . As the average dopant concentration is increased, the dopant concentration at the grain boundary increases compared with the bulk. This has two important effects: (1) dopant incorporation at the grain boundary shifts from electronic to vacancy compensation and the formation of high‐resistive layers, and (2) grain‐boundary mobility is impeded and grain growth retarded with increased dopant additions. Thus, for high dopant concentrations, donor‐doped BaTiO 3 becomes insulating. The model discusses in detail the nonequilibrium heterogeneous defect chemistry as a function of thermal‐processing and accounts for barrier layer phenomena.