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Interfacial Segregation in Perovskites: IV, Internal Boundary Layer Devices
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.tb06469.x
Subject(s) - grain boundary , materials science , resistive touchscreen , condensed matter physics , boundary layer , layer (electronics) , acceptor , chemical physics , depletion region , boundary (topology) , space charge , doping , composite material , electron , optoelectronics , chemistry , mechanics , electrical engineering , microstructure , mathematical analysis , physics , mathematics , quantum mechanics , engineering
A proposed model for interfacial segregation in perovskites, with induced heterogeneous defect distributions, is extended here to account for the formation of internal boundary layer devices, such as positive temperature coefficient of resistance (PTCR) thermistors and internal boundary layer capacitors (IBLC). Boundary layer effects in doped BaTiO 3 are attributed to factors which contribute to the formation of highly resistive boundary layers by a segregation‐induced shift in donor incorporation and/or acceptor segregation, and the inhibiting action of segregated donors on boundary mobility and grain growth. The distribution of space charges, formed by electron transfer from conductive grains to resistive boundary layers, leads to the formation of impedance barriers in the grain‐boundary vicinity. Depending on the grain size, and on relative size and spatial distribution of the space charge layer and the resistive layer, a transition from semiconducting properties to insulating properties may take place. This model accounts for the observed PTCR and IBLC phenomena.