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A Bimodal Grain Size Model for Predicting the Dielectric Constant of Calcium Copper Titanate Ceramics
Author(s) -
Pan MingJen,
Bender Barry A.
Publication year - 2005
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.1551-2916.2005.00455.x
Subject(s) - dielectric , materials science , ceramic , grain size , copper , barrier layer , composite material , calcium titanate , logarithm , high κ dielectric , mineralogy , condensed matter physics , layer (electronics) , metallurgy , optoelectronics , mathematics , mathematical analysis , chemistry , physics
The bimodal distribution of grain size is frequently observed in calcium copper titanate (CaCu 3 Ti 4 O 12 or CCTO) ceramics that exhibit high dielectric constant. In this study, we propose an analytical model composed of grains of two different sizes to estimate the dielectric behavior of CCTO based on microstructural features. Important assumptions are (1) CCTO is a barrier layer dielectric and (2) the insulating layer thickness is the same in both large and small grains. Explicit expressions for the effective dielectric constant of serial, parallel, and logarithmic mixture models are given. When compared with experimental results, the present bimodal model appears to be acceptable for describing the dielectric behavior of CCTO.