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Microcrystalline BaTiO 3 by Crystallization from Glass
Author(s) -
HERCZOG ANDREW
Publication year - 1964
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.1151-2916.1964.tb14366.x
Subject(s) - materials science , dielectric , crystallization , grain size , mineralogy , microcrystalline , composite material , barium titanate , lead titanate , phase (matter) , ferroelectricity , crystallography , thermodynamics , geology , chemistry , optoelectronics , organic chemistry , physics
The properties and composition of glasses suitable for crystallization of BaTiO 3 are described. The crystallization of certain glasses results in a nearly complete recovery of BaTiO 3 , besides the feldspar BaAl 2 SiO 3 as a minor phase. The mechanism of crystallization was investigated by thermal analysis, viscosity, and grainsize measurements as a function of the temperature whereas density data were used for evaluation of the BaTiO 3 content. Within the range 30 to 60% by volume of BaTiO 3 at about 1μ grain size, the measured dielectric constant increased from 100 to 1200. The calculated partial dielectric constant of the Titanate phase at this grain size was about 3500. As the grain size approached 0.1μ, the dielectric constant decreased and became nearly independent of the temperature because of the predominance of surface states. Other effects were attributed to special structural characteristics, such as absence of porosity and clamping of the titanate particles within the microcrystalline matrix. Data are also presented on dielectric constant and loss tangent at different frequencies, dc breakdown strength, dc resistivity, and ferroelectric properties as a function of the grain size of the crystallized material.