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Microstructure and Electrical Properties of Sc 2 O 3 ‐Doped, Rare‐Earth‐Oxide‐Doped, and Undoped BaTiO 3
Author(s) -
MAZDIYASNI K. S.,
BROWN L. M.
Publication year - 1971
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.1151-2916.1971.tb12202.x
Subject(s) - materials science , microstructure , grain size , sintering , doping , curie temperature , composite material , crystallite , dielectric , grain growth , oxide , mineralogy , metallurgy , ferromagnetism , condensed matter physics , chemistry , physics , optoelectronics
Polycrystalline BaTiO 3 prepared from alkoxy‐derived high‐purity submicron powders was studied. Highly dense bodies with uniform grain size were obtained typically by uniaxial cold‐pressing at 3000 psi and isostatic pressing at 30,000 psi followed by sintering at 1300° to 1350°C in air for 0.5 to 1 h. Using the same consolidation parameters and intimate mixing of residual concentrations of highly active fine‐particulate rare‐earth oxides to act as grain‐growth inhibitors, nearly theoretically dense bodies with a uniform microstructure and 1 to 1.5 μm grain size were obtained. Typical microstructures with well‐defined 90° and 180° domain patterns characteristic of BaTiO 3 : were observed. Also, an example of a checkerboard pattern resulting from a 〈111〉 ingrown twin plane in the structure which is independent of the Curie temperature was found. Electrical measurements on the undoped material indicated room‐temperature dielectric constant and tan δ values of 5000±500 and 4×10 −3 , respectively. Very high k values and dissipation factors were observed with the La 2 O 3 ‐ and Nd 2 O 3 ‐doped samples.