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Phase evolution and <110>‐orientation mechanism in RTGG‐processed BaTiO 3 ceramics with electrical properties
Author(s) -
Khanal Gopal P.,
Fujii Ichiro,
Ueno Shintaro,
Wada Satoshi
Publication year - 2021
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/jace.17798
Subject(s) - materials science , sintering , phase (matter) , dielectric , nucleation , grain growth , ferroelectricity , barium titanate , ceramic , grain size , titanate , piezoelectricity , mineralogy , composite material , chemical engineering , crystallography , chemistry , optoelectronics , engineering , organic chemistry
The <110>‐oriented BaTiO 3 ceramics were fabricated using BaCO 3 matrix and H 1.08 Ti 1.73 O 4 . n H 2 O (HTO) template particles, and the mechanism of BaTiO 3 phase formation was investigated. The dielectric, ferroelectric, and piezoelectric properties were also investigated. The transformation of the HTO phase into the TiO 2 bronze or TiO 2 (B) phase was observed at 600°C, where the BaTiO 3 nucleation was accompanied by the formation of a Ba 2 TiO 4 phase. The TiO 2 phase reacted with the Ba 2 TiO 4 phase at 800°C to give a BaTiO 3 phase, whereas its reaction with the BaTiO 3 resulted in the formation of BaTi 2 O 5 phase that got decomposed into BaTiO 3 and Ba 6 Ti 17 O 40 phase at sintering temperature ≥1300°C. Sintering with samples’ embedding in BaTiO 3 powders prevented the formation of the Ba 6 Ti 17 O 40 secondary phase. The crystallographic orientation along the <110> direction ( F 110 ) was developed by the epitaxial grain growth mechanism. In addition to the contribution of the grain‐size increment for enhancing the F 110 , the preservation of the platelike structure was also found to have a significant impact. The ceramics prepared by the embedded sintering (grain size ≈12.4 µm and F 110 = 83%) exhibited the room‐temperature dielectric constant of 1708 and piezoelectric strain constant of 445 pm/V, which are higher than those of the BaTiO 3 ceramics with randomly oriented grains.