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Electric current‐controlled synthesis of BaTiO 3
Author(s) -
Nakagawa Yu,
Yoshida Hidehiro,
Uehashi Akinori,
Tokunaga Tomoharu,
Sasaki Katsuhiro,
Yamamoto Takahisa
Publication year - 2017
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.14938
Subject(s) - sintering , materials science , electric field , flash (photography) , microstructure , current (fluid) , voltage , shrinkage , analytical chemistry (journal) , oxygen , electric current , composite material , mineralogy , electrical engineering , chemistry , optics , physics , organic chemistry , chromatography , quantum mechanics , engineering
In BaTiO 3 , flash‐sintering associated with a surge of the specimen electric current sometimes results in an inhomogeneous microstructure including Ti‐excess secondary phases because of discharging. We applied field‐assisted sintering technique ( FAST ) under precisely controlled specimen current that was set just below the threshold value for the occurrence of flash event for BaTiO 3 , to avoid the occurrence of the discharging. As a result, uniform and fine‐grained compacts were obtained without any secondary phases. A relative density of approximately 92% was achieved under FAST condition of 100 V/cm with a limiting current of 72 mA and soaking time of 3 hours at 1070°C. The voltages during sintering under a constant current of 72 mA were found to decrease during the soaking process. Electron energy loss spectroscopy revealed the generation of excess oxygen vacancies at/near grain boundaries. The excess oxygen vacancies induced by application of DC electric fields were confirmed to reduce the voltages and to retard the shrinkage rate in a final sintering stage.