Premium
Defect Chemistry and Microstructure of Hydrothermal Barium Titanate
Author(s) -
Hennings Detlev F. K.,
Metzmacher Christoph,
Schreinemacher B. Seriyati
Publication year - 2001
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.1151-2916.2001.tb00627.x
Subject(s) - hydrothermal circulation , materials science , microstructure , grain boundary , ceramic , barium titanate , crystallite , nanometre , chemical engineering , hydrothermal synthesis , mineralogy , microporous material , oxygen , calcium titanate , composite material , metallurgy , chemistry , organic chemistry , engineering
Hydrothermal powders of BaTiO 3 and (Ba,Ca)(Ti,Zr)O 3 contain large amounts of protons in the oxygen sublattice. The proton defects are compensated by vacancies on metal sites. When the powder is annealed, water is released and the point defects disappear in the temperature range of 100°–600°C. Metal and oxygen vacancies combine to small nanometer‐sized intragranular pores. At temperatures of >800°C, the intragranular pores migrate to the grain boundaries and disappear. In multilayer ceramic capacitors that have been prepared from hydrothermal powders, the intragranular pores are preferentially collected at the inner electrodes, which results in “bloating,” cracks, and delamination.