Grain-boundary chemistry of barium titanate and strontium titanate. Part 1; High temperature equilibrium space charge

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb06450.x· OSTI ID:5162078

Chiang, Y M; Takagi, T ^[1]

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1. Dept. of Materials Science and Engineering, Massachusetts Inst. of Technology, Cambridge, MA (US)

This paper reports on direct observations using scanning transmission electron microscopy (STEM) of the grain-boundary chemistry of selectively doped SrTiO{sub 3} and BaTiO{sub 3} that show the predominant solute segregation in both systems to be that of acceptors (negative effective charge). Appreciable donor segregation is not observed even at lattice concentrations as high as 10 mol%. Donor and acceptor codoped materials show segregation of the acceptor only. The results are consistent with a grain-boundary space-charge distribution consisting of a positive boundary and negative space charge. All grain boundaries examined also show an excess of Ti relative to the A-site cations, suggesting that the positive boundary charge is at least partially accommodated by an excess of Ti ions. The sign and magnitude of the electrostatic potential appear to be remarkably insensitive to changes in lattice defect structure with solute doping. Grain-boundary chemistry appears dominated by space-charge segregation, in contrast with the predictions of recent atomistic simulations which neglect the space-charge potential.

• OSTI ID: 5162078
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 73:11; ISSN 0002-7820; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHEMICAL PROPERTIES
CRYSTAL STRUCTURE
DEFECTS
DOPED MATERIALS
ELECTRON MICROSCOPY
GRAIN BOUNDARIES
MATERIALS
MICROSCOPY
MICROSTRUCTURE
OXYGEN COMPOUNDS
SEGREGATION
SPACE CHARGE
STRONTIUM COMPOUNDS
STRONTIUM TITANATES
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY