Title :
PTC behavior in yttria doped BaTiO3 as related to grain boundary structure
Author :
Roseman, R.D. ; Kim, J. ; Buchanan, R.C.
Author_Institution :
Dept. of Mater. Sci. & Eng., Illinois Univ., Urbana, IL, USA
fDate :
30 Aug-2 Sep 1992
Abstract :
Lattice structure and phase distribution along the grain boundaries in Y2O3-doped BaTiO3, with Zr4+ as a counterdopant were investigated with respect to their impact on PTC (positive-temperature-coefficient) behavior. This doping, related to A and B-site occupancy, creates ionic defect states which segregate during annealing to different morphological regions along the grain boundaries, identified as nondomain and domain regions. TEM (transmission electron microscope) high-resolution imaging, and HOLZ pattern and EDS (electron diffraction spectroscopy) analysis of these regions showed differences in composition, lattice parameters, and lattice plane coherency across the grain boundaries. Optimum doping in light of these structural changes resulted in lower resistivity and enhanced PTC effects, the stress release being the driving force for sharp PCT transitions
Keywords :
annealing; barium compounds; electric domains; electrical conductivity of crystalline semiconductors and insulators; electron diffraction examination of materials; ferroelectric materials; grain boundary segregation; transmission electron microscope examination of materials; yttrium compounds; zirconium; A-site occupancy; B-site occupancy; BaTiO3-Y2O3:Zr4+ doped; HOLZ pattern; annealing; composition; counterdopant; domain regions; doping; electron diffraction spectroscopy analysis; grain boundary structure; ionic defect states; lattice parameters; lattice plane coherency; lattice structure; morphological regions; nondomain regions; phase distribution; positive temperature coefficient behavior; positive-temperature-coefficient; resistivity; stress release; transmission electron microscope high resolution imaging; Annealing; Diffraction; Doping; Grain boundaries; High-resolution imaging; Image analysis; Lattices; Spectroscopy; Transmission electron microscopy; Zirconium;
Conference_Titel :
Applications of Ferroelectrics, 1992. ISAF '92., Proceedings of the Eighth IEEE International Symposium on
Conference_Location :
Greenville, SC
Print_ISBN :
0-7803-0465-9
DOI :
10.1109/ISAF.1992.300658
