Phase Relations and Thermal Expansion in the System HfO2-TiO2

Autor:	V. A. Patel, E. G. Charles, G. W. Hollenberg, Robert Ruh
Rok vydání:	1976
Předmět:	Materials science Analytical chemistry chemistry.chemical_element Mineralogy Titanate Thermal expansion Hafnium Lattice constant chemistry Differential thermal analysis Materials Chemistry Ceramics and Composites Anisotropy Chemical composition Phase diagram
Zdroj:	Journal of the American Ceramic Society. 59:495-499
ISSN:	1551-2916 0002-7820
Popis:	The system HfO/sub 2/-TiO/sub 2/ was investigated in the 0 to 60 mol percent TiO/sub 2/ region using x-ray diffraction analysis, differential thermal analysis, melting-point studies, and dilatometry. For samples quenched from 1500 and 1250/sup 0/C, single-phase HfTiO/sub 4/ is present from approximately 36 to 53 percent TiO/sub 2/, with HfO/sub 2/ coexisting as a second phase below 36 percent TiO/sub 2/ and TiO/sub 2/ coexisting as a second phase above 53 percent TiO/sub 2/. Room-temperature lattice parameters of the hafnium titanate phase decreased linearly with composition for samples quenched from 1500/sup 0/C and furnace-cooled from 1600/sup 0/C. High-temperature lattice parameter studies confirmed the expansion anisotropy of the hafnium titanate phase in the single-phase region. Linear thermal-expansion measurements revealed very low coefficients (less than 1 x 10/sup -6///sup 0/C) for compositions in the 30 to 40 percent TiO/sub 2/ range and relatively high coefficients (approximately 4 x 10/sup -6///sup 0/C) for the 25, 45, 50, and 60 mol percent TiO/sub 2/ compositions. The low expansion was attributed to microcracking. 5 fig.
Databáze:	OpenAIRE
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