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Phase transformation kinetic study and microstructure characterization of ball‐milled m ‐ZrO 2 –10 mol% a ‐TiO 2 by Rietveld method
Author(s) -
Dutta H.,
Manik S. K.,
Pradhan S. K.
Publication year - 2003
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889803000748
Subject(s) - monoclinic crystal system , rietveld refinement , materials science , nanocrystalline material , crystallography , annealing (glass) , microstructure , ball mill , lattice constant , analytical chemistry (journal) , crystal structure , chemistry , diffraction , metallurgy , nanotechnology , organic chemistry , optics , physics
High‐energy ball milling of a monoclinic ZrO 2 –10 mol% anatase TiO 2 mixture results in the formation of a nanocrystalline cubic ZrO 2 polymorphic phase with equimolar fraction of the starting materials. The cubic phase is presumed to have formed from the m ‐ZrO 2 solid solution based on the (001) plane of the m ‐ZrO 2 phase. In the course of milling, the most dense (111) plane of the cubic lattice became parallel to the most dense (11) plane of the monoclinic lattice due to an orientation effect. Annealing of a 12 h milled sample at 773, 873 and 973 K for 1 h results in almost complete transformation of the m ‐ZrO 2 to the c ‐ZrO 2 phase. At 1273 K annealing temperature (1 h), the nanocrystalline sample decomposed into individual starting phases. This suggests that the cubic phase is a metastable one and its stability depends on particle size as well as the working temperature. Formation of the cubic phase at such a low temperature using anatase TiO 2 as a phase stabilizer has not been reported previously. The microstructures of the unmilled, all the ball‐milled and the annealed samples have been characterized by employing Rietveld's X‐ray powder structure refinement methodology. The particle size, root mean square (r.m.s.) lattice strain, lattice parameters, molar fraction, etc ., of individual phases have been estimated from Rietveld analysis and are utilized to interpret the results.