HTXRD and DSC used for phase equilibria studies

HTXRD and DSC used for phase equilibria studies
of a fast oxygen ion conductor

Characterization of high temperature phase transformation in bismuth strontium oxide, a fast oxygen ion conductor

A combined DSC and high temperature XRD study of the phase transformation reported for the beta-phase solid solution (Bi₂O₃)_1-x(SrO)_x was undertaken for the composition Bi_1.6Sr_0.2O_2.6.Ê The DSC and high temperature XRD results were in good agreement.Ê A reversible phase transformation was observed over a narrow temperature range around 650^oC, characterized by a large increase in the c lattice parameter, although both the low and high temperature phases have the same crystal symmetry.

"High Temperature Phase Transformation in Rhombohedral Bismuth Strontium Oxide" E.A. Payzant, W.D. Porter, and C.R. Hubbard, Thermochimica Acta 318:(1-2) 45-50 September 7, 1998.

HTXRD patterns taken on cooling from 750 ^oC, using a position sensitive detector in scanning mode, of the closely related high temperature (top) and low temperature (bottom) phases.Ê Coexistance of both phases at 630^oC is illustrated by the splitting of the 009 reflection (at 2-theta = 28.3^o) in the middle trace.

	Heating and cooling DSC curves taken at 20 ^o/min. The phase transformation (1) occurs with an onset temperature around 650 ^oC, with some hysteresis between heating and cooling. The small second event (2) also occurs on heating and cooling.
High Temperature X-Ray Diffractometer Differential Scanning Calorimeter

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Acknowledgments
URL: http://www.html.ornl.gov/tpuc/simul.html