In Situ Diffraction from Levitated Solids Under Extreme Conditions - Structure and Thermal Expansion in the Eu^sub 2^O^sub 3^-ZrO^sub 2^ System

• Published in: Journal of the American Ceramic Society Vol. 98; no. 4; p. 1292
• Main Authors: Maram, Pardha S, Ushakov, Sergey V, Weber, Richard JK, Benmore, Chris J, Navrotsky, Alexandra
• Format: Journal Article
• Language: English
• Published: Columbus Wiley Subscription Services, Inc 01.04.2015
• Subjects: Accuracy; Binary system; Cooling; Diffraction; Phase transitions; Solid solutions; Temperature
• ISSN: 0002-7820; 1551-2916

The accurate determination of structure and thermal expansion of refractory materials at temperatures above 1500°C is challenging. Here, for the first time, we demonstrate the ability to reliably refine the structure and thermal expansion coefficient of oxides at temperatures to 2200°C using in situ synchrotron diffraction coupled with aerodynamic levitation. Solid solutions in the Eu...O...-ZrO... binary system were investigated, including the high-temperature order-disorder transformation in Eu...Zr...O... The disordered fluorite phase is found to be stable above 1900°C, and a reversible phase transition to the pyrochlore phase is noticed during cooling. Site occupancies in Eu...Zr...O... show a gradual increase in disorder on both cation and anion sublattices with increasing temperature. The thermal expansion coefficients of all cubic solid solutions are relatively similar, falling in the range 8.6-12.0 x 10... C... These studies open new vistas for in situ exploration of complex structural changes in high-temperature materials. (ProQuest: ... denotes formulae/symbols omitted.)