Thermal Expansion and Phase Transition Behavior of Al2-xMx(WO4)3 (M=Y, Ga and Sc) Ceramics

Abstract

In order to obtain materials with a tailored thermal expansion, in particular zero-thermal-expansion between -50~100°C, the possibility of preparation, thermal expansion behavior and phase transition of Al2-xMx(WO4)3 (M: Y, Ga and Sc) have been examined. Y was not substituted for the Al site in Al2(WO4)3. Al2-xGax(WO4)3 single phase could be prepared in x range as high as 0.4. The phase transition temperature involving abrupt expansion increased with an increase of Ga content, resulting in no phase transition for Al1.6Ga0.4(WO4)3 between -50~100°C. However, zero-thermal expansion could not be obtained in Al2-xGax(WO4)3 at the temperature range. Al2-xScx(WO4)3 single phase was obtained for the whole x range. The temperature of the phase transition decreased with an increase of Sc content and the abrupt expansion due to the phase transition disappeared above -50°C for the specimen with x larger than 0.3. The thermal expansion coefficient could be controlled with Sc content and zero-thermal-expansion was observed for the specimens with x around 0.1 and 1.5.