Netsu Sokutei, 39 (W39), p. 23, (2012)


Preparation of Al2-xScx(MoO4)3 with Low Thermal Expansion and Analysis of Its Structural Phase Transition Behavior

Single phase of Al2-xScx(MoO4)3 (x = 0.0, 0.5, 1.0, 1.5, 2.0) ceramics were successfully prepared at sintering temperature as low as 800 oC. Specimens with more homogeneous cation distribution were obtained by Pechini method using aqueous solution of Al(NO3)3•9H2O, Sc2O3 and MoO3 than those prepared by solid state reaction method using mixture of Al2O3, Sc2O3 and MoO3 powder. Sc substitution of only 0.5 decreased the temperature of the structural phase transition from monoclinic to orthorhombic observed in Al2 (MoO4)3from 200 oC below -50 oC, resulting in low thermal expansion of the specimens with x more than 0.5 above -50 oC. The abrupt decrease of the structural phase transition temperature with x as low as 0.5 suggested existence of miscibility gap, showing agreement with observation of both monoclinic and orthorhombic phases in the specimens with 0.0 < x < 0.5.