Structural and controllable thermal expansion properties of Sc2−xAlxMo3O12

The crystal structure and thermal expansion properties of solid solutions Sc2−xAlxMo3O12 (x = 0.0-2.0) are systematically investigated by X-ray diffraction. Rietveld refinement results indicate that samples with x ⩽ 1.3 crystallize in a Sc2Mo3O12-type orthorhombic (Pnca) structure, whereas others have an Al2Mo3O12-type monoclinic (P21/a) structure. Substitution of 15% Al3+ for Sc3+ leads to a rapid change in linear thermal expansion coefficient from −2.334 × 10−6 °C−1 to −0.732 × 10−6 °C−1. The thermal expansion coefficients of Sc2−xAlxMo3O12 monotonously increase with increased Al3+ content.