In2Mo3O12: A low negative thermal expansion compound

Orthorhombic In2Mo3O12 has low negative linear coefficient of thermal expansion (αl = −1.85 × 10−6 °C−1) as evaluated by X-ray powder diffraction using a synchrotron facility. The linear coefficient of thermal expansion for orthorhombic In2Mo3O12 is directly dependent on the inherent volume distortion parameter (υ) of InO6. This finding strongly corroborates the recently proposed relationship between the linear coefficient of thermal expansion in A2M3O12 compounds (αl) and the distortion level of AO6 polyhedra. With the increase of inherent distortion parameter (υ) of AO6 polyhedra, the linear coefficient of thermal expansion becomes more negative. Another important feature of AO6 polyhedra, including InO6, is that their distortion increases as a function of temperature. Orthorhombic In2Mo3O12 is stable in the studied temperature range, 370–760 °C.