In-situ non-ambient X-ray diffraction studies of indium tungstate

In situ variable temperature and high pressure X-ray diffraction studies were carried out on indium tungstate (In2W3O12). This material displays positive volume expansion in both its low temperature monoclinic and high temperature orthorhombic phases, with negative thermal expansion along the a axis and positive thermal expansion along the b and c axes. Upon hydrostatic compression in a diamond anvil cell, one crystalline to crystalline phase transition is observed in the range 1.9 to 2.7 GPa, and progressive irreversible amorphization occurs at pressures above 4.3 GPa. The crystalline high pressure phase appears to be isostructural to previously observed high pressure phases in other A2M3O12 compounds. - Graphical abstract: Variable pressure X-ray diffraction patterns of In2W3O12 collected in a diamond anvil cell. A phase transition is clearly observed between 2.2 and 2.7 GPa, followed by irreversible amorphization. Highlights: ► The structure of In2W3O12 was studied as a function of temperature and pressure. ► Uniaxial negative thermal expansion was observed above 250 °C. ► A pressure-induced phase transition occurred between 2.2 and 2.7 GPa. ► Pressure-induced irreversible amorphization was observed above 4.3 GPa.