Negative thermal expansion in Y2Mo3O12

The crystal structure of Y2Mo3O12 was refined by the Rietveld method for 130 °C as orthorhombic with space group Pbcn (No. 60). It is isostructural to Fe2Mo3O12 and consists of vertex sharing YO6 and MoO4 building polyhedra. Y2Mo3O12 has very high negative thermal expansion along all three crystallographic directions in the 130-900 °C temperature range. The overall linear coefficient of thermal expansion (αl=αv/3) is −1.26×10−5°C. Water molecules enter freely in Y2Mo3O12 microchannels and seem to have a role in partial amorphization of this compound at room temperature.