Crystal structures and thermal expansion properties of Y2-xErxMo4O15 (x = 0.0–2.0) solid solutions

Abstract A new series of rare earth compounds, Y 2-x Er x Mo 4 O 15 ( x = 0.0–2.0), were synthesized and their structures were determined by powder X-ray diffraction (XRD). Rietveld analysis of XRD patterns reveals that the compounds of this series crystallize in monoclinic system with space group P 2 1 / c . The lattice parameters a, b, c , β and the unit cell volume V decrease linearly with increasing Er content. The thermal expansion properties of these compounds were studied under high-temperature XRD. Positive thermal expansions of compounds Y 2-x Er x Mo 4 O 15 are found to be anisotropic along the three crystallographic directions where a and c axes expand while b axis contracts in the whole temperature range. By analysis of data, the expansion of weak band Mo2-O14 with rising temperature should be responsible for positive thermal expansion.