Thermal expansion of calcium cobalt vanadate garnet, Ca2.5Co2V3O12

Abstract

Calcium cobalt vanadate of Ca2.5Co2V3O12 (CCVO) formula is characterized by a defect garnet structure involving a partial (5/6) occupation of the dodecahedral cation site. In this work, the crystal structure and thermal expansion are investigated for this compound using powder X-ray diffraction. Temperature variations of lattice parameter and volumetric thermal expansion coefficient (αV) were determined. In the 302–920 K range, the lattice parameter a increases from 12.448(2) Å to 12.548(2) Å, whereas αV rises from 32(4) to 42(1) MK−1. The atomic coordinates of oxygen ion vary marginally with increasing temperature. The thermal expansion at room temperature is comparable to those reported for other calcium vanadates, but is larger than for a number of oxide garnets of formulae A3B2C3O12.