Synthesis and crystal structure of the new vanadate AgCaVO4: Comparison with the arcanite structure

Abstract We report the synthesis and the crystal structure of the new vanadate AgCaVO 4 from laboratory powder X-ray data. Contrary to the previously reported AgBVO 4 (B=Mg, Cd), AgCaVO 4 exhibits the arcanite structure (β-K 2 SO 4 ). Although it exhibits the same structure than arcanite, significant differences are observed. These differences are explained by deriving the atomic displacement field. The change of connectivity within the structure between β-K 2 SO 4 and AgCaVO 4 results from a rotation of the VO 4 tetrahedra giving rise to a change from a face sharing to an edge sharing octahedral chains. Additionally, the thermal expansion of AgCaVO 4 has been investigated up to 800°C.