Crystal Growth, Structure, Polarization, and Magnetic Properties of Cesium Vanadate, Cs₂V₃O₈: A Structure–Property Study

Cesium vanadate, Cs2V3O8, a member of the fresnoite-type structure, was synthesized via a hydrothermal route and structurally characterized by single-crystal X-ray diffraction. Cs2V3O8 crystallizes in a noncentrosymmetric polar space group, P4bm, with crystal data of a = 8.9448(4) Å, c = 6.0032(3) Å, V = 480.31(4) Å3, and Z = 2. The material exhibits a two-dimensional layered crystal structure consisting of corner-shared V5+O4 and V4+O5 polyhedra. The layers are separated by the cesium cations. The alignment of the individual polyhedra results in a macroscopic polarity for Cs2V3O8. Frequency-dependent polarization measurements indicate that the material is not ferroelectric. A pyroelectric coefficient of −2.0 μC m–2 K–1 was obtained from pyroelectric measurements taken as a function of the temperature. The magnetic susceptibility data were measured as a function of the temperature and yielded an effective magnetic moment of 1.78 μB for the V4+ cation. Short-range magnetic ordering was observed around 7 K. The susceptibility data were fit to the Heisenberg square-lattice model supporting that the short-range magnetic interactions are antiferromagnetic and two-dimensional. IR and thermal properties were also characterized.