Rubidium vanadium(iii) vanadyl(iv) phosphate, Rb3V3+(V4+O)(PO4)(H0.5PO4)2: crystal chemistry and low-dimensional magnetism

Abstract

In this paper, we present the synthesis and characterization of a rubidium vanadium(III) vanadyl(IV) phosphate, obtained under hydrothermal conditions. The new compound crystallizes in the triclinic space group P with the unit cell parameters a = 9.637(1), b = 12.254(2), c = 12.336(2) Å, α = 105.82(1), β = 104.81(1) and γ = 102.75(1)°. Its crystal structure was determined by single crystal X-ray diffraction. The structure of Rb₃V³⁺(V⁴⁺O)(PO₄)(H_0.5PO₄)₂ is formed from V³⁺-centered octahedra sharing all oxygen vertices and one edge with phosphate tetrahedra to form ribbons parallel to the [011] direction. These ribbons are further linked via V⁴⁺O₅ polyhedra in a three-periodic framework with channels running parallel to the a and b axes. Rb atoms occupy positions inside the framework channels. The title compound achieves a long range ordered antiferromagnetic state at T_N = 2.1 K and formally demonstrates a high value of the magnetic frustration parameter f equal to the ratio of the Weiss and Néel temperatures |Θ|/T_N = 15, which can be attributed to the reduced dimensionality of the magnetic subsystem. At T < T_N, the magnetization curve exhibits the signature of the 1/3 plateau.