Crystal structure and magnetic properties of Cr3Te5O13Cl3

Abstract

A new chromium tellurite oxochloride, Cr₃Te₅O₁₃Cl₃, has been prepared by solid-state reaction and the crystal structure was determined by single crystal X-ray diffraction. The compound crystallizes in the non-centrosymmetric space group P2₁2₁2₁ with the unit cell a = 4.90180(10) Å, b = 17.3394(2) Å, c = 17.5405(2) Å, Z = 4, R₁ = 0.0282. The Cr³⁺ ions have octahedral [CrO₆] oxygen coordination, the Te⁴⁺ ions have one sided [TeO₃] and [TeO₃Cl] coordinations. The [CrO₆] octahedra are edge sharing and form chains extending along [100]. These are connected by corner sharing [TeO₃] and [TeO₃Cl] groups to form layers parallel to (110). The layers are connected by weak interactions in between Te⁴⁺ in the layers and Cl⁻ ions located in between. The compound undergoes antiferromagnetic ordering at ∼34 K with a Weiss constant of −230 K. Isothermal magnetization measurements reveal a critical field of about 0.25 T above which the magnetization versus field changes from linear to a Brillouin-like saturation behaviour. The frustration ratio amounts to ∼6.8 indicative of sizable competing antiferromagnetic spin-exchange interaction. The dielectric constant ε (6 kHz) amounts to ∼7.9 and decreases by about 1% on cooling from 50 K to liquid helium temperatures.