Synthesis, structure and magnetic behaviour of mixed metal leucophosphite

A synthetic analogue of leucophosphite, an iron phosphate, was synthesized hydrothermally at 180 °C and its chemical composition determined to be {K[(FeV)(PO4)2(OH)(H2O)]·H2O}. The compound crystallizes in the monoclinic P21/c space group, with a=9.7210(19) Å, b=9.6500(19) Å, c=12.198(4) Å and β=128.569(18)°. While the original all-iron compound is reported to be antiferromagnetic, the inclusion of substitutional vanadium(III) ions renders the structure ferrimagnetic. Diffraction studies and magnetic characterization show that iron and vanadium are disordered throughout the crystallographic sites. The magnetic behaviour of this system was interpreted in terms of a classic ferrimagnetic mean field model, consisting of two antiferromagnetically coupled non-crystallographic “sublattices”.