Synthesis and magnetic properties of two isostructural fluorophosphates BaMPO4F (M = Cu, Co) with a tunnel structure

Abstract

Two fluorophosphates, BaMPO₄F (M = Cu, Co), have been synthesized by a conventional hydrothermal method, and they crystallize in the orthorhombic system with the space group P2₁2₁2₁, exhibiting a tunnel structure built by distorted MO₄F square-pyramids and PO₄ tetrahedra. The magnetic behaviors of the two compounds are investigated by means of magnetic susceptibility, magnetization, and heat capacity measurements. The results indicate that BaCuPO₄F exhibits a paramagnetic behavior down to 2 K, while BaCoPO₄F undergoes long-range antiferromagnetic ordering at 11.3 K and short-range magnetic ordering at ∼22 K.