Synthesis and magnetic properties of two isostructural fluorophosphates BaMPO 4 F (M = Cu, Co) with a tunnel structure.

Two fluorophosphates, BaMPO4 F (M = Cu, Co), have been synthesized by a conventional hydrothermal method, and they crystallize in the orthorhombic system with the space group P21 21 21 , exhibiting a tunnel structure built by distorted MO4 F 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 BaCuPO4 F exhibits a paramagnetic behavior down to 2 K, while BaCoPO4 F undergoes long-range antiferromagnetic ordering at 11.3 K and short-range magnetic ordering at ∼22 K.