Synthesis, structure and magnetic behaviors of a new fluorophosphate PbCuPO4F

A new fluorophosphate PbCuPO4F was obtained by a hydrothermal method, which is found to crystallize in the monoclinic system with a P2(1)/c space group, exhibiting a tunnel structure built by distorted CuO4F square-pyramids and PO4 tetrahedra. Magnetic measurements show that this compound possesses a short-range magnetic order at similar to 7.9 K without any antiferromagnetic transitions down to 2 K, indicating a singlet ground state. The fit using a modified spin-dimer model indicates intradimer interaction J/k(B) = 12.2 K and interdimer interaction J'/k(B) = 3.5 K in the system, while the critical field for the spin gap between the singlet ground state (S = 0) and the excited triplet state (S = 1) is observed at H-c = similar to 4.7 T. Although PbCuPO4F and BaCuPO4F have a similar tunnel structure, their magnetic behaviors are remarkably different. This may be due to a slight change of interaction exchange in PbCuPO4F, leading to a coupled spin-dimer of Cu-O-P-O-Cu pathway in the 4-column tunnels. Also, solid-state UV-vis diffuse reflectance spectra show that PbCuPO4F has a wide optical band gap of 3.42 eV.

Automated summary

A new fluorophosphate PbCuPO4F was synthesized via a hydrothermal method, displaying unique tunnel structure and magnetic behavior, as well as possessing a wide optical band gap.