Synthesis and characterizations of two anhydrous metal borophosphates: MIII2BP3O12 (M=Fe, In)

Two members of MIII2BP3O12 borophosphates, namely Fe2BP3O12 and In2BP3O12, were synthesized by the solid-state method and characterized by the X-ray single crystal diffraction, the powder diffraction and the electron microscopy. They both crystallize in the hexagonal system, space group P6(3)/m (no. 176) and feature 3D architectures, build up of the M2O9 units and B(PO4)3 groups via sharing the corners; however, they are not isomorphic for the different crystallographically distinct atomic positions. Optical property measurements of both compounds and magnetic susceptibility measurements of Fe2BP3O12 also have been performed. Moreover, in order to gain further insights into the relationship between physical properties and band structure of the MIII2BP3O12 borophosphates, theoretical calculations based on density functional theory (DFT) were performed using the total-energy code CASTEP.