Phase Formation in the Mg3 – nNinBPO7 System

Mg 3 – n Ni n BPO 7 samples ( n = 0–3) were synthesized by gel combustion followed by annealing at 980°C, cooled under inertial-thermal conditions, and then studied by X-ray powder diffraction analysis, IR spectroscopy, and X-ray fluorescence spectrometry. A crystalline phase of Ni 3 BPO 7 with the β-Zn 3 BPO 7 structure was experimentally obtained for the first time. When varying the composition of the samples from Mg 3 BPO 7 to Ni 3 BPO 7 , in borophosphate, a region of coexistence of α‑Mg 3 BPO 7 and β-Ni 3 BPO 7 was discovered. Analysis of diffuse reflectance spectra of Mg 1.5 Ni 1.5 BPO 7 showed the presence of Ni 2+ cations in an environment different from the symmetrical octahedral or tetrahedral environment.