Preparation of Nickel Aluminum–Manganese Spinel Oxides NixAl1-xMn2O4 for Oxygen Electrocatalysis in Alkaline Medium: Comparison of Properties Stemming from Different Preparation Methods

New NZP-type phosphates of the formula PbM3+M4+P3O12 (M3+=Cr, Fe, and In; M4+=Ti, Zr, Hf, and Sn) were synthesized. The evolution of lattice parameters with radii of M3+ and M4+ cations indicates the anomalous behavior of tin-containing compounds. The room temperature structure of PbFeZrP3O12 has been refined using powder neutron diffraction data. The compounds were characterized by infrared and electronic spectroscopic methods. Pb0.5Mo2P3O12 with molybdenum present in the reduced state (+4) was synthesized. It is found that Pb0.5Mo2P3O12 is structurally related to TlMo2P3O12 and crystallizes in an orthorhombic system with parameters a= 8.621?; b=9.492 ?; c=12.486 ?.