Room temperature metathetic synthesis and characterization of α-hopeite, Zn3(PO4)2·4H2O

The synthesis of crystalline zinc phosphates (α-hopeite phase) through the metathetic pathway has been investigated. The reaction has been carried out by room-temperature grinding. High lattice energy of the by-product NaCl has driven the reaction in the forward direction, and as a result, stable phosphate phases have been synthesized. Reaction of a different phosphorus source (like Na3PO4, Na2HPO4, NaH2PO4, and K2HPO4) with ZnCl2 has been attempted. The structural, vibrational, thermal, optical, and chemical properties of synthesized powders are determined by powder X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and diffused reflectance spectra (DR) in the UV–vis range. The direct band gap of the title compound was determined to be 3.6 ± 0.2 eV.