Nanocrystalline manganese dihydrogen phosphate dihydrate Mn(H2PO4)2·2H2O and its decomposition product (Mn2P4O12) obtained by simple precipitation route

Manganese dihydrogenphosphate dihydrate (Mn(H2PO4)2·2H2O) was prepared by using MnCO3–H3PO4 and Mn(c)–H3PO4 systems at ambient temperature. The precipitates were investigated by thermoanalytical techniques (TG/DTG/DTA), scanning electron microscope (SEM), X-ray powder diffraction (XRD), and FTIR spectroscopy. Thermal treatment of obtained Mn(H2PO4)2·2H2O from two synthetic systems at 400 °C yielded a crystalline dehydrated manganese cyclo-tetrametaphosphate (Mn2P4O12). The XRD and FTIR results indicate that the prepared Mn(H2PO4)2·2H2O and its dehydration product Mn2P4O12 from both synthetic systems have a pure monoclinic phase without the presence of any phase impurities. The lattice parameters and particles sizes analyzed from XRD spectra of Mn(H2PO4)2·2H2O and its dehydration product Mn2P4O12 are different for both systems. The difference of some physical and chemical properties of Mn(H2PO4)2·2H2O and its dehydration product Mn2P4O12 from both synthetic systems are discussed.