Nanocrystalline serrabrancaite (MnPO4•H2O) prepared by a simple precipitation route at low temperature

MnPO4 center dot H2O was precipitated from manganese nitrate tetrahydrates and phosphoric acid in the presence of water-ethanol system at low temperature. The precipitates were characterized by TG/DTG/DTA, XRD, scanning electron microscope (SEM), FTIR and UV-vis-near IR techniques. The presence of ethanol in the spontaneous precipitation process of serrabrancaite leads to highly crystalline powder. Thermal treatment at 600 degrees C yields a crystalline manganese pyrophosphate (Mn2P2O7). The particle sizes obtained from X-ray line broadening are 66 +/-28 and 54 +/- 18 nm for the MnPO4 center dot H2O and Mn2P2O7, respectively. FTIR spectrum of MnPO4 center dot H2O is assigned base on the PO43- ion and water molecules in the structure. The diffuse reflectance spectrum revealed that MnPO4 center dot H2O presents a strong Jahn-Teller effect, which is in agreement with the crystal structure. (C) 2007 Elsevier B.V. All rights reserved.