Abstract
Three powder samples of lanthanum phosphate were prepared via the precipitation method. La2O3, LaCL3, (NH4)3PO4 and H3PO4 were used as precursor materials. Chemical and thermal analyses, infrared spectra, X-ray diffraction and particle size techniques were used for characterization. The results of chemical analysis indicated that the three samples are in non-stoichiometric state which attributed to the solubility of the products in the aqueous medium and/or to the partial precipitate of HPO42- and H2PO4- species. The results of infrared spectra exhibited the specific bands of phosphate salts such OH, O=P-O, P-O and O-P-O. A band at 1380 cm-1 corresponding to PO22- is observed in sample I and II which may due to make complexation species between the phosphates and the metal ions.
The X-ray diffraction indicated the formation of lanthanum phosphates of hexagonal structure of rhabdophane LaPO4.0.5H2O. DTA/TGA curves show that the prepared samples remain thermally stable at high temperatures.
