Mechanochemical effects on synthesis of Rhabdophane-type neodymium and cerium phosphates

摘要

Mechanochemical effects were investigated in the mixture of a rare earth compound (Nd(NO_3)_3·6H_2O, NdCl_3·6H_2O, Nd_2(CO_3)_3·8H_2O Ce(NO_3)_3·6H_2O, CeCl_3·7H_2O, or Ce_2(CO_3)_3·8H_2O) and (NH_4)_2HPO_4. These mixtures were ground and then heated. These ground mixtures and thermal products were characterized by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), thermogravi-metry-differential thermal analyses (TG―DTA), and adsorption of nitrogen. By grinding, Rhabdophane-type rare earth (Nd or Ce) phosphate was formed in the mixture of Nd(NO_3)_3·6H_2O―(NH_4)_2HPO_4 or Ce(NO_3)_3·6H_2O―(NH_4)_2HPO_4. By mechanical treatment, Rhabdophane-type neodymium phosphate was formed at lower temperature in the mixture of NdCl_3·6H_2O―(NH_4)_2HPO_4. The mixture of CeCl_3·7H_2O―(NH_4)_2HPO_4 indicated XRD peaks of CeO_2 by heating, whereas ground mixtures transformed to Rhabdophane-type cerium phosphate. Specific surface areas of Rhabdophane-type neodymium and cerium phosphates verified from 0.1 to 120m~2/g depending on various synthetic conditions. Rhabdophane-type neodymium and cerium phosphates which had large specific surface area were obtained by grinding with ethanol and then heating.