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

Mechanochemical effects were investigated in the mixture of a rare earth compound (Nd(NO3)3·6H2O, NdCl3·6H2O, Nd2(CO3)3·8H2O, Ce(NO3)3·6H2O, CeCl3·7H2O, or Ce2(CO3)3·8H2O) and (NH4)2HPO4. 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), thermogravimetry–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(NO3)3·6H2O–(NH4)2HPO4 or Ce(NO3)3·6H2O–(NH4)2HPO4. By mechanical treatment, Rhabdophane-type neodymium phosphate was formed at lower temperature in the mixture of NdCl3·6H2O–(NH4)2HPO4. The mixture of CeCl3·7H2O–(NH4)2HPO4 indicated XRD peaks of CeO2 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 120 m2/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.