摘要

A facile oxides-hydrothermal (O-HT) method is demonstrated to prepare high-purity monazite-type LaPO4 nanomaterials. In this approach, La2O3 and P2O5 powder are first directly used as precursors under additive-free hydrothermal conditions. The as-prepared samples are characterized with X-ray diffraction, Fourier transform IR spectroscopy, thermogravimetry, scanning electron microscopy, transmission electron microscopy (high-resolution TEM, energy dispersive spectroscopy) and selected-area electron diffraction. The typical sample obtained at 433 K in 24 h comprises uniform single-crystal nanofibres with a diameter of similar to 15-28 nm and an aspect ratio of 30-50. The influences of treatment time, synthesis temperature and P/La molar ratio are investigated. The phase transition from hexagonal hydrate to monoclinic anhydrous lanthanum phosphate and the growth process of nanofibres are revealed by the experimental results. The formation mechanism of the monoclinic LaPO4 is discussed. The result indicates that the P/La ratio does not influence the composition and crystal phase but changes the morphology of the product in the O-HT system.