Synthesis and conductivity of GdPO4 nanorods: Impacts of particle size and Ca2+ doping

A series of Gd1−xCaxPO4·nH2O nanorods were prepared using a simple hydrothermal reaction which was optimized by tuning the pH values of the precursor. The resulted nanorods were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, and alternative current impedance technique. It is demonstrated that all Gd1−xCaxPO4·nH2O nanorods crystallized in a pure hexagonal structure. For x = 0, the particle dimension decreased with increasing the pH value. For x > 0, the solid solution limit of Ca2+ in GdPO4·nH2O nanorods was about 3 mol%, below which the lattice volume increased with increasing the doping level of Ca2+. The conductivities of nanorods were highly dependent on both the particle size and Ca2+ concentration, as indicated by the increased conductivity as particle size reduces or Ca2+ doping level increases. These observations were understood in terms of the dehydration and the introduction of HPO42− defects by Ca2+ doping.

Research highlights▶ Hydrated Gd1−xCaxPO4 nanorods were prepared by a hydrothermal method. ▶ The nanorods have dimensions of 20 nm in diameters and several hundred nm in lengths. ▶ The solid solution limit of Ca2+ in GdPO4·nH2O nanorods was about 3 mol%. ▶ The conductivity increased with the reduction of particle size. ▶ Ca2+ doping improved the conductivities of the hydrated Gd1−xCaxPO4 nanorods.