Di Weihua, Wang Xiaojun, Zhao Haifeng
Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, People's Republic of China.
J Nanosci Nanotechnol. 2007 Oct;7(10):3624-8. doi: 10.1166/jnn.2007.847.
Aqueous precipitation method has been used to synthesize lanthanide orthophosphates LnPO4 x nH2O (Ln = La, Ce, Gd, Tb, Dy) with high purity and yield. It has been shown by XRD, TGA, and FTIR characterization that the as-synthesized samples are the LnPO4 hydrates (LnPO4 x nH2O) with hexagonal rhabdophane-type structure. The X-ray diffraction peaks and absorption of PO4(3-) groups show a systematic shift from LaPO4 x nH2O to DyPO4 x nH2O due to the effect of lanthanide ionic contraction. The value of n in LnPO4 x nH2O depends on the lanthanide element and synthetic condition. Field-emission scanning electron microscopy observations show the morphology of as-synthesized samples, which consist entirely of nanorods/nanowires with diameters of 30-100 nm and lengths ranging from several hundreds of nanometers to several micrometers. The anisotropic growth of crystals should be responsible for the formation of nanorods/nanowires, which is related to the hexagonal crystal structure.
采用水相沉淀法合成了高纯度、高产率的稀土正磷酸盐LnPO₄·nH₂O（Ln = La、Ce、Gd、Tb、Dy）。XRD、TGA和FTIR表征表明，合成的样品为具有六方水磷铈矿型结构的LnPO₄水合物（LnPO₄·nH₂O）。由于镧系离子收缩效应，PO₄³⁻基团的X射线衍射峰和吸收峰从LaPO₄·nH₂O到DyPO₄·nH₂O呈现出系统性的位移。LnPO₄·nH₂O中n的值取决于镧系元素和合成条件。场发射扫描电子显微镜观察显示了合成样品的形貌，其完全由直径为30 - 100 nm、长度从几百纳米到几微米不等的纳米棒/纳米线组成。晶体的各向异性生长应是纳米棒/纳米线形成的原因，这与六方晶体结构有关。
