中文摘要：

以乙醇为溶剂、稀土硝酸盐和NaF为反应物，采用LSS法制备NaYF4纳米晶体。通过改变反应物加入量、溶剂体积、反应温度及时间，制备出一系列尺寸可调、形貌不同（立方、棒状）的NaYF4纳米晶体。探讨了各种反应参数对NaYF4纳米晶体的晶相、形貌以及尺寸的影响，进一步研究β相NaYF4纳米晶体的生长机制，从而优选其制备条件。研究证明，实验所得的形貌规整、尺寸均一的β相NaYF4样品为六边形截面、长度约为1μm的纳米棒。提高反应物NaF添加量、升高反应温度以及延长反应时间将促进β相 NaYF4纳米晶体的生成；溶剂乙醇对产物晶相和形貌没有影响。制备形貌较规整、尺寸分布均一的纯β相NaYF4米晶体的最佳反应条件为：NaF加入量为2．0 mol/L、体积为4 mL ，溶剂乙醇加入量为20 mL ，反应温度为200℃，反应时间为24 h。

英文摘要：

NaYF4 nanocrystals are prepared by liquid-solid-solution （LSS） method through using etha-nol as the solvent ,lanthanide nitrate and NaF as the reactants .By changing the amount of reactants ,sol-vent volume ,reaction temperature and time ,a series of NaYF4 nanocrystals with adjustable sizes and dif-ferent shapes （cube and rodlike） are obtained .The effects of various reaction parameters on crystalline phase ,morphology and size of NaYF4 nanocrystals are discussed .And the grow th mechanism of β-NaYF4 nanocrystals is further investigated ,so as to select the optimum preparation conditions .T he results show that the NaYF4 nanocrystals with regular shape and uniform size were nanorods with hexagon section and the length of about 1 μm .Increasing the amount of NaF ,raising the reaction temperature and extending reaction time would promote generation of β-NaYF4 nanocrystals . The ethanol had no influence on the crystalline phase and morphology of the product .The best preparation conditions are of β-NaYF4 nanocrys-tals with regular shape and uniform size ：4 mL NaF （2 .0 mol/L） ,20 mL ethanol ,200℃ ,and 24 h .