纳米晶钛镧酸盐的水热合成和表征

Mild Hydrothermal Syntheses and Characterization of Nanocrystalline Titanlanthanates

报道了在ＴｉＯ２－Ｌａ２Ｏ３－Ｍ２Ｏ－Ｈ２Ｏ水热体系中，新型钛镧酸盐Ｍ０．５Ｌａ０．５ＴｉＯ３（Ｍ＝Ｌａ，Ａｇ０．６６Ｎａ０．３３，Ｌｉ０．６Ｎａ０．４）的水热合成，用ＸＲＤ、ＳＥＭ、ＴＥＭ、ＩＣＰ、ＤＴＡ－ＴＧ、ＩＲ和ａｃ阻抗分析技术进行了结构表征．讨论了水热合成反应体系ｐＨ、反应混合物的组成比以及晶化温度等因素对合成的影响．ＸＲＤ分析表明，Ｎａ０．５Ｌａ０．５ＴｉＯ３和Ａｇ０．３３Ｎａ０．１７Ｌａ０．５ＴｉＯ３具有立方结构，晶胞参数分别为ａ＝０．３８７７ｎｍ和ａ＝０．３８９０ｎｍ．Ｌｉ０．３Ｎａ０．２Ｌａ０．５ＴｉＯ３具有正交结构，ａ＝０．３８９４ｎｍ，ｂ＝０．３９１２ｎｍ，ｃ＝０．３８９０ｎｍ．ＴＥＭ测定显示Ｎａ０．５Ｌａ０．５ＴｉＯ３和Ａｇ０．３３Ｎａ０．１７Ｌａ０．５ＴｉＯ３是纳米尺度晶体，平均粒度分别为５０ｎｍ和７０ｎｍ．Ｌｉ０．３Ｎａ０．２Ｌａ０．５ＴｉＯ３的平均粒度分布为５μｍ．Ａｇ０．３３Ｎａ０．１７Ｌａ０．５ＴｉＯ３在４４０℃的电导率为１．９×１０－５Ｓ／ｃｍ，Ｌｉ０．３Ｎａ０．２Ｌａ０．５ＴｉＯ３的电导率为１．５×１０－６Ｓ／ｃｍ．

Novel perovskite titanlanthanates, M 0.5 La 0.5 TiO 3 (M=Na, Ag 0.66 Na 0.33 , Li 0.6 Na 0.4 ) were hydrothermally synthesized under mild conditions, and characterized by means of X ray diffraction(XRD), scanning electron microscopy(SEM), differential thermal and thermogravometric analyses(DTA TG), inductively coupled plasma analysis(ICP) and infrared spectroscopy(IR). The ionic transport properties were measured by an ac impedance method. Some factors, e.g., crystallization temperature, pH, and Ti/La molar ratio in reaction mixture dominate the hydrothermal syntheses of the single phase products. Na 0.5 La 0.5 TiO 3 and Ag 0.33 Na 0.17 La 0.5 TiO 3 crystallized in cubic system with cell parameters: a =0.387 7 nm and a =0.389 0 nm, respectively, whereas Li 0.3 Na 0.2 La 0.5 TiO 3 has orthorhombic symmetry with parameters a =0.389 4 nm, b =0.391 2 nm and c =0.3890 nm. Under a similar experimental condition, the average particle sizes of the products are 50 nm for Na 0.5 La 0.5 TiO 3 , 70 nm for Ag 0.33 Na 0.17 La 0.5 TiO 3 and 5 μm for Li 0.3 Na 0.2 La 0.5 TiO 3. An ac impedance study indicates that conductivities of Ag 0.33 Na 0.17 La 0.5 TiO 3 and Li 0.3 Na 0.2 La 0.5 TiO 3 at 713 K are 1×10 -5 and 1×10 -6 S/cm, respectively.