纳米晶钛镧酸盐的水热合成和表征

报道了在TiO₂-La₂O₃-M₂O-H₂O水热体系中,新型钛镧酸盐M_0.5La_0.5TiO₃(M=La,Ag_0.66Na_0.33,Li_0.6Na_0.4)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,Na_0.5La_0.5TiO₃和Ag_0.33Na_0.17La_0.5TiO₃具有立方结构,晶胞参数分别为a=0.3877nm和a=0.3890nm.Li_0.3Na_0.2La_0.5TiO₃具有正交结构,a=0.3894nm,b=0.3912nm,c=0.3890nm.TEM测定显示Na_0.5La_0.5TiO₃和Ag_0.33Na_0.17La_0.5TiO₃是纳米尺度晶体,平均粒度分别为50nm和70nm.Li_0.3Na_0.2La_0.5TiO₃的平均粒度分布为5Lm.Ag_0.33Na_0.17La_0.5TiO₃在440℃的电导率为1.9×10^-5S/cm,Li_0.3Na_0.2La_0.5TiO₃的电导率为1.5×10^-6S/cm.

Mild Hydrothermal Syntheses and Characterization of Nanocrystalline Titanlanthanates

Novel perovskite titanlanthanates, M_0.5La_0.5TiO₃ (M=Na, Ag_0.66Na_0.33, Li_0.6Na_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_0.5La_0.5TiO₃ and Ag_0.33Na_0.17La_0.5TiO₃ crystallized in cubic system with cell parameters: a =0.3877 nm and a =0.3890 nm, respectively, whereas Li_0.3Na_0.2La_0.5TiO₃ has orthorhombic symmetry with parameters a =0.3894 nm, b =0.3912 nm and c =0.3890 nm. Under a similar experimental condition, the average particle sizes of the products are 50 nm for Na_0.5La_0.5TiO₃, 70 nm for Ag_0.33 Na_0.17La_0.5TiO₃ and 5 Lm for Li_0.3Na_0.2La_0.5TiO₃. An ac impedance study indicates that conductivities of Ag_0.33 Na _0.17La_0.5TiO₃ and Li_0.3Na_0.2La_0.5TiO₃ at 713 Kare 1×10^-5 and 1×10^-6 S/cm, respectively.