掺镧改性钛酸钡纳米多晶粉体的制备和表征

Preparation and Characterization of La^(3+)-doped Barium Titanate Nanosize Polycrystalline Powders

以La（OAc）3,Ba（OAc）2,Ti（On-Bu）4为起始物,采用共溶-水凝胶法制备掺镧改性钛酸钡纳米多晶粉体LaxBa1-xTiO3（x=0.00,005,0.10,0.20,0.30）,利用正交试验对制备溶胶的主要工艺进行优化:溶胶是由总浓度为0.7mol/L的起始物逐步滴入蒸馏水进行共溶水解而得,其介质为氨水调节的pH=3.8和70℃的醋酸.将溶胶陈化和浓缩而得湿凝胶,干凝胶是将湿凝胶在烘箱中经50℃/24h处理而得.对干凝胶及其焙烧粉体进行了七项特性表征:首先取少量干凝胶进行TG-DTG和FT-IR测试,以确定焙烧温度范围和历程;然后另取一部分干凝胶在该温度范围内的不同温度点上焙烧,以便制得系列粉体试样,对其进行FT-IR、XRD、SEM、EDS、TEM及LRS表征,以比较各试样的晶相组成、原始晶粒尺寸、晶格常数及其四方相畸变度δ（即晶轴比c/α）、团粒形貌及微区金属元素含量等并从中优选工艺,探讨共溶-水凝胶过程及掺镧改性机理等.

Nanosize polycrystalline powders of lanthanum doped barium titanate were prepared by the cosolubilized- hydrous gel process using titanium butoxide and lanthanum acetate as well as barium acetate with 0.7mol/L total concentration of precursor. The sol was obtained by cosolubilized hydrosis of starting materials using HOAc as medium and catalyst with pH=3.8. The wet-gel was acquired by concentrating and aging sol at room temperature. The wet-gel to dry-gel conversion was performed at 50degreesC/24h in an electrical oven. The TG-DTG measurement of dry-gel was carried out to determine the appropriate temperature range of calcination. Then a series of polycrystal powders were prepared by calcining dry-gel at different points of above temperature range. Powder samples were characterized detailedly to confirm the phase formation, crystalline size, grain morphology, elemental composition and the fine structure by FT-IR, XRD, SEM, EDS, TEM and LRS. So that opitimizing 800degreesC/2h as the suitable condition for calcination of dry-gel to prepare nanosize polycrystal powders LaxBa1-xTiO3(x=0.00, 005, 0.10, 0.20, 0.30).