化学溶液法合成La0.5Sr0.5TiO3导电薄膜的研究

采用化学溶液沉积法制备了La0.5Sr0.5Ti O3(LSTO)外延薄膜作为第二代高温超导带材YBCO涂层导体的缓冲层.以乙酸镧、碳酸锶和钛酸丁酯为前驱物,配制了La离子浓度为0.14 mol/L的前驱液,经旋转涂覆和适当的热处理制得LSTO薄膜.对薄膜前驱粉末进行了热重与差热分析,确定了LSTO的合成过程.X射线衍射分析表明,在840,890℃恒温60 min的热处理后样品薄膜为单相的LSTO,具有明显的(100)择优生长取向,缓慢升温更有利于LSTO薄膜的结晶.扫描电镜结果表明:LSTO薄膜表面光滑致密,采用四探针法测得薄膜电阻率约为1×10-2Ω.cm.这种方法制取的LSTO薄膜电阻率小,外延性好,可作为YBCO涂层导体的导电缓冲层.

Preparation of Conductive La_(0.5)Sr_(0.5)TiO_3 Thin Films by Chemical Solution Deposition

Epitaxial La0.5Sr0.5TiO3(LSTO) thin films were prepared by chemical solution deposition as buffer layer for YBCO coated conductor, i.e. the high-temperature 2nd-generation superconducting strip. Lanthanum acetate (La(CH3COO)3 · 1.5H2O), strontium carbonate (SrCO3) and butyl titanium (C16H36O4Ti) were used as precursors to synthesize the precursor solution where the La concentration is about 0.14 mol/L. The precursor solution was deposited by spin-coating method on the substrate and the LSTO film was obtained after proper heat treatment. Differential thermal analysis and thermogravimetric analysis were both made to determine the synthesize process of LSTO film. XRD results showed that the films annealed at 840°C and 890°C are of single-phase LSTO with (100)preferred orientation, and slow temperature rise benefits the crystallization of LSTO films. SEM observation showed that the LSTO films are smooth and dense. The resistivity of these films is about 1 × 10^-2 Ω · cm as the result of four probe method. The epitaxial conductive LSTO films can be a promising buffer layer for YBCO coated conductor.