前驱液中添加聚乙烯吡咯烷酮对YBa_2Cu_3O_(7-δ)膜形貌和性能的影响

Effect of polyvinylpyrrolidon (PVP) in precursor solution on the morphology and properties of YBCO films

用三氟乙酸金属有机物沉积(TFA-MOD)方法在LaAlO3(100)基底上生长YBa2Cu3O7-δ(YB-CO)超导薄膜,研究了向前驱液中添加聚乙烯吡咯烷酮(PVP)对YBCO薄膜微结构和超导性能的影响。涂膜在氧气环境中进行200～250℃热解,再经775℃氩气环境下结晶后获得YBCO超导薄膜。在相同热处理条件下,未添加PVP的前驱液制得的YBCO薄膜临界电流密度为4050A/cm2,添加PVP的前驱液制得的YBCO薄膜临界电流密度为5800A/cm2。后者表现出较少的孔洞,较强的c轴取向,较纯的双轴织构和较高的临界电流密度。因此,向前驱液中添加PVP的化学方法可以改进YBCO涂层导体的MOD制备过程。总压,氧分压和热处理温度等工艺条件将进一步优化,以提高临界电流密度。

Superconductive YBa2Cu3O7-δ （YBCO） thin films were grown on LaAlO3 （100） substrates by trifluoroacetate metal organic deposition （TFA-MOD） method, and the influences by adding polyvinylpyrrolidone （PVP） into the precursor solution on the microstructures and superconducting properties of YBCO films were investigated. Coated film was calcined at 200-250℃ in a moisture-containing oxygen atmosphere, and superconducting YBCO films have been obtained by conducting a conversion heat treatment at 775℃ in a moisture-containing Ar （1000×10^-6 oxygen） atmosphere. In the same conditions, the critical current density （Jc） of YBCO film were 4500A/cm^2 （without PVP） and 5800A/cm^2 （with PVP）, respectively. The later showed less pores, stronger c-axis orientation, purer biaxial texture and higher Jc. So this chemical modification approach adding PVP into the precursor solution is a possible candidate for improving MOD-processing of YBCO coated conductor. Further optimization of processing conditions such as total pressure, oxygen partial pressure, annealing temperature, etc. is in progress to improve critical current density.