高温超导氧化物薄膜的激光化学气相沉积技术

In the second generation of high temperature superconducting films, GdBa2Cu3O7-x (GdBCO) shows superrior superconductivities than YBa2Cu3O7-x in high magnetic fields. In the present project, a brand-new laser chemical vapor depositon (Laser CVD) system is self-designed and constructed to prepare GdBCO film at a high speed. The laser CVD is equipped by a large irradiation diameter of 20 to 100 mm, high laser power up to 500 W in a Super-Gaussian distributed continous mode diode pump solid state laser, and constructed a continous inject system of liquid precursors to meet the prepration of high temperature superconducting long tap. The effects of laser power, oxygen partial pressure and deposition rate on the preferred orientation, epitaxial growth, micro- and nano-structure and superconducting properties are investigated. The GdBCO films with a high critical current and high critical current density were developed by increasing the film's thickness and pinning center through doping of Zr and Ca. The electrical properties of GdBCO films prepared by laser CVD is investigated in high magnetic fields. The mechanism of high-speed deposition in laser CVD technology is discussed by comparing the deposition rate, micro- and nano- structure of the GdBCO films using three kinds of laser generator, i.e., CO2, Nd:YAG and diode laser.

第二代高温超导薄膜中，GdBa2Cu3O7-x（GdBCO）在强磁场应用领域具有比YBa2Cu3O7-x更优异的超导性能。本项目申请人自行设计新型激光化学气相沉积（激光CVD）系统用于高速制备GdBCO薄膜。该激光CVD配置有照射直径20-100 mm、激光功率高达500 W的超高斯分布连续性泵浦固体激光，并建立液体原料喷雾供给系统使之适用于高温超导长带材的制备。重点研究激光功率、氧气分压、沉积速度对薄膜的生长取向、外延模式、微观结构的影响，获得织构组织和电学性能优异的GdBCO超导薄膜。通过增加膜厚和由Zr、Ca等元素掺杂形成的大量钉扎中心提高其载流能力，获得临界电流密度和临界电流更大的GdBCO薄膜。研究激光CVD法制备GdBCO薄膜的电学性能在强磁场中的变化。通过比较三种不同波长的激光对GdBCO薄膜的微观结构和沉积速度的影响探索激光CVD高速沉积速度的机理。

第二代高温超导薄膜中，GdBa2Cu3O7-x（GdBCO）在强磁场应用领域具有比YBa2Cu3O7-x更优异的超导性能，本项目申请人自行设计新型激光化学气相沉积（激光CVD）系统用于高速制备GdBCO薄膜。该激光CVD配置有照射直径20-100 mm、激光功率高达500 W的超高斯分布连续性泵浦固体激光，并建立原料连续供给系统使之适用于高温超导长带材的制备。重点研究激光功率、氧气分压、沉积速度对薄膜的生长取向、外延模式、微观结构的影响，获得织构组织和电学性能优异的GdBCO超导薄膜。通过增加膜厚和钉扎中心提高其载流能力，获得临界电流密度和临界电流更大的REBCO薄膜。研究激光CVD法制备GdBCO薄膜的电学性能在强磁场中的变化。通过调查沉积条件-微观结构-超导特性的相关性，提出了激光CVD制备REBCO高温超导薄膜的高速沉积机理。