SYNTHESIS OF HIGH TRANSITION-TEMPERATURE SUPERCONDUCTING Y-BA-CU-O FILMS BY RADIOFREQUENCY PLASMA FLASH EVAPORATION

The authors have successfully developed a novel process for the deposition of multicomponent systems, namely radio-frequency (RF) plasma flash evaporation, in which powder mixtures of constituents are continuously injected into a RF plasma and are coevaporated and codeposited onto a substrate. The Y-Ba-Cu-O films prepared by this method showed excellent superconducting properties without postannealing; a deposition rate above several hundred nm/min was achieved. The film deposited on a MgO (100) substrate at 700°C revealed c-axis-oriented, polycrystalline orthorhombic oxygen-deficient perovskite showing a superconducting transition temperature of 87 K and a critical current density on the order of 1 × 106 A/cm2 at 77 K estimated from the magnetization. The conditions of plasmas during the deposition were measured by optical emission spectroscopy.