AS-GROWN PREPARATION OF HIGH-CRITICAL-TEMPERATURE SUPERCONDUCTING Y1BA2CU3O7-X FILMS BY RADIOFREQUENCY PLASMA FLASH EVAPORATION

As-grown superconducting Y1Ba2Cu3O7-x films were successfully synthesized on (100) MgO and (100) SrTiO3 substrates by radio-frequency (rf) plasma flash evaporation, in which fine powder mixtures of constituents are continuously injected into an rf plasma, co-evaporated, and co-deposited onto a substrate. In particular, films deposited on a (100) SrTiO3 substrate at 670-degrees-C exhibited a superconducting transition temperature T(c) of 92 K and critical current density J(c) of 3 x 10(5) A/cm2 under zero magnetic field at 77 K. The excitation temperatures of several species during the depositions were estimated from optical emission spectroscopy. The temperature of Y+ was a few thousand degrees lower than that of Ba+ and Cu. The difference in these excitation temperatures revealed that this plasma process was a nonequilibrium deposition.