Superconducting YBCO Films Prepared by Electrodeposition and Spray Pyrolysis
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Superconducting YBCO Films Prepared by Electrodeposition and Spray Pyrolysis S. Phok, P.D. Spagnol, T. Chaudhuri, and R.N. Bhattacharya National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401, USA
ABSTRACT Biaxially textured YBa2Cu3O7-δ films were fabricated by non-vacuum electrodeposition and spray pyrolysis techniques. Electrodeposited YBCO was prepared on sputtered copper/single-crystal substrates. Electrodeposition was carried out at constant voltage and the deposition was completed in only few minutes. The thickness of the as-deposited films was in the range of 0.6 to 2 µm. The optimized sputtered copper layer thickness was about 200 Å on SrTiO3. In the spray pyrolysis method, the solution is sprayed directly onto SrTiO3 substrates. The substrate temperature is about 100°C. The thickness of the as-deposited films was in the range of 1.2 to 2 µm. The electrodeposited and spray-deposited films were annealed at temperatures ranging from 800º to 920ºC under various flowing gas mixtures. X-ray diffraction analysis revealed that processed electrodeposited and spray-deposited films were biaxially textured, where YBCO grains were well oriented along the c-axis and in the (a,b) plane. ∆ω, deduced from the rocking curve on the (005) reflection, was as low as 0.46º. ∆ϕ, deduced from the phi-scan on the (103) reflection, was as low as 0.54º. The critical current density for these types of films is about 0.5 MA/cm2 at 77 K and 0 T.
INTRODUCTION Electrodeposition and spray pyrolysis techniques are promising alternative nonvacuum methods for fabricating high critical temperature superconducting (HTSC) materials. Electrodeposition and spray pyrolysis techniques are simple, low cost, and can be scaled up for continuous large-area, long-length deposition. Electrodeposition has been used to prepare biaxially textured superconducting materials such as (Tl,Bi)-(Sr, Ba)-Ca-Cu-O oxides with transport density current, Jc, above 1 MA/cm2 [1] and Bi-SrCa-Cu-O oxides with Jc about 0.8 MA/cm2 [2]. Superconducting YBa2Cu3O7-δ (YBCO) films have also been investigated by the electrodeposition process. Sequentially electrodeposited films prepared on silver substrate have been reported with Jc of about 0.1 MA/cm2 [3]. Epitaxial, thick YBCO films with Jc above 1 MA/cm2 [4] were also obtained by an ultrasonic high-temperature (825°C substrate temperature) spray pyrolysis technique. In this paper, we describe YBCO films prepared by electrodeposition and spray pyrolysis at low temperature. YBCO was electrodeposited on sputtered copper substrates.
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EXPERIMENTAL DETAILS The electrodeposition bath was a mixture of yttrium nitrate, barium trifluoromethane sulfonate [Ba(CF3SO3)2], and copper nitrate salts dissolved in dimethyl sulfoxide (DMSO). Single-crystal substrates coated with a thin sputtered copper layer was used as a working electrode (substrate). The electrodeposition system was composed of a reference Pt electrode, two counting Pt electrodes, and a working electrode. Electrodeposition was performed at room te
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