Epitaxial growth of biaxially aligned Y-Ba-Cu-O superconductors by spray pyrolysis on textured Ag ribbons and single crystal substrates

The deposition of Y-123 films by spray pyrolysis at room pressure on textur ed Ag ribbons was studied as an alternative to the high vacuum coated tapes techniques. It is shown that an epitaxial growth, at a rate of 0.35 mum/mi n, is obtained on rolled and annealed {110}< 011 > textured Ag ribbons, wit hout buffer layers. Processing parameters are optimized in order to get biaxially aligned Y-123 films with a thickness of a few micrometers, A nitrate solution of Y, Ba a nd Cu was sprayed on the substrate heated at 850 degreesC - 900 degreesC. T he films were then annealed in air in the same temperature range and then o xygen loaded in flowing oxygen. By a careful control of the nitrate stoichi ometry in the aqueous initial solution, phase pure Y-123 films were deposit ed on (110) oriented Ag single crystals, (110)< 011 > Ag textured tapes and (100) SrTiO3 substrates, X-ray investigations show a high degree of c-axis alignment. A biaxial orientation is found from X-ray pole figures and phi -scans. FWHM values as small as 1 degrees, 4 degrees and 11 degrees are mea sured on SrTiO3, (110) Ag single crystal and (110)< 011 > Ag textured ribbo ns, respectively. The critical temperature was 90 K.