Cracking of rare earth barium cuprate films prepared by liquid phase epitaxy

A high growth rate of REBa2Cu3O7-delta (RE rare earth elements) superconduc ting films is achieved with liquid phase epitaxy. The occurance of cracks i s one of the major problems for applications of these thick films. To achie ve crack free films, it is necessary to understand the formation of cracks in REBa2Cu3O7-delta films. Investigations were carried out on YBa2Cu3O7-del ta and (Y,Pr)Ba2Cu3O7-delta films on NdGaO3 substrates and on new SrPrGaO4 substrates with tetragonal K2NIF4 structure (space group I4/mmm). A thermod ynamic model for understanding the crack spacing together with mechanical p roperties determined in melt textured YBa2Cu3O7-delta bulk samples was appl ied.