Segregation and competition of Y-based impurities in Y-rich biepitaxial YBCO samples is investigated. The analysis of distribution and microstructure of the precipitates is performed by high resolution electron microscopy HREM.. Y2O3 precipitates are found in 103. YBCO films grown on 110. SrTiO3 STO. substrates. On the same biepitaxial samples, Y2BaCuO5 Y211. precipitates are found in 001. YBCO films deposited on an intermediate 110. MgO seed layer. Agglomeration of Y211 precipitates is observed near the edge in the MgO seed layer. The experimental data are discussed in the context of phase competition, nucleation, epitaxy and surface migration in the Y–Ba–Cu–O system. It is deduced that the change of supersaturation and surface energy, also governed by the favorable epitaxy of the secondary phase with the substrate or the YBCO matrix, plays a major role in determining the segregation of either Y211 or Y2O3 precipitates
Phase competition between YBa2Cu3O7-x and Y2O3 precipitates in Y – rich YBCO thin films
TAFURI, Francesco;
1999
Abstract
Segregation and competition of Y-based impurities in Y-rich biepitaxial YBCO samples is investigated. The analysis of distribution and microstructure of the precipitates is performed by high resolution electron microscopy HREM.. Y2O3 precipitates are found in 103. YBCO films grown on 110. SrTiO3 STO. substrates. On the same biepitaxial samples, Y2BaCuO5 Y211. precipitates are found in 001. YBCO films deposited on an intermediate 110. MgO seed layer. Agglomeration of Y211 precipitates is observed near the edge in the MgO seed layer. The experimental data are discussed in the context of phase competition, nucleation, epitaxy and surface migration in the Y–Ba–Cu–O system. It is deduced that the change of supersaturation and surface energy, also governed by the favorable epitaxy of the secondary phase with the substrate or the YBCO matrix, plays a major role in determining the segregation of either Y211 or Y2O3 precipitatesI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
