Preparation of REBa2Cu3O7-x films grown by metal trifluoro acetate precursors

Metal organic deposition (MOD) process using metal trifluoroacetate (TFA) p recursors was applied to the NdBa2Cu3O6+y (Nd123) and the T-c dependence of experimental conditions such as oxygen partial pressure (P-O2) and substra te temperature (T-s) for annealing was investigated. Thin films grown on si ngle crystal SrTiO3 at T-s = 800 degreesC under P-O2 = 3 x 10(-4) atm showe d a T-c0 of 89 K. However, from the results of TEM-EDS measurements, the su bstitution value of x in Nd1-xBa2-xCu3O6+y increased from the substrate tow ard the surface in the film. These experimental results could be explained thermodynamically by the following model. The basic idea of our model is th at the Ba potential is changed by coarsening of BaF2 during the annealing f or the growth. This model predicts that the small substitution value can be obtained with a higher growth rate of the Nd123 phase under low P-O2. (C) 2001 Elsevier Science B.V. All rights reserved.