J. Phys. IV France 7 (1997) C2-1121-C2-1122
EXAFS and XANES Study of Structural and Electronic Changes in Y1-xPrxBa2Cu3O7M. Khaled1, N.L. Saini1, S.J. Gurman2, J.C. Amiss3 and K.B. Garg1
1 Department of Physics, University of Rajasthan, Jaipur 30 2004, India
2 Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
3 Biomedical Sciences, Sheffield Hallam University, Sheffield S1 1WB, UK
We present X-ray absorption fine structure (EXAFS) data from Y,Pr,Ba and Cu edges for various concentrations of Pr in Y1-xPrxBa2Cu3O7. Analysis of Y K-edge EXAFS shows no evidence for major changes in interatomic distance or in its mean square variation with composition. The individual Ba-O distances have weak compositional dependence. The Pr-O distance is found to vary linearly with composition. We have interpreted the changes in Pr-O distance to conclude the existence of Pr in a mixture of Pr3+ and Pr4+ States. The Cu-O coordinates at about 2.4 Å (the apical oxygen for Cu) appear to have a compositional dependence. Changes in electronic structure are also discussed besides structural changes along with their correlation.
© EDP Sciences 1997