Structural distortion in (La,Sr)(2)CuO4 cuprates: an insight using luminescence and EPR probes

We have demonstrated that Eu3+. luminescence can be successfully employed a s a local probe to explore the microscopic symmetry of the cationic sites i n the Sr2+-substituted lanthanum cuprate superconductor(s). It has been fou nd that Sr2+ substitution in La1-xSrxCuO4 (x similar to 0.4) does not alter the microscopic symmetry of the cationic site(s). Further, using electron paramagnetic resonance spectroscopy we have demonstrated that the hole cent ers arising out of Sr2+ substitution are localized around Cu2+ site(s). (C) 1999 Elsevier Science B.V. All rights reserved.