Measuring oxygen stoichiometry in YBa2Cu3O7-x by micro-Raman spectroscopy

Abstract

Micro-Raman spectroscopy is well suited for microstructural analysis of YBa2Cu3O7-x (YBCO) superconductors. Of particular interest is the oxygen stoichiometry, 7 - x, on which many superconducting properties depend. It is common to use the frequency of the Raman Ag spectral peak near 500 cm-1 to obtain a quantitative measure of 7 - x. Another Ag peak exists near 335 cm-1. The variation of the position of this peak appears to be minimal as 7 - x changes. However, this peak is asymmetric for orthorhombic YBCO and symmetric for tetragonal YBCO. We have observed a variation in the asymmetry of this peak with 7 - x, in Raman spectra obtained from single grains in a sample of polycrystalline YBCO. We propose the use of this peak's asymmetry as a quantitative means to measure oxygen stoichiometry. Show more