X-ray adsorption study at Pr L3-edge in (Y, Br)Ba2Cu3O7−δ system

X-ray absorption study of the system

“…The presence of two distances at mixed compositions suggests that not too much weight should be put on the simple bond valence model (although most complex oxide materials show the presence of several cation-oxygen distances and the model has been successfully applied to these) but a possible change in Pr valence could again be of significance for the superconductivity. Our Pr L 3 XANES results [9] also suggest a change in the Pr valence as the composition changes, as do those of Lytle et al [7].…”

“…A change in Pr-O distance may be expected to change the Pr valence and several measurements [3,4] show such a change. However, some x-ray spectroscopy and photoemission measurements [5,6] suggest that Pr occurs only in the trivalent state in these materials, although others [7,8], including our XANES results [9], do suggest a variable Pr valence. Such results may, however, be affected by the perturbing effects of the holes introduced.…”

“…This study provides detailed structural information, in particular on local distortions around the Y and Pr sites. We also briefly consider the XANES results [9] which indicate possible valence changes. Our results are interpreted in terms of a change in the valence of the Pr ion, from 4+ close to x = 0 to 3+ at x = 1.0.…”

Comparative study on structure and magnetic properties of polycrystalline PrxY1−xBa2Cu3O7−δ prepared in oxygen and argon atmosphere

“…At the same time, it was argued that a change in Pr-O distance might cause a change of Pr valence (and several measurements [14,15] seem to confirm such a change). Even though some X-ray spectroscopy and photoemission measurements [16,17] suggest that Pr occurs only in the trivalent state in these materials, others [18][19][20] strongly suggest a possibility of variable Pr valence. In the last two decades, superconductivity in Pr-123 samples has been reported by some authors where the method of syntheses appears to be responsible for the formation of the stable superconducting phase [21][22][23].…”

X-ray spectroscopic study of the electronic structure ofY1−xPrxBa2Cu3Yamaoka1, Oohashi2, Jarrige3 et al. 2008Phys. Rev. B204220View full textAdd to dashboardCite

“…Thus, the ratio of the Pr 4+ component was reported to be inversely proportional to x by means of x-ray absorption spectroscopy ͑XAS͒. [21][22][23][24] Neukirch et al suggested an upper limit of 10% on the relative Pr 4+ content in YPrBCO by means of Pr M and Pr L edge XASs. 25 Yet, Hilscher et al 26 found an admixture of ϳ15% of Pr 4+ using XAS at the Pr L 3 and Pr L 2 edges.…”