XANES Study of the Valence of Pb IN (Tl_(0.5)Pb_(0.5))Sr_2Ca_(1-x)Y_xCu_2O_(7- δ)

Abstract

Near edge x-ray-absorption spectra at Pb L_3-edges have been measured for (Tl_(0.5)Pb_(0.5))Sr_2Ca_(1-x)Y_xCu_2O_(7-δ) compound series. It is found that the intensity of the 2p→6s transition feature decreases with the substitution of Ca^(+2) by Y^(+3). This result indicates that some electronic charges have been transferred into the Pb(Tl)-O layers by this substitution. Detailed analysis suggests that the valence value of Pb in this compound series is close to +4 and it decreases with the increase of the Y-doping level x.

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