Quantitative XANES Spectroscopy Study on the Prototype Hole- and Electron-Doped High-T-c Superconductor Systems, (La,Sr)(2)CuO4 and (Nd,Ce)(2)CuO4
Journal
Chemistry of Materials
Journal Volume
20
Journal Issue
16
Pages
5414-5420
Date Issued
2008
Author(s)
Abstract
Here we demonstrate that the Cu L-edge XANES (X-ray absorption near-edge structure) spectroscopy can be employed for quantitative analysis of the level of carrier-doping in the prototype hole- and electron-doped high-Tc superconductor systems, (La1-x-Srx)2CuO 4+δ and (Nd1-xCex)2CuO 4+δ. The progress in holedoping in the (La1-x) 2CuO4+δ system is seen as development of the shoulder peak (due to nominally trivalent copper) on the high-energy side of the main peak (due to nominally divalent copper) in the Cu L3-edge region, whereas the progress in electron-doping in the (Nd1-xCex) 2CuO4+δ system results in an additional absorption peak at about 934 eV (due to nominally monovalent copper), together with a decrease in the intensity of the main peak (due to nominally divalent copper). On the basis of these features, Cu-valence values are quantitatively obtained in excellent agreement with those calculated for the same samples from the precise oxygen contents, 4+δ, determined by means of wet-chemical analysis. The valence of Ce in (Nd1-xCex)2CuO 4+δ is revealed to be somewhat lower than +4 (ca. +3.8) on the basis of Ce M5-edge XANES data. In the O K-edge XANES spectra, the increase in the CuO2-plane hole concentration with increasing x in (La1-xSrx)2CuO4+δ is seen as an enhancement in the intensity of the pre-edge feature at ∼528.9 eV, whereas for (Nd1-xCex)2CuO4+δ, no signs are observed that could be directly assigned to the change in electron-doping level. © 2008 American Chemical Society.
SDGs
Type
journal article