Using xhyphen;rayhyphen;absorption nearhyphen;edge spectroscopy (XANES) the Pr valence in the pseudoternary Pr2(CoxFe1minus;x)14B compounds has been directly determined. PraseodymiumLIIIedge XANES structures were obtained for thex=0, 0.3, 0.5, 0.7, and 1 compositions spanning the entire Co concentration range. It is found that the Pr valence is constant through the series and is identical to that in formally trivalent praseodymium acetate. The results demonstrate that the anomalous variation of the magnetocrystalline anisotropy withxin the Pr2(CoxFe1minus;x)14B compounds vishyphen;agrave;hyphen;vis their Ndhyphen;based counterparts does not arise from a Pr valence instability, as has been speculated in the literature, but must originate elsewhere. For comparison purposes XANES spectra for some relevant Ce and Nd materials are also reported.
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