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Description
X-ray Absorption Spectroscopy (XAS) measurements for Nickel-doped borate glass, xLi2O.(1 − x − y)B2O3 + yNiO, where x = 0.33 and y = 0.05, have been conducted at The Photon Factory, Tsukuba, Japan. The X-ray absorption near edge structure (XANES) at the energy-region just above the nickel K-edge (8333eV) includes a superimposed X-ray absorption fine structure (XAFS). XAFS measurements have the potential for providing the highest accurate positioning of atoms in proximity to the photoemitter. Typical standard data collection for XAFS does not, however, adequately account for key systematics, which degrades accuracy, and impacts subsequent analysis. XAFS here are obtained using the X-ray Extended Range Technique (XERT), which has the advantage of recording all known contributions to uncertainty during the experiment and correcting for these during data analysis [1]. This work heralds the first application of XERT for dilute borate glass and provides a critical test-of-application for disordered glass. We use our fitting software, efeffit, particularly because of its uncertainty propagation capability. We performed four Trend Studies according to the inner lattice to which borate or lithium oxide tetrahedrons are connected. Trend Studies included: 1, distorted octahedral Ni.(6-X)BO4.XLiO4, where X=1, 2, 3, 4, 5; 2, distorted planar Ni.(4-X)BO4.XLiO4, where X=1, 2, 3; 3, distorted planar but space-filling Ni.(4-X)BO4.XLiO4, where X=1, 2, 3; and 4, distorted tetrahedral Ni.(4-X)BO4.XLiO4, where X=1, 2, 3. Our results use fixed values of S02 of 1.00 or 0.80 for structure 1, and S02 =1.00 for other Trend Studies. These studies are followed by ab initio calculations for glass [2] with particular stoichiometries [3]. We do an extensive multi-dimensional grid and structural investigation of these hypotheses. We find exciting possible structures in a partially disordered system. We present our findings as a basis for any ab initio determination of XAFS structure in any quantum system.