Local structure relaxation in nanosized tungstates

Local structure of nanosized tungstates revealed by evolutionary algorithm

“…A well known correlation between the frequency of stretching vibration and the length of the WO bond [47] suggests that the bond length corresponding to the observed Raman peak should be about 1.7 Å long. The remaining second group of two WO bonds with the length about 2.3–2.4 Å arguably can be associated with non‐bridging hydrogenated WOH bonds, as evidenced by FTIR spectra , or to bridging and randomly oriented bonds between touching nanoparticles.…”

“…The calculation of the cluster potential was performed only once at the beginning (before the main EA‐EXAFS calculations) for the average atom configurations, corresponding to the bulk CoWO 4 and CuWO 4 crystallographic structures. Also the values of E 0 (the energy reference of the photoelectron kinetic energy ) and (the amplitude scaling factor , in this work) parameters were fixed at their values determined for crystalline tungstates . The complex exchange‐correlation Hedin–Lundqvist potential and default values of muffin‐tin radii, as provided within the FEFF8 code, were employed .…”

“…X‐ray absorption spectroscopy may be a proper tool to investigate the structure of wolframite‐type compounds due to its local sensitivity and element selectivity . In our recent works we have used extended X‐ray absorption spectroscopy (EXAFS) to study the local structure of microcrystalline and nanocrystalline tungstates (ZnWO 4 , NiWO 4 , MnWO 4 , CoWO 4 , CuWO 4 , CaWO 4 , SrWO 4 , BaWO 4 , SnWO 4 ). EXAFS studies of AgWO 4 (W L 3 ‐edge) , CdWO 4 (W L 3 and Cd K‐edges) , PbWO 4 single crystals (W L 3 ‐edge) and microcrystalline PbWO 4 (W and Pb L 3 ‐edges) are reported in literature.…”

Synchrotron-based far-infrared spectroscopy of nickel tungstate

“…Recent interests on NiWO 4 have been stimulated by its applications as a catalyst [9,10], in supercapacitors [10,11] and light-controlled bipolar resistive switching devices [12] as well as by numerous possibilities to produce it in nanostructured form [13][14][15][16][17][18][19][20].…”

UV-VUV synchrotron radiation spectroscopy of NiWO4

“…Radial distribution functions (RDFs) G(R) (Fig. 3) for [34,36,37] from the Ni(Zn) K-edge and W L 3 -edge extended x-ray absorption fine structure (EXAFS) spectra. Theoretical scattering amplitude and phase shift functions, employed in the EXAFS simulations, were calculated for NiWO 4 and ZnWO 4 crystallographic structures by the ab initio FEFF8 code [38,39] using complex exchange-correlation Hedin-Lundqvist potential.…”