84 research outputs found
Synchrotron-based far-infrared spectroscopy of nickel tungstate
Monoclinic antiferromagnetic NiW ₄ was studied by far-infrared (30–600 cm−¹) absorption spectroscopy in the temperature range of 5–300 K using the synchrotron radiation from SOLEIL source. Two isomorphous CoWO₄ and ZnWO₄ tungstates were investigated for comparison. The phonon contributions in the far-infrared range of tungstates were interpreted using the first-principles spin-polarized linear combination of atomic orbital calculations. No contributions from magnetic excitations were found in NiWO₄ and CoWO₄ below their Neel temperatures down to 5 K
UV-VUV synchrotron radiation spectroscopy of NiWO₄
Photoluminescence and excitation spectra of microcrystalline and nanocrystalline nickel tungstate (NiWO₄) were measured using UV-VUV synchrotron radiation source. The origin of the bands is interpreted using comparative analysis with isostructural ZnWO₄ tungstate and based on the results of recent first-principles band structure calculations. The influence of the local atomic structure relaxation and of Ni²⁺ intra-ion d–d transitions on the photoluminescence band intensity are discussed
Phonon study of rhombohedral BS under high pressure
Raman spectra of rhombohedral boron monosulfide (r-BS) were measured under
pressures up to 34 GPa at room temperature. No pressure-induced structural
phase transition was observed, while strong pressure shift of Raman bands
towards higher wavenumbers has been revealed. IR spectroscopy as a
complementary technique has been used in order to completely describe the
phonon modes of r-BS. All experimentally observed bands have been compared with
theoretically calculated ones and modes assignment has been performed. r-BS
enriched by 10B isotope was synthesized, and the effect of boron isotopic
substitution on Raman spectra was observed and analyzed
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