Electronic excitations in ZnWO4 and ZnxNi1−xWO4 (x = 0.1 − 0.9) using VUV synchrotron radiation

• Published in: Central European journal of physics 2011-04, Vol.9 (2), p.432-437
• Main Authors: Kalinko, Aleksandr, Kotlov, Alexey, Kuzmin, Alexei, Pankratov, Vladimir, Popov, Anatoli I., Shirmane, Liana
• Format: Article
• Language: English
• Subjects: Biological and Medical Physics; Biophysics; Environmental Physics; Geophysics/Geodesy; Physical Chemistry; Physics; Physics and Astronomy; Research Article
• ISSN: 1895-1082; 1644-3608
• DOI: 10.2478/s11534-010-0108-7

The photoluminescence spectra and luminescence excitation spectra of pure microcrystalline and nano-sized ZnWO 4 as well as the Zn x Ni 1− x WO 4 solid solutions were studied using vacuum ultraviolet (VUV) synchrotron radiation. The samples were also characterized by x-ray powder diffraction. We found that: (i) the shape of the photoluminescence band at 2.5 eV, being due to radiative electron transitions within the [WO 6 ] 6− anions, becomes modulated by the optical absorption of Ni 2+ ions in the Zn x Ni 1− x WO 4 solid solutions; and (ii) no significant change in the excitation spectra of Zn 0.9 Ni 0.1 WO 4 is observed compared to pure ZnWO 4 . At the same time, a shift of the excitonic bands to smaller energies and a set of peaks, attributed to the one-electron transitions from the top of the valence band to quasi-localized states, were observed in the excitation spectrum of nano-sized ZnWO 4 .