Temperature dependent bandgap in NaBi(WO4)2 single crystals

Isik, M.
Hasanlı, Nızamı
Darvishov, N.H.
Bagiev, V.E.
© 2022 Elsevier GmbHThe double tungstates have been an attractive research interest due to their optoelectronic applications. In the present work, NaBi(WO4)2, one of the members of double tungstates family, was grown by Czochralski method as single crystal form and optically investigated. X-ray diffraction pattern presented three peaks associated with tetragonal scheelite crystalline structure. Optical properties of the crystal were studied by performing temperature-dependent transmission measurements between 10 and 300 K. The shift of the absorption edge to higher energies was observed with decrease of temperature. The analyses indicated that direct band gap energy increases from 3.50 to 3.60 eV when the temperature was decreased from room temperature to 10 K. The temperature dependency of bandgap was studied considering the Varshni model and fitting of the experimental data under the light of model presented the optical parameters of band gap energy at 0 K, rate of band gap change with temperature and Debye temperature as Eg(0) = 3.61 eV, γ = − 8.83 × 10−4 eV/K and β = 456 K, respectively. Urbach energies were also determined from the analyses as 122 and 113 meV for 10 and 300 K experimental data, respectively.


Public-private partnership as a policy instrument : the case of Çalbir
Özkan, Umut Rıza; Üstüner, Mustafa Yılmaz; Department of Political Science and Public Administration (2007)
This dissertation assesses the nature and features of public-private partnerships in the case of ÇALBĐR. In this study, the public policy literature (especially policy transfer, policy formation and implementation, and network approach) has been used to explain the policy process for the adoption of such a policy instrument. The findings of this study can be summarized as: Firstly, this study indicates that the selection of policy instrument- public private partnership- in the case of ÇALBĐR was not neutral...
Temperature dependence of the Raman frequencies for the ammonia solid II lattice mode
Yurtseven, Hasan Hamit (2003-04-01)
This study gives our calculations of the Raman frequencies for the rotatory lattice (librational) mode of ammonia solid 11 using volume data at various temperatures, which are close to its melting temperature, for the pressures of 3.65, 5.02, and 6.57 kbars. Our calculated Raman frequencies for this mode vary linearly with the temperature and agreed very well with the observed frequencies for all the pressures studied. This shows that, by calculating the Raman frequencies from the volume data, the spectrosc...
Structural and temperature-tuned bandgap characteristics of thermally evaporated beta-In2S3 thin films
Surucu, O.; Isik, M.; Terlemezoglu, M.; Hasanlı, Nızamı; Parlak, M. (2021-05-01)
In2S3 is one of the attractive compounds taking remarkable interest in optoelectronic device applications. The present study reports the structural and optical characteristics of thermally evaporated beta-In2S3 thin films. The crystalline structure of the thin films was found as cubic taking into account the observed diffraction peaks in the X-ray diffraction pattern. The atomic compositional ratio of constituent elements was obtained as consistent with chemical formula of In2S3. Three peaks around 275, 309...
Optical transitions in Si/Ge superlattices
Erkoc, S; Katırcıoğlu, Şenay (1997-02-28)
We have performed self-consistent field calculations of the electronic structure of Si/Ge square-well superlattices within the effective-mass theory. We have computed the optical transition matrix elements involving transitions from the hole states to states in the conduction band, and we have also computed the oscillator strength matrix elements for the transitions between the states in the conduction band. (C) 1997 Elsevier Science S.A.
Sensory applications of resonator based metamaterial absorber
Metamaterials are attractive media for scientific society for their potential multi-functional and a wide range of applications due to their unusual electromagnetic properties. In this paper, we present several important applications including pressure, density and volumetric moisture sensing based on rectangular split ring structure with a strip line. These applications are carried out experimentally and numerically. Since the sensing ability is mostly connected with the resonance frequencies, we have care...
Citation Formats
M. Isik, N. Hasanlı, N. H. Darvishov, and V. E. Bagiev, “Temperature dependent bandgap in NaBi(WO4)2 single crystals,” Optik, vol. 258, pp. 0–0, 2022, Accessed: 00, 2022. [Online]. Available: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85126396777&origin=inward.