Temperature dependent bandgap in NaBi(WO4)2 single crystals


Isik M., HASANLI N., Darvishov N., Bagiev V.

Optik, vol.258, 2022 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 258
  • Publication Date: 2022
  • Doi Number: 10.1016/j.ijleo.2022.168811
  • Journal Name: Optik
  • Journal Indexes: Science Citation Index Expanded, Scopus, Academic Search Premier, Aerospace Database, Communication Abstracts, Compendex, INSPEC
  • Keywords: Double tungstates, NaBi(WO4)(2), NaBi(MoO4)(2), Optical properties, Electronic structure

Abstract

© 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.