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Band structure and optical constants of SnS <sub/>2</sub> single crystals
摘要： Absorption (K), reflection (R) and wavelength modulated transmission (ΔT/Δλ) spectra in SnS2 crystals of hexagonal phase (space group P63/mmc) were investigated in temperature interval from 300 to 10 K. It was established that indirect band gap (Eg ind - 2.403 eV) is due to unpolarized indirect transitions between Γ and M points of Brillouin zone. A minimal direct band gap (Eg dir - 2.623 eV) in E||b polarization is formed by direct allowed transitions and in E⊥b polarization (2.698 eV) by forbidden transitions in Γ point of Brillouin zone. A magnitude of refractive index (n) changes from 3 to 4 and has a maximum at 2.6 eV. Optical functions (n, k, ε1 and ε2) in energy region E > Eg (3 - 6.5 eV) were calculated from measured reflection spectra by Kramers-Kronig analysis. Features observed in reflection and optical function spectra were assigned to electron transitions. This electron transitions were localized in framework of theoretically calculated band structure.
关键词： optical functions,electronic band structure,layered SnS2 crystals,absorption, reflection and transmission spectra
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Bistable Optical Functions of Polyethylene Glycol
摘要： Polyethylene glycol takes both transparent and translucent phases during the phase transition process at around room temperature. This bistability seems useful to create optical devices including 3D displays and tunable random lasers. These devices, however, require a spot-heating technique that controls the phase of each microelement. Self-heating of microelements is achievable if the electric conductivity of the polyethylene glycol is enhanced by the dissolution of alkaline halide salts.
关键词： ionic conduction,bistability,optical functions,polyethylene glycol,phase transition
更新于2025-09-23 15:23:52