Urbach Band Research Articles

Structural, and Physical properties of Antimonite glass in the (80-x) Sb2O3-20PbO-xZnO ternary system

The study of vitreous systems based on antimony oxide Sb2O3 has been investigated. The glass formation limits in the Sb2O3-PbO-ZnO ternary system are reported. The Tg is greater than 300°C, according to thermal measurements performed using differential scanning calorimetry. Tg increases with the zinc oxide content as a general rule. In the (80-x) Sb2O3-20PbO-xZnO system, the effect of ZnO substitution on optical and physical properties was investigated: As zinc oxide concentration rises, so do Vickers hardness and Young's modulus. E or density, an inverse relationship is observed. UV transmission has been stabilized at around 75%. The Urbach's band gap of the glass sample, 05% ZnO, is 2.69 eV, and it has a multiphonon relaxation with length =7.16m. FTIR and Raman spectra provide information on the structural of the glass, specifically the formation of pyramids based on triangular SbO3.

Effects of annealing and structural phase transformation on the Urbach absorption in thin silver sulphide films

The sub-band gap optical absorption in silver sulphide thin films prepared by chemical conversion technique has been studied in the light of Urbach absorption law at different annealing temperatures. The study reveals the Urbach absorption parameters and band gap of the material are sensitive to annealing temperature. Interestingly, these parameters undergo a sudden change as the annealing temperature exceeds a certain critical value. The observed changes in the values of absorption parameters have been attributed to the structural phase transition and the modification of grain boundary interfaces and/or changes in the crystallographic orientation due to annealing.

Optical band gap studies and estimation of two photon absorption coefficient in alkali bismuth borate glasses

The optical absorption spectra of the glasses with composition xBi2O3·(30 − x)R2O·70B2O3 (R˭Li, Na, K) and xBi2O3·(70 − x)B2O3·30Li2O (0 ≤ x ≤ 20) have been recorded in the wavelength range 350–650 nm. The glass samples were prepared by the normal melt–quench technique. The fundamental absorption edge for all the series of glasses is analyzed using the theory of Davis and Mott. The position of absorption edges and the values of optical band gap are dependent on the mol% of Bi2O3. The absorption in these glasses is associated with indirect transitions. The values of Urbach's energy and band tailing parameters are reported. The two photon absorption coefficient, β, in these glasses has also been estimated from the optical band gap and its value ranges from 1.3 to 11.6 cm/GW. The relationship between β and glass composition has also been discussed in terms of the electronic structure of the glass system.