Polymorphism of InS at high pressures

In situ X-ray diffraction has been used to study high-pressure polymorphism of InS up to ～ 13 Gpa in the 293–573 K temperature range. The phase transition InS I?arr2;InS II is found under isothermal compression at p_t = 7.5 ± 0.5 GPa and T = 293 K; at p_t = 6.0 ± 0.5 GPa and T = 573 K. InS II crystallizes in the structural type of Hg₂Cl₂: $\text{a = 3.823 ± 0.008}\text{A}\text{?}$; $\text{c = 10.868 ± 0.030}\text{A}\text{?}$; c/a = 2.843; Z = 4; D_4h¹⁷(I4/mmm); V_p/V₀ = 0.85; p = 10 GPa, T = 293 K. X-ray powder data indicate a continuous change of the orthorhombic structure of InS I with increasing pressure associated with the transition to the tetragonal phase InS II.     

Nature of the cathode polarization during reduction of chromate ions in alkaline solutions

The effect of potential scanning rate and temperature on the kinetics of the reduction of chromate ions in alkaline solutions was studied, and the nature of polarization in separate stages of the cathode process was determined.     

Thermally stimulated current measurements in as-grown TlGaSeS layered single crystals

Charge carrier traps in as-grown TlGaSeS layered single crystals were studied using thermally stimulated current measurements. The investigations were performed in temperatures ranging from 10 to 100 K. The experimental evidences were found for the presence of one shallow hole trapping center in TlGaSeS, located at 12 meV from the valence band. The trap parameters have been calculated using various methods of analysis, and these agree well with each other. Its capture cross-section and concentration have been found to be 8.9 × 10⁻²⁶ cm² and 2.0 × 10¹⁴ cm⁻³, respectively. Analysis of the thermally stimulated current data at different light excitation temperatures leads to a value of 19 meV/decade for the shallow hole traps distribution.     

Trapping centers in undoped GaS layered single crystals

Nominally undoped p-GaS layered single crystals were grown using the Bridgman technique. Thermally stimulated current measurements in the temperature range 10–300 K were performed at a heating rate of 0.10 K/s. The analysis of the data revealed six trap levels at 0.05, 0.06, 0.12, 0.63, 0.71, and 0.75 eV. The calculations for these traps yielded 1.2×10^-21, 2.9×10^-23, 2.4×10^-21, 8.0×10^-9, 1.9×10^-9 and 4.3×10^-10 cm² for the capture cross sections and 1.6×10¹³, 5.0×10¹², 7.3×10¹², 1.2×10¹⁴, 8.9×10¹³ and 2.6×10¹³ cm^-3 for the concentrations, respectively. PACS 71.55.-i; 72.20.Jv; 72.80.Jc     

Effect of substitution-type disorder in GaS1-xSex layer solid solutions on Raman scattering spectra

An experimental study has been carried out to investigate Raman scattering spectra of GaS_1-xSe_x solid solutions in which a one-dimensional localization of interlayer mode due to a disorder in the layer stacking was observed.     

Effect of isomorphic atom substitution on the refractive index and oscillator parameters of TlInS2xSe2(1‐x) (0.25 ≤ x ≤ 1) layered mixed crystals

The optical properties of TlInS_2xSe_2(1‐x)mixed crystals (0.25 ≤ x ≤ 1) have been studied at room temperature through the transmittance and reflectivity measurements in the wavelength range of 400–1100 nm. The spectral dependence of the refractive index for all compositions of studied crystals were obtained. The dispersion of the refractive index is discussed in terms of the Wemple–DiDomenico single‐effective‐oscillator model. The compositional dependencies of refractive index dispersion parameters: oscillator energy, dispersion energy and zero‐frequency refractive index were revealed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Composition-tuned refractive index and oscillator parameters in TlGaxIn1−xS2 layered mixed crystals (0≤x≤1)

The optical properties of TlGa_xIn_1?xS₂ mixed crystals have been studied through transmission and reflection measurements in the wavelength range 400–1100 nm. These measurements allowed determination of the spectral dependence of the refractive index for all compositions of the mixed crystals studied. The dispersion of the refractive index is discussed in terms of the Wemple–DiDomenico single-effective-oscillator model. The compositional dependences of the refractive index dispersion parameters (oscillator energy, dispersion energy and zero-frequency refractive index) were revealed.     

Space-charge-limited currents and photoconductive properties of Tl2InGaSe4 layered crystals

The extrinsic electronic parameters of Tl₂InGaSe₄ layered crystals were investigated through measurement of the temperature-dependent dark conductivity, space-charge-limited currents and photoconductivity. Analysis of the dark conductivity reveals the existence of two extrinsic energy levels at 0.40 and 0.51 eV below the conduction band edge, which are dominant above and below 260 K, respectively. Current–voltage characteristics show that the one at 0.51 eV is a trapping energy level with a concentration of (4.8–7.7) × 10¹⁰ cm^?3. Photoconductivity measurements reveal the existence of another energy level located at 0.16 eV. In the studied temperature range, the photocurrent increases with increasing temperature. The dependence of the photoconductivity on the incident light intensity exhibits a linear recombination character near room temperature and a supralinear character as the temperature decreases. The change in recombination mechanism is attributed to an exchange in the behavior of sensitizing and recombination centres.