[en] Raman spectra of CuGa₃Te₅ that has a chalcopyrite-related structure with space group P anti 42c were obtained at room temperature from measurements performed under parallel (z vertical stroke xx vertical stroke z) and perpendicular (z vertical stroke xy vertical stroke z) polarization dependent configurations. A tentative assignment of the observed lines was made by comparison with the reported phonon modes for ZnTe, which is the binary analogue of CuGaTe₂, and also by using theoretical models reported in the literature for multinary compounds. The main lines observed at 129, 144, and 187 cm^-1 were assigned to the three A1-symmetry modes for P anti 42c ternary compounds predicted by group theory, and other lines at 91 and 277-285 cm^-1 to the B₁ modes. Also, lines at 55, 64, 102, 172, 224, 265-269, and 333-334 cm^-1 and lines at 78, 172, 224, 205-209, 242-249, and 342 cm^-1 were assigned to E and B₂ modes, respectively. The higher-phonon frequencies observed at 291-297, 303-310, and 319-323 cm^-1 are attributed to an overtone of the A₁ mode at 144 cm^-1, and a combination of A₁ and E modes, respectively. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] The nature of phase interaction in the SnTe-GaTe and SnTe-Ga₂Te₃ systems is studied in detail and the solubility is other in the Sn-Ga-Te system at 820 K is plotted. The research of alloys of the Sn_0.984-GaTe cross section has shown that GaTe introduction in the amount exceeding solubility limit in the above cross section (∼ 2 mol.%) bring up about the appearance of GaTe lines on roentgenograms. However, the increase of GaTe content upto 25 mol.% brings about additional lines on roentgenograms belonging to Sn and Ga₂Te₃ which proves the nonquasibinary nature of the Sn_0.984Te-GaTe cross section

[en] The structure and band structure of Ga₂Se₃,Ga₂Te₃ and Ga₂(Se_1-xTe_x)₃ have been investigated systematically, providing a good and extensive foundation for further experimental and theoretical investigations. The upper bound of self-consistent (sc) GW band-gap variation due to vacancy ordering variation for Ga₂Se₃ and Ga₂Te₃ is 0.33 and 0.21 eV, respectively, whereas the upper bound of band-gap variation based on GGA (PBE) calculations is larger, 0.55 and 0.51 eV, respectively. Hybrid density functional theory calculations have little effect on the band-gap variation upper bound of Ga₂Se₃, but reduce the band-gap variation upper bound of Ga₂Te₃ by ∼0.1 eV (when the default mixing ratio (0.25) is used). Zigzag-line vacancy ordering and straight-line vacancy ordering produce a valence band maximum at the Γ point and not at the Γ point, respectively. The conduction band minimum is at Γ point and not at Γ point for Ga₂Se₃ and Ga₂Te₃, respectively. The calculated scGW band-gaps of mono-Ga₂Se₃, ortho-Ga₂Se₃, mono-Ga₂Te₃ and ortho-Ga₂Te₃ at 0 K are 2.53, 2.20, 1.54 and 1.33 eV, respectively. The calculated band-gap is noticeably dependent on the level of self-consistency of the GW methods. The band-gap is larger for a higher level of self-consistency of the GW method, from G0W0 to scGW. The calculated band-gap curve of Ga₂(Se_1-xTe_x)₃ is noticeably convex downwards. The deviation between our experimental measured band-gap curve and the calculated band-gap curve based on completely disordered anion distribution and straight-line vacancy ordering is small and relatively large at the Te-rich end, for PBE + correction and HSE06, respectively. In addition, our previous method (Huang et al., 2013) based on the shift of plane layer atoms to generate disordered vacancies is extended in this paper to the shift of the zigzag plane layer of atoms, which is important for explaining the cubic symmetry of vacancy-disordered phases

[en] Surface properties of gallium telluride were studied. It was found that the surface after vacuum cleavage is partly reconstructed from monoclinic to hexagonal. Peculiarities of the surface topology are also discussed

No abstract available

[en] The mass-spectrometric studies of Ga₂Te₃ sublimation process in the 938-1024 K pange is carried out. The incongruent character of the Ga₂Te₃ sublimation process is established. The equations of temperature dependences of paptial pressures of vapour components above the Ga₂Te₃ compound are calculated. By the methods of statistic thermodynamics thermodynamic functions of Tesub(2g) are detepmined; thermodynamic functions of Ga₂Te+ GaTe, GaTe₂+ Ga₂Te₂ gaseous molecules are evaluated. By the 2-nd and3-rd laws of thermodynamics standard heats of gas-phase vapour component equlibpia aboVe Ga₂Te₃ have been found

[en] The GaTe-As₂Se₃-GaSe-As₂Te₃ system liquidus consists of seven primary crystallization fields. The triangulating secants divide the system into three phase triangles. Five non-variant equilibrium points are available in the system: three of which (E₁, E₂ and E₃) are eutectic points and two (P₁ and P₂) - transition points

No abstract available

No abstract available

[en] A particular cell configuration is proposed for measuring the electrical conductivity and the Hall-coefficient of melts which is based on using van der Pauw's measurement method. The advantages of this particular cell configuration for measurements of semiconducting and metallic melts are discussed. The electrical conductivity and the Hall-coefficient of liquid Ga₂Te₃ obtained with this cell configuration and van der Pauw's method are compared with previous results. (author)