Phase equilibria in the Ag4SSe-SnTe system

The phase diagram of the system Ag₄SSe-SnTe is studied by means of X-ray diffraction, differential thermal and metallographic analyses and measurements of the microhardness and the density of the material. This diagram is divided into two eutectic-type subdiagrams by the composition Ag₄SSe·2SnTe. The unit-cell parameters of the intermediate phases 3Ag₄SSe·SnTe (phase A) and -Ag₄SSe·2SnTe (phase B) are determined as follows: for phase A: a=0.7851 nm, b=0.7196 nm, c=0.6296 nm, =101.32°, =85.90°, =111.36°; for phase B: a=0.3662 nm, b=0.3303 nm, c=0.3343 nm, =90.74°, =108.94°, =91.91°. The phase Ag4SSe·2SnTe melts congruently at 615°C and a polymorphic transition of the phase takes place at T _- =110°C.This revised version was published online in November 2005 with corrections to the Cover Date.     

Phase equilibria in the Ag4SSe–As2Se3 system

The phase diagram of the system Ag₄SSe–As₂Se₃ is studied by means of X-ray diffraction, differential thermal analyses and measurements of the microhardness and the density of the materials. The unit-cell parameters of the intermediate phases 3Ag₄SSe·As₂Se₃ (phase A) and Ag₄SSe·2As₂Se₃ (phase B) are determined as follows for phase A: a=4.495 Å, b=3.990 Å, c=4.042 Å, α=89.05°, β=108.98°, γ=92.93°; for phase B: a=4.463 Å, b=4.136 Å, c=3.752 Å, α=118.60°, β=104.46°, γ=83.14°. The phase 3Ag₄SSe·As₂Se₃ and Ag₄SSe·2As₂Se₃ have a polymorphic transition α?β consequently at 105 and 120°C. The phase A melts incongruently at 390°C and phase B congruently at the same temperature.     

Glass forming region in the GeSe2–GeTe–PbTe system and some physicochemical properties of glassy alloys

New chalcogenide glasses from the GeSe₂–GeTe–PbTe system were synthesized. The glass forming region was determined using visual, X-ray diffraction and scanning electron microscopy analyses. It is extended towards the GeSe₂ and lies partially on the GeSe₂–GeTe (0–58 mol% GeTe) and GeSe₂–PbTe (20.0–57.5 mol% PbTe) sides. No glasses were obtained in the GeTe–PbTe system. The investigated physicochemical properties vary between 4.04–6.21 g/cm³ (density, d); 97–121 kgf/mm² (microhardness, HV); ?0.187 ÷ 0.007 (compactness, C) and 14.3–17.8 GPa (elasticity modulus, E), respectively.     

Phase equilibria in the GeSe2-SnTe system

Journal of Thermal Analysis and Calorimetry - The phase diagram of the system GeSe2-SnTe is studied by means of X-ray diffraction, differential thermal and measurements of the microhardness and the...     

Optical characterization of As2Se3-Ag4SSe-SnTe amorphous thin films

Amorphous thin films from the system As₂Se₃-Ag₄SSe-SnTe were prepared by thermal vacuum evaporation from the corresponding bulk glassy samples. The film structure and surface morphology were investigated by scanning electron microscopy and atomic force microscopy; the results revealed uniform, smooth and homogeneous coatings. The amorphous chalcogenide films are transparent in a wide spectral range as shown by transmission and reflection measurements in the VIS and NIR regions. The optical band gap was determined and its compositional dependence is discussed in terms of structural considerations and the formation of charged defect centers.     

Phase equilibria in the CdI<Subscript>2</Subscript>-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The phase diagram of the system CdI₂-Bi₂O₃ is studied by means of X-ray diffraction, differential thermal analysis and measurements of the density of the material. As a result of the synthetic and peritectic interactions, two incongruently melting intermediate phases i.e. phase A — CdI₂·2Bi₂O₃ and phase B — CdI₂·4Bi₂O₃ (stable in the temperature interval 370–850°C) are formed.The phase A exists in two polymorphic forms with a temperature of the phase transition T =320–370°C. The unit cell parameters at low temperature modification of -CdI₂°2Bi₂O₃ were determined. (a=1.032 nm, b=1.046 nm, c=1.046 nm, =115.02°, =109.11° and =82.04°). The phases A and B have fields of homogeneity.The authors acknowledge thankfully the financial support for this work from the Ministry of Education and Science (Fond Scientific investigations — contract TN-1102).     

Glass formation in the As2Se3-As2Te3-Sb2Te3 system

Chalcogenide glasses from the As₂Se₃-As₂Te₃-Sb₂Te₃ system were synthesized for the first time. The glass-forming region was determined by X-ray diffraction and electron microscopic analyses.The basic physicochemical parameters such as density (d), microhardness (HV) and temperatures of phase transformations (glass transition T_g, crystallization T_cr and melting T_m) were measured. Compactness and some thermomechanical characteristics such as volume (V_h) and formation energy (E_h) of micro-voids in the glassy network as well as the elasticity module (E) were calculated. The glass-forming ability was evaluated according to Hruby's criteria (K_G). The correlation between composition and properties of the (As₂Se₃)_x(As₂Te₃)_y(Sb₂Te₃)_z glasses was established and comprehensively discussed.