Ternary Ge Research Articles

Phase diagram of the ternary system GeSbSe

The ternary system GeSbSe was investigated by differential thermal analysis, differential scanning calorimetry, thermogravimetry, X-ray diffraction at fixed and varying temperatures and metallographic microscopy. The quasi-binary system Sb 2Se 3GeSe 2, and various isoplethal and isothermal sections were determinated. In the quadrilateral GeGeSe 2Sb 2Se 3Sb system there is a large liquid-liquid miscibility gap and a solid ternary solution. Seven reactions were observed corresponding to a monotectic, three peritectics, a eutectic, peritectoid and a eutectoid. The triangle GeSe 2Sb 2 Sc 3Se is of the eutectic type.

Phase diagram of the ternary system GeTeSe

The ternary system GeTeSe was investigated by differential thermal analysis, thermogravimetry, X-ray diffraction and scanning electron microscopy. The quasi-binary systems, various isoplethal sections and the liquidus surface of the system were constructed. The liquid—liquid miscibility gaps have been obtained. The principal results are summarized as follows. 1. No ternary compound appears in the system. 2. The GeSe 2Te and GeTeGeSe 2 junctions form true quasi-binary systems. 3. The reactions at the main invariant points are ▪ 4. Three liquid—liquid miscibility gaps exist: the first is situated entirely in the ternary system giving the monotectic reaction ▪ in the GeSe 2Te quasi-binary system. The other liquid—liquid miscibility gaps are based on those occurring in the GeSe 2Ge system.

Solid state electrochemical study of the phase diagram and thermodynamics of the ternary system CuGeO

Coulometric titrations using solid zirconia ionic conductors have been employed to determine the phase diagram of the ternary system CuGeO in the temperature range from 750 to 950°C. CuGeO 3 was found to be the only existing ternary compound in the system. It is in equilibrium with Cu 2O, CuO, GeO 2, and oxygen of atmospheric pressure. Cu and Cu 2O may coexist with GeO 2. The standard Gibbs energy of formation of CuGeO 3 was found to be ΔG° f (CuGeO 3) = −424.5 kJ/mole at 900°C. The standard enthalpy and entropy of formation are ΔH 0 f = −756.8 kJ/mole and ΔS° f = −283 J/mole·K, respectively.

Superconductivity of A15 compounds in the system NbGeSn synthesized by chemical vapor deposition

A series of ternary NbGeSn superconducting compounds with the A15 crystal structure were synthesized by the method of chemical vapor transport. For constant Nb content and varying ratio of Ge/Sn, the lattice parameters were found to follow a linear Vegard-type behavior while both the superconducting transition temperatures T c and residual resistance ratios exhibited minima. These results are interpreted on the basis of T c in this system being governed by disorder at the Ge-Sn sites.

A study of glass phases of the germaniumsulphurindium system

The glass-forming region of the ternary GeSIn system is determined by differential thermal analysis (DTA), X-ray diffraction and electron microscope studies. The glass phases of the system have a region of maximum In content of 15 atomic percent. The experimental studies determined the transition temperature T g, the density d, the microhardness H and the refraction index n. An interpretation of the results from a chemical bond point of view has been made. The resistivity ϱ (2.0 + 7.5 × 10 14) ω cm has also been measured and a switching effect has been observed. These physical and electrical studies have been carried out with regard to the practical applications of the formed glasses of the GeSIn system.

Infrared studies of Se-based polynary chalcogenide glasses (III): Y xZ xS xSe 100−3 x (Y = Ge, As; Z = As, Te)

The infrared (IR) absorption spectra for Y x Z x S x Se 100−3 x glasses (Y = Ge, As; Z = As, te), with x = 2.5 and 5.0, are measured in the wavenumber region 700-60 cm −1 at room temperature. These IR spectra are qualitatively explained by comparing with the IR spectra of the binary and ternary glasses. In Ge x As x S x Se 100−3 x glasses ( x ⩽ 5.0), the main spectral features are explained by both spectra of the two ternary glasses Ge x S x Se 100−2 x and As x S x Se 100−2 x . In Ge x S x Te x Se 100−3 x glasses ( x ⩽ 5.0), the main spectral features are well explained by both spectra of the two ternary glasses Ge x S x Se 100−2 x and Ge x Te x Se 100−2 x . On the other hand, main spectral features in As x S x Te x Se 100−3 x glasses ( x ⩽ 5.0) are well explained by both spectra of the ternary glasses As x S x Se 100−2 x and the binary glasses Se 100− x Te x . In these glasses with low concentrations ( x ⩽ 5.0) some chemical bonds are confirmed and some structural units estimated.

Ternary tungsten oxides with the Mo 5O 14 structure

Following the discovery of a ternary GeW oxide with the Mo 5O 14 structure, a large number of ternary MWO systems were surveyed to investigate the frequency of occurrence of this structure type. Samples were prepared by heating tungsten oxides and the appropriate ternary element or a suitable compound of the ternary element in evacuated silica ampoules at 1373°K for 1 week. The compositions investigated were close to M 0.02W 0.98O 2.80. Oxides with the Mo 5O 14 structure were found in many systems across the whole of the periodic table, from Li to Bi. Some aspects of the formation of these phases and the way in which they could affect the course of reduction of WO 3 to W metal are discussed.

Thermally-induced structural and electrical effects in GeTe-based amorphous alloys

The thermal, structural electrical properties of bulk glasses based on GeTe compositions near the binary eutectic, Ge 15Te 85, are studied. Information regarding the non-crystalline state and the transformation from the non-crystalline to the crystalline state is reported. The particular alloys studied represent binary (Ge 17Te 83), ternary (Ge 15Te 80As 5) and quaternary (Ge 15Te 81Sb 2S 2) compositions. Structural information is obtained using X-ray diffraction techniques and density measurements. Thermal data are reported from differential scanning calorimetry (DSC), thermogravimetry (TGA) and mass spectrometry results. The electrical conductivity is measured as a function of temperature and, on the ‘as-prepared’ glasses, shows semi-conducting behavior with activation energies, E, of 0.43–0.48 eV. DSC, TGA and X-ray powder diffraction patterns indicate the samples crystallize as Te and GeTe in a two-step process, and melt at the binary eutectic temperature. The binary vaporizes as Te and GeTe in a two-step process. GeTeAs and GeTeSbS vaporize by essentially the same mechanism, with As evaporating (<300° C) before the Te, and Sb and S evaporating (420–480°C) after the Te but before GeTe. The results show that the properties of the bulk ‘as-prepared’ glasses are strikingly similar. Thermally-induced changes in the structural and electrical properties of bulk samples have been examined following a series of anneals (5 h, vacuum) at temperatures from 111°C to 190°C (glass transition temperature ⋍125−133° C ; crystallization temperature ⋍206−228° C as determined by DSC). DSC, TGA and mass spectrometry results have been correlated to electrical and structural changes. Results show that crystalline Te nucleates at the surface and forms a conductive surface layer. The conductivity of this surface layer is nearly temperature independent with E ≈ 10 −2 eV for all three alloys. Crystallization and the associated electrically conductive regions extend into the bulk material with further annealing. In these disordered alloys the additives As and Sb + S apparently do not act as electrical dopants in the sense of affecting the conductivity activation energy. The additives Sb + S however do retard crystallization of GeTe. The secondary crystallization product, GeTe, apparently changes the conduction mechanism to either a metallic or degenerate semiconductor type behavior.