Solubility Of Germanium Research Articles

Thermodynamic modeling of the thulium–germanium binary system

The thulium–germanium binary system has been critically assessed by means of the CALculation of PHAse Diagram technique through Thermo-Calc software package. The thulium–germanium binary system contains nine phases based on eight compounds, the intermediate phases with no solubility ranges: Tm5Ge3, Tm5Ge4, Tm11Ge10, TmGe, Tm4Ge5, TmGe1.5, and Tm0.9Ge2 were treated as stoichiometric phases, while the compound with homogeneity range TmGe1.8 (TmGe1.8_LT and TmGe1.8_HT) was modeled using two sublattices model as (Ge,Tm)0.358(Ge)0.642. The liquid phase was modeled as substitutional solution phase, in which the excess Gibbs free energy was formulated with Redlich–Kister polynomial. The germanium (diamond_A4) and thulium (hcp_A3) were kept as pure element phases since no solubility of germanium in thulium and vice versa. The calculations based on the thermodynamic modeling agree well with the phase diagram data and few experimental thermodynamic values from the literature.

Investigation of the Equilibrium Germanium-Substituted Wustite with Metal and Spinel Solutions in the Fе-Gе-O System

The phase equilibrium in the Fe-Ge-O system is investigated by measuring EMF of galvanic elements with solid oxygen-conductive electrolytes. The samples for investigation were prepared by the solid phase reaction at 900 °C. The samples were analyzed to determine the total and phase composition. The gross composition of the samples was refined by chemical analysis. The iron content was determined by the standard method of bichromatometric titration, while that of germanium was determined by the photometric method, which is based on measuring the optical density of the colored colloid solution of germanium phenyl fluoronate, which is formed upon the interaction of germanium dioxide with phenylfluorone in the acidic medium. The phase composition was established using X-ray diffractometry and electron probe microanalysis using a DRON-3 diffractometer and a JEOL JSM-6460LV computer controlled scanning (raster) microscope. The experimental function of EMF galvanic elements of temperature is formulated. After processing the obtained data, the equilibrium oxygen pressures over the samples were calculated, the solubility of germanium in iron monoxide (wustite) was determined, the phase composition of the regions bordering the wustite region was established, the isothermal sections of the state diagram of the system were constructed at 1173 and 1273 K in the equilibrium region of the wustite solution with metallic and spinel phases

Thermodynamic assessment of the Ytterbium–Germanium binary system

The Ytterbium–Germanium binary system was evaluated using the CALPHAD method through Thermo-Calc software package; the thermodynamic parameters involved in the Gibbs free energy models of the phases are optimized based on all available literature experimental data including the phase equilibria information and few thermodynamic measurements. The Ytterbium–Germanium system contain six intermetallic compounds Yb2Ge, Yb5Ge3, Yb5Ge4, Yb11Ge10, Yb3Ge5, and Yb3Ge8, which are all treated as stoichiometric phases. The excess term of the Gibbs free energy of the liquid phase was assessed with the recent exponential temperature dependence of the interaction energies by Kaptay and compared with the linear temperature dependence of Redlich–Kister polynomial equation results. The Germanium (Diamond_A4) and the two allotropic transformations of Ytterbium: βYb (fcc_A1) and γYb (bcc_A2), were kept as pure element phases since no solubility of Germanium in Ytterbium and vice versa. A reasonable agreement between the calculated results (the phase diagram and model parameters) and literature data was obtained for this system. The optimization process allows us to accomplish the results which are reported in a series of figures and tables.

Thermodynamic description of Ge-Mn-Si

ABSTRACTLiterature data of the Mn-Si system is analyzed and discordances are pointed out. First principles calculations are performed to clarify the enthalpies of formation of the intermetallic phases. Especially the enthalpies of formation of the various possible structures of the MnSix are discussed. On the basis of these new data, a thermodynamic description of the Gibbs energy of the phases is performed using the Calphad method. The system Ge-Mn is also assessed using the Calphad method for the first time.The mixing enthalpy in the D88 solid solution is calculated between Mn5Ge3 and Mn5Si3 by DFT calculations.Finally a thermodynamic description of the ternary system is suggested. Especially the solubility of germanium in MnSix is modeled.

Microstructures of niobium-germanium alloys processed in inert gas in the 100 meter drop tube

The 100 meter drop tube at NASA’s Marshall Space Flight Center has been used for a series of experiments with niobium-germanium alloys. These experiments were conducted with electromagnetic levitation melting in a 200 torr helium environment. Liquid alloys experienced large degrees of undercooling prior to solidification in the drop tube. Several interesting metastable structures were observed. However, the recalescence event prevented extended solid solubility of germanium in the A-15 beta phase. Liquids of eutectic composition were found to undercool in the presence of solid alpha and solid Nb5Ge3.

Diagramme de phase du système chrome-germanium

The Cr-Ge system has been completely reinvestigated by thermal analysis, X-ray diffraction, microhardness and electron microprobe. The five known intermetallic phases melt incongruently: Cr 3Ge at 1564 °C (homogeneous from 20.5 up to 25 at.% Ge) and Cr 5Ge 3 at 1262 °C (37.4 − 38.2 at.% Ge) with an allotropic transformation at 1002 °C; the three other phases Cr 11Ge 8 (melting at 1170 °C), CrGe (998 °C) and Cr 11Ge 19 (928 °C) are stoichiometric. The solubility of germanium in solid chromium varies from 4 at.% (800 °C) up to 11 at.% (1564 °C). Chromium is practically insoluble in solid germanium at any temperature. The system is compared with other binary alloys of germanium with transition metals.

Voltammetric and chronoamperometric investigation of germanium amalgams Part I. Properties of the homogenous amalgam

Using cyclic voltammetry and chronoamperometry with several anodic steps the deposition and particularly the oxidation of germanium from a HMDE was investigated within pH range 4–12 at Ge (IV) concentrations ranging from 4×10−7 M to 1×10−4 M in the absence of ligands capable to form the complex compounds with Ge(IV) in a solution. It was found that the initially formed product of electrodeposition is a homogeneous, usually supersaturated amalgam. Germanium from this amalgam oxidizes at about 1 V (vs. mercury sulphate reference electrode) or after some induction period, the length of which depends on concentration of Ge(0) in mercury, it begins to crystallize forming heterogenous germanium amalgam. Germanium from this heterogenous amalgam oxidizes in a separate voltammetric peak at more positive potentials. The solubility of germanium in mercury was evaluated on the basis of the oxidation current of homogenous amalgam and the value obtained is equal to (2±0.5)×10−7 M i.e. (1.1±0.3)×10−7 wt. %. Applying the Stevens and Shain method the diffusion coefficient of germanium in mercury was found to be (1.32±0.1)×10−5 cm2 s−1.

Voltammetric and chronoamperometric investigation of germanium amalgams: Part I. Properties of the homogenous amalgam

Using cyclic voltammetry and chronoamperometry with several anodic steps the deposition and particularly the oxidation of germanium from a HMDE was investigated within pH range 4–12 at Ge (IV) concentrations ranging from 4×10 −7 M to 1×10 −4 M in the absence of ligands capable to form the complex compounds with Ge(IV) in a solution. It was found that the initially formed product of electrodeposition is a homogeneous, usually supersaturated amalgam. Germanium from this amalgam oxidizes at about 1 V (vs. mercury sulphate reference electrode) or after some induction period, the length of which depends on concentration of Ge(0) in mercury, it begins to crystallize forming heterogenous germanium amalgam. Germanium from this heterogenous amalgam oxidizes in a separate voltammetric peak at more positive potentials. The solubility of germanium in mercury was evaluated on the basis of the oxidation current of homogenous amalgam and the value obtained is equal to (2±0.5)×10 −7 M i.e. (1.1±0.3)×10 −7 wt. %. Applying the Stevens and Shain method the diffusion coefficient of germanium in mercury was found to be (1.32±0.1)×10 −5 cm 2 s −1.

Measurement of the solubility of germanium in aluminum utilizing MeV He+ backscattering

The solubility of germanium in thin (1000 to 6000A) aluminum films has been measured over the temperature range 120° to 390°C using the technique of MeV He+ backscattering. The results are in general agreement with previous measurements. The technique is described and its advantages and limitations for measurements of this type are discussed.

Einfluss von zusätzen dritter elemente auf das kritische Magnetfeld von Titan-Niob-Legierungen

Additions of germanium or copper to β-TiNb solid solutions with about 50 wt.% Nb (wires 1 mm in diameter) reduce the critical magnetic field H c of the binary alloy to an amount of 10 kG/% Ge or 4 kG/% Cu. By measurements of H c it is assumed, that at 700 °C less than 0.5 % Ge and more than 1 % Cu are in solid solution. The maximum critical field H c of 117.7 kG in TiNb49Ge2.3 of 97% cold worked samples after heat treatment 250 h at 400 °C is increased to 119.4 kG in TiNb48Ge4.5 of 97 % cold worked and 16 h at 500 °C annealed samples. The highest H c -value of the investigated binary alloys (TiNb55 with 117.5 kG) is exceeded because of the enrichment of niobium in the matrix. The solubility of germanium in the β-solid solution at 400 °C is very low and the intermetallic compound Ti 5Ge 3 is precipitated. H c of the alloys with copper additions reaches, in spite of the enrichment of niobium in the matrix after the heat treatment, not the H c -values of the alloys containing germanium, because the solubility of copper in the β-solid solution is higher than that of germanium. Additions of 2 at.% Sn, Ga, In, Fe, Mn, Cr, Al, Zr, Ag or Ge to 97 % cold worked and 10 h at 400 °C aged wires with 50 wt. % Nb decrease H c , while an addition of 2 at.% Cu does not change the value of TiNb50 (114 kG) and an addition of 2 at. % Nb raises H c to 116.1 kG. The change of H c by ageing between 300 ° and 700 °C is explained by the dissolution of microsegregations in the β-solid solution, by precipitations of the pre-stage of the ω-phase, the ω- and α-phase, Ti 5Ge 3 or Ti 2Cu or other intermetallic compounds.

The solubility of germanium (II) hydroxide in perchloric acid and sodium hydroxide at 25°C

The solubility of Ge(OH) 2 was measured in dilute solutions of perchloric acid and sodium hydroxide and in water at 25°C. Apparently this oxide does not form true solutions in sodium hydroxide as evidenced by the formation of a deep red colour both in the solid and in the liquid media. Other observations also indicate that colloids form.

The solubility of germanium (IV) oxide in aqueous NaOH solutions at 25°C

The solubility of GeO 2 was measured in dilute aqueous NaOH solutions at 25°C. The data indicate the predominance of the following reaction from 0·03 to 0·07 M NaOH: GeO 2(s) + OH − = HGeO 3 −. This conclusion was corroborated by conductometric titrations. The acid dissociation constant of metagermanic acid was calculated: K 5 = 2·75 × 10 −12.