Ge Ternary System Research Articles

Phase diagram of ternary Co–Fe–Ge system (I): Experimental

Co–Fe–Ge is an important material system for magnetic and catalyst applications. However, phase equilibria information of the Co–Fe–Ge ternary system is limited. Ternary Co–Fe–Ge alloys equilibrated at 950 °C were prepared. The microstructures, chemical compositions and crystal structure of each phase were determined. The phase equilibria isothermal section at 950 °C of the Co–Fe–Ge ternary system was then proposed. A continuous solid solution phase was formed between the Co5Ge3 and Fe5Ge3 phases and was labeled the β(Co,Fe)5Ge3 phase. There are five three-phase regions in the system at 950 °C. A wide α2 single-phase, and liquid phase regions with large composition ranges being confirmed at the Ge-poor and Ge-rich sides, respectively.

Epitaxial growth of magnetron sputtered NiAl on Ge mediated by native GeOx

In this work, the growth of a magnetron sputtered NiAl film on Ge was investigated. Two growth parameters were varied: the deposition temperature and the presence of native GeOx. An epitaxial layer was obtained at a deposition temperature of 400 ∘C and without removal of the native GeOx prior to deposition. At this growth condition, Ni and Al diffused into the Ge forming an epitaxial germanide. This germanide is most likely the τ 3 phase of the Ni–Al–Ge ternary system. The growth of the τ 3 phase is enabled by the GeOx acting as a diffusion barrier for Al. The native GeOx was found to be amorphous and to contain holes through which the NiAl can directly contact the τ 3 germanide and grow epitaxially. These holes are likely formed by thermal degradation when the substrate is heated for deposition. The electrical resistivity for epitaxial NiAl was found to be 13 .cm at a thickness of 30 nm which was the lowest value of the tested conditions. Epitaxial NiAl can be used as a seed layer to grow other layers epitaxially in a CMOS-compatible process, e.g. Fe(Co), Cr, MgO, and Heusler alloys.

Phase equilibria of Zr-Co-Ge ternary system at 1023, 1173 and 1373 K

Phase equilibria of the Zr−Co−Ge ternary system at 1023, 1173 and 1373 K were precisely measured via alloy sampling associated with electron probe microanalysis (EPMA) and X-ray diffraction (XRD) techniques. The isothermal sections in the Zr−Co−Ge system were appropriately constructed, containing 29, 28, and 26 three-phase regions at 1023, 1173, and 1373 K, respectively. Except for confirming the five ternary compounds previously reported in the literature, a new ternary phase τ was detected with a remarkable homogeneity range, consisting of 13.8−19.4 at.% Co at 1023 K, 12.9−19.0 at.% Co at 1173 K and 12.3−14.9 at.% Co at 1373 K. And, an invariant reaction was deduced to occur at a temperature between 1023 and 1173 K, i.e., τ+τ1τ4+ZrGe2. Besides, the third element Ge can partly substitute Co in some Co−Zr intermediate phases, e.g., CoZr2 and Co23Zr6 where the maximum solubility of Ge can separately reach up to 22.8 at.% and 20.3 at.%, respectively.

Interaction between the components in Tm-Cr-Ge system at 1070 K

The phase equilibrium diagram of the Tm–Cr–Ge ternary system was constructed at a temperature 1070 K based on the results of X-ray phase, microstructural analyzes and energy-dispersive X-ray spectroscopy in the whole concentration range. At the temperature of investigation, two new ternary compounds are realized in the system: TmCr6Ge6 (SmMn6Sn6 structure type, space group P6/mmm, a=0.51506(1), c=0.82645(2) nm) and Tm4Cr4Ge7 (Zr4Co4Ge7 structure type, space group I4/mmm, а=1.39005(9), с=0.54441(1) nm). Inclusion of Cr atoms in the structure of the binary germanide TmGe2 (structure type ZrSi2) up to 10 at. % Cr leads to the formation of a solid solution TmCrxGe2 (x = 0-0.33).

Phase equilibria in the Gd–Cr–Ge system at 1070 K

The isothermal section of the phase diagram of the Gd–Cr–Ge ternary system was constructed at 1070 K over the whole concentration range using X-ray diffractometry, metallography and electron microprobe (EPM) analysis. Three ternary compounds are realized in the Gd–Cr–Ge system at the temperature of annealing: Gd117Cr52Ge112 (Tb117Fe52Ge112 structure type, space group Fm-3m, Pearson symbol cF1124, a = 2.8971(6) nm), GdCr6Ge6 (SmMn6Sn6 structure type, space group P6/mmm, Pearson symbol hP16, a = 0.51797(2), c = 0.82901(4) nm) and GdCr1-хGe2 (CeNiSi2 structure type, space group Cmcm, Pearson symbol oS16, a = 0.41569(1)-0.41593(8), b = 1.60895(6)-1.60738(3), c = 0.40318(1)-0.40305(8) nm). For the GdCr1-xGe2 compound the homogeneity range was determined (x=0.73 – 0,69).

Er-Cr-Ge Ternary System

The isothermal section of the phase diagram of the Er–Cr–Ge ternary system was constructed at 1070 K over the whole concentration range using X-ray diffractometry, metallography and electron microprobe (EPM) analysis. The interaction between the elements in the Er−Cr−Ge system results in the formation of two ternary compounds: ErCr6Ge6 (MgFe6Ge6-type, space group P6/mmm, Pearson symbol hP13; a = 5.15149(3), c = 8.26250(7) Ǻ; RBragg = 0.0493, RF = 0.0574) and ErCr1-хGe2 (CeNiSi2-type, space group Cmcm, Pearson symbol oS16, a = 4.10271(5), b = 15.66525(17), c = 3.99017(4) Ǻ; RBragg = 0.0473, RF = 0.0433) at investigated temperature. For the ErCr1-xGe2 compound, the homogeneity region was determined (ErCr0.28-0.38Ge2; a = 4.10271(5)-4.1418(9), b = 15.6652(1)-15.7581(4), c = 3.99017(4)-3.9291(1) Ǻ).

Y–Cr–Ge ternary system at 1 070 K

This paper is part of a systematic study of the interaction of rare earth metals with transition metals and germanium. Polycrystalline samples were prepared by arc melting of the stoichiometric amounts of the constituent elements (nominal purities: Y − 99.9 wt. %, Cr − 99.99 wt. %, Ge − 99.999 wt. %) on a water-cooled copper hearth under a protective Ti-gettered argon atmosphere. Subsequently the buttons were annealed at 1070 K for 720 h in evacuated silica tubes, followed by quenching in cold water. Quality of the prepared samples was tested by X-ray powder diffraction (diffractometer DRON-2.0, Fe K α radiation) and Scanning Electron Microscopy (JEOL JSM-7600F electron microscope equipped with an energy-dispersive spectroscopy (EDS) X-ray analyser). XRPD data were collected in the transmission mode on a STOE STADI P diffractometer. Calculations of the crystallographic parameters were performed using the Full Prof Suite program packages. The microhardness was measured using a Microhardness Tester FM-100. The square-based pyramidal diamond was pressed using a force of10 pound for a loading time of 10 s; at least eight areas across each joint were tested in our measurements to obtain an average value. In the Y–Cr–Ge system at 1070 K two ternary compounds were found. The existence of YCr 6 Ge 6 (structure type MgFe 6 Ge 6; space group P 6/ mmm ; Pearson symbol hP 13; a = 5.1692(2), c = 8.2649(9) Å) was confirmed. The crystal structure refinements of YCr 0 .23 Ge 2 was performed using X-ray powder diffraction method (CeNiSi 2 structure type; space group Cmcm ; Pearson symbol oS 16; a = 4.12792(6), b = 15.8899(2), c = 4.00530(5) Å). The atomic parameters are: Y in (4c): 0 y ¼, y = 0.1048(1), B iso = 0.50(4) (hereafter Å 2 ); Cr in (4c) y = 0.2975(7); site occupations G = 0.23(0), B iso = 0.66(1); Ge1 in (4c), y = 0.4492(1), B iso = 0.50(4); Ge2 in (4c), y = 0.7477(1); B iso = 0.89(1); R Bragg = 0.0770, R F = 0.0671). Binary germanide Cr 3 Ge (structure type Сr 3 Si) dissolves up to 3 at. % Y, as evidenced by changes in the lattice parameter а = 4.6303(1) for Cr 3 Ge, а = 4.6313(2) Å for Y 3 Cr 7 5 Ge 2 2 sample. The results of the measurement of microhardness of Y 3 Ge 4 , Cr 3 Ge, YCr 6 Ge 6 compounds indicated its dependence on the composition and crystalline structure of the compound. Keywords: X-ray diffraction, EDX, phase equilibria, crystal structure, microhardness.

Experimental Investigation of Phase Equilibria in Ti–Zr–Ge System

Phase equilibria in the Ti–Zr–Ge ternary system at 1073 and 1173 K were investigated experimentally using equilibrated alloys with electron probe microanalysis and x-ray diffraction analysis. No ternary compounds were detected. Eleven and nine three-phase regions were determined in the Ti–Zr–Ge isothermal section at 1073 and 1173 K, respectively. Intermediate compounds ZrGe2, Zr5Ge4, Zr5Ge3, Ti5Ge4, and Ti5Ge3, possessing large solubility, extended along the Ge isoconcentration line, indicating remarkable substitution of Ti for Zr in the Zr–Ge compounds or of Zr for Ti in the Ti–Ge compounds. The solubility of Ti in ZrGe2 increased from 16.0 at.% at 1073 K to 19.3 at.% at 1173 K, while that of Zr in Ti5Ge3 remained nearly 41.0 at.% at both 1073 and 1173 K.

Interaction of the component in Y–{V, Fe}–Ge systems at 870 K

This paper is part of a systematic study of the interaction of rare earth metals with transition metals and germanium. The interaction of components in Y–V–Ge and Y–Fe–Ge ternary systems was studied using X-ray diffraction and microstructure analyses. Isothermal sections of the systems have been constructed at 870 K. A new ternary compound YV 0.16 Ge 1.54 was found in Y–V–Ge system at the temperature of study. The crystal structure refinement of YV 0.16 Ge 1.54 was performed using X-ray powder diffraction method. It was indicated that the new compound belongs to CeNiSi 2 structure type (ST) (space group Cmcm ,Pearson symbol oS 16, a = 0.40815(1), b = 1.58775(5), c = 0.39429(1) nm, R B = 0.0286, R р = 0.0564, R wp = 0.0759). The existence of substitutional solid solution based onY 5 Ge 3 binary compound (ST Mn 5 Si 3 ) up to 10 at. % V was observed. V 3 Ge (SТСr 3 Si)binary germanide dissolves up to 3 at. % Y as evidenced by changes in the lattice parameter а = 0.4784 for V 3 Ge, а = 0.4789(2) nm for Y 3 V 72 Ge 25 sample. Existence of the following five ternary germanides: YFe 6 Ge 6 (ST TbFe 6 Sn 6 ), YFe 2 Ge 2 (SТ CeGa 2 Al 2 ),YFe 4 Ge 2 (SТ ZrFe 4 Si 2 ), Y 117 Fe 52 Ge 112 (SТ Tb 117 Fe 52 Ge 112 ) and YFe 1- x Ge 2 (SТ CeNiSi 2 ), was confirmed in Y–Fe–Ge ternary system at the temperature of study. The refinement of crystal structure of YFe 0.34 Ge 2 phase was performed by powder method (CeNiSi 2 – type, a = 0.41172(2), b = 1.58838(6), c = 0.39989(2) nm, R I =0.0193). On the basis of Y 5 Ge 3 binary compound (Mn 5 Si 3 -type) the existence of substitutional solid solution Y 5 Fe x Ge 3- x up to 5 аt. % Fe ( a = 0.8472(2); c = 0.6347(2) nm for Y 5 Ge 3 , a = 0.8462(1); c = 0.6378(2) nm for Y 62.5 Fe 5 Ge 32.5 ) was discovered. The substitution of M -component produces the change of character of phase diagrams, number of compounds, their composition and crystal structure. The number of ternary germanides in Y− M −Ge systems increases from 1 to 10 at V → Cr → Mn → Fe → Co → Ni transition and decreases to 5 at the transition to Cu. In all studied systems Y M 1- x Ge 2 compound with CeNiSi 2 -type is observed. Most ofR −M− Ge ternary systems are characterized by similar component interaction. The formation of R M 1- x Ge 2 compounds is the feature of Y−{V, Fe}−Ge and R−{Mn, Fe, Co, Ni, Cu}−Ge systems. These germanides are characterized by the presence of defects in the position of M component or statistical mixture ( M , Ge), which causes deviation of their compositions from ideal R M Ge 2 towards lower content of M component. Keywords: X-ray diffraction, EDX, phase equilibria, ternary compound, crystal structure.

ChemInform Abstract: Isothermal Section of the Ternary Phase Diagram U—Fe—Ge at 900 °C and Its New Intermetallic Phases.

AbstractThe isothermal section at 900 °C of the phase diagram of the U—Fe—Ge ternary system is investigated by melting and annealing the elements for 4 weeks prior to quenching in H2O.

Isothermal section of the ternary phase diagram U–Fe–Ge at 900 °C and its new intermetallic phases

The isothermal section at 900°C of the U–Fe–Ge ternary system was assessed using experimental results from X-ray diffraction and observations by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy chemical analysis. The phase diagram at this temperature is characterized by the formation of fourteen stable phases: four homogeneity ranges and ten intermetallic compounds. Among these, there is an extension of the binary compound UFe2 into the ternary system (UFe2−xGex,x<0.15), three ternary line compounds, U2Fe17−xGex (2<x<3.7), UFe1−xGe2 (0.58<x<0.78), UFe6+xGe6−x (x<0.7), and ten ternary stoichiometric compounds, U2Fe3Ge, U6Fe16Ge7, UFe4Ge2, U6Fe22Ge13, UFeGe, U3Fe4Ge4, UFe2Ge2, U34Fe3.32Ge33, U3Fe2Ge7, and U9Fe7Ge24.

Phase equilibria in the La–Mg–Ge system at 500 °C and crystal structure of the new ternary compounds La11Mg2Ge7 and LaMg3−xGe2

The whole 500°C isothermal section of the La–Mg–Ge ternary system was constructed. The existence and crystal structure of three ternary compounds were confirmed: La2+xMg1−xGe2 (τ2, P4/mbm, tP10–Mo2FeB2, 0≤x≤0.25), La4Mg5Ge6 (τ3, Cmc21, oS60–Gd4Zn5Ge6) and La4Mg7Ge6 (τ4, C2/m, mS34, own structure type). Five novel compounds were identified and structurally characterized: La11Mg2Ge7 (τ1, P42/ncm, tP88-8, own structure type, a=1.21338(5), c=1.57802(6)nm), LaMg3−xGe2 (τ5, P3¯1c, hP34-0.44, own structure type, x=0.407(5), a=0.78408(4), c=1.45257(7)nm), La6Mg23Ge (τ6, Fm3¯m, cF120–Zr6Zn23Si, a=1.46694(6)nm), La4MgGe10−x (τ7, x=0.37(1), C2/m, mS60-1.46, own structure type, a=0.88403(8), b=0.86756(8), c=1.7709(2)nm, β=97.16°(1) and La2MgGe6 (τ8, Cmce, oS72–Ce2(Ga0.1Ge0.9)7, a=0.8989(2), b=0.8517(2), c=2.1064(3)nm). Disordering phenomena were revealed in several La–Mg–Ge phases in terms of partially occupied sites. The crystal structures of La11Mg2Ge7 and LaMg3−xGe2 are discussed in details. The latter is a √3a×√3a×2c superstructure of the LaLi3Sb2 structure type; the symmetry reduction scheme is shown in the Bärnighausen formalism terms.

Experimental study and thermodynamic description of the Au–Cu–Ge system

Phase equilibria in the Au–Cu–Ge ternary system, including the solid state phase relations at 450°C as well as four vertical sections, were studied by means of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Based on the present experimental results and the available information in the literature, a thermodynamic description of the Au–Cu–Ge ternary system has been developed using the CALPHAD (CALculation of PHAse Diagram) method. A consistent set of thermodynamic parameters for each phase was derived. The calculated phase diagrams and thermodynamic properties are in reasonable agreement with the experimental data obtained in the present study as well as those reported in the literature.

The isothermal section of the phase diagram of Li–La–Ge ternary system at 400 °C

The isothermal section of the phase diagram of Li–La–Ge ternary system at 400 °C in the 30–100 at.% Ge concentration range was built and formation of seven ternary compounds were observed. For all ternary compounds: τ1–LiLa2Ge6−x (Cmmm space group, LiPr2Ge6 structure type), τ2–LiLaGe2 (Pnma, LiCaSi2), τ3–Li2La2Ge3 (Cmcm, Li2Ce2Ge3), τ4–Li8La7Ge10 (Cmmm, own structure type), τ5–Li12La11Ge16 (Immm, own structure type), τ6–Li4La3Ge4 (Immm, Gd3Cu4Ge4) and τ7–LiLa4Ge4 (Pnma, LiTm4Ge4) the crystal structures are known. The Li2La2Ge3, Li12La11Ge16, Li8La7Ge10 and Li4La3Ge4 ternary phases form the homologous series which is based on the simple Al2MgCu and AlB2 structure types. The crystal structures of LixLa5Ge3 phase, which formed by incorporation of lithium atoms into octahedral voids of La5Ge3 binary phase, was studied more precisely by X-ray powder diffraction and electrochemical investigation. According to electronic structure calculations using the tight-binding linear muffin-tin orbital-atomic spheres approximations (TB–LMTO–ASA) method the strong covalent Ge–Ge interactions were established.

Isothermal section of the Al–Dy–Ge ternary system at 673 K

The isothermal section of the phase diagram of the Al–Dy–Ge ternary system at 673 K has been investigated by X-ray powder diffraction and scanning electron microscope equipped with energy dispersive X-ray spectroscopy in backscattered electron imaging modes. The existence of thirteen binary compounds including Dy 3Ge 4 in the system Dy–Ge has been confirmed. Four ternary compounds, namely AlDyGe, Al 3Dy 2Ge 4, AlDy 2Ge 3, and AlDy 2Ge 2 were observed, and five new ternary compounds, i.e., Al 0.33DyGe 2, AlDy 2Ge 6, Al 2DyGe 2, AlDy 3Ge 3, and Al 3− x Dy 11Ge 7+ x ( x ≤ 0.7), and one pseudo-binary compound Al 3− x DyGe x were found in this system at 673 K. The maximum solid solubility of Ge in the pseudo-binary compounds Al 3− x DyGe x is about 7.5 at.% with x = 0.3 at 673 K.

Thermodynamic description of the Au–Ag–Ge ternary system

The Ag–Ge binary system has been assessed thermodynamically using the CALPHAD method through the Thermo-calc ® software based on the available experimental information from the published literature. The solution phases including liquid, fcc_A1(Au,Ag), and diamond_A4(Ge), were modeled as substitutional solutions and their excess Gibbs energies were expressed by the Redlich–Kister polynomial. On the basis of the previous assessments of the Au–Ag and Au–Ge binary systems, the thermodynamic description of the Au–Ag–Ge ternary system has been performed. The liquidus projection and several vertical sections of this ternary system have been calculated, which are in good agreement with the reported experimental data.

ChemInform Abstract: Reinvestigation of the Isothermal Section of the Ce—Co—Ge Ternary System, at 700 °C.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reinvestigation of the isothermal section of the Ce–Co–Ge ternary system, at 700 °C

The solid state phase equilibria in the Ce–Co–Ge ternary system at 700 °C were investigated by means of X-ray diffraction and scanning electron microscope–energy dispersive X-ray spectroscopy. A total number of nine intermediate phases were characterized and the homogeneity ranges of the various ternary solid solutions of the binary boundary systems (Ce–Co, Ce–Ge and Co–Ge) were studied. The new ternary phase, CeCo 13− x Ge x (4 ≤ x ≤ 4.5) has been discovered. It crystallizes in the tetragonal space group I4 /mcm (no. 140), with the cell parameters a = 7.974(5) Å and c = 11.856(5) Å for x = 4. CeCo 9Ge 4 derives from the CeNi 8.5Si 4.5-type, but, with a perfect ordering of the atoms on the crystallographic sites. The phase diagram comprises seven extensions of binaries into the ternary system, eight stoichiometric ternary phases, CeCoGe, CeCo 2Ge 2, CeCoGe 3, Ce 2Co 3Ge 5, Ce 2CoGe 3, Ce 3CoGe 2, Ce 5CoGe 2 and Ce 5Co 4Ge 13 and two intermediate solid solutions, CeCo 1− x Ge 2 (0 ≤ x ≤ 0.24) and CeCo 13− x Ge x (4 ≤ x ≤ 4.5).

First-principles calculations assisted thermodynamic assessment of the Pt–Ga–Ge ternary system

The Pt–Ga–Ge ternary system was thermodynamically assessed by the CALPHAD (CALculaton of PHAse Diagram) approach with help of first-principles calculations. Firstly, the formation enthalpies of the Pt–Ge and Pt–Ga compounds were calculated by the first-principles method. Subsequently, the Pt–Ge system was modeled and the Pt–Ga system was re-assessed. The solution phases, Liquid, Diamond_A4 (Ge) and Fcc_A1 (Pt), were modeled as substitutional solutions, of which the excess Gibbs energy was formulated with the Redlich–Kister polynomial. The binary intermetallics, Ga 7Pt 3, Ga 2Pt, Ga 3Pt 2, GaPt, Ga 3Pt 5, GaPt 2, Ge 2Pt, Ge 3Pt 2, GePt, Ge 2Pt 3 and GePt 2, were treated as stoichiometric compounds while GePt 3 was described with a two-sublattice model. Finally, based on the currently optimized Pt–Ga and Pt–Ge binary systems along with the already assessed Ga–Ge system, phase equilibria in the Pt–Ga–Ge ternary system were extrapolated. The isothermal sections at 473 K, 973 K and 1073 K of the ternary system were calculated, showing good agreement with the experimental data. In addition, the liquidus projection of the Pt–Ga–Ge ternary system was predicted using the obtained model parameters.

ChemInform Abstract: The Isothermal Section of the Dy—Fe—Ge Ternary System at 773 K.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.