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The electrochemical behavior of manganese silicide-germanides with different ratios of germanium and silicon is studied using the methods of voltammetry and impedance spectroscopy in 0.5 M aqueous sodium sulfate solution. It is shown that the oxidation stability of materials decreases with an increase in the ratio of germanium, which, unlike silicon, is incapable of forming a layer of stable oxides on the material surface. [ABSTRACT FROM AUTHOR]

The ternary germanide Mg5.57Ni16Ge7.43 (cubic, space group Fmm, cF116) belongs to the structural family based on the Th6Mn23‐type. The Ge1 and Ge2 atoms fully occupy the 4a (mm symmetry) and 24d (m.mm) sites, respectively. The Ni1 and Ni2 atoms both fully occupy two 32f sites (.3m symmetry). The Mg/Ge statistical mixture occupies the 24e site with 4m.m symmetry. The structure of the title compound contains a three‐core‐shell cluster. At (0,0,0), there is a Ge1 atom which is surrounded by eight Ni atoms at the vertices of a cube and consequently six Mg atoms at the vertices of an octahedron. These surrounded eight Ni and six Mg atoms form a [Ge1Ni8(Mg/Ge)6] rhombic dodecahedron with a coordination number of 14. The [GeNi8(Mg/Ge)6] rhombic dodecahedron is encapsulated within the [Ni24] rhombicuboctahedron, which is again encapsulated within an [Ni32(Mg/Ge)24] pentacontatetrahedron; thus, the three‐core‐shell cluster [GeNi8(Mg/Ge)6@Ni24@Ni32(Mg/Ge)24] results. The pentacontatetrahedron is a new representative of Pavlyuk's polyhedra group based on pentagonal, tetragonal and trigonal faces. The dominance of the metallic type of bonding between atoms in the Mg5.57Ni16Ge7.43 structure is confirmed by the results of the electronic structure calculations. The hydrogen sorption capacity of this intermetallic at 570 K reaches 0.70 wt% H2. [ABSTRACT FROM AUTHOR]

M n 5 G e 3 is a ferromagnetic phase of the Mn-Ge system that is a potential contact material for efficient spin injection and detection. Here, we investigate the creation of M n 5 G e 3 -based contacts on a Ge/SiGe quantum well heterostructure via solid-state synthesis. X-ray diffraction spectra fitting indicates the formation of M n 5 G e 3 -based contacts on bulk Ge and Ge/SiGe. High-resolution scanning transmission electron microscopy imaging and energy dispersive X-ray spectroscopy verify the correct M n 5 G e 3 -based phase formation. Schottky diode measurements, transmission line measurements, and Hall measurements reveal that M n 5 G e 3 -based contacts serve as good p-type contacts for Ge/SiGe quantum well heterostructures due to having a low Schottky barrier height of 0.10 e V (extracted from a M n 5 G e 3 /n-Ge analogue) and a contact resistance in the order of 1 k Ω. Furthermore, we show that these electrical characteristics have a gate-voltage dependence, thereby providing tunability. [ABSTRACT FROM AUTHOR]

Mn5Ge3 is a ferromagnetic phase of the Mn-Ge system that is a potential contact material for efficient spin injection and detection. Here, we investigate the creation of Mn5Ge3-based contacts on a Ge/SiGe quantum well heterostructure via solid-state synthesis. X-ray diffraction spectra fitting indicates the formation of Mn5Ge3-based contacts on bulk Ge and Ge/SiGe. High-resolution scanning transmission electron microscopy imaging and energy dispersive X-ray spectroscopy verify the correct Mn5Ge3-based phase formation. Schottky diode measurements, transmission line measurements, and Hall measurements reveal that Mn5Ge3-based contacts serve as good p-type contacts for Ge/SiGe quantum well heterostructures due to having a low Schottky barrier height of 0.10eV (extracted from a Mn5Ge3/n-Ge analogue) and a contact resistance in the order of 1 kΩ. Furthermore, we show that these electrical characteristics have a gate-voltage dependence, thereby providing tunability.

The equiatomic germanide LaNiGe was synthesized from the elements by arc‐melting and subsequent annealing at 1173 K for 14 days. Its non‐centrosymmetric LaPtSi type structure was refined from single‐crystal X‐ray diffractometer data: I41md, a = 420.80(6), c = 1440.3(3) pm, wR = 0.0477, 284 F2 values and 14 variables. The nickel and germanium atoms build up a three‐dimensional [NiGe]δ– polyanionic network (2 × 241 and 1 × 242 pm Ni–Ge) in which the lanthanum atoms fill cavities with coordination number 12. This picture of chemical bonding is supported by an evaluation of the electron localization function. Physical properties of LaNiGe were studied by means of magnetic susceptibility, magnetization, specific heat and electrical resistivity measurements. The compound was found to be a Pauli paramagnet with a molar magnetic susceptibility of about χ = 1.6 × 10–4 emu·mol–1·Oe–1. The temperature dependence of the electrical resistivity shows Bloch‐Grüneissen‐Mott behavior indicating the metallic character of LaNiGe, which is in full agreement with the results of electronic structure and density of states calculations. No superconducting transition was observed in the temperature regime down to 1.72 K. [ABSTRACT FROM AUTHOR]

We report two new variants of the X‐phase (orthorhombic, space group Pnnm) derived from the Mn–Co–Ge system. Two compositionally related crystals were investigated by means of single‐crystal X‐ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X‐phase and adopt the Mn14(Mn0.11Co0.64Si0.25)23 structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X‐phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X‐phase have yet been reported. [ABSTRACT FROM AUTHOR]

Effects of carbon implantation (C-imp) on the contact characteristics of Ti/Ge contact were investigated. The C-imp into Ti/Ge system was developed to reduce severe Fermi-level pinning (FLP) and to improve the thermal stability of Ti/Ge contact. The current density (J)-voltage (V) characteristics showed that the rectifying behavior of Ti/Ge contact into an Ohmic-like behavior with C-imp. The lowering of Schottky barrier height (SBH) indicated that the C-imp could mitigate FLP. In addition, it allows a lower specific contact resistivity (ρc) at the rapid thermal annealing (RTA) temperatures in a range of 450–600 °C. A secondary ion mass spectrometry (SIMS) showed that C-imp facilitates the dopant segregation at the interface. In addition, transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) mapping showed that after RTA at 600 °C, C-imp enhances the diffusion of Ge atoms into Ti layer at the interface of Ti/Ge. Thus, carbon implantation into Ge substrate can effectively reduce FLP and improve contact characteristics.

The intermetallic compound CaFe 2 Ge 2 has been synthesized by ball-milling a stoichiometric mixture of pre-melted "FeGe" alloy with elemental Ca and subsequent annealing in welded niobium ampoule in a resistance furnace. Its crystal structure has been investigated by powder X-ray diffraction method: ThCr 2 Si 2 structure type (space group I 4/ mmm, Z = 2), a = b = 3.99366(4) Å, c = 10.7060(1) Å. Like iron-based superconductors, the main structural motif in CaFe 2 Ge 2 is a square-planar layer of Fe atoms that are tetrahedrally coordinated by Ge atoms. The (Fe 2 Ge 2) layers are alternating along the c -axis with the layers of Ca2+ cations and are interconnected via Ge–Ge bonds, resulting in a three-dimensional (Fe 2 Ge 2)2– polyanionic framework. The topological analysis of the Electron Localization Function (ELF) confirms 3D character of (Fe 2 Ge 2) layers similar to reported 122 iron tetrelides YFe 2 Ge 2 and CaFe 2 Si 2. CaFe 2 Ge 2 fills the gap in the row of Ca T 2 Ge 2 (T = Mn–Zn), being a fully-substituted variant (Ge/As) of the well-known superconducting collapsed tetragonal CaFe 2 As 2. Magnetic measurements revealed the occurrence of ferromagnetic order in CaFe 2 Ge 2 below 50 K. CaFe 2 Ge 2 has been synthesized by an unconventional solid-state method. This iron germanide crystallizes in the ThCr 2 Si 2 structure type. CaFe 2 Ge 2 is a fully-substituted (As/Ge) variant of iron-pnictide superconductor CaFe 2 As 2 and isoelectronic to its uncollapsed form. CaFe 2 Ge 2 orders ferromagnetically below 50 K. Image 1 • New ternary iron-germanide CaFe 2 Ge 2 has been synthesized by an unconventional solid-state method. • CaFe 2 Ge 2 is a fully-substituted (As/Ge) variant of iron-pnictide superconductor CaFe 2 As 2 and isoelectronic to its uncollapsed form. • CaFe 2 Ge 2 orders ferromagnetically below 50 K. [ABSTRACT FROM AUTHOR]

By means of ab initio calculations, we have estimated stability of 2D Me 2 X (Me = Mg , Ca, Sr, Ba and X = Si , Ge, Sn) in the T and Td phases, which are similar to the ones of 2D transition metal chalcogenides, in addition to their phonon spectra. The T phase is found to be more stable for 2D Ca 2 X , Sr 2 X and Ba 2 X , whereas the Td phase is predicted to be the ground state for 2D Mg 2 X. We have also discussed that imaginary frequencies in the calculated phonon spectra of 2D Me 2 X , which appeared in the vicinity of the Γ point, were not necessarily associated with the dynamic instability. [ABSTRACT FROM AUTHOR]

Single crystals of dicerium trialuminium tetragermanide, Ce2Al3Ge4, have been synthesized from a high‐temperature reaction using an eutectic mixture of Al and Ge as a metal flux. Through single‐crystal X‐ray diffraction it was established that Ce2Al3Ge4 crystallizes in the centrosymmetric space group Cmce (No. 64) with the Ba2Cd3Bi4 structure type (Pearson code oC36). Five atoms compose the asymmetric unit, i.e. one Ce, two Al, and two Ge atoms, all in special positions with Wyckoff symbols 8f (Ce), 4a and 8e (Al), and 8e and 8f (Ge). The structure can be described as a three‐dimensional network of Al and Ge atoms, with Ce atoms occupying the cavities of the framework. [ABSTRACT FROM AUTHOR]

The influence of the partial substitution of Ni atoms by the similarly sized but electron-richer Ge atoms with a similar electronegativity in the binary Laves phase MgNi2 is investigated. A small degree of substitution in MgNi2- xGe x ( x = 0.1) leads to the change of the hexagonal MgNi2-type structure (C36) to the cubic C15 type, whereas higher amounts of Ge lead to the formation of the two new Laves phases Mg2Ni3Ge and MgNi1.30(5)Ge0.70, which were synthesized by the direct reaction of the elements in alumina and niobium crucibles using an induction furnace. The crystal structures of the two phases were determined by single-crystal X-ray diffraction. Mg2Ni3Ge ( hR18-MgNi2- xGe x, x = 0.5) crystallizes in the Y2Rh3Ge-type structure, which is an ordered variant of the cubic Laves phase MgCu2: space group R 3 m, a = 5.0300(7), c = 11.330(2) Å. hP36-MgNi2- xGe x with x = 0.70(6) crystallizes as a superstructure of the hexagonal Laves phase MgZn2: space group P63/ mcm, a = 8.6946(2), c = 7.8127(3) Å. MgNi1.3Ge0.7 represents a new structure type. Gradual substitution of Ni by Ge in the Laves phase MgNi2 corresponds to an increase in the valence electron concentration (VEC) in the ternary phase system and leads to the series MgCu2 (C15 type), hR18-Mg2Ni3Ge (superstructure of MgCu2 type), and hP36-MgNi1.3Ge0.7 (superstructure of MgZn2 type). The electronic structures are discussed based on band structure calculations, and the results are compared to the pristine Laves phase MgNi2, MgCu2, and MgZn2 with VEC = 2/3, 4/3 and 2, respectively. [ABSTRACT FROM AUTHOR]

The influence of the partial substitution of Ni atoms by the similarly sized but electron-richer Ge atoms with a similar electronegativity in the binary Laves phase MgNi2 is investigated. A small degree of substitution in MgNi2- xGe x ( x = 0.1) leads to the change of the hexagonal MgNi2-type structure (C36) to the cubic C15 type, whereas higher amounts of Ge lead to the formation of the two new Laves phases Mg2Ni3Ge and MgNi1.30(5)Ge0.70, which were synthesized by the direct reaction of the elements in alumina and niobium crucibles using an induction furnace. The crystal structures of the two phases were determined by single-crystal X-ray diffraction. Mg2Ni3Ge ( hR18-MgNi2- xGe x, x = 0.5) crystallizes in the Y2Rh3Ge-type structure, which is an ordered variant of the cubic Laves phase MgCu2: space group R 3 m, a = 5.0300(7), c = 11.330(2) Å. hP36-MgNi2- xGe x with x = 0.70(6) crystallizes as a superstructure of the hexagonal Laves phase MgZn2: space group P63/ mcm, a = 8.6946(2), c = 7.8127(3) Å. MgNi1.3Ge0.7 represents a new structure type. Gradual substitution of Ni by Ge in the Laves phase MgNi2 corresponds to an increase in the valence electron concentration (VEC) in the ternary phase system and leads to the series MgCu2 (C15 type), hR18-Mg2Ni3Ge (superstructure of MgCu2 type), and hP36-MgNi1.3Ge0.7 (superstructure of MgZn2 type). The electronic structures are discussed based on band structure calculations, and the results are compared to the pristine Laves phase MgNi2, MgCu2, and MgZn2 with VEC = 2/3, 4/3 and 2, respectively. [ABSTRACT FROM AUTHOR]

The germanides RE3Pt4Ge6 (RE = Y, Pr, Nd, Sm, Gd-Dy) have been synthesized by arc-melting of the elements followed by inductive annealing to improve the crystallinity and allow for structural order. The compounds have been studied by powder X-ray diffraction; additionally the structure of Y3Pt4Ge6 has been refined from single-crystal X-ray diffractometer data. It exhibits a (3 + 1)D modulated structure, indicating isotypism with Ce3Pt4Ge6. The crystal structure can be described as an intergrowth between YIrGe2- and CaBe2Ge2-type slabs along [100]. Temperature-dependent magnetic susceptibility measurements showed Pauli paramagnetism for Y3Pt4Ge6 and Curie-Weiss paramagnetism for Pr3Pt4Ge6 and Nd3Pt4Ge6. Sm3Pt4Ge6 exhibits van Vleck paramagnetism, while antiferromagnetic ordering at TN = 8.1(1) K and TN = 11.0(1) K is observed for Gd3Pt4Ge6 and Tb3Pt4Ge6, respectively. [ABSTRACT FROM AUTHOR]

Our recent study on formal halide adducts of disilenes led to the investigation of the synthesis and properties of β-fluoro- and chlorodisilanides. The reaction of the functionalized neopentasilanes (Me3Si)3SiSiPh2NEt2 and (Me3Si)3SiSiMe2OMe with KOtBu in the presence of 18-crown-6 provided access to structurally related β-alkoxy- and amino-substituted disilanides. The obtained Et2NPh2Si(Me3Si)2SiK·18-crown-6 was converted to a magnesium silanide and further on to Et2NPh2Si(Me3Si)2Si-substituted ziroconocene and hafnocene chlorides. In addition, an example of a silanide containing both Et2NPh2Si and FPh2Si groups was prepared with moderate selectivity. Also, the analogous germanide Et2NPh2Si(Me3Si)2GeK·18-crown-6 could be obtained.

Tm5Pd4Ge8 was synthesized by melting of the elements in an arc-melting furnace. The new germanide was characterized by powder and single-crystal X-ray diffraction: own structure type, P21/m, a = 574.3(1), b = 1380.4(3), c = 836.4(1) pm, β = 107.57(2)°, V = 0.6321 nm3, wR2 = 0.0578, 2533 F2 values, 86 variables. The palladium and germanium atoms built up a three-dimensional [Pd4Ge8]15- polyanionic network which contains a unique germanium substructure composed of the Zintl anions Ge26- dumb-bells and Ge410- chains in cis-conformation. The palladium atoms within the network have distorted square pyramidal germanium coordination. The three crystallographically independent thulium atoms have coordination numbers 15, 16 and 17 with partial motifs of the Frank-Kasper type polyhedra. The isotypic germanide Er5Pd4Ge8 forms only after annealing the arc-melted sample at 1070 K for 1 week: a = 575.14(9), b = 1386.3(3), c = 838.4(1) pm, β = 107.51(2)°, V = 0.6375 nm³. [ABSTRACT FROM AUTHOR]

The structure and the chemical composition of Pd germanides formed on Ge(100) were investigated using transmission electron microscopy (TEM), in-situ X-ray diffraction (XRD), and atom probe tomography (APT). An ultrathin Si film used as a marker was deposited on Ge(100) prior to Pd film deposition in order to identify the diffusing species during the Pd 2 Ge growth. The observations evidenced the formation of a thin interfacial polycrystalline Pd 2 Ge layer during Pd room-temperature deposition on Ge(100). In-situ XRD thermal treatments ranging from 50 to 400 °C revealed that the Si marker had no influence on the sequential formation of Pd 2 Ge and PdGe. Ex situ APT and TEM characterizations showed that the Si marker layer was located closer to the Pd 2 Ge/Ge interface than to the Pd 2 Ge surface, after reaction. This result indicates that Ge and Pd self-diffusion are in the same order of magnitude during Pd 2 Ge growth. [ABSTRACT FROM AUTHOR]

Reactive pulsed laser deposition is a technique suitable for producing homogenous thin layers of silicon or germanium with high concentration of embedded manganese atoms. Linear calibration of EDS (Energy Dispersive X-ray Spectroscopy) was utilized for an elemental analysis of thin layers. MnSi and MnGe (manganese-silicon and manganese-germanium) layers containing non-oxidized Mn were obtained for Mn molar concentration in the range from 15 to 50%. Electron diffraction showed an amorphous character of MnSi layers. MnGe layers contained two different types of nanoparticles incorporated inside an amorphous matrix. The layers were semiconducting with resistivities from 10 − 3 to 10 − 5 Ω m. [ABSTRACT FROM AUTHOR]

Pr3Rh4Ge4 was synthesized by melting of the elements in an arc-melting furnace followed by annealing in a sealed tantalum ampoule in a muffle furnace. Structure refinement was based on temperature dependent single-crystal X-ray diffractometer data. At ambient temperature Pr3Rh4Ge4 adopts the U3Ni4Si4 type structure with strongly enhanced anisotropic displacement parameters for Rh1. Below 230 K additional reflections start to appear and at 110 K the structure could be described with the (3+1)D superspace group I2/ m(α0γ)00; α=1/2, γ=1/2; ( Z=2). This commensurately modulated structure could be refined with 1448 F2 values, 39 variables and residuals of wR=0.0417 for the main reflections and wR=0.1520 for the satellites of 1st order, [ a=408.36(2), b=421.12(3) and c=2504.4(2) pm]. The commensurate description could be transformed to a 3D supercell with space group A2/ m and Z=4: a=816.72(2), b=421.12(3), c=2537.5(1) pm, β=99.26(1)°, 1448 F2 values, 69 variables and wR=0.0499. The relation of the U3Ni4Si4 type structure, the (3+1)D modulated and the 3D supercell is discussed on the basis of a group-subgroup scheme. Temperature dependent magnetic susceptibility data reveal Curie-Weiss paramagnetism with an experimental moment of 3.72(2) μB/Pr atom and a Weiss constant of -12.6(5) K. No magnetic ordering is evident down to 3 K. [ABSTRACT FROM AUTHOR]

Pr3Rh4Ge4 was synthesized by melting of the elements in an arc-melting furnace followed by annealing in a sealed tantalum ampoule in a muffle furnace. Structure refinement was based on temperature dependent single-crystal X-ray diffractometer data. At ambient temperature Pr3Rh4Ge4 adopts the U3Ni4Si4 type structure with strongly enhanced anisotropic displacement parameters for Rh1. Below 230 K additional reflections start to appear and at 110 K the structure could be described with the (3+1)D superspace group I2/ m(α0γ)00; α=1/2, γ=1/2; ( Z=2). This commensurately modulated structure could be refined with 1448 F2 values, 39 variables and residuals of wR=0.0417 for the main reflections and wR=0.1520 for the satellites of 1st order, [ a=408.36(2), b=421.12(3) and c=2504.4(2) pm]. The commensurate description could be transformed to a 3D supercell with space group A2/ m and Z=4: a=816.72(2), b=421.12(3), c=2537.5(1) pm, β=99.26(1)°, 1448 F2 values, 69 variables and wR=0.0499. The relation of the U3Ni4Si4 type structure, the (3+1)D modulated and the 3D supercell is discussed on the basis of a group-subgroup scheme. Temperature dependent magnetic susceptibility data reveal Curie-Weiss paramagnetism with an experimental moment of 3.72(2) μB/Pr atom and a Weiss constant of -12.6(5) K. No magnetic ordering is evident down to 3 K. [ABSTRACT FROM AUTHOR]

• Growth methods allow to tune the phase formation in the manganese germanide thin films. • The effective heat of formation model is a suitable framework to describe the phase formation. • The epitaxy of Mn5Ge3 on Ge(111) expands the range of the thermal stability of this compound. We have studied the stability of manganese germanide thin films grown on Ge(111) substrates by three different growth methods: solid phase epitaxy, reactive deposition epitaxy and co-deposition. By combining X-ray diffraction and magnetic measurements, we demonstrate that we can form either Mn 5 Ge 3 or Mn 11 Ge 8 thin films depending on the growth processes. In the case of solid phase epitaxy, we explain the phase formation sequence by taking into consideration the kinetic and thermodynamic processes involved. Tuning phase formation of the manganese germanide thin films was determined using in situ X-ray diffraction and the effect of the thin film thickness on the Mn 5 Ge 3 thermal stability was investigated. [ABSTRACT FROM AUTHOR]

Pd-Ge reactive-diffusion in two different samples Pd/Ge(001) and Pd/PdGe/Ge(001) was studied experimentally and theoretically, in order to clearly identify the driving force controlling the first-phase selection in the sequential phase formation regime. The experimental and theoretical results both show that only the atomic transport kinetic in the phases controls the first-phase selection: the phase exhibiting the fastest atomic self-diffusion forms first, even if its formation energy is not the lowest. [ABSTRACT FROM AUTHOR]

The quaternary germanides RE3 TRh4Ge4 ( RE = Ce, Pr, Nd; T = Nb, Ta) were synthesized from the elements by arc-melting and subsequent annealing in a muffle furnace. The structure of Ce3TaRh4Ge4 was refined from single-crystal X-ray diffractometer data: new type, Pbam, a = 719.9(2), b = 1495.0(3), c = 431.61(8), wR2 = 0.0678, 1004 F2 values, and 40 variables. Isotypy of the remaining phases was evident from X-ray powder patterns. Ce3TaRh4Ge4 is a new superstructure variant of the aristotype AlB2 with an ordering of cerium and tantalum on the aluminum site, whereas the honey-comb network is built up by a 1:1 ordering of rhodium and germanium. This crystal-chemical relationship is discussed based on a group-subgroup scheme. The distinctly different size of tantalum and cerium leads to a pronounced puckering of the [Rh4Ge4] network, which shows the shortest interatomic distances (253-271 pm Rh-Ge) within the Ce3TaRh4Ge4 structure. Another remarkable structural feature concerns the tantalum coordination with six shorter Ta-Rh bonds (265-266 pm) and six longer Ta-Ge bonds (294-295 pm). The [Rh4Ge4] network fully separates the tantalum and cerium atoms (Ce-Ce > 387 pm, Ta-Ta > 431 pm, and Ce-Ta > 359 pm). The electronic density of states DOS from DFT calculations show metallic behavior with large contributions of localized Ce 4f as well as itinerant ones from all constituents at the Fermi level but no significant magnetic polarization on Ce could be identified. The bonding characteristics described based on overlap populations illustrate further the crystal chemistry observations of the different coordination of Ce1 and Ce2 in Ce3TaRh4Ge4. The Rh-Ge interactions within the network are highlighted as dominant. The bonding magnitudes follow the interatomic distances and identify differences of Ta bonding vs. Ce1/Ce2 bonding with the Rh and Ge substructures. [ABSTRACT FROM AUTHOR]

The quaternary germanides RE3 TRh4Ge4 ( RE = Ce, Pr, Nd; T = Nb, Ta) were synthesized from the elements by arc-melting and subsequent annealing in a muffle furnace. The structure of Ce3TaRh4Ge4 was refined from single-crystal X-ray diffractometer data: new type, Pbam, a = 719.9(2), b = 1495.0(3), c = 431.61(8), wR2 = 0.0678, 1004 F2 values, and 40 variables. Isotypy of the remaining phases was evident from X-ray powder patterns. Ce3TaRh4Ge4 is a new superstructure variant of the aristotype AlB2 with an ordering of cerium and tantalum on the aluminum site, whereas the honey-comb network is built up by a 1:1 ordering of rhodium and germanium. This crystal-chemical relationship is discussed based on a group-subgroup scheme. The distinctly different size of tantalum and cerium leads to a pronounced puckering of the [Rh4Ge4] network, which shows the shortest interatomic distances (253-271 pm Rh-Ge) within the Ce3TaRh4Ge4 structure. Another remarkable structural feature concerns the tantalum coordination with six shorter Ta-Rh bonds (265-266 pm) and six longer Ta-Ge bonds (294-295 pm). The [Rh4Ge4] network fully separates the tantalum and cerium atoms (Ce-Ce > 387 pm, Ta-Ta > 431 pm, and Ce-Ta > 359 pm). The electronic density of states DOS from DFT calculations show metallic behavior with large contributions of localized Ce 4f as well as itinerant ones from all constituents at the Fermi level but no significant magnetic polarization on Ce could be identified. The bonding characteristics described based on overlap populations illustrate further the crystal chemistry observations of the different coordination of Ce1 and Ce2 in Ce3TaRh4Ge4. The Rh-Ge interactions within the network are highlighted as dominant. The bonding magnitudes follow the interatomic distances and identify differences of Ta bonding vs. Ce1/Ce2 bonding with the Rh and Ge substructures. [ABSTRACT FROM AUTHOR]

The thermal stability of PdGe on Ge(100) was investigated by scanning electron microscopy, X-ray diffraction and atom probe tomography. The initial PdGe film agglomerates when heated at high temperature (≥ 500 °C), forming spherical islands. This degradation is highly detrimental for PdGe ohmic contact fabrication in the Ge-based nano-electronics technology. However, capping the Pd layer with W before Pd-Ge reaction increases the thermal stability of the PdGe film up to 600 °C. In addition, the PdGe texture is modified if the sample is heated during Pd deposition, increasing the thermal stability of PdGe up to 700 °C with the W cap. [ABSTRACT FROM AUTHOR]