Amounts Of Ge Research Articles

Investigation of the atomic and electronic structures of highly ordered two-dimensional germanium on Au(111)

Low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and photoelectron spectroscopy have been used to study an ordered structure formed by Ge atoms deposited onto the Au(111) surface. Based on a careful analysis of STM images and LEED patterns, we propose a new unit cell for the atomic structure of the Ge layer. Core level data indicate that some Ge atoms diffuse into the Au(111) crystal during annealing after deposition at room temperature. This is further corroborated by angle resolved photoelectron spectroscopy measured for different amounts of Ge remaining after sputtering and annealing. The results of the ARPES study clearly exclude the interpretation, in the literature, of a parabolic band as part of a Dirac cone of germanene.

From eutectic to peritectic: Effect of Ge on morphology, structure, and coarsening of Cr-Cr3Si alloys

The influence of germanium on microstructure, crystallography, and thermal stability of the eutectic Cr-Cr3Si alloy was investigated. Fine eutectic microstructures could be preserved but slightly degenerated when up to 2 at.% Si was substituted by Ge. A transition from eutectic to peritectic microstructure composed of primary dendrites and A15 Cr3Si matrix was observed when higher amounts of Ge were added. X-ray diffraction results showed no limit for substitution of Si and Ge in the studied composition range. The lattice parameter of both Cr solid-solution and A15 silicide increased with increasing the Ge/Si ratio. A macro was developed for the ImageJ program to automate the quantitative microstructural image analysis. Results showed that Ge addition increases the A15 phase fraction of the two-phase alloys. Microstructural investigations on annealed alloys at 1350 °C demonstrated that the coarsening of both binary Cr-Cr3Si and ternary Cr-Cr3(Si, Ge) is interface-controlled. Although Ge addition to the eutectic alloy offered an isotropic microstructure, it decreased the thermal stability by degeneration of the lamellar structure.

The Influence of the Valence Electron Concentration on the Structural Variation of the Laves Phases MgNi2–xGex

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–xGex (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–xGex, x = 0.5) crystallizes in the Y2Rh3Ge‐type structure, which is an ordered variant of the cubic Laves phase MgCu2: space group R3m, a = 5.0300(7), c = 11.330(2) Å. hP36‐MgNi2–xGex 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.

Experimental and thermodynamic assessment of the Ge-Nb-Si ternary phase diagram

Niobium silicide-based in-situ composites have the potential to supersede nickel-based superalloys due to their excellent high temperature mechanical properties and low density. The addition of small amounts of germanium into these systems can significantly improve oxidation resistance. The effect of germanium on the phases formed in bulk niobium silicide-based in-situ composites is not particularly well understood, in particular the effect of introducing germanium on the formation of the Nb5Si3 intermetallic. Limited data is available in the literature. To provide coherent information on the effect of germanium on the phase equilibrium in the Nb-Si system, a comprehensive thermodynamic description of the Ge-Nb-Si system has been developed in the current paper using the CALPHAD method. Initially the Ge-Nb phase diagram was reassessed using the CALPHAD method to take into account recent ab initio data. To supplement limited information on the ternary system in the literature between 800 and 1820 °C, the pseudo binary between Nb5Si3 and Nb5Ge3 was studied experimentally between 1200 and 1500 °C. Experimental and modelling results indicate that the W5Si3 prototype of Nb5Si3 can be stabilised to lower temperatures on the addition of germanium. Ge contents in excess of 12.4 at. % at 1200 °C in stoichiometric Nb5(Ge,Si)3 stabilise the W5Si3 prototype. In non-stoichiometric Nb5(Ge,Si)3, where Nb < 62.5 at. %, lower amounts of Ge are required to stabilised the W5Si3 prototype. The liquidus projection suggests a ternary eutectic with Nb5(Ge,Si)3, Nbss and Nb3Si can form in Nb-Si rich alloys during solidification.

РЕГУЛЯТОРНИЙ ВПЛИВ РІЗНИХ ДОЗ ЦИТРАТУ ГЕРМАНІЮ НА ФІЗІОЛОГО-БІОХІМІЧНІ ПРОЦЕСИ ОРГАНІЗМУ САМЦІВ F2

Studied the impact of prolonged watering of different amounts of citrate Ge, obtained by nanotechnology method, on the biochemical processes and antioxidant activity blood of male rats F2 1 and 2nd offspring in times of physiological and puberty. Established differently directed influence citrate Ge on the biochemical parameters bloods of animals of all ages – the increase of creatinine, phosphorus and triacylglycerol in male 4-month-old 1st offspring, while in animals 2 offspring grew albumin, calcium, phosphorus and triacylglycerols. Noted growth activity of antioxidant enzymes – catalase, SOD and GP animals 2-month-old 1st offspring, while the 4 months activity remained at the level of the control group, but males 2nd offspring grew – SOD and GP. For the watering 200 mkg Ge content hydroperoxides lipid and TBA products in the blood is reduced by 4 months of age the animals received both the first and second litters.

Oriented control of Al locations in the framework of Al-Ge-ITQ-13 for catalyzing methanol conversion to propene

Locations of Al in the Al-Ge-ITQ-13 framework were regulated by adding different amounts of Ge and Al for the purpose of developing a potential methanol-to-propene catalyst. Ge had no significant influence on acid site number, strength, and type, but influenced acid site distribution and catalytic properties. The Al sited at T2, T5, and particularly T9 sites rapidly deactivated Al-Ge-ITQ-13, but attempts to locate Al at T3 and T6 by adjusting Ge and Al content remarkably increased its catalytic life and propene selectivity, by 686% and 44% respectively. A simple method for roughly estimating the great effects of acid site distribution and density on the catalytic life was developed by measuring the intensity of 27Al MAS NMR signal around 51.4–53.4ppm, even though changes in acid site density are always accompanied by alterations of acid site distribution. The hydrothermal treatment of Al-Ge-ITQ-13 confirms its potential for use in industry.

ChemInform Abstract: Negative Thermal Expansion and Low‐Temperature Heat Capacity Anomalies of Ge31P15Se8 Semiclathrate.

AbstractPolycrystalline Ge31P15Se8 samples are prepared by solid state reaction of stoichiometric amounts of Ge, red P, and Se (evacuated silica tubes, 874 K, 8 d).

Cu2ZnSnSe4-Based Solar Cells With Efficiency Exceeding 10% by Adding a Superficial Ge Nanolayer: The Interaction Between Ge and Na

Recently, beneficial effects of the incorporation of small amounts of Ge into Cu2ZnSnSe4 (CZTSe)-based solar cells have been reported, showing that the presence of Ge can enhance the crystalline properties of CZTSe, assisting the grain growth, leading to high-efficiency devices. In this study, we prepare CZTSe layers by a sequential process consisting of the sputtering of metallic stacks followed by a reactive annealing under Se atmosphere, previously adding different Ge nanolayers on top (from 0 to 50 nm). The present work is focused on the study of the interaction between germanium and sodium. As is widely known, Na is a very important dopant in kesterite, which plays an essential role in the doping level control. We demonstrate that during the annealing process, a Ge–Se liquid phase is formed which dissolves preferably Na-related phases modifying the content of this last element in the CZTSe absorber and impacting notably on the electrical properties of the layers and, concomitantly, on the performance of the devices. We support our Ge–Na interaction model with experiments using Na-free substrates, showing the importance of accurately controlling the Na content when Ge is used to increase the efficiency of CZTSe-based solar cells.

Measurement of Recombination Lifetimes in Gesn Alloys

Silicon photonics requires the development of Si-based lasers, modulators, waveguides, and detectors operating in the infrared beyond the band gap of silicon. A number of approaches to solving this problem have been pursued, including epitaxial growth of lower band gap materials on Si. The SiGe alloy system was explored for many years, but limitations in quality due the large lattice mismatch between Si and SiGe with high amounts of Ge, as well as the band gap (0.66 eV at its lowest for pure Ge) and its indirect nature, have prevented its widespread use. Integration of III-V materials such as InGaAs has also been tried extensively, but the problems of phase segregation and film quality have not been overcome. The GeSn alloy system has been gaining attention in the photonics world due to its unique optical properties, and the growth of these alloys on Si platforms has jumpstarted efforts to employ this technology for the fabrication of CMOS-compatible infrared optoelectronics. These crystalline alloy films are grown directly on Si or Ge-buffered Si, have band gaps below that of Si or Ge, and are grown to thicknesses of up to 1 µm. Additionally, the band gap of GeSn should be direct for concentrations greater than about 10% Sn. Much work has been done on the development of GeSn materials, and theoretical designs for lasers based on these alloys have been appearing in the literature frequently. However, the realization of complex optoelectronic devices like laser diodes requires materials with long recombination lifetimes to achieve population inversion. Thus, the study of recombination lifetimes in GeSn alloys is of paramount importance to the actualization of GeSn lasers. Unfortunately, the standard method of time-resolved photoluminescence (TRPL) is not well-suited to the study of GeSn alloys. For low Sn contents (<10% Sn), the band gap is indirect, so the intensity of optical emission is not high. Such a measurement would require single photon counting, but single photon detectors are not available at the emission wavelengths for the materials of interest. Conductivity-based methods should be more suitable, but the standard techniques of microwave photoconductive decay (µ-PCD) and RF-coupled photoconductive decay (RFPCD) suffer from low sensitivity in thin films or low temporal resolution. In this work, we employ a new conductivity-based method for measurement of recombination lifetimes in thin film GeSn alloys. The method of transmission-modulated photoconductive decay (TMPCD) uses the transverse transmission of microwaves through a thin film, allowing for a very large interaction volume between the free carriers and the microwaves, thereby increasing the sensitivity for thin film materials. We will discuss this new method and show preliminary results on GeSn films with up to 7% Sn.

Improving soft magnetic properties in FINEMET-like alloys. A study

An approach to improve the soft magnetic properties of nanocomposite FINEMET-like alloys is presented by the study of the theoretical behavior of the coercive field with the crystallized fraction, Hc(νcr), curves where the total anisotropy is taken into account. These curves can exhibit a minimum value that should be used for a proper design of soft magnetic alloys, consisting in matching that value with the optimal crystallized fraction of the alloy. For this, the effect of Si, Ge, Co and Al on the magnetic properties on the material phases and on its microstructure was analyzed while a good relationship between theoretical results and data in the literature was found. Small amounts of Ge and/or Al can improve the magnetic properties of FINEMET while the addition of Co deteriorates the coercive field as is predicted by the theory. Simultaneous addition of two or more solute elements to the α-Fe crystals was also evaluated and discussed. Results indicate the importance of knowing the effect of the alloying element on the crystalline magnetostriction constant and on the crystallized fraction of the microstructure.

Unique surface structure formations on a Ge-covered Si(110)-16×2 surface

Si–Ge structures forming new shapes on a Si(110)-16×2 reconstructed surface were investigated via scanning tunneling microscopy. Pyramidal-shaped Si–Ge nanoislands lying along the <111> directions were formed on the striped structure at Ge coverage between 3 and 6 monolayers. However, when a single monolayer of Ge was deposited on the Si(110)-16×2 surface, single-domain of 16×2 striped structure disappeared, and a new double-domain striped structure was formed over the surface along directions that differed from the <112> directions. This structure represents a new Si–Ge striped structure that forms by the mixing of Ge and Si due to high temperature annealing. These results indicate that the surface structure changes specifically with trace amounts of Ge.

The synthesis of super-hydrophilic and acid-proof Ge–ZSM-5 membranes by simultaneous incorporation of Ge and Al into a Silicalite-1 framework

A new method for synthesis of super-hydrophilic and acid-proof zeolite membranes was presented. It involved simultaneous incorporation of suitable amounts of Ge and Al into a Silicalite-1 framework. The precursor sol was prepared in an ice-water bath, and the alcohols in the precursor sol were removed at about 80°C. It was shown that using the ice-water bath would prevent the formation of GeO2 and removing the alcohols at a relatively high temperature would lead to suitable amounts of Ge and Al in the membranes. The obtained Ge–ZSM-5 membranes were acid-proof and showed high pervaporation performance for dehydrating acetic acid and ethanol solutions. At 353K, for feed acetic acid solutions in a concentration range of 30–98wt%, the permeation flux of water was almost constant (about 0.57kg/m2h), and very little acetic acid permeated through the membrane, resulting in a very high separation factor. Similarly, for dehydration of ethanol solutions (10–98wt%) at 343K a water flux of approximately 2.4kg/m2h was obtained.

On the geological availability of germanium

Based on a detailed statistical analysis of chemical data published in the scientific literature, estimates were made of the minimum amounts of recoverable Ge contained within sulphidic zinc ores and coals, given current processing technologies. It is expected that at least 119 kt (∼7 kt in zinc ores and ∼112 kt in coal) of recoverable germanium exist within proven reserves (at present stage of knowledge) at grades in excess of 100 ppm in sphalerite and 200 ppm in coal, while at least 440 kt (∼50 kt in zinc ores and ∼390 kt in coal) should become recoverable in the future, being associated to coal reserves at 8–200 ppm Ge and zinc resources containing in excess of 100 ppm Ge in sphalerite. Mississippi Valley Type (MVT) deposits are expected to be the most important hosts of germanium-rich sphalerite, while both brown and hard coals are expected to be equally important as hosts of germanium. The approach taken in this publication shows that reliable minimum estimates for the availability of by-product metals lacking suitable reserve/resource data may be attained by using robust statistical methods and geochemical data published in the scientific literature

Inhibiting molecular array formation on Si(111)-7×7using site-selective Ge/Si exchange

The Si(111)-$7\ifmmode\times\else\texttimes\fi{}7$ surface reconstruction can be used to template an array of mesitylene (1,3,5-trimethyl-benzene) molecules in which each molecule bridges a corner Si adatom and a neighboring Si rest atom. The molecules adsorb in corner sites to minimize a weak steric interaction associated with nearest-neighbor bridging sites. We demonstrate that the formation of the molecular array can be blocked by adding submonolayer amounts of Ge to the surface. The Ge atoms block the formation of the array because they substitute preferentially for Si adatoms located in corner sites, and the Ge--C bond strength is $\ensuremath{\approx}$0.8 eV weaker than the Si--C bond strength.

Liquid-phase furfural hydrogenation employing silica-supported PtSn and PtGe catalysts prepared using surface organometallic chemistry on metals techniques

Platinum–germanium and platinum–tin catalysts supported on silica, containing different amounts of Sn and Ge, were synthesized using the surface organometallic chemistry on metals technique. The catalysts were characterized using transmission electron microscopy, X-ray photoelectron spectra and X-ray absorption near edge structure and extended X-ray absorption fine structure; and were tested in the liquid-phase selective hydrogenation of furfural. The atomic ratio between the two metals resulted the key factor towards the optimization of the activity and selectivity of the bimetallic catalysts. The bimetallic catalysts were more active than the parent Pt/SiO2 catalyst in the hydrogenation of furfural. These results can be accounted for by considering a new type of active site having an architecture which would favor the hydrogenation of the C=O group is created, allowing an increased activity towards obtaining furfuryl alcohol. All the studied systems allowed to obtain furfuryl alcohol with high selectivity.

Separation of trace amounts of Ga and Ge in aqueous solution using nano-particles micro-column

A simple and rapid analytical method for the separation of trace amounts of gallium and germanium from aqueous solution by solid-phase extraction with nano-particles was developed. It was found that only Ga(III) could be quantitatively retained on nano-SiO2 in the pH range of 3–4 and 8–12 while Ge(IV) was not adsorbed, but both Ga(III) and Ge(IV) ions could be adsorbed quantitatively on nano-TiO2 within the pH range of 4–11. These two ions adsorbed by nano-particles could be desorbed quantitatively. Effects of acidity, concentration of elution solution and interfering ions on the recovery of the analytes were systematically investigated. The sorption data could be well interpreted by the Langmuir model. Based on the Langmuir model equation, the monolayer adsorption capacity of nano-SiO2/nano-TiO2 was calculated to be 4.26mgg−1/19.68mgg−1 for Ga(III)/Ge(IV). Moreover, thermodynamic functions, the change of free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) of the adsorption reaction were estimated for each metal ion. Experimental data were also evaluated in terms of kinetic characteristics of adsorption and the adsorption process for both metal ions followed well pseudo-second-order kinetics. Finally, the proposed method was applied to the determination of trace Ga(III) and Ge(IV) in some water samples using loaded nano-particles columns, and it is found that the recoveries of Ga(III) and Ge(IV) were obtained to be in the range of 96.4–105.0%. And the method was validated with certified reference material (GBW07311, GBW 07406) and the values obtained for Ga(III) and Ge(IV) were in good agreement with the certified values.

Doping Effects on the Thermoelectric Properties of Cu&lt;SUB&gt;3&lt;/SUB&gt;SbSe&lt;SUB&gt;4&lt;/SUB&gt;

We present the first systematic doping study on the ternary semiconductor Cu3SbSe 4 . We have developed a novel synthesis procedure that produces high-quality polycrystalline samples with hole concentrations an order of magnitude lower than have been reported for the undoped compound. The hole concentration can be increased by adding small amounts of either Ge or Sn on the Sb site. The power factor increases with increasing doping, reaching a maximum value of 16 W/cmK^2 . The thermoelectric properties are optimized for the 2% Sn doped compound which has ZT=0.72 at 630K, rivaling that of state-of-the-art thermoelectric materials in this temperature range.

Interaction and Interdependent Packaging of Tegument Protein UL11 and Glycoprotein E of Herpes Simplex Virus

The UL11 tegument protein of herpes simplex virus plays a critical role in the secondary envelopment; however, the mechanistic details remain elusive. Here, we report a new function of UL11 in the budding process in which it directs efficient acquisition of glycoprotein E (gE) via a direct interaction. In vitro binding assays showed that the interaction required only the first 28, membrane-proximal residues of the cytoplasmic tail of gE, and the C-terminal 26 residues of UL11. A second, weaker binding site was also found in the N-terminal half of UL11. The significance of the gE-UL11 interaction was subsequently investigated with viral deletion mutants. In the absence of the gE tail, virion packaging of UL11, but not other tegument proteins such as VP22 and VP16, was reduced by at least 80%. Reciprocally, wild-type gE packaging was also drastically reduced by about 87% in the absence of UL11, and this defect could be rescued in trans by expressing U(L)11 at the U(L)35 locus. Surprisingly, a mutant that lacks the C-terminal gE-binding site of UL11 packaged nearly normal amounts of gE despite its strong interaction with the gE tail in vitro, indicating that the interaction with the UL11 N terminus may be important. Mutagenesis studies of the UL11 N terminus revealed that the association of UL11 with membrane was not required for this function. In contrast, the UL11 acidic cluster motif was found to be critical for gE packaging and was not replaceable with foreign acidic clusters. Together, these results highlight an important role of UL11 in the acquisition of glycoprotein-enriched lipid bilayers, and the findings may also have important implications for the role of UL11 in gE-mediated cell-to-cell spread.

Crystalline monolayer surface of liquid Au–Cu–Si–Ag–Pd: Metallic glass former

It is demonstrated by means of x-ray synchrotron reflectivity and diffraction that the surface of the liquid phase of the bulk metallic glass forming alloy Au49Cu26.9Si16.3Ag5.5Pd2.3 consists of a two-dimensional crystalline monolayer phase for temperatures of up to about 50 K above the eutectic temperature. The present alloy as well as glass forming Au82Si18 and Au–Si–Ge alloys containing small amounts of Ge are the only metallic liquids to exhibit surface freezing well above the melting temperature. This suggests that the phenomena of surface freezing in metallic liquids and glass forming ability are related and probably governed by similar physical properties.

Influence of Ge doping level on the EPR signal of Ge(1), Ge(2) and E'Ge defects in Ge-doped silica

We present an experimental investigation on the Ge doping level dependence of the Electron Paramagnetic Resonance (EPR) signal spectral features of the Ge(1), Ge(2) and E'Ge defects induced in Ge doped silica. We have studied samples produced by sol–gel or PCVD techniques and doped with different amounts of Ge up to 20% by weight. The samples were gamma or beta ray irradiated and successively they were thermally treated to isolate the EPR signals of the different point defects. The data show that the EPR line shapes of the Ge(1) and the Ge(2) centers are progressively modified for doping level higher than 1%, whereas the line shape of the E'Ge defect appears independent from the doping. Together with the EPR investigation, we have also recorded Raman spectra of the investigated samples. The Ge doping induces detectable modifications of Raman lines when the doping level is higher than 1% by weight. Basing on these observations, the structural modifications detected by Raman spectroscopy are tentatively considered the origin of the changes in the EPR features.