Germanium Atoms Research Articles

Exploring the structure of pure germanophospate glasses with different concentrations probed by magic angle spinning NMR spectroscopy.

Phosphate-based glasses such as pure germanophosphate can be achieved at moderately low temperature by means of affordable chemical substances. Nowadays, they become more stimulating because they can be easily doped with alkali, transition metal ions, and rare earth oxides to afford the anticipated physical and/or chemical features for nanoscience applications. Herein, we report an experimental study dealing with the structure of pure germanophosphate glass samples of prepared with different concentrations ranging from 20 up to 70 mole%. 31 P magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy has been employed to characterize the co-formed glasses by two different glass-forming oxides. The components of the phosphate species ( ) in each sample were determined by analyzing the MAS NMR spectra. Interestingly, 31 P MAS NMR spectrum for each sample was found to be characteristic powder patterns of the middle units Q2 . Q2 unit found herein has one oxygen atom bonded towards one germanium atom (non-bridging) and the other two oxygens are bonding towards two phosphorus atoms (bridging) of phosphate group (PO4 ). The results show that Q2 split into two units, Q2 I and Q2 II, due to different shielding of the phosphorus nucleus provided by the next nearest neighbor atoms. The chemical shift is interpreted in terms of the structure of each building unit of the phosphate group. The results obtained herein shed light on the way how to explore the revealed structure of the prepared glasses for the development of supported catalysts. Indeed, owing to their high chemical/thermal stability, the co-formed germanophosphate glasses obtained may prove as useful substrates for potential nanocatalysts.

Gerüsterweiterung eines Silicoids um ein einzelnes Germaniumatom über isolierte Zwischenprodukte

AbstractDas Wachstum von (Halb‐)Metallclustern ist entscheidend für Keimbildungsprozesse in gasförmigen und kondensierten Phasen. Wir berichten nun über die Isolierung von Zwischenprodukten während der Erweiterung eines stabilen, ungesättigten Siliciumclusters (Silicoid) um ein einzelnes Germaniumatom durch eine Abfolge von Substitution, Umlagerung und Reduktion. Die Reaktion von ligato‐lithiiertem Hexasilabenzpolaren LiSi6Tip5 (Li⋅(thf)2, Tip=2,4,6‐Triisopropylphenyl) mit GeCl2⋅NHC (NHC=1,3‐Diisopropyl‐4,5‐dimethylimidazol‐2‐yliden) liefert zunächst das Produkt mit exohedraler Germanium(II)‐Funktionalität, die dann in eine Si−Si Bindung des Si6‐Gerüsts insertiert. Die gleichzeitige Übertragung der Chlorfunktionalität von Germanium auf ein benachbartes Siliciumatom bewahrt die elektronenpräzise Natur des gebildeten endohedralen Germylens. Der vollständige Einbau des Germaniumheteroatoms in den Si6Ge‐Clusterkern wird schließlich entweder durch Reduktion unter Verlust des koordinierenden NHC oder direkt durch Reaktion von 1Li⋅(thf)2 mit GeCl2⋅1,4‐Dioxan erreicht.

Siliconoid Expansion by a Single Germanium Atom through Isolated Intermediates.

The growth of (semi‐)metal clusters is pivotal for nucleation processes in gaseous and condensed phases. We now report the isolation of intermediates during the expansion of a stable unsaturated silicon cluster (siliconoid) by a single germanium atom through a sequence of substitution, rearrangement and reduction. The reaction of ligato‐lithiated hexasilabenzpolarene LiSi6Tip5 (1Li⋅(thf)2, Tip=2,4,6‐triisopropylphenyl) with GeCl2⋅NHC (NHC=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) initially yields the product with exohedral germanium(II) functionality, which then inserts into an Si−Si bond of the Si6 scaffold. The concomitant transfer of the chloro functionality from germanium to an adjacent silicon preserves the electron‐precise nature of the formed endohedral germylene. Full incorporation of the germanium heteroatom to the Si6Ge cluster core is finally achieved either by reduction under loss of the coordinating NHC or directly by reaction of 1Li⋅(thf)2 with GeCl2⋅1,4‐dioxane.

Effekt of adsorbed Ge atoms on the photoemission properties of GaAs

A3B5 semiconductor compounds in the future are the most promising for further detailed consideration. In this regard, gallium arsenide is a semiconductor compound formed by elements of groups III and V of the periodic system – gallium Ga and arsenic As. Gallium arsenide and its surface properties attract much attention of researchers due to the possibility of its wide application in micro- and nanoelectronics technology. Despite numerous studies of the surface of semiconductors, many issues related to its properties and processes at the interface between two phases remain insufficiently clarified, especially in terms of the effect of the surface state on the energy spectrum of electrons in crystals. Interest in these issues is constantly growing not only from a scientific point of view, but also from a practical one, in connection with the development of semiconductor micro- and nanotechnologies. The development of its sections such as thin-layer nanoelectronics and optoelectronics, devices with MIS structures and charge coupling, cold cathodes and efficient photocathodes require an understanding of the processes in the near-surface layer of a semiconductor both with a free surface and with this free surface during the adsorption of other substances on it. This is also important for elucidating the possibility of changing the surface and near-surface properties of solids in a quite definite way. Gallium arsenide is the closest binary analog of germanium. By introducing appropriate impurities, gallium arsenide can be obtained with both n-type and p-type conductivity with different current carrier concentrations. This structure belongs to the crystallographic class of the cubic system, like germanium. Gallium arsenide and germanium crystallize in the structure of zinc blende. In view of the foregoing, it is interesting to study the influence of adsorbed germanium layers on the surface properties of gallium arsenide single crystals of various types of conductivity by photoemission method in ultrahigh vacuum. The questions of the influence of these coatings not only on the emission properties of gallium arsenide single crystals, but also the influence of these adsorbed germanium atoms on the energy structure in the near-surface region of single crystals are considered.

Synthesis of Microdiamonds and Germanium Nanotubes In the Argon-Germanium Arc

The paper describes a technique for the synthesis of microdiamonds, germanium nanoballs and nanotubes in an argon-germanium arc. The evaporation of germanium atoms was carried out from the surface of a graphite rod, which served as the anode of the arc discharge. The synthesis of microdiamonds was observed on graphite substrates near the anode; germanium nanotubes and germanium nanoballs were also found nearby. It has been established that germanium promotes the synthesis of nano and microdiamonds. Synthesized diamonds have a classic structure with rectangle faces and four hexagons adjacent to the edges of this rectangle. The sizes of microdiamonds reach tens of microns. The diameters of germanium nanotubes are of the order of 50-100 nm, and the length is of the order of 10 μm.

Calcium Substitution in Rare‐earth Metal Germanides with the Gd 5 Si 4 Type Structure

An extended series of rare-earth metal calcium germanides have been synthesized and structurally characterized. The compounds have the general formula RE5−xCaxGe4 (1.5<x<3.6; RE=rare-earth metal; Ce, Nd, Sm, Tb−Lu) and their structures have been established from single-crystal X-ray diffraction methods. They crystallize with the Gd5Si4-type in the orthorhombic space group Pnma (No. 62; Z=4; Pearson symbol oP36), where the germanium atoms are interconnected into two kinds of Ge2-dimers, formally [Ge2]6−. These studies show that Ca can be successfully incorporated into the host RE5Ge4 structure, whereby trivalent rare-earth metal atoms can be substituted by divalent calcium atoms. Rare-earth metal and calcium atoms are arranged in distorted trigonal prisms and cubes, centered by either Ge or Ca atoms. On one of the metal sites, the substitution is preferential and in 9 out of the 10 refined structures, the Wyckoff site 4c is found almost exclusively occupied by Ca. On the other two metal sites the substitution patterns appear to be governed by the mismatch between the size of the RE3+ and Ca2+ ions. This work further demonstrates the ability for the Gd5Si4 structure type to accommodate the substitution of a non-magnetic element while maintaining the global structural integrity.

New Ceramics Precursors Containing Si and Ge Atoms-Cubic Germasilsesquioxanes-Synthesis, Thermal Decomposition and Spectroscopic Analysis.

Compounds of the silsesquioxane type are attractive material precursors. High molecular weights and well-defined structures predestine them to create ceramics with a controlled composition at the molecular level. New molecular precursors of ceramic materials with the ratio of Si:Ge = 7:1 atoms were obtained. The influence of organic substituents on the thermal decomposition processes of germasilsesquioxanes was investigated. Some of the structures obtained are characterized by a high non-volatile residue after the thermal decomposition process. The introduction of the germanium atom to the structure of the silsesquioxane molecular cage reduces the thermal stability of the obtained structures.

Crystal structure of Dy11Ge4.33In5.67 and Tm11Ge4In6 from X-ray single-crystal and powder data

Abstract Single crystals of Dy11Ge4.33In5.67 were grown from a sample of the starting composition Dy55Ge20In25 by arc-melting and subsequent annealing. Dy11Ge4.33In5.67 crystallizes with the Sm11Ge4In6-type structure, space group I4/mmm, which was refined from single-crystal X-ray diffractometer data: a = 11.4329(16), c = 16.168(3) Å, wR2 = 0.0341, 927 F 2 values and 42 refined parameters. The isotypic compound Tm11Ge4In6 was characterized by X-ray powder diffraction: a = 11.262(2), c = 15.979(3) Å, R Bragg = 3.53%. The Sm11Ge4In6-type structure is a coloring variant of the Ho11Ge10 type, realized through germanium-indium ordering. The p-element substructure has four crystallographically independent sites: isolated germanium atoms (Ge4− Zintl anions), In4 squares and In/Ge–In/Ge dumb-bells with pronounced Ge/In mixing.

Influence of oxygen co-implantation on germanium out-diffusion and nanoclustering in SiO2/Si films

The thermally activated diffusion of germanium atoms implanted in the middle of SiO2 layers has been studied by Rutherford Backscattering Spectroscopy (RBS), X-ray Photoelectron Spectroscopy (XPS), µ-Raman spectroscopy and X-Ray Diffraction (XRD), with and without the presence of co-implanted 16O− ions. The important role of implantation-induced defects, in particular atomic recoil of silicon and oxygen atoms, on the well-known asymmetric redistribution of germanium depth-profile is discussed for samples solely implanted with germanium, as a function of the fluence. This is shown how both the stoichiometric state of the implanted SiO2 layer and their chemical environment influence the mobility of Ge atoms. For samples co-implanted with oxygen, RBS shows an enhancement of germanium diffusion under thermal activation at 1100 °C as long as the oxygen over-saturation of the SiO2 film is not achieved. This change in the germanium diffusion is associated to the formation of GeOx compounds during the implantation, as shown by XPS measurements. This is responsible, during the annealing step, of the formation of highly mobile GeO at low oxygen fluences and less mobile GeO2 at higher fluences. Combination of XRD and µ-Raman analyses is used to highlight the impact of the co-implanted O atoms on the size dispersion of germanium nanocrystals.

Impurity diffusion in ion implanted AlN layers on sapphire substrates by thermal annealing

We report on impurity diffusion in ion implanted AlN layers after thermal annealing. Silicon, tin, germanium, and magnesium ions were implanted into single-crystal Al-polar AlN layers grown on sapphire substrates. By annealing at 1600 °C, silicon and magnesium atoms were diffused in the AlN layer, while less change was observed in the distribution of germanium atoms. Silicon implantation introduced vacancy-related defects. By annealing at temperatures over 1300 °C, the vacancy-related defects were reduced, while oxygen atoms were diffused from the substrate due to sapphire decomposition. We reproducibly achieved silicon-implanted AlN layers with electrical conductance by controlling the annealing temperature and distribution of silicon and oxygen concentrations.

2-Germaazulene: Synthesis and Properties of 2-Heteraazulene Containing a Germanium Atom as a Skeletal Element

Abstract We have succeeded in the synthesis of a 2-germaazulene stable in solution, in which the carbon atom at the 2-position of azulene is replaced by a germanium atom, the fourth period element in Group 14. The properties of the obtained 2-germaazulene were verified both experimentally and theoretically, indicating its sufficient aromaticity. In comparison with the parent azulene, significant differences were found in its orbital levels, charge distribution, and the resulting properties.

Giant Optical Oscillator Strengths in Perturbed Hexagonal Germanium

By means of ab initio calculations we demonstrate that perturbed hexagonal germanium is a superior material for active optoelectronic devices in the infrared spectral region. Perfect lonsdaleite germanium is a pseudodirect semiconductor, with a direct fundamental band gap but almost vanishing optical transitions. Perturbing the system by replacing a germanium atom with a silicon atom in the primitive cell increases the oscillator strength at the onset gap by orders of magnitude, with a concurrent blue shift of the transition energies. This effect is mainly due to the increased s character of the lowest conduction band because of the perturbation‐induced wave function mixing. A structural distortion of pure lonsdaleite Ge can enhance as well optical oscillator strengths, but their magnitude significantly depends on the specific details of the resulting atomic geometry. In particular, moderate tensile uniaxial strain can induce an order inversion of the two lowest conduction bands, leading to an extremely efficient enhancement of the dipole matrix elements at the minimum gap. In general, chemical and/or structural perturbations are shown to make lonsdaleite germanium a suitable material for light emitting devices.

Nature of the local environment of germany atoms in amorphous films (GeTe)-=SUB=-x-=/SUB=-(Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-)

Using Messbauer spectroscopy on 119Sn impurity atoms, it was demonstrated that in amorphous (GeTe)x(Sb2Te3) films (where x=0.5, 1, 2, 3) tin atoms replace atoms of tetravalent germanium, which forms a tetrahedral system of chemical bonds with atoms in its local environment. In crystalline films, tin replaces divalent six-coordinated germanium in positions 4b of the NaCl-type crystal lattice. Keywords: amorphous films, phase memory, Messbauer spectroscopy.

Природа локального окружения атомов германия в аморфных пленках (GeTe)-=SUB=-x-=/SUB=-(Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-)

Using Mössbauer spectroscopy on 119Sn impurity atoms, it was demonstrated that in amorphous (GeTe)x(Sb2Te3) films (where x = 0.5, 1, 2, 3) tin atoms replace atoms of tetravalent germanium, which forms a tetrahedral system of chemical bonds with atoms in its local environment. In crystalline films, tin replaces divalent six-coordinated germanium in positions 4 b of the NaCl-type crystal lattice.

Local structure of amorphous (GeTe)-=SUB=-x-=/SUB=-(Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-) films

By the method of Messbauer spectroscopy on the isotope 119Sn, it was shown that tetravalent germanium atoms in amorphous films (GeTe)x(Sb2Te3) (where x=0.5, 1, 2, 3) form a tetrahedral system of chemical bonds, and in their local environment there are mainly tellurium atoms. In crystalline films (GeTe)x(Sb2Te3) is divalent hexoordinated germanium at positions 4 b of the NaCl type crystal lattice. By the meth-od of Messbauer spectroscopy on 121Sb and 125Te atoms, it was shown that the amorphization of (GeTe)x(Sb2Te3) films does not change the lo-cal environment of antimony and tellurium atoms Keywords: amorphous films, phase memory, Messbauer spectroscopy.

Локальная структура аморфных пленок (GeTe)-=SUB=-x-=/SUB=-(Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-)

By the method of Mössbauer spectroscopy on the isotope 119Sn, it was shown that tetravalent germanium atoms in amorphous films (GeTe)x(Sb2Te3) (where x = 0.5, 1, 2, 3) form a tetrahedral system of chemical bonds, and in their local environment there are mainly tellurium atoms. In crystalline films (GeTe)x(Sb2Te3) is divalent hexoordinated germanium at positions 4 b of the NaCl type crystal lattice. By the meth-od of Mössbauer spectroscopy on 121Sb and 125Te atoms, it was shown that the amorphization of (GeTe)x(Sb2Te3) films does not change the lo-cal environment of antimony and tellurium atoms.

Exploring the structure and electronic properties of germanium doped boron clusters using density functional theory based global optimization method

Density functional theory calculations to investigate the effect of single and double germanium atom doping on the geometric structure and electronic properties of boron clusters with 10 to 20 atoms.

In Ukrainian

By the method of density functional theory (B3LYP, 6-31G **) three types of displacements are calculated, namely oscillations as a whole, rotation and diffusion of dimers &gt; Ge = Ge &lt;, &gt; Ge = Si &lt; and &gt; Si = Si &lt;, which are formed on the crystalline surface of Si (001) (4×2) during the deposition of germanium atoms under conditions of molecular beam epitaxy. Calculations of angles of buckling of addimers are carried out. It is shown that when the addimers as a whole oscillate around the equilibrium position, the energy barriers are quite low, the highest of them occurs for a mixed addimer &gt; Si = Ge &lt;. Pure adders &gt; Ge = Ge &lt; and &gt; Si = Si &lt; oscillate between two degenerate states with an energy barrier of 0.042 and 0.014 eV, respectively. The structures of the transition state and the intermediate when the addimer &gt; Ge = Ge &lt; is moved between adjacent cells in the approximation of the constant bond length &gt; Ge = Ge &lt; are obtained. As calculations have shown, all transformations of surface dimers occur with relatively small activation energies, the numerical values of which agree satisfactorily with the results of STM experiments available in the literature.

Doping two boron atoms in germanene nanoribbons in an external electric field

Germanene is a two-dimensional system made of germanium atoms, its configuration is hexagonal honeycomb. Germanene nanoribbons (GNRs) are one-dimensional systems made from germanene with hydrogen-modified edges. The GNRs configuration studied here consists of 12 germanium atoms and 4 hydrogen atoms per unit cell. This work investigated the doping of two boron atoms into the unit cell of GNRs. Changing the different doping sites produces different configurations, the configurations been studied as meta-configuration, para-configuration, and ortho-configuration. By using density functional theory (DFT), the formation energies, energy band structures, and density of states of the configurations are studied. The ortho-configuration for the formation energy is the smallest, so this configuration is the most stable. The appearance of an external electric field changes the band gap and the energy band structure of the system.

Influence of small additives of germanium on the physical properties of chalcogenide glasses based on composition As30.5S44.5I25

Advanced for the infrared region of the spectrum chalcogenide glass composition As30.5S44.5I25 with small germanium additives were investigated. The concentration dependences of some physical and chemical properties indicate an increase in the performance of glasses due to the modification of the glass network. The character of the change in the short-wavelength absorption edge with an increase in the content of germanium atoms had an exponential character, shifting from 597 to 582 nm. A non-monotonic dependences were also found for the values of density, refractive index, and glass transition temperature. A joint analysis of the results obtained and structural studies described in the literature for similar glass systems made it possible to propose possible structural groups of glass compositions under investigation.