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https://www.readbyqxmd.com/read/29451129/stress-evolution-of-ge-nanocrystals-in-dielectric-matrices
#1
Rahim Bahariqushchi, Rosario Raciti, Ahmet Emre Kasapoğlu, Emre Gür, Meltem Sezen, Eren Kalay, Salvatore Salvatore Mirabella, Atilla Aydınlı
Germanium nanocrystals (Ge NCs) embedded in single and multilayer silicon oxide and silicon nitride matrices have been synthesized using plasma enhanced chemical vapor deposition (PECVD) followed by conventional furnace annealing (CFA) or rapid thermal processing (RTP) in N2 ambient. Compositions of the films were determined by Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS). Formation of nanocrystals under suitable process conditions were observed with high resolution transmission electron microscope (HRTEM) micrographs and Raman spectroscopy...
February 16, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29446555/ge14br8-pet3-4-a-subhalide-cluster-of-germanium-first-step-into-a-novel-field-in-germanium-chemistry
#2
Andreas Bernd Schnepf, Claudio Schrenk, Tanja Kunz
Heating a metastable solution of Ge(I)Br to room temperature leads to the first structurally characterized metalloid subhalide cluster Ge14Br8(PEt3)4 (1). Furthermore 1 can be seen as the first isolated binary halide cluster on the way from Ge(I)Br to elemental germanium, giving insight into the complex reaction mechanism of its disproportionation reaction. Quantum chemical calculations further indicate that within 1 a classical bonding situation is realized and that the last step of the formation of 1 might include the trapping of GeBr2 units...
February 15, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29443001/short-and-medium-range-structures-of-80gese-sub-2-sub-20ga-sub-2-sub-se-sub-3-sub-chalcogenide-glasses
#3
Elena Petracovschi, Laurent Calvez, Laurent Cormier, David LE Coq, Jincheng Du
The short and medium range structures of the 80GeSe2-20Ga2Se3 (or Ge23.5Ga11.8Se64.7) chalcogenide glasses have been studied by combining ab initio molecular dynamics (AIMD) simulations and experimental neutron diffraction studies. Structure factor and total correlation function were calculated from glass structures generated from AIMD simulations and compared with neutron diffraction experiments showing reasonable agreement. The atom structures of the ternary chalcogenide glasses were analyzed in detailed and it was found that gallium atoms are four-fold coordinated by selenium and form [GaSe4] tetrahedra...
February 14, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29425048/electro-optic-response-in-germanium-halide-perovskites
#4
Grant Walters, Edward H Sargent
Electro-optic materials that can be solution-processed and provide high crystalline quality are sought for the development of compact, efficient optical modulators. Here we present density functional theory investigations of the linear electro-optic coefficients of candidate materials cesium and methylammonium germanium halide perovskites. As with their lead halide counterparts, these compounds can be solution-processed; but in contrast, they possess the non-centrosymmetric crystal structures needed to provide a linear electro-optic effect...
February 9, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29416052/cross-scale-molecular-analysis-of-chemical-heterogeneity-in-shale-rocks
#5
Zhao Hao, Hans A Bechtel, Timothy Kneafsey, Benjamin Gilbert, Peter S Nico
The organic and mineralogical heterogeneity in shale at micrometer and nanometer spatial scales contributes to the quality of gas reserves, gas flow mechanisms and gas production. Here, we demonstrate two molecular imaging approaches based on infrared spectroscopy to obtain mineral and kerogen information at these mesoscale spatial resolutions in large-sized shale rock samples. The first method is a modified microscopic attenuated total reflectance measurement that utilizes a large germanium hemisphere combined with a focal plane array detector to rapidly capture chemical images of shale rock surfaces spanning hundreds of micrometers with micrometer spatial resolution...
February 7, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29411846/synthesis-of-low-oxidation-state-germanium-clusters-comprising-a-functional-anchor-group-synthesis-and-characterization-of-ge0-5-ge-r-3-ge-ch2-n-ch-double-bond-length-as-m-dash-ch2-with-r-si-sime3-3
#6
Sabine Frischhut, Thomas F Fässler
The first alkenyl-functionalized, uncharged deltahedral germanium clusters [{Si(SiMe3)3}3Ge9(CH2)nCH[double bond, length as m-dash]CH2] (n = 1 or 3) comprising five Ge0 atoms are presented. All compounds were NMR-spectroscopically and mass-spectrometrically characterized. [{Si(SiMe3)3}3Ge9(CH2)3CH[double bond, length as m-dash]CH2] was further characterized by X-ray structure analysis and Raman spectroscopy. Temperature-dependent NMR studies reveal dynamic behavior for both compounds in solution at room temperature...
February 7, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29410993/enhancement-of-tunneling-current-in-phosphorene-tunnel-field-effect-transistors-by-surface-defects
#7
Juan Lu, Zhi-Qiang Fan, Jian Gong, Jie-Zhi Chen, Huhe ManduLa, Yan-Yang Zhang, Shen-Yuan Yang, Xiang-Wei Jiang
The effects of the staggered double vacancies, hydrogen (H), 3d transition metals, for example cobalt, and semiconductor covalent atoms, for example, germanium, nitrogen, phosphorus (P) and silicon adsorption on the transport properties of monolayer phosphorene were studied using density functional theory and non-equilibrium Green's function formalism. It was observed that the performance of the phosphorene tunnel field effect transistors (TFETs) with an 8.8 nm scaling channel length could be improved most effectively, if the adatoms or vacancies were introduced at the source channel interface...
February 7, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29405464/tris-imidazole-phosphine-complexes-of-pnictogen-tetrel-and-triel-cations
#8
Neil Burford, Riccardo Suter, Paul Gray, Robert McDonald
The synthesis and characterization of salts with the generic formula [P(Im)3M][OTf]x (Im = imidazole; M = phosphorus, arsenic or antimony and x = 3; M = tin or germanium and x = 2) are reported. In all cases, the cations adopt a cage structure with two chemically and energetically distinct apical lone pairs. In contrast, complexes of gallium and indium engage two P(Im)3 ligands resulting in a distorted octahedral geometry for the triel centre in compounds of the generic formula [{P(Im)3}2M][OTf]3. An assessment of the acidity and basicity of the new compounds is presented...
February 5, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29405301/monte-carlo-simulations-of-elemental-imaging-using-the-neutron-associated-particle-technique
#9
Michael R Abel, Linda H Nie
PURPOSE: The purpose of this study is to develop and employ a Monte Carlo (MC) simulation model of associated particle neutron elemental imaging (APNEI) in order to determine the three-dimensional (3D) imaging resolution of such a system by examining relevant physical and technological parameters and to thereby begin to explore the range of clinical applicability of APNEI to fields such as medical diagnostics, intervention, and etiological research. METHODS: The presented APNEI model was defined in MCNP by a Gaussian-distributed and isotropic surface source emitting deuterium + deuterium (DD) neutrons, iron as the target element, nine iron-containing voxels (1 cm3 volume each) arranged in a 3-by-3 array as the interrogated volume of interest, and finally, by high-purity germanium (HPGe) gamma-ray detectors anterior and posterior to the 9-voxel array...
February 6, 2018: Medical Physics
https://www.readbyqxmd.com/read/29400731/investigation-of-a-pressure-dependent-refractive-index-of-germanium-film-with-an-optical-fiber-film-sensor
#10
Dongxu Yuan, Hongyun Gao, Hao Chen, Min Li
The refractive index of Ge is found in decline with applied pressure at a specific wavelength in the absorption region below 1900 nm, where the absorption coefficient rises dramatically with decreased wavelength. In this paper, we use a Ge-coated fiber optic probe to demonstrate quantitatively that the downward trend in the refractive index to increasing pressure matches the theoretically simulated optical properties of Ge with a measurement error of 1.03×10-3 in the refractive index, which is further calculated within the framework of density functional theory with local density approximation...
February 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29387568/assessment-of-natural-radioactivity-in-various-commercial-tiles-used-for-building-purposes-in-nigeria
#11
E S Joel, O Maxwell, O O Adewoyin, C O Ehi-Eromosele, Z Embong, F Oyawoye
In this study, we evaluated the activity concentration of natural radionuclides (226Ra, 232Th and 40K) for fifteen (15) different brands of tile samples used for building purposes in Nigeria. The tile samples were analyzed using High purity Germanium gamma detector. The mean activity concentrations of 226Ra, 232Th, and 40K were observed to be 61.1 ± 5.5 Bq/kg, 70.2 ± 6.08 Bq/kg and 514.7 ± 59.8 Bq/kg respectively. Various hazard indices such as absorbed dose rate, external and internal hazard index, annual effective dose rate, Gamma activity Index (Iγ) and Alpha Index (Iα) were calculated...
2018: MethodsX
https://www.readbyqxmd.com/read/29384660/h2mbh2-and-m-%C3%AE-h-2bh2-molecules-isolated-in-solid-argon-interelement-m-b-and-m-h-b-bonds-m-ge-sn
#12
Jie Zhao, Helmut Beckers, Tengfei Huang, Xuefeng Wang, Sebastian Riedel
Laser-ablated boron atoms react with GeH4 molecules to form novel germylidene borane H2GeBH2, which undergoes a photochemical rearrangement to the germanium tetrahydroborate Ge(μ-H)2BH2 upon irradiation with light of λ = 405 nm. For comparison, the boron atom reactions with SnH4 only gave the tin tetrahydroborate Sn(μ-H)2BH2. Infrared matrix-isolation spectroscopy with deuterium substitution and the state-of-the-art quantum-chemical calculations are used to identify these species in solid argon. A planar structure of H2GeBH2 with an electron-deficient B-Ge bond with a partial multiple bond character (bond order = 1...
January 31, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29382885/comparative-analysis-of-natural-radioactivity-content-in-tiles-made-in-nigeria-and-imported-tiles-from-china
#13
E S Joel, O Maxwell, O O Adewoyin, C O Ehi-Eromosele, M A Saeed
In this investigation, natural radioactive contents in tiles manufactured in Nigeria and tiles imported from China were measured using gamma ray spectroscopy. High Purity Germanium detector was used to estimate the concentrations of some radioisotopes present in 17 samples of various tiles from Nigeria and China. The average activity concentrations of 226Ra, 232Th, and 40K for the tiles were found to be 68.2 ± 0.5; 173.9 ± 9.2 and 490 ± 15 Bq/kg and 58.2 ± 0.5, 161.5 ± 9.4 and 455...
January 30, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29382869/enhancing-thermal-transport-in-layered-nanomaterials
#14
Abhinav Malhotra, Kartik Kothari, Martin Maldovan
A comprehensive rational thermal material design paradigm requires the ability to reduce and enhance the thermal conductivities of nanomaterials. In contrast to the existing ability to reduce the thermal conductivity, methods that allow to enhance heat conduction are currently limited. Enhancing the nanoscale thermal conductivity could bring radical improvements in the performance of electronics, optoelectronics, and photovoltaic systems. Here, we show that enhanced thermal conductivities can be achieved in semiconductor nanostructures by rationally engineering phonon spectral coupling between materials...
January 30, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29382200/seed-initiated-anisotropic-growth-of-unidirectional-armchair-graphene-nanoribbon-arrays-on-germanium
#15
Austin J Way, Robert M Jacobberger, Michael S Arnold
It was recently discovered that the chemical vapor deposition (CVD) of CH4 on Ge(001) can directly yield long, narrow, semiconducting nanoribbons of graphene with smooth armchair edges. These nanoribbons have exceptional charge transport properties compared with nanoribbons grown by other methods. However, the nanoribbons nucleate at random locations and at random times, problematically giving rise to width and bandgap polydispersity, and the mechanisms that drive the anisotropic crystal growth that produces the nanoribbons are not understood...
January 30, 2018: Nano Letters
https://www.readbyqxmd.com/read/29381143/self-organised-fractional-quantisation-in-a-hole-quantum-wire
#16
Yilmaz Gul, Stuart N Holmes, Maksym Myronov, Sanjeev Kumar, Michael Pepper
We have investigated hole transport in quantum wires formed by electrostatic confinement in strained germanium two-dimensional layers. The ballistic conductance characteristics show the regular staircase of quantum levels with plateaux at n2e2/h, where n is an integer, e is the fundamental unit of charge and h is Planck's constant. However as the carrier concentration is reduced, the quantised levels show a behaviour that is indicative of the formation of a zig-zag structure and new quantised plateaux appear at low temperatures...
January 30, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29377662/monolayered-silicon-and-germanium-monopnictide-semiconductors-excellent-stability-high-absorbance-and-strain-engineering-of-electronic-properties
#17
Ai-Qiang Cheng, Zi He, Jun Zhao, Hui Zeng, Ru-Shan Chen
The discovery of stable two-dimensional (2D) semiconductors with exotic electronic properties is crucial to the future electronic technologies. Using the first principles calculations, we predict the monolayered Silicon- and Germanium-monopnictides as a new class of semiconductors owning excellent dynamical and thermal stabilities, prominent anisotropy, and high possibility of experimental exfoliation. These semiconductors, including the monolayered SiP, SiAs, GeP, and GeAs, possess wide bandgaps of 2.08∼2...
January 29, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29376348/hafnocene-based-bicyclo-2-1-1-hexene-germylenes-formation-reactivity-and-structural-flexibility
#18
Zhaowen Dong, Katja Bedbur, Marc Schmidtmann, Thomas Müller
2,5-Disilylsubstituted germole dianions 1 react with hafnocene dichloride to give hafnocene-based bicyclo[2.1.1]hexene germylenes (BCHGe's) 3. Their formation proceeds via hafnocene-germylene complexes 2 that were identified by NMR and UV-spectroscopy. Germylenes 3 are stabilized by homoconjugation between the empty 4p(Ge) orbital and the π-bond of the innercyclic C2=C3 double bond. This interaction can be understood as σ2, π-coordination of the butadiene part to the dicoor-dinated germanium atom that leaves the 16e- hafnocene moiety electronically unsaturated...
January 27, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29372891/lithium-effects-on-the-mechanical-and-electronic-properties-of-germanium-nanowires
#19
Armando González-Macías, Fernando Salazar Posadas, Alvaro Miranda, Alejandro Trejo Baños, Luis A Perez, Eliel Carvajal, Miguel Cruz-Irisson
Semiconductor nanowire arrays promise rapid development of a new generation of lithium (Li) batteries because they can store more Li atoms than conventional crystals due to their large surface areas. During the charge-discharge process, the electrodes experience internal stresses that fatigue the material and limit the useful life of the battery. The study of the electronic and mechanical properties of lithiated nanowire arrays using theoretical models allows designing electrode materials that improve battery performance...
January 26, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29371614/biosensing-with-the-singular-phase-of-an-ultrathin-metal-dielectric-nanophotonic-cavity
#20
Kandammathe Valiyaveedu Sreekanth, Sivaramapanicker Sreejith, Song Han, Amita Mishra, Xiaoxuan Chen, Handong Sun, Chwee Teck Lim, Ranjan Singh
The concept of point of darkness has received much attention for biosensing based on phase-sensitive detection and perfect absorption of light. The maximum phase change is possible at the point of darkness where the reflection is almost zero. To date, this has been experimentally realized using different material systems through the concept of topological darkness. However, complex nanopatterning techniques are required to realize topological darkness. Here, we report an approach to realize perfect absorption and extreme phase singularity using a simple metal-dielectric multilayer thin-film stack...
January 25, 2018: Nature Communications
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