Surroundings Of Atoms Research Articles

Thermal Quenching of Intrinsic Photoluminescence in Amorphous and Monoclinic HfO2 Nanotubes.

Nanotubular hafnia arrays hold significant promise for advanced opto- and nanoelectronic applications. However, the known studies concern mostly the luminescent properties of doped HfO2-based nanostructures, while the optical properties of nominally pure hafnia with optically active centers of intrinsic origin are far from being sufficiently investigated. In this work, for the first time we have conducted research on the wide-range temperature effects in the photoluminescence processes of anion-defective hafnia nanotubes with an amorphous and monoclinic structure, synthesized by the electrochemical oxidation method. It is shown that the spectral parameters, such as the position of the maximum and half-width of the band, remain almost unchanged in the range of 7-296 K. The experimental data obtained for the photoluminescence temperature quenching are quantitatively analyzed under the assumption made for two independent channels of non-radiative relaxation of excitations with calculating the appropriate energies of activation barriers-9 and 39 meV for amorphous hafnia nanotubes, 15 and 141 meV for monoclinic ones. The similar temperature behavior of photoluminescence spectra indicates close values of short-range order parameters in the local atomic surrounding of the active emission centers in hafnium dioxide with amorphous and monoclinic structure. Anion vacancies VO- and VO2- appeared in the positions of three-coordinated oxygen and could be the main contributors to the spectral features of emission response and observed thermally stimulated processes. The recognized and clarified mechanisms occurring during thermal quenching of photoluminescence could be useful for the development of light-emitting devices and thermo-optical sensors with functional media based on oxygen-deficient hafnia nanotubes.

Laminated dihydrazone Zn(II) coordination polymer with prospects for sensory and multifunctional biomedical applications

This study introduces a new laminated coordination polymer, {[Zn3(HL)2(H2O)6](SO4)2⋅1.5dmf·2.5H2O}n (1), synthesized through the direct interaction of ZnSO4·7H2O with dihydrazone Schiff base ligand (H2L = 2,6-diacetylpyridine bis(isonicotinoylhydrazone)) at room temperature. Comprehensive characterization of the compound, employing various methods (SCXRD, PXRD, IR, TGA) revealed different coordination surrounding of metal atoms and a combination of photoluminescent properties and biological activity. The polymeric layers are corrugated along the b-axis, mutually intertwined forming channels filled with outer sphere anions (SO42-) and solvent molecules (water and dmf). It was shown that solvent molecules have a decisive influence on the photoluminescent properties of the compound. The partial removal of water molecules leads to increased photoluminescence, the intensity of which doubles compared to the synthesized crystals. Furthermore, the compound demonstrates robust antibacterial effects against four Gram+ positive and two Gram- negative bacteria. In addition, its impact on cell proliferation, both in cancerous and non-cancerous cells, reveals the compound's antiproliferative effect on breast cancer cells in vitro, coupled with biocompatibility with human fibroblasts. This multifaceted approach positions the synthesized polymer as a promising candidate with vast potential for applications in luminescent materials and biomedical research.

Electronic structure and composition of tin oxide thin epitaxial and magnetron layers according to synchrotron XANES studies

The materials of the tin-oxygen system and thin-film structures based on them are modern and actual for the creation of a wide range of electronic devices, for example, resistive gas sensors of high sensitivity and short response time with low energy consumption and high manufacturability. An important direction in the study of such materials and structures is the control of properties with variations in technological formation regimes. Information on the composition, local atomic and electronic structure of thin layers of the tin-oxygen system with varying approaches to their production is in demand. The work is devoted to the study of the electronic structure of thin layers of tin oxides obtained by modern methods of molecular beam epitaxy and magnetron sputtering. A study of the local partial density of electronic states in the conduction band by X-ray absorption near edge structure spectroscopy of tin and oxygen has been carried out. The data were obtained using high-intensity synchrotron radiation, which allows varying the monochromatized radiation quantum energy without loss in intensity, that is necessary to obtain high-resolution X-ray spectral data. It is shown that the composition, local atomic surrounding, electronic spectrum and their features depend on the technology of formation and storage conditions of the studied structures. Synchrotron X-ray spectroscopy data show the presence of intermediate oxides of the tin-oxygen system in the studied materials after prolonged storage in laboratory conditions. The data obtained indicate the possibility of controlled variation in the composition, local atomic surrounding and electronic spectrum of thin-film structures of tin oxides of small thickness. The results of the work can be used in the formation and subsequent modification of thin and ultrathin layers of tin oxides by magnetron sputtering and molecular beam epitaxy, as well as in their further application as active layers of microelectronics devices

Features of Tribooxidation of the High-Entropy Coating (AlCrZrTiTa)N during Dry High-Speed Cutting

The high-entropy PVD coating (AlCrZrTiTa)N, characterized by its high hardness (50–60 GPa), elastic modulus above 300 MPa, and high heat resistance up to 1300 °C, is used for coating cutting tools operating under extreme metalworking conditions. The nanostructured monolayer 3 μm PVD coating was deposited on cutting plates in the hybrid arc deposition PVD coater. The coating had an amorphous nanocrystalline microstructure with a grain size of about 10–50 nm. The samples of SS 304 steel were investigated during dry high-speed (600 m/min) cutting. Raman spectroscopy was used to study the formation of tribooxides on the tool surface at the running-in stage of the cutting. After 130 m of cutting, Cr2O3 oxide appears on the wear surface while other elements are bound with N atoms. When the cutting length is increased to up to 260 m, oxide Al2O3 · ZrO2 (mullite) and amorphous oxides TaO2 and CrO2 are formed. The method EELFS made it possible to determine the amorphous nanocrystalline structure of triboceramics based on CrO2 and Al2O3 · ZrO2. The nearest atomic surrounding of Cr-Cr, O-O, and Cr-O and their subsequent comparison with the available literature data allow us to calculate the equilibrium lattice constants of the CrO2 unit cell, which are equal to (a, b) = 4.3754 Å and c = 0.5927. The triboceramic films on the base of non-equilibrium mullite Al2O3·ZrO2 have an amorphous structure. In the first coordination sphere, the interatomic distances of Zr-O and Al-O were 1.79 and 1.89 Å. An accelerated adaptive reaction to extreme external stimuli, at the very beginning of the running-in stage, is established. The tribological adaptability of the high-entropy ultra-fine amorphous nanocrystalline coating under extremely loaded dry high-speed cutting is based on non-equilibrium phenomena: the partial oxidation of fragments of the nitride and dynamic formation of protective tribooxides, which have a good thermal barrier and frictional properties. These factors interact synergistically and determine the life of the cutting tool.

General Theoretical Concepts of the Liquid State from the Point of View of Statistical Thermodynamics

t. The article presents General theoretical concepts of the liquid state from the point of view of statistical thermodynamics, as well as computer modeling of the dynamic properties of the liquid state. It is shown that in melts, due to the high mobility of its particles and the absence of a long-range order (as in a crystal lattice), the nearest surroundings of different atoms or molecules can differ quite significantly both in the number of neighbors and in their spatial location. In this regard, the correlation function was calculated using the molecular dynamics method and the radial distribution function. A machine experiment for modeling the structure of melts, as well as for constructing the geometry of cluster structures, is characterized. Specific algorithms for their implementation are considered. Cyclic BornKarman boundary conditions are introduced, the base cell is surrounded by its own replicas, and each such replica exactly repeats the microstates of the base lattice. A General algorithm for constructing Voronoi polyhedra using computer programs is given

CRYSTAL STRUCTURE OF THE Pr3Ag4xGe1,25-xSe7 (x = 0,10; 0,15)

The samples of composition Pr3Ag4xGe1,25-xSe7 (x = 0,10; 0,15), weighing one gram, obtained by sintering elementary components in vacuumed quartz containers at a maximum temperature of 1150 °C. The diffraction patterns for X‑ray phase analysis were recorded at a DRON4–13 diffractometer for 2Q range of 10–100 ° (CuKα radiation, scan step 0,02 °, 20 s exposure in each point). For data processing and the determination of the crystal structure used WinCSD software package. Visualization of the crystal structure, stacking and coordination polyhedra was performed using VESTA program. The crystal structure of the quaternary compound Pr3Ag0,40Ge1,15Se7 (a = 1,06466(4) nm, с = 0,60552(3) nm, RI = 0,0511, Rp = 0,2455) and Pr3Ag0,60Ge1,10Se7 (a = 1,06556(2) nm, c = 0,60583(2) nm, RI = 0,0618, Rp = 0,2068) was investigated by powder X‑ray method. The structure of the compound belongs to the La3CuSiS7 structural type (space group P63, Pearsoncode hP24, a = 1,028 nm, c = 0,575 nm). In this structure, the Pr atom is located in the 6c site and, together with selenium atoms, form trigonal prisms with two additional atoms [Pr Se14Se23Se3] (CN = 8). The atoms of the statistical mixture M1 (0,15 Ge + 0,40 Ag) and M2 (0,10 Ge + 0,60 Ag) occupying one site 2a are located in triangles [M 3Se2] (CN = 3). The Ge atoms are localized in site 2b and have a tetrahedral surrounding of Selenium atoms [Gе Se13Se3] (CN = 4). Atoms Se1 (site 2b) and Se3 (site 6c) also have a tetrahedral surrounding. Se2 atoms (site 6c) are surrounded by five neighbors. Inter-atomic distances are consistent with the sum of the respective ionic radii. Germanium-containing Pr3Ag0,40Ge1,15Se7 and Pr3Ag0,60Ge1,10Se7 selenides based on praseodymium are promising chalcogenide phases on the basis of which materials for nonlinear optics can be created.

Atomic scale network structure of a barium aluminosilicate glass doped with different concentrations of rare-earth ions explored by molecular dynamics simulations

Molecular dynamics (MD) simulation is employed for exploring the coordination of atoms in peralkaline BaO-Al2O3-SiO2 glasses of variable Gd3+ doping concentrations between 1 and 3.8 mol% Gd2O3. For this the MD simulation procedure of inherent structure sampling was used which provides statistically robust information on the local atomic surrounding of the doped rare earth ions. Distributions of Si/Al/Ba/Gd cations in the first, second and third coordination spheres are investigated. Special focus is laid on the effect of Gd3+ doping concentration on the local surrounding of the Gd3+ ions, i. e. rare earth clustering, and general glass structure. The simulations show that SiOAl bonds are preferred in comparison to SiOSi and AlOAl connections with respect to the random model predictions. Deviations from a statistical Si/Al distribution around the BaOp and GdOq polyhedra are observed. The network modifier ions are preferably surrounded by other network modifier ions, rather than by network formers. It is shown that the incorporation of Gd does not affect radial distribution functions, cumulative radial distribution function curves and the coordination sphere of Gd for Gd2O3 doping concentrations of up to 3.8 mol%, i.e. no rare earth clustering is observed. However, increasing Gd2O3 concentrations decrease the number of bridging oxygen and increase the number of non-bridging oxygen (NBO) species in the glass structure. Charge compensation of the additional non-bridging oxygen species is achieved by increasing NBO coordination numbers with Ba2+.

Neutron diffraction study of concentration phases transition in the TiC0.50Hy alloy

The study belongs to the field of hydrogen materials science. A neutron diffraction study of titanium carbohydride TiC0.50Hy was carried out in the range of hydrogen concentration у = 0.50 ÷ 0.60. It is shown that high-temperature titanium carbohydride TiC0·50H0.50 of equiatomic composition has a face-centered cubic lattice (sp. gr. Fm3¯m), where hydrogen atoms are located in tetrahedral interstices. It has been established that in this alloy in vacuum, the phenomenon of hydrogen thermal emission is observed - complete removal of hydrogen with preservation of the FCC lattice of the TiС0.50 interstitial alloy. For the first time in the Ti–C–H system, a first-order concentration phase transition FCC (sp. gr. Fm3¯m) → HCP (sp. gr. Pm3¯1) in TiC0.50Hy carbohydride at a hydrogen concentration y > 0.50 was discovered without changing the octahedral environment of carbon atoms and tetrahedral the surroundings of hydrogen atoms by Ti atoms. The HCP phase in vacuum is heat-resistant at temperatures T < 600 K. The unit cell volume of the hcp phase is two times smaller than the unit cell volume of the FCC phases TiC0.50Hy and TiH2 of equiatomic composition. The results of studying the fcc phase of the equiatomic composition of TiC0·50H0.50 can be used to prepare a high-temperature hydrogen reservoir in hydrogen energy. The HCP phase can be used as a biological protective material in transport nuclear power plants and on nuclear submarines instead of titanium dihydride TiH2.

On the nature of the magnetostructural phase transition in Ce(Fe1-xSix)2

To ascertain the nature of the magnetostructural phase transition in Ce(Fe1-xSix)2 compounds with low silicon content, which crystalize into the structure of cubic Laves phase, we studied local structure peculiarities using high-precision 57Fe Mössbauer spectroscopy (with a high discretization of the velocity reference signal). Unlike the earlier published works on this type of compounds, in the study presented, the occurrence of at least two different types of local surrounding of Fe atoms in the binary compound CeFe2 and non-random Si distribution in the Ce(Fe1-xSix)2 crystal structure is reported for the first time. To specify the type of ordering of Si atoms, the experimental data are compared with results of mathematical simulation of different types of ordering, and, in this way, a conclusion on the mechanism of magnetostructural phase transition is made.

Mössbauer Studies of the Local Surrounding of Atoms in Amorphous and Crystalline Ge2Sb2Te5 Films

Mössbauer Studies of the Local Surrounding of Atoms in Amorphous and Crystalline Ge2Sb2Te5 Films

Chemical bonding analysis in Ti1–x–yAlxTayN solid solutions

A comprehensive study of the evolution of electronic structure and chemical bonding in disordered Ti1−xAlxN and Ti1−x−yAlxTayN systems was performed by means of ab initio density functional theory calculations using crystal orbital Hamilton population technique. Progressive changes in the character of interatomic chemical bonding were revealed when sequentially alloyed TiN with Al and Ta. Alloying TiN with Al leads to the change in the TiN bonding character from ionic to covalent, whereas AlN bonds being strongly ionic. The following alloying of Ti1−xAlxN solid solutions with Ta results in a significant reduction of the ionicity of the AlN bonds, while retaining the covalency of the TiN bonds. In addition, alloying with Ta introduces metallic character of chemical bonding in Ti1−x−yAlxTayN, with the degree of metallicity increasing with growing Ta concentration. The gain in metallicity was found to be provided not only by TaTa bonds, which make the main contribution, but also by TaN bonds, which have covalent-metallic character. A strong dependence of bonding energies in Ti1−x AlxN and Ti1−x−y AlxTayN on local atomic surrounding was found.

Charge Anisotropy of Nitrogen: Where Chemical Intuition Fails

For more than half a century computer simulations were developed and employed to study ensemble properties of a wide variety of atomic and molecular systems with tremendous success. Nowadays, a selection of force-fields is available that describe the interactions in such systems. A key feature of force-fields is an adequate description of the electrostatic potential (ESP). Several force-fields model the ESP via point charges positioned at the atom centers. A major shortcoming of this approach, its inability to model anisotropies in the ESP, can be mitigated using additional charge sites. It has been shown that nitrogen is the most problematic element abundant in many polymers as well as large molecules of biological origin. To tackle this issue, small organic molecules containing a single nitrogen atom were studied. In performing rigorous scans of the surroundings of these nitrogen atoms, positions where a single extra charge can enhance the ESP description the most were identified. Significant improvements are found for ammonia, amines, and amides. Interestingly, the optimal location for the extra charge does not correlate with the chemically intuitive position of the nitrogen lone pair. In fact, the placement of an extra charge in the lone-pair location does not lead to significant improvements in most cases.

Single-Crystal 31P and 7Li NMR of the Ionic Conductor LiH2PO4

The electronic surroundings of phosphorus and lithium atoms in the ionic conductor lithium dihydrogen phosphate (LDP) have been studied by single-crystal nuclear magnetic resonance (NMR) spectroscopy at room temperature. From orientation-dependent NMR spectra of a large homegrown LDP single crystal, the full 31P chemical shift (CS) and 7Li quadrupole coupling (QC) tensor was determined, using a global fit over three rotation patterns. The resulting CS tensor is characterized by its three eigenvalues: δ 11 P A S = ( 67.0 ± 0.6 ) ppm, δ 22 P A S = ( 13.9 ± 1.5 ) ppm, and δ 33 P A S = ( − 78.7 ± 0.9 ) ppm. All eigenvalues have also been verified by magic-angle spinning NMR on a polycrystalline sample, using Herzfeld–Berger analysis of the rotational side band pattern. The resulting 7Li QC tensor is characterized by its quadrupolar coupling constant χ = Q 33 P A S = ( − 71 ± 1 ) kHz and the two eigenvalues Q 11 P A S = ( 22.3 ± 0.9 ) kHz, and Q 22 P A S = ( 48.4 ± 0.8 ) kHz. The initially unknown orientation of the mounted crystal, expressed by the orientation of the rotation axis in the orthorhombic crystal frame, was included in the global data fit as well, thus obtaining it from NMR data only.

Особенности взаимодействия трис(2-метокси-5-бромфенил)стибина с нитратом серебра

By the reaction of tris (2-methoxy-5-bromophenyl)stibine with silver nitrate in a solution of dioxane and acetonitrile, a complex of nitrato-O,O'-(acetonitrile)[ tris (2-methoxy-5-bromophenyl)stibine]silver in the form of solvate with dioxane (2-MeO-5-BrC 6 H 3 ) 3 SbAg(NO 3 )(MeCN)×(C 4 H 8 O 2 ) ( 1 ) was synthesized. The structure of 1 was determined by X-ray diffraction analysis and IR spectroscopy. The IR spectrum of complex 1 contains bands, characteristic for tris [(2-methoxy)(5-bromo) phenyl]stibine, C≡N and NO 3 groups. X-ray diffraction analysis of the complex was performed on a Bruker D8 Quest automatic four-circle diffractometer (Мо К α radiation, λ = 0.71073 Å, graphite monochromator) at 293 K. Crystal Data: triclinic, space group P -1, a = 9.35(2), b = 17.04(3), c = 22.01(4) Å, a = 104.22(5)°, β = 94.33(10)°, g = 99.30(8)°, V = 3329(12) Å 3 , Z = 2, r calc 1.9529g/cm 3 , 2q 5.78-47.14°, 44984 reflections measured, 9679 unique reflections, the number of refinement variables 765, R int = 0.2108, GOOF 1.107, R factors for F 2 &gt; 2σ( F 2 ) R 1 = 0.0584, wR 2 = 0.1500, R factors for all reflections R 1 = 0.0818, wR 2 = 0.1750, largest diff. peak and hole, 1.11/-1.74 e /Å 3 . In crystal 1 , there are two types of crystallographically independent molecules (A, B) and two types of crystallographically independent dioxane solvate molecules. In the distorted tetrahedral surroundings of silver atoms, there are acetonitrile molecules coordinated by cyano group nitrogen atom, a triarylstibine molecule, and O,O'-coordinated nitrate group. The distances Ag-N and Ag-Sb are 2.260(13), 2.291(12) Å and 2.625(5), 2.618(5) Å, respectively. Ag-O distances vary (2.428(11) and 2.493(10) Å; 2.426(9) and 2.534(10) Å).

THE TlPb2Br5–MPb2Br5 (M = K, Rb) SYSTEMS AND CRYSTAL STRUCTURE OF THE K0.45Tl0.55Pb2Br5 PHASE

Physico-chemical interaction in the TlPb2Br5–КPb2Br5 and TlPb2Br5–RbPb2Br5 systems was investigated by XRD and differential thermal analysis methods. Lattice parameters of the samples were calculated using WinCSD software package. Crystallographic parameters were refined using Rietveld method.Phase diagrams of the quasi-binary systems TlPb2Br5–МPb2Br5 (M = K, Rb) were constructed using physico-chemical analysis methods (XRD, DTA). The investigated systems are of eutectic type with the eutectic point coordinates 73 mol.% KPb2Br5, 645 K and 71 mol.% RbPb2Br5, 633 K. The TlPb2Br5–КPb2Br5 system is characterized by the formation below the temperature of the phase transition of TlPb2Br5 of a continuous solid solutions series with the monoclinic structure (S.G. Р21/с). The TlPb2Br5–RbPb2Br5 system features two solid solution ranges, of the low-temperature modification of TlPb2Br5 with the monoclinic structure (S.G. Р21/с) extending to 57 mol.%, and of RbPb2Br5 with the tetragonal structure (S.G. I4/mcm) extending to 21 mol.%.The K0.45Tl0.55Pb2Br5 single crystal was grown by the solution-melt method at a Bridgman-Stockbarger set-up. The upper and lower zone temperatures were 710 K and 570 K, respectively. The temperature gradient at the solid-melt interface was 12 K/cm, and the lowering rate of the container was 8 mm/day.The quaternary phase K0.45Tl0.55Pb2Br5 crystallizes in the NH4Pb2Cl5 structure type (S.G. Р21/с, a=0.92745(8), b=0.83504(7), c= 1.3026(1) nm, β=89.90(2)°). It is formed by the isovalent substitution of thallium atoms by potassium in the TlPb2Br5 structure. All atoms in the structure occupy the 4e sites. However, the partial occupation of the site with Tl and K atoms is 0.55 and 0.45, respectively. The position of K atoms corresponds to the defect position of Tl atoms in the TlPb2Br5 structure. The closest surrounding of Pb1 and Pb2 atoms of eight Br atoms corresponds to the trigonal prism with two additional atoms. Tl atoms coordinate nine Br atoms forming a trigonal prism with three additional atoms against the side faces. The coordination surrounding of K atoms has 6 Br atoms and a neighboring Tl atom forming a trigonal antiprism. This arrangement of the atoms may give rise to new properties of the quaternary phase K0.45Tl0.55Pb2Br5 compared to the original ternary compounds.

Complexes of Np(VI) with Cyclobutanecarboxylic Acid Anions and Single-Charged Cations in the Outer Sphere: [NH4][NpO2(cbc)3], [C(NH2)3][NpO2(cbc)3], and [N(CH3)4][NpO2(cbc)3

Three new Np(VI) complexes with cyclobutanecarboxylic acid anions and single-charged outer-sphere anions: ammonium, [NH4][NpO2(cbc)3] (I), guanidinium, [C(NH2)3][NpO2(cbc)3] (II), and tetramethyl-ammonium, [N(CH3)4][NpO2(cbc)3] (III), were synthesized and studied by single-crystal X-ray diffraction. The coordination surrounding of the Np atoms in I–III is a hexagonal bipyramid with three bidentate cyclic C4H7COO− anions in the equatorial belt. In compounds I and II, the outer-sphere $$\rm{NH}_4^+$$ and $$\rm{C}(NH_2)_3^+$$ cations are linked with the anionic complexes [NpO2(cbc)3]− to form a three-dimensional framework via N–H⋯O hydrogen bonding. In complex III, large outer-sphere $$\rm{N}(CH_3)_4^+$$ cations cause differences in the structure of the anionic complexes [NpO2(cbc)3]−.

11B NMR STUDY OF AMORPHOUS ALLOYS Fe85-xCrxB15 (x = 0-20)

Amorphous alloys Fe85-xCrxB15 (x = 0-20), prepared by rapid quenching of the melt, have been studied by pulsed nuclear magnetic resonance (NMR) on nuclei 11B at a temperature of 4,2 K. The amorphous alloys consist of nanoclusters with short-range order of the tetragonal t-(Fe, Cr)3B and α-(Fe, Cr) phases which contain chromium atoms in the nearest surroundings of boron atoms. The average magnetic moments of magnetic atoms in the nearest sphere of boron atoms in nanoclusters and their dependence on the chromium content in alloys are estimated.

Antisite Defects in Ge–Te and Ge–As–Te Semiconductor Glasses

The formation of antisite defects in Ge20Te80 and Ge15As4Te81 vitreous alloys in the form of tin atoms in tellurium sites and tellurium atoms in germanium sites is shown by emission Mossbauer spectroscopy with the 119mmSn(119mSn), 119mTe(119mSn), 125Sn(125Te), and 125mTe(125Te) isotopes. It is shown that the isovalent substitution of germanium atoms by tin atoms does not vary the symmetry of the local surrounding of germanium sites, while tin and tellurium atoms reconstruct their local surrounding in sites unnatural for them.

Non-Wiener Dynamics of Open Systems for Nonzero Number Density of Surrounding Photons

We propose a collective decay model for a localized ensemble of identical atoms in a vacuum broadband electromagnetic field with a nonzero photon number density considering second-order terms in the atom–field interaction constant. The model is based on the stochastic differential equation for the evolution operator for the atomic ensemble and surroundings, which is controlled by the main quantum random processes and independent classical Wiener processes. It is shown that in some cases, nonzero photon number density does not influence the suppression of collective emission of atoms, and its existence is manifested as an additional mechanism of redistribution of atoms over collective sublevels.

Антиструктурные дефекты в полупроводниковых стеклах Ge-Te и Ge-As-Te

AbstractThe formation of antisite defects in Ge_20Te_80 and Ge_15As_4Te_81 vitreous alloys in the form of tin atoms in tellurium sites and tellurium atoms in germanium sites is shown by emission Mössbauer spectroscopy with the ^119 mm Sn(^119 m Sn), ^119 m Te(^119 m Sn), ^125Sn(^125Te), and ^125 m Te(^125Te) isotopes. It is shown that the isovalent substitution of germanium atoms by tin atoms does not vary the symmetry of the local surrounding of germanium sites, while tin and tellurium atoms reconstruct their local surrounding in sites unnatural for them.