Journal articles: 'Crystal structure of metals'

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Носенко, Владимир, Vladimir Nosenko, Александр Фетисов, Alexander Fetisov, С. Носенко, S. Nosenko, Валентин Харламов, and Valentin Kharlamov. "Contact interaction intensity and material transfer at grinding and refractory metal micro-scratching." Science intensive technologies in mechanical engineering 2, no. 10 (October 4, 2017): 9–18. http://dx.doi.org/10.12737/article_59d496eb7ba532.91441180.

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Peculiarities in the contact surfaces formation and material transfer at micro-scratching and grinding of refractory metals are investigated. There is shown a connection of metal quantity transferred to the area of crystal wear, a degree of ground surface charging with silicon carbide crystals and wear of an abrasive tool with the electron structure of atoms in refractory metals. It is defined, that the intensity of metal transfer in a crystal surface layer decreases with the increase of a principle quantum number of metal valence electrons. According to the intensity of the interaction silicon carbide during grinding and micro-cutting the refractory metals are classified into adhesion-active metals of IVB, VB sub-groups and inert metals of VIB subgroup of the Periodic Table.

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Gärtner, Stefanie. "Spotlight on Alkali Metals: The Structural Chemistry of Alkali Metal Thallides." Crystals 10, no. 11 (November 7, 2020): 1013. http://dx.doi.org/10.3390/cryst10111013.

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Alkali metal thallides go back to the investigative works of Eduard Zintl about base metals in negative oxidation states. In 1932, he described the crystal structure of NaTl as the first representative for this class of compounds. Since then, a bunch of versatile crystal structures has been reported for thallium as electronegative element in intermetallic solid state compounds. For combinations of thallium with alkali metals as electropositive counterparts, a broad range of different unique structure types has been observed. Interestingly, various thallium substructures at the same or very similar valence electron concentration (VEC) are obtained. This in return emphasizes that the role of the alkali metals on structure formation goes far beyond ancillary filling atoms, which are present only due to charge balancing reasons. In this review, the alkali metals are in focus and the local surroundings of the latter are discussed in terms of their crystallographic sites in the corresponding crystal structures.

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Widom, M., and M. Mihalkovic. "Stability of Fe-Based Alloys With Structure Type C6Cr23." Journal of Materials Research 20, no. 1 (January 2005): 237–42. http://dx.doi.org/10.1557/jmr.2005.0028.

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Bulk metallic glass forms when liquid metal alloys solidify without crystallization. In the search for iron-based bulk glass-forming alloys of the metal–metalloid type (Fe–B- and Fe–C-based), crystals based on the structural prototype C6Cr23 often preempt the amorphous phase. Destabilizing this competing crystal structure could enhance glass formability. We carried out first-principles total energy calculations of enthalpy of formation to identify third elements that can effectively destabilize C6Cr23. Yttrium appears optimal among transition metals, and rare earths also are suitable. Atomic size is the dominant factor.

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Макарова, О. В., М. Н. Палатников, И. В. Бирюкова, and Н. В. Сидоров. "Влияние электронного строения примеси на физические свойства, дефектную структуру и особенности технологии легирования кристаллов ниобата лития." Журнал технической физики 89, no. 12 (2019): 1971. http://dx.doi.org/10.21883/jtf.2019.12.48498.230-18.

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Macro- and microstructure were researched for doped LiNbO3 crystals. The transmission spectra and the effective distribution coefficients of the dopant were studied. The analysis of literature data on ternary phase diagrams of systems Li2O-Nb2O5-dopant oxide and electronic configurations of dopants has revealed a possibility to predict technological growth conditions and quality of doped lithium niobate crystals. At this p-elements (boron) provide growth of structurally and compositionally uniform LiNbO3 crystals without incorporation of a dopant into the structure. Metals, s- and d-elements (magnesium and zinc) influence the melts and the crystal properties similar. At this non-periodical domain structures and similar types of point defects appear. Metals of f-elements (cerium) order the melt structure in such a way that provide forming of growth regular domain structure in LiNbO3 crystals due to their electron configurations. Keywords: crystal, lithium niobate, doping, optical microscopy.

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Radka, Christopher D., Lawrence J. DeLucas, Landon S. Wilson, Matthew B. Lawrenz, Robert D. Perry, and Stephen G. Aller. "Crystal structure ofYersinia pestisvirulence factor YfeA reveals two polyspecific metal-binding sites." Acta Crystallographica Section D Structural Biology 73, no. 7 (June 30, 2017): 557–72. http://dx.doi.org/10.1107/s2059798317006349.

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Gram-negative bacteria use siderophores, outer membrane receptors, inner membrane transporters and substrate-binding proteins (SBPs) to transport transition metals through the periplasm. The SBPs share a similar protein fold that has undergone significant structural evolution to communicate with a variety of differentially regulated transporters in the cell. InYersinia pestis, the causative agent of plague, YfeA (YPO2439, y1897), an SBP, is important for full virulence during mammalian infection. To better understand the role of YfeA in infection, crystal structures were determined under several environmental conditions with respect to transition-metal levels. Energy-dispersive X-ray spectroscopy and anomalous X-ray scattering data show that YfeA is polyspecific and can alter its substrate specificity. In minimal-media experiments, YfeA crystals grown after iron supplementation showed a threefold increase in iron fluorescence emission over the iron fluorescence emission from YfeA crystals grown from nutrient-rich conditions, and YfeA crystals grown after manganese supplementation during overexpression showed a fivefold increase in manganese fluorescence emission over the manganese fluorescence emission from YfeA crystals grown from nutrient-rich conditions. In all experiments, the YfeA crystals produced the strongest fluorescence emission from zinc and could not be manipulated otherwise. Additionally, this report documents the discovery of a novel surface metal-binding site that prefers to chelate zinc but can also bind manganese. Flexibility across YfeA crystal forms in three loops and a helix near the buried metal-binding site suggest that a structural rearrangement is required for metal loading and unloading.

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Eberhart, Mark. "From topology to geometry." Canadian Journal of Chemistry 74, no. 6 (June 1, 1996): 1229–35. http://dx.doi.org/10.1139/v96-138.

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A systematic study of the charge density topologies corresponding to a number of transition metal aluminides with the B2 structure indicates that unstable crystal structures are sometimes associated with uncharacteristic topologies. This observation invites the speculation that the "distance" to a topological instability might relate to a metals phase behavior. Following this speculation, a metric is imposed on the topological theory of Bader, producing a geometrical theory, where it is now possible to assign a distance from a calculated charge density topology to a topological instability. For the cubic transition metals, these distances are shown to correlate with single crystal elastic constants, where the metals that are furthest from an instability are observed to be the stiffest. Key words: crystal structure, charge density topology, mechanical properties, brittle/ductile failure.

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Degtyareva, Olga. "Crystal structure of simple metals at high pressures." High Pressure Research 30, no. 3 (September 2010): 343–71. http://dx.doi.org/10.1080/08957959.2010.508877.

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Gulay, Nataliya, Yuriy Tyvanchuk, Marek Daszkiewicz, Bohdan Stel’makhovych, and Yaroslav Kalychak. "Crystal structure of Sc3Co1.64In4 and Sc10Co9In20 from single-crystal data." Zeitschrift für Naturforschung B 74, no. 3 (March 26, 2019): 289–95. http://dx.doi.org/10.1515/znb-2018-0275.

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AbstractTwo compounds in the Sc-Co-In system were obtained by arc-melting of the pure metals and their crystal structures have been determined using single crystal X-ray diffraction data. The structure of Sc3Co1.64In4 (space group P6̅, а=7.6702(5), c=3.3595(2) Å, Z=1, R1=0.0160, wR2=0.0301) belongs to the Lu3Co2−xIn4 type structure, which is closely related to the ZrNiAl and Lu3CoGa5 types. The structure of Sc10Co9In20 (space group P4/nmm, а=12.8331(1), c=9.0226(1) Å, Z=2, R1=0.0203, wR2=0.0465) belongs to the Ho10Ni9In20 type, which is closely related to HfNiGa2.

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Heying, Birgit, Oliver Niehaus, Ute Ch Rodewald, and Rainer Pöttgen. "Indides RE3T2In4 (RE = Y, Gd–Tm, Lu; T = Ni, Ru, Rh) with a ZrNiAl superstructure." Zeitschrift für Naturforschung B 71, no. 12 (December 1, 2016): 1261–67. http://dx.doi.org/10.1515/znb-2016-0167.

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AbstractThree series of rare earth-transition metal-indides RE3T2In4 (RE=Y, Gd–Tm, Lu; T=Ni, Ru, Rh) were synthesized from arc-melted RE3T2 precursor compounds and indium tear shot in sealed niobium ampoules using different annealing sequences. The new indides crystallize with the hexagonal Lu3Co2In4-type structure, space group P6̅. All samples were characterized on the basis of Guinier powder patterns and six structures were refined from single crystal X-ray diffractometer data. The RE3T2In4 structures are derived from the ZrNiAl type through RE/In ordering, paralleled by a symmetry reduction from P6̅2m to P6̅. This induces twinning for some of the investigated crystals. The main crystal chemical motifs of the RE3T2In4 structures are trigonal prisms of rare earth, respectively indium atoms that are filled by the transition metals.

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Tyvanchuk, Yuriy, Nataliya Gulay, Inna Bigun, Yaroslav Galadzhun, and Yaroslav Kalychak. "The crystal structure of Sc5Co2In4." Zeitschrift für Naturforschung B 70, no. 4 (April 1, 2015): 283–87. http://dx.doi.org/10.1515/znb-2014-0216.

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AbstractThe new intermetallic compound Sc5Co2In4 was synthesized by arc melting of the pure metals. Its crystal structure was investigated from single-crystal X-ray data: Pbam, a = 17.3400(7), b = 7.5940(5), c = 3.3128(2) Å, R1 = 0.0337, wR2 = 0.0620 for 1502 independent reflections with [I >2 σ(I)]. It is the first representative of the Lu5Ni2In4 type with cobalt.

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Okuno, Yu, Yoshiyuki Hattori, Tomonori Ohba, Katsumi Kaneko, and Hirofumi Kanoh. "Mesoporous Ni–Fe Alloys." Adsorption Science & Technology 26, no. 8 (October 2008): 581–88. http://dx.doi.org/10.1260/026361708788059839.

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A nano-structured alloy of Ni and Fe was prepared using poly(vinyl alcohol) (PVA) as a polymer precursor, followed by the reduction of Ni2+ and Fe3+ ions to the corresponding metals by heat treatment of the PVA film containing the metal ions under an inert atmosphere. The alloy obtained was characterized by nitrogen adsorption studies, X-ray diffraction and electron microscopy measurements, and by X-ray photoelectron spectroscopy. The nano-structured alloy had the same crystal structure as that of metallic Ni although metallic Fe formed a different structure. The introduction of Fe atoms caused disorder and less crystallinity in the crystal structure of the alloy, whereas Ni atoms tended to maintain the original crystal structure. Nitrogen adsorption measurements at 77 K showed that the nano-structured Ni–Fe alloy contained mesopores of 4–10 nm in diameter.

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Nakamura, Kounosuke, Hiromoto Kitahara, and Shinji Ando. "Analysis of {10-12} Twin Structure by Molecular Dynamics Method." Materials Science Forum 654-656 (June 2010): 1586–89. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1586.

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{10 2} twin is common in pure hcp metals. In this study, initiation and development of {10 2} twin in hcp metal was simulated by molecular dynamics (MD) method. Two types of model crystals were stretched along the y-axis by applying displacement of 0.005a (a is lattice constant of the basal plane) every 1000 MD steps and relaxed atoms by molecular dynamics method. The Y-boundary of the model was applied fixed boundary condition and the X and the Z-boundary were free boundary condition. The Lennard-Jones type interatomic potential was employed in this simulation. In the single crystal, {10 1} pyramidal slip initiated at the crack tip and the pyramidal slip was stopped at Y-boundary atoms. After that, a {10 2} twin was initiated at a front of the slip. With increasing external strain, the twin grew with increasing external strain. In the bi-crystal, {10 0} prismatic slip occurred at the crack tip in Crystal 1 and a-dislocation of the slip stopped at a grain boundary between the Crystal 1 and 2. With increasing applied strain, {10 2} twin was initiated in the Crystal 2 at the grain boundary. From the simulation results, the ‘shuffling’ process of twin deformation was estimated.

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O'Toole, Nicholas J., and Victor A. Streltsov. "Synchrotron X-ray analysis of the electron density in CoF2 and ZnF2." Acta Crystallographica Section B Structural Science 57, no. 2 (April 1, 2001): 128–35. http://dx.doi.org/10.1107/s0108768100017353.

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Accurate structure factors for small crystals of the rutile-type structures CoF2, cobalt difluoride, and ZnF2, zinc difluoride, have been measured with focused λ = 0.8400 (2) Å synchrotron X-radiation at room temperature. Phenomenological structural trends across the full series of rutile-type transition metal difluorides are analysed, showing the importance of the metal atom in the degree of distortion of the metal–F6 octahedra in these structures. Multipole models reveal strong asphericities in the electron density surrounding the transition metals, which are consistent with expectations from crystal field theory and the structural trends in these compounds. Transition metal 3d-orbital populations were computed from the multipole refinement parameters, showing significant repopulation of orbitals compared with the free atom, particularly for CoF2.

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Taguchi, Takeyoshi, and Peter S. White. "Use of the Metals Data File (CRYSTMET) in XAFS analysis." Acta Crystallographica Section B Structural Science 58, no. 3 (May 29, 2002): 358–63. http://dx.doi.org/10.1107/s0108768102004135.

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The X-ray absorption spectrometry (XAS) technique has been widely used to determine the local structure of materials that are poorly suited to study by ordinary diffraction methods, such as fine particles or amorphous matter. XAS is among the major applications at synchrotron radiation facilities and many existing beamlines perform the measurement of XAFS (X-ray absorption fine structure) spectra. XAFS spectra can also be measured with conventional X-ray sources. Measurement of XAFS spectra is relatively straightforward, but real difficulties arise in the analysis and interpretation of the data. Contrary to single-crystal diffraction techniques, the structure is not obtained directly from the measured XAFS data. Model structures must be assumed and the corresponding simulated XAFS spectra must be calculated, with determination of which models best fit the measured data. Model building is a most important part of XAFS analysis, but creation of three-dimensional structures from crystal-chemical considerations can be a very time-consuming task. Utilization of a database of crystal structures and of its built-in structure analysis and display tools can considerably reduce the time and effort required by this task. As XAS is often used to study metals, a database of alloys and intermetallic compounds, such as CRYSTMET, incorporating an array of powerful tools, is then very useful.

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SODERLIND, P., and K. MOORE. "When magnetism can stabilize the crystal structure of metals." Scripta Materialia 59, no. 12 (December 2008): 1259–62. http://dx.doi.org/10.1016/j.scriptamat.2008.08.031.

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Fujihana, Takanobu, Masahiko Taniguchi, Yoshio Okabe, and Masaya Iwaki. "Crystal structure of carbon-implanted Group 4 transition metals." Surface and Coatings Technology 83, no. 1-3 (September 1996): 120–23. http://dx.doi.org/10.1016/0257-8972(95)02804-8.

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Xu, W., B. Zhang, X. Y. Li, and K. Lu. "Suppressing atomic diffusion with the Schwarz crystal structure in supersaturated Al–Mg alloys." Science 373, no. 6555 (August 5, 2021): 683–87. http://dx.doi.org/10.1126/science.abh0700.

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High atomic diffusivity in metals enables substantial tuneability of their structure and properties by tailoring the diffusional processes, but this causes their customized properties to be unstable at elevated temperatures. Eliminating diffusive interfaces by fabricating single crystals or heavily alloying helps to address this issue but does not inhibit atomic diffusion at high homologous temperatures. We discovered that the Schwarz crystal structure was effective at suppressing atomic diffusion in a supersaturated aluminum–magnesium alloy with extremely fine grains. By forming these stable structures, diffusion-controlled intermetallic precipitation from the nanosized grains and their coarsening were inhibited up to the equilibrium melting temperature, around which the apparent across-boundary diffusivity was reduced by about seven orders of magnitude. Developing advanced engineering alloys using the Schwarz crystal structure may lead to useful properties for high-temperature applications.

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Lussier, A. J., F. C. Hawthorne, Y. Abdu, S. Herwig, V. K. Michaelis, P. M. Aguiar, and S. Kroeker. "The crystal chemistry of ‘wheatsheaf’ tourmaline from Mogok, Myanmar." Mineralogical Magazine 75, no. 1 (February 2011): 65–86. http://dx.doi.org/10.1180/minmag.2011.075.1.65.

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AbstractTourmalines of unusual (mushroom) habit are common in granitic pegmatites of Momeik, northeast of Mogok, Myanmar. Here, we examine a sample of elbaite of significantly different habit, consisting of a series of diverging crystals, resembling a sheaf of wheat and ranging in colour from light purplish-red at the base to dark purplish-red at the tip with a thin green cap at the termination. The crystal structures of eight crystals are refined to R1-indices of ∼2.5% using graphite-monochromated Mo-Kα X-radiation; the same crystals were analysed by electron microprobe. 11B and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra were collected on four regions of the wheatsheaf crystal, and show ∼0.3 a.p.f.u. [4]B and <0.1 a.p.f.u. [4]Al in the structure. 57Fe Mössbauerspectr oscopy was done on the dark green rim at the termination of the crystal, showing all Fe in this region (∼0.6 a.p.f.u.) to be Fe2+. Detailed electron-microprobe traverses show that the principal compositional variation involves the substitutions [4]B + YAl → Si + YFe*, where transition metals are present, and [4]B2 + YAl → Si2 + YLi, where transition metals are not present, although several other minor substitutions also affect crystal composition. Successive microscopic bifurcation of crystallites causes divergence of growth directions along the c axis, imparting the overall ‘wheatsheaf’ shape to the crystal aggregate. We suggest that such bifurcation is common in pegmatitic elbaite crystals, resulting in their common divergent habit.

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Chunikhin, Sergey S., Oleg V. Ershov, Alexandr V. Yatsenko, Viktor A. Tafeenko, Natalia E. Dmitrieva, and Mikhail Yu Ievlev. "Alkali metal salts of a tetracyanopyridine (TCPy) derivative: structure characterization and luminescence properties." CrystEngComm 23, no. 15 (2021): 2816–24. http://dx.doi.org/10.1039/d1ce00028d.

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Only lithium cations among the metals of the IA group caused a blue-shift of solid-state photoluminescence of alkali metal salts of a tetracyanopyridine derivative due to the special features of the crystal packing.

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Sow, Chaitali, Suchithra P, Gangaiah Mettela, and Giridhar U. Kulkarni. "Noble Metal Nanomaterials with Nontraditional Crystal Structures." Annual Review of Materials Research 50, no. 1 (July 1, 2020): 345–70. http://dx.doi.org/10.1146/annurev-matsci-092519-103517.

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Noble metals (Ru, Os, Rh, Ir, Pd, Pt, Ag, and Au) are known for their extraordinary oxidant-resistant behavior, good electrical and thermal conductivity, high work function, and brilliant luster. All occur in close-packed crystal structures: Ru and Os in hexagonal close-packed (hcp) and the rest in face-centered cubic (fcc) structures, both possessing high-symmetry structures and, therefore, a high degree of stabilization. Numerous studies in the literature have attempted to stabilize these metals away from their conventional crystal structures with the aim of realizing new properties. While obtaining conventional fcc metals in hcp structure or vice versa has been the subject of most studies, there are also examples of fcc metals crystallizing in lower-symmetry structures such as monoclinic. The nonnative crystal structures are generally realized during the crystallite growth itself, with a few exceptions in which a posttreatment was required for lattice transformation. In most cases, the new crystal structures pertain to the nanometer-length scale in the form of nanoparticles, nanoplates, nanoribbons, and nanowires, but there are good examples from microcrystallites as well. In this article, we review this active area of research, focusing on ambient stable crystal systems with some account of their interesting properties as reported in recent literature.

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Suzuki, Atsushi, and Takeo Oku. "Electronic Structures, Spectroscopic Properties, and Thermodynamic Characterization of Alkali Metal and Transition Metal Incorporated Perovskite Crystals by First-Principles Calculation." Materials Proceedings 4, no. 1 (November 11, 2020): 79. http://dx.doi.org/10.3390/iocn2020-07942.

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The influence of alkali metals (Na, K) or transition metals (Co, Cr, Cu, and Y) incorporated into perovskite crystal on the electronic structures, spectroscopic, and magnetic properties, and thermodynamic properties was investigated by first-principles calculation. Incorporation of Na or K into the perovskite crystal generated 3s, 3p, 4s, and 4p orbitals of Na or K above the conduction band, which promoted the charge transfer from alkali metal to the conduction band, accelerating the electron diffusion related to the photovoltaic properties. For the Cr, Cu, and Y-incorporated perovskite crystals, the electron density distribution of d-p hybrid orbital on the transition metal and iodine halogen ligand were delocalized at frontier orbital. The electronic correlation worked in between the localized spin on 3d orbital of the metal, and the itinerant carriers on the 5p orbital of the iodine halogen ligand and the 6p orbital of the lead atom in the perovskite crystal. The vibration behavior of the Raman and infrared spectra were associated with change of polarization and slight distortion near the coordination structure. The considerable splitting of chemical shift of 127I-NMR and 207Pb-NMR in the magnetic field was caused by crystal field splitting with the Jahn-Teller effect with nearest-neighbor nuclear quadrupole interaction based on the charge distribution. Decrease of the Gibbs free energy and entropy indicated the thermodynamic stabilization without scattering carrier diffusion as phonon effectiveness. The decrease of the entropy was based on a slight change of stretching vibration mode of Pb–I bond with vending mode of N–H and C–H bonds in the infrared and Raman spectra. The minor addition of alkali metal or transition metal into the perovskite crystal would improve the photovoltaic properties, open voltage related to band gap, and short-circuit current density based on the carrier diffusion with phonon effectiveness.

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McMahon, M. I., O. Degtyareva, and R. J. Nelmes. "Ba-IV-Type Incommensurate Crystal Structure in Group-V Metals." Physical Review Letters 85, no. 23 (December 4, 2000): 4896–99. http://dx.doi.org/10.1103/physrevlett.85.4896.

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Vasil’ev, S. V., A. Yu Ivanov, and V. A. Liopo. "Changes in the crystal structure of metals under laser radiation." Journal of Engineering Physics and Thermophysics 80, no. 5 (September 2007): 857–63. http://dx.doi.org/10.1007/s10891-007-0115-8.

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Yaniv, Gili, Daniel Vidal, David Fuks, and Louisa Meshi. "Bonding and Stability of Ternary Structures in the CeT2Al20 (T=Ta, W, Re) and YRe2Al20 Alloys." Metals 10, no. 4 (March 25, 2020): 422. http://dx.doi.org/10.3390/met10040422.

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A-T-Al aluminides, where A = actinide, lanthanide or rare earth elements and T=transition metals, have attracted considerable attention as potential materials where heavy fermions may be formed. This led to the discovery of superconducting properties in cubic AT2Al20 compounds with CeCr2Al20-type crystal structure. Other Al-rich aluminides, belonging to these A-T-Al systems, exhibited different physical properties as a function of their crystal structure. Thus, predicting the stable structure of the Al-richest phase that will form in the A-T-Al systems is highly valuable. Stability of the crystal structures, forming in the CeT2Al20 and YRe2Al20 systems, was studied in current research using density functional theory (DFT) calculations. It is demonstrated that the total spin magnetic moment of the transition metal can be used as a descriptor for phase stability assessment in the AT2Al20 systems, where T is a 5d transition metal. Basing on crystallographic considerations, degree of distortion of the coordination polyhedrons, formed around T atoms, can be directly connected to the specific type of structure crystallizing in these systems.

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Bruno, Ian J., Gregory P. Shields, and Robin Taylor. "Deducing chemical structure from crystallographically determined atomic coordinates." Acta Crystallographica Section B Structural Science 67, no. 4 (July 18, 2011): 333–49. http://dx.doi.org/10.1107/s0108768111024608.

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An improved algorithm has been developed for assigning chemical structures to incoming entries to the Cambridge Structural Database, using only the information available in the deposited CIF. Steps in the algorithm include detection of bonds, selection of polymer unit, resolution of disorder, and assignment of bond types and formal charges. The chief difficulty is posed by the large number of metallo-organic crystal structures that must be processed, given our aspiration that assigned chemical structures should accurately reflect properties such as the oxidation states of metals and redox-active ligands, metal coordination numbers and hapticities, and the aromaticity or otherwise of metal ligands. Other complications arise from disorder, especially when it is symmetry imposed or modelled with the SQUEEZE algorithm. Each assigned structure is accompanied by an estimate of reliability and, where necessary, diagnostic information indicating probable points of error. Although the algorithm was written to aid building of the Cambridge Structural Database, it has the potential to develop into a general-purpose tool for adding chemical information to newly determined crystal structures.

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Manuel, Sorrow George, Jack Santo Cross, David Mick Silvester, Romano Proud Blour, and Janet Napolion Stagger. "Destructive testing method for specimen and crystal structure on maximum solubility." International research journal of management, IT and social sciences 6, no. 5 (September 4, 2019): 234–41. http://dx.doi.org/10.21744/irjmis.v6n5.734.

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From non-destructive testing, we have found various flaws in both specimens so no method in the universe is perfect but we can rectify the defects but cannot be removed completely. From destructive testing we have found that First specimen MS (MS) sustain stress without failure due its similar crystal structure (BCC) on the other hand second specimen have failed within the lower stress range due to lack of cohesion, adhesion between the dissimilar metals MS and SS, and also both have different crystal structures BCC and FCC respectively. Thus, to gain maximum strength of weld bead, welding should be done using similar metals with maximum solubility.

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Sun, Gang, Alexander Hawken, and Peter Harrowell. "The displacement field associated with the freezing of a melt and its role in determining crystal growth kinetics." Proceedings of the National Academy of Sciences 117, no. 7 (February 3, 2020): 3421–26. http://dx.doi.org/10.1073/pnas.1915806117.

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The atomic displacements associated with the freezing of metals and salts are calculated by treating crystal growth as an assignment problem through the use of an optimal transport algorithm. Converting these displacements into timescales based on the dynamics of the bulk liquid, we show that we can predict the activation energy for crystal growth rates, including activation energies significantly smaller than those for atomic diffusion in the liquid. The exception to this success, pure metals that freeze into face-centered cubic crystals with little to no activation energy, are discussed. The atomic displacements generated by the assignment algorithm allows us to quantify the key roles of crystal structure and liquid caging length in determining the temperature dependence of crystal growth kinetics.

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Bogdanova, A. N., A. V. Irodova, G. Andre, and F. Bouree. "The ZrV2D6 crystal structure." Journal of Alloys and Compounds 356-357 (August 2003): 50–53. http://dx.doi.org/10.1016/s0925-8388(02)01214-8.

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Hoistad Strauss, Laura, and Chad M. Delp. "Crystal structure of SmAsS." Journal of Alloys and Compounds 353, no. 1-2 (April 2003): 143–45. http://dx.doi.org/10.1016/s0925-8388(02)01308-7.

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Yaropolov, Yu L., S. S. Agafonov, V. P. Glazkov, V. A. Somenkov, and V. N. Verbetsky. "Crystal Structure of TbNiD3.3." Inorganic Materials 47, no. 3 (March 2011): 245–50. http://dx.doi.org/10.1134/s0020168511030228.

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Braun, Thomas P., and Francis J. DiSalvo. "Crystal structure of Tm2Ni12P7." Journal of Alloys and Compounds 307, no. 1-2 (July 2000): 111–13. http://dx.doi.org/10.1016/s0925-8388(00)00829-x.

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Shpanchenko, R. V., A. M. Abakumov, E. V. Antipov, and L. M. Kovba. "Crystal structure of Ba5In2Al2ZrO13." Journal of Alloys and Compounds 206, no. 2 (May 1994): 185–88. http://dx.doi.org/10.1016/0925-8388(94)90033-7.

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33

Oryshchyn, S., V. Babizhetskyy, S. Chykhriy, L. Aksel'rud, S. Stoyko, J. Bauer, R. Guérin, and Yu Kuz'ma. "Crystal Structure of Ni5P2." Inorganic Materials 40, no. 4 (April 2004): 380–85. http://dx.doi.org/10.1023/b:inma.0000023960.30599.22.

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34

Titov, Y. A., N. M. Belyavina, V. Ya Markiv, M. S. Slobodyanik, V. V. Chumak, and V. P. Yaschuk. "Crystal structure of La5Ti4GaO17." Journal of Alloys and Compounds 430, no. 1-2 (March 2007): 81–84. http://dx.doi.org/10.1016/j.jallcom.2006.05.024.

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Titov, Y. A., N. M. Belyavina, V. Ya Markiv, M. S. Slobodyanik, and V. V. Chumak. "Crystal structure of Ca5TiNb4O17." Journal of Alloys and Compounds 387, no. 1-2 (January 2005): 82–85. http://dx.doi.org/10.1016/j.jallcom.2004.06.032.

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36

Sato, Masashi, Marit Stange, Jan Petter Maehlen, and Volodymyr A. Yartys. "Crystal structure of LaNi5Sn." Journal of Alloys and Compounds 397, no. 1-2 (July 2005): 165–68. http://dx.doi.org/10.1016/j.jallcom.2005.01.031.

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37

Murashova, E. V., A. I. Tursina, Zh M. Kurenbaeva, A. V. Gribanov, and Yu D. Seropegin. "Crystal structure of CeRu0.88In2." Journal of Alloys and Compounds 454, no. 1-2 (April 2008): 206–9. http://dx.doi.org/10.1016/j.jallcom.2006.12.123.

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38

Orishchin, S. V., V. S. Babizhetskii, and Yu B. Kuz’ma. "Crystal structure of Ni4Ge0.33P1.17." Inorganic Materials 36, no. 8 (August 2000): 788–92. http://dx.doi.org/10.1007/bf02758598.

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39

Pham, Tien-Lam, Duong-Nguyen Nguyen, Minh-Quyet Ha, Hiori Kino, Takashi Miyake, and Hieu-Chi Dam. "Explainable machine learning for materials discovery: predicting the potentially formable Nd–Fe–B crystal structures and extracting the structure–stability relationship." IUCrJ 7, no. 6 (September 23, 2020): 1036–47. http://dx.doi.org/10.1107/s2052252520010088.

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New Nd–Fe–B crystal structures can be formed via the elemental substitution of LA–T–X host structures, including lanthanides (LA), transition metals (T) and light elements, X = B, C, N and O. The 5967 samples of ternary LA–T–X materials that are collected are then used as the host structures. For each host crystal structure, a substituted crystal structure is created by substituting all lanthanide sites with Nd, all transition metal sites with Fe and all light-element sites with B. High-throughput first-principles calculations are applied to evaluate the phase stability of the newly created crystal structures, and 20 of them are found to be potentially formable. A data-driven approach based on supervised and unsupervised learning techniques is applied to estimate the stability and analyze the structure–stability relationship of the newly created Nd–Fe–B crystal structures. For predicting the stability for the newly created Nd–Fe–B structures, three supervised learning models: kernel ridge regression, logistic classification and decision tree model, are learned from the LA–T–X host crystal structures; the models achieved maximum accuracy and recall scores of 70.4 and 68.7%, respectively. On the other hand, our proposed unsupervised learning model based on the integration of descriptor-relevance analysis and a Gaussian mixture model achieved an accuracy and recall score of 72.9 and 82.1%, respectively, which are significantly better than those of the supervised models. While capturing and interpreting the structure–stability relationship of the Nd–Fe–B crystal structures, the unsupervised learning model indicates that the average atomic coordination number and coordination number of the Fe sites are the most important factors in determining the phase stability of the new substituted Nd–Fe–B crystal structures.

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40

Zhang, Tongxin, Dennis L. O’Neal, and Stephen T. McClain. "Impact of Environmental Conditions on Frost Crystal Structure." International Journal of Air-Conditioning and Refrigeration 28, no. 02 (June 2020): 2050014. http://dx.doi.org/10.1142/s2010132520500145.

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Frost crystal type and distribution were characterized in the initial periods of frost growth on an aluminum surface. Experiments were carried out for a range of wall temperatures from [Formula: see text]C to [Formula: see text]C, air temperatures from [Formula: see text]C to [Formula: see text]C, relative humidities from 15% to 85%, and air velocities from 0.5 to 5.0[Formula: see text]m/s. The results showed that frost crystal type was strongly dependent on the wall temperature and humidity. Changing the air temperature shifted the region of some frost crystal types. Decreasing the air temperature from 22 down to either [Formula: see text]C or [Formula: see text]C led to the decrease of feather crystals but increased the region of scroll crystals. Air velocity had smaller impacts on frost crystal type but had a strong influence on the distance between the crystals, particularly at lower air velocities. The results were compared to prior researchers. The results should provide a better understanding of frost morphology during the early stages of frost growth on metal surfaces.

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Øien-Ødegaard, Sigurd, and Karl Lillerud. "Twinning in Zr-Based Metal-Organic Framework Crystals." Chemistry 2, no. 3 (September 16, 2020): 777–86. http://dx.doi.org/10.3390/chemistry2030050.

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Ab initio structure determination of new metal-organic framework (MOF) compounds is generally done by single crystal X-ray diffraction, but this technique can yield incorrect crystal structures if crystal twinning is overlooked. Herein, the crystal structures of three Zirconium-based MOFs, that are especially prone to twinning, have been determined from twinned crystals. These twin laws (and others) could potentially occur in many MOFs or related network structures, and the methods and tools described herein to detect and treat twinning could be useful to resolve the structures of affected crystals. Our results highlight the prevalence (and sometimes inevitability) of twinning in certain Zr-MOFs. Of special importance are the works of Howard Flack which, in addition to fundamental advances in crystallography, provide accessible tools for inexperienced crystallographers to take twinning into account in structure elucidation.

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42

Hong, Ji Hwa, Yongju Jung, and Seok Kim. "Synthesis of Bi-Metallic Organic Frameworks and Their Capacitive Behaviors According to Metal Mixing Ratio." Journal of Nanoscience and Nanotechnology 20, no. 5 (May 1, 2020): 2987–91. http://dx.doi.org/10.1166/jnn.2020.17467.

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Metallic organic frameworks (MOFs) with mixed metals has attracted attention as electrochemical energy storage material because it has high specific surface area, synergy of two metals, and a new crystal structure different from that of conventional MOF. In this study, we synthesized MOFs, including nickel and zinc, by hydrothermal method at a time. We investigated the effect of two metal ratios on the capacitive behavior. Through the structure and morphology analysis, it was found that Ni–Zn-MOF forms a completely different crystal structure from MOF using one metal, and found that it is a porous material. As a result of electrochemical measurements with cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD), the specific capacitance of Ni–Zn-MOF 2:1 with a nickel to zinc ratio of 2:1 was 616 F g−1 at a current density was 1 A g−1.

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43

Tanaka, Ayako, Keisuke Kawakami, Yasufumi Umena, and Nobuo Kamiya. "High-resolution and low-dose X-ray crystal structure of Photosytem II." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1502. http://dx.doi.org/10.1107/s2053273314084976.

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Photosystem II (PSII) is a large multi-subunit membrane protein embedded in thylakoid membranes as a dimeric form with molecular weight of 700 kDa. The oxygen-evolving complex (OEC) of PSII is the heart of photosynthesis to split water molecules and to produce electrons and protons. The X-ray crystal structure of PSII was reported recently at a resolution of 1.9 Å with an averaged coordinate error (DPI) of 0.11 Å [1]. The chemical composition of OEC was fixed to as Mn4CaO5(H2O)4, and the structure was unambiguously determined for the first time including all amino-acid residues and oxo-bridging oxygen atoms ligated to the metal atoms.After the structure determination, two problems are newly showed up. One is the resolution problem. The resolution of 1.9 Å is extremely high in comparison with that of crystal structure previously reported [2], however, it is not enough to obtain precise information for bond lengths between metals and oxo-bridging oxygen atoms in OEC. The other is the X-ray reduction problem on Mn atoms. The reflection intensities were measured by a slide-oscillation method at a low X-ray dose of 0.85 MGy. According to the EXAFS studies reported by Glöckner et al. [3], the dose value corresponded to that 25% of OEC in crystal was damaged into Mn(II) aqua complexes. In order to overcome these problems, we have succeeded to get high quality crystals of PSII, which show much higher resolution and isomorphism. The high isomorphism is very important to obtain low-dose data using multiple crystals. Sixteen partial datasets were reduced using XDS and merged to a resolution of 1.77 Å. The calculated X-ray dose was 0.11 MGy, only 13 % of that for the 1.9 Å resolution data. Based on the merged data, structure determination is underway.

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Postnikov, Valery A., Nataliya I. Sorokina, Artem A. Kulishov, Maria S. Lyasnikova, Vadim V. Grebenev, Alexey E. Voloshin, Oleg V. Borshchev, et al. "Highly luminescent crystals of a novel linear π-conjugated thiophene–phenylene co-oligomer with a benzothiadiazole fragment." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, no. 6 (November 14, 2019): 1076–85. http://dx.doi.org/10.1107/s2052520619012484.

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The synthesis, growth from solutions and structure of crystals of a new linear thiophene–phenylene co-oligomer with a central benzothiadiazole fragment with a conjugated core, (TMS-2T-Ph)2-BTD, are presented. Single-crystal samples in the form of needles with a length of up to 7 mm were grown and their crystal structure was determined at 85 K and 293 K using single-crystal X-ray diffraction. The conformational differences between the crystal structures are insignificant. The parameters of melting and liquid crystalline phase transitions of (TMS-2T-Ph)2-BTD were established using differential scanning calorimetry and the thermal stability of the crystals was investigated using thermogravimetric analysis. The optical absorption and photoluminescence spectra of the solutions and crystals of (TMS-2T-Ph)2-BTD were obtained, and the kinetics of their photodegradation under the action of UV radiation were studied.

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45

Ludwig, M., R. Niewa, and R. Kniep. "Dimers [Al2N6]12- and Chains 1∞[AlN4/23-] in the Crystal Structures of Ca6[Al2N6] and Ba3[Al2N4]." Zeitschrift für Naturforschung B 54, no. 4 (April 1, 1999): 461–65. http://dx.doi.org/10.1515/znb-1999-0407.

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Pale yellow transparent single crystals of Ca6[Al2N6] (P21/c, No. 14, a = 693.7(3), b = 614.9(3), c = 987.1(5) pm, ß = 94.01(5)°; Z = 4) and colourless transparent single crystals of Ba3[Al2N4] (Pnna, No. 52, a = 617.9(2), b = 1005.2(4), c = 1023.0(4) pm; Z = 4) were obtained from reactions of mixtures of the representative metals with nitrogen at Tmax = 1000 °C. The crystal structure of Ca6[Al2N6] contains isolated units [Al2N6]12- built of two edge-sharing tetrahedra. Ba3[Al2N4] is an isotype of Sr3[Al2N4]. The crystal structure contains infinite chains 1∞ [AlN4/23-] of trans edge-sharing tetrahedra.

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46

Kamimura, Yasushi, Keiichi Edagawa, and Shin Takeuchi. "Peierls Stresses Estimated from CRSS Vs. Temperature Curve and their Relation to the Crystal Structure." Key Engineering Materials 465 (January 2011): 97–100. http://dx.doi.org/10.4028/www.scientific.net/kem.465.97.

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Peierls stresses P of a variety of pure crystals, bcc metals, NaCl type crystals, elemental and compound tetrahedrally coordinated crystals, intermetallic compounds and ceramic crystals, have been estimated from the critical resolved shear stress (c) vs. temperature curves. For high P crystals where CRSS data are available only at high temperatures, P has been estimated from the critical temperature T0 at which steep temperature dependence of c vanishes: T0 is related to the kink-pair formation energy which is a function of P, material parameters and dislocation character controlling the deformation. The estimated p/G values are semi-log plotted against h/b value, where G is the shear modulus, h the slip plane spacing and b the Burgers vector. Two facts should be noted. First, P/G values for a group of crystals with the same crystal structure are within a range of a factor of 10. Second, most of the data points lie in between the classical Peierls-Nabarro relation and the Huntington’s modified relation. These facts indicates that Peierls stress is primarily determined by the crystal structure.

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47

Yan, Nan, Nan Xia, Lingwen Liao, Min Zhu, Fengming Jin, Rongchao Jin, and Zhikun Wu. "Unraveling the long-pursued Au144 structure by x-ray crystallography." Science Advances 4, no. 10 (October 2018): eaat7259. http://dx.doi.org/10.1126/sciadv.aat7259.

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The transition from nanocluster to nanocrystal is a central issue in nanoscience. The atomic structure determination of metal nanoparticles in the transition size range is challenging and particularly important in understanding the quantum size effect at the atomic level. On the basis of the rationale that the intra- and interparticle weak interactions play critical roles in growing high-quality single crystals of metal nanoparticles, we have reproducibly obtained ideal crystals of Au144(SR)60 and successfully solved its structure by x-ray crystallography (XRC); this structure was theoretically predicted a decade ago and has long been pursued experimentally but without success until now. Here, XRC reveals an interesting Au12 hollow icosahedron in thiolated gold nanoclusters for the first time. The Au–Au bond length, close to that of bulk gold, shows better thermal extensibility than the other Au–Au bond lengths in Au144(SR)60, providing an atomic-level perspective because metal generally shows better thermal extensibility than nonmetal materials. Thus, our work not only reveals the mysterious, long experimentally pursued structure of a transition-sized nanoparticle but also has important implications for the growth of high-quality, single-crystal nanoparticles, as well as for the understanding of the thermal extensibility of metals from the perspective of chemical bonding.

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48

Fort, D. "Solid-state crystal growth of rare earth metals and alloys adopting the h.c.p. crystal structure." Journal of Alloys and Compounds 177, no. 1 (December 1991): 31–47. http://dx.doi.org/10.1016/0925-8388(91)90054-y.

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49

Nguyen, Ba Duc, Quang Tho Vu, Phi Hiep Trinh, and Quynh Lam Nguyen Thi. "Thermodynamic parameters depend on temperature with the influence of doping ratio of the crystal structure metals in extended X-Ray absorption fine structure." SCIENTIFIC JOURNAL OF TAN TRAO UNIVERSITY 4, no. 10 (April 6, 2021): 5–10. http://dx.doi.org/10.51453/2354-1431/2018/238.

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The effects of the doping ratio and temperature on the cumulants andthermodynamic parameters of crystal structure metals and their alloys wasinvestigated using the anharmonic correlated Einstein model, in extended X-ray absorption fine structure (EXAFS) spectra. We derived analytical expressions for the EXAFS cumulants, correlated Einstein frequency, Einstein temperature, and effective spring constant. We have considered parameters of the effective Morsepotential and the Debye-Waller factor depend on temperature and the effects of the doping ratio of face-centered-cubic (fcc) crystals of copper (Cu-Cu), silver (Ag-Ag), and hexagonal-close-packed (hcp) crystal of zinc (Zn-Zn), and their alloys of Cu-Ag and Cu-Zn. The derived anharmonic effective potential includes the contributions of all the nearest neighbors of the absorbing and scattering atoms. This accounts for three-dimensional interactions and the parameters of theMorse potential, to describe single-pair atomic interactions. The numericalresults of the EXAFS cumulants, thermodynamic parameters, and anharmonic effective potential agree reasonably with experiments and other theories.

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Söderlind, P., R. Ahuja, O. Eriksson, J. M. Wills, and B. Johansson. "Crystal structure and elastic-constant anomalies in the magnetic 3dtransition metals." Physical Review B 50, no. 9 (September 1, 1994): 5918–27. http://dx.doi.org/10.1103/physrevb.50.5918.

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Journal articles on the topic 'Crystal structure of metals'

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