Journal articles: 'Metal crystals'

1

JIA, JIN-FENG, X. LIU, S. C. LI, J. Z. WANG, J. L. LI, H. LIU, M. H. PAN, et al. "ARTIFICIAL METAL NANOCLUSTER CRYSTALS." Modern Physics Letters B 16, no. 23n24 (October 20, 2002): 889–94. http://dx.doi.org/10.1142/s0217984902004408.

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Artificial metal nanocluster crystals, (i.e. periodic lattices consisting of identical metal nanoclusters) were fabricated using a novel technique in which surface mediated magic clustering was used to achieve identical cluster size, while the Si(111)-7 × 7 surface was used as a template for ordering the clusters. The universality of this strategy was demonstrated by fabricating more than 10 different nanocluster arrays with different metals and alloys. The atomic structures, formation mechanism and stability of the nanoclusters were studied with in situ scanning tunneling microscopy combined with first-principles total energy calculations. Our study shows that delicate control of growth kinetics is extremely important for cluster crystal fabrication.

2

Shao, Lixiong, Jiang Diao, Wang Zhou, Tao Zhang, and Bing Xie. "Non-isothermal crystallization behavior of spinel crystals in FeO-SiO2-TiO2-V2O3-Cr2O3 slag." Metallurgical Research & Technology 116, no. 1 (December 18, 2018): 110. http://dx.doi.org/10.1051/metal/2018033.

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The growth behaviour of spinel crystals in vanadium slag with high Cr2O3 content was investigated and clarified by statistical analyses based on the Crystal Size Distribution (CSD) theory. The results indicate that low cooling rate and Cr2O3 content benefit the growth of spinel crystals. The chromium spinel crystals firstly precipitated and then acted as the heterogeneous nuclei of vanadium and titanium spinel crystals. The growth mechanisms of the spinel crystals at the cooling rate of 5 K/min consist two regimes: firstly, nucleation control in the temperature range of 1873 to 1773 K, in which the shapes of CSD curves are asymptotic; secondly, surface and supply control within the temperature range of 1773 to 1473 K, in which the shapes of CSD curves are lognormal. The mean diameter of spinel crystals increases from 3.97 to 52.21 µm with the decrease of temperature from 1873 to 1473 K.

3

Zhou, Wu Zong. "Mesoporous Crystals of Transition Metal Oxides." Solid State Phenomena 140 (October 2008): 37–46. http://dx.doi.org/10.4028/www.scientific.net/ssp.140.37.

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Using mesoporous silicas as hard templates and facilitating crystal growth of transition metal oxides inside the pores, some mesoporous crystals can be produced after removing the templates. This paper gives a brief review of the research of mesoporous crystals of transition metal oxides in the last five years, including the technical development and potential applications of the new form of oxides.

4

Jackson, Michael R., and Thomas L. Selby. "Crystallization, optimization and preliminary X-ray characterization of a metal-dependent PI-PLC fromStreptomyces antibioticus." Acta Crystallographica Section F Structural Biology and Crystallization Communications 68, no. 11 (October 30, 2012): 1378–86. http://dx.doi.org/10.1107/s1744309112041371.

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A recombinant metal-dependent phosphatidylinositol-specific phospholipase C (PI-PLC) fromStreptomyces antibioticushas been crystallized by the hanging-drop method with and without heavy metals. The native crystals belonged to the orthorhombic space groupP222, with unit-cell parametersa= 41.26,b= 51.86,c = 154.78 Å. The X-ray diffraction results showed significant differences in the crystal quality of samples soaked with heavy atoms. Additionally, drop pinning, which increases the surface area of the drops, was also used to improve crystal growth and quality. The combination of heavy-metal soaks and drop pinning was found to be critical for producing high-quality crystals that diffracted to 1.23 Å resolution.

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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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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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Krasavin, V. V., and A. V. Krasavin. "Study of the elastic properties of hexagonal metal single crystals." Industrial laboratory. Diagnostics of materials 85, no. 9 (September 28, 2019): 29–35. http://dx.doi.org/10.26896/1028-6861-2019-85-9-29-35.

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Hexagonal metals (e.g., Be, Zr, Ti) are widely used in the nuclear industry, space and aircraft engineering (in manufacturing of the structural elements operating under extreme conditions). A promising way to improve the quality of products made of them is to improve the physical properties of materials using the natural anisotropy of metal single crystals. The results of studying anisotropy and a comparative analysis of the technical characteristics of the elastic properties of single crystals of hexagonal metals are presented. The equations of the elastic compliance matrix components are derived in the explicit form for arbitrary crystallographic direction proceeding from transformations of the elastic compliance tensor in the principal axes to a new arbitrary coordinate system with a subsequent use of Euler angles. Analytical expressions are presented for the technical characteristics of the elastic properties (shear and Young's moduli, Poisson's ratio) of the single crystals of 10 hep metals for an arbitrary crystallographic direction. The axial symmetry of the characteristics about the hexagonal axis is revealed. The sums of the elastic compliance coefficients which determine the shear moduli and the Poisson's ratios in two mutually perpendicular directions are constant in any crystallographic plane of the single crystal. A comparative analysis of the anisotropy of the elastic properties of single crystals of the studied group of metals revealed auxetic properties of Zn and Be single crystals and the region of crystallographic directions of uniaxia tension, leading to an auxetic effect The auxetic effect in Zn was observed under tension in the directions of the plane perpendicular to the hexagonal axis of the single crystal. The planes of the auxetic effect manifestation in Be single crystals are perpendicular to the directions making an angle of 45° with the hexagonal axis.

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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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Yurov, V. M. "ANISOTROPY OF THE SURFACE OF CUBIC BODY-CENTERED CRYSTAL LATTICES." Eurasian Physical Technical Journal 18, no. 1 (March 30, 2021): 9–15. http://dx.doi.org/10.31489/2021no1/9-15.

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In the work of Shebzukhova and Arefieva, by the method of electronic-statistical calculation of the anisotropy of the surface energy of metals, a method for estimating the work function of electrons from a metal was determined. The surface energy and electron work function of four main faces of cadmium and zinc crystals and five faces of mercury are estimated. In the work of Bokarev, the anisotropy of the surface energy of single crystals was calculated from the model of coordination melting of crystals. Based on experimental studies and theoretical calculations, it is shown that the model of coordination melting of crystals unambiguously links the physicochemical properties of the surface of single crystals with their crystal structure. In our proposed empirical model, not only the anisotropy is calculated, but also the thickness of the surface layer of the metal. It is shown that the thickness of the surface layer is determined by one fundamental parameter - the molar (atomic) volume, which periodically changes in accordance with the table of D.I. Mendeleev. It is shown in the work that the work function of electrons changes proportionally with a change in the surface energy of the metal. This means that the device we have developed can be used to measure the state of the metal surface and its anisotropy.

10

KIRUBAVATHI, K., K. SELVARAJU, and S. KUMARARAMAN. "STUDIES ON GROWTH AND CHARACTERIZATION OF BIS THIOUREA LEAD CHLORIDE: A NOVEL NONLINEAR OPTICAL CRYSTAL." Journal of Nonlinear Optical Physics & Materials 18, no. 01 (March 2009): 153–59. http://dx.doi.org/10.1142/s0218863509004531.

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Single crystals of the metal-organic nonlinear optical material bis thiourea lead chloride were grown from solution growth technique for the first time. The grown crystals were characterized by single crystal X-ray diffraction analysis to confirm the crystal structure. The presence of various functional groups and the coordination of metal ions to thiourea were confirmed by Fourier transform infrared analysis. UV-Vis. spectrum was recorded to study the optical transparency of the grown crystals. The second order nonlinear optical property of the grown crystal was examined by Kurtz powder technique and mechanical behavior was studied by Vickers micro hardness test.

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Sreenivasan, R. S., N. Kanagathara, G. Ezhamani, N. G. Renganathan, and G. Anbalagan. "Effect of Metal Dopant on Ninhydrin—Organic Nonlinear Optical Single Crystals." Journal of Spectroscopy 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/386024.

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In the present work, metal (Cu2+)-substituted ninhydrin single crystals were grown by slow evaporation method. The grown crystals have been subjected to single crystal XRD, powder X-ray diffraction, FTIR, dielectric and SHG studies. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in monoclinic system with noncentrosymmetric space group P21 with lattice parametersa=11.28 Å,b=5.98 Å,c=5.71 Å,α=90∘,β=98.57,γ=90∘, andV=381 (Å)3, which agrees very well with the reported value. The sharp and strong peaks in the powder X-ray diffraction pattern confirm the good crystallinity of the grown crystals. The presence of dopants marginally altered the lattice parameters without affecting the basic structure of the crystal. The UV-Vis transmittance spectrum shows that the crystal has a good optical transmittance in the entire visible region with lower cutoff wavelength 314 nm. The vibrational frequencies of various functional groups in the crystals have been derived from FT-IR analysis. Based on the shifts in the vibrations, the presence of copper in the lattice of the grown crystal is clearly established from the pure ninhydrin crystals. Both dielectric constant and dielectric loss decrease with the increase in frequency. The second harmonic generation efficiency was measured by employing powder Kurtz method.

12

Hayashi, Tomohiro, Hidemoto Shiga, Masayoshi Sadakata, Tatsuya Okubo, and Masahiro Yoshimura. "Hydrothermal growth of millimeter-sized aluminosilicate sodalite single crystals in noble metal capsules." Journal of Materials Research 13, no. 4 (April 1998): 891–95. http://dx.doi.org/10.1557/jmr.1998.0120.

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Aluminosilicate sodalite Na8[SiAlO4]6Cl2 single crystals are synthesized by hydrothermal processing at 873–973 K and 100–150 MPa in noble metal capsules to avoid contamination. The starting material is aluminosilicate gel, and spontaneous nucleation followed by its growth takes place. The largest size of the single crystals obtained is 1 mm across. Longer aging and heating result in larger single crystals. It is also found that the aluminum source in the synthesis gel and the element used in the noble metal capsules influence the single crystal growth. Judging from x-ray diffraction (XRD) (powder and single-crystal), optical microscopy, and thermogravimetry and differential thermal analysis (TG-DTA), the sodalite single crystals grown have good quality compared with the conventional powder.

13

Kobayashi, Jun, Keisuke Shimura, Keisuke Mikurube, Saki Otobe, Takashi Matsumoto, Eri Ishikawa, Haruo Naruke, and Takeru Ito. "Polyoxomolybdate Layered Crystals Constructed from a Heterocyclic Surfactant: Syntheses, Pseudopolymorphism and Introduction of Metal Cations." Materials 15, no. 7 (March 25, 2022): 2429. http://dx.doi.org/10.3390/ma15072429.

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Crystals with layered structures are crucial for the construction of functional materials exhibiting intercalation, ionic conductivity, or emission properties. Polyoxometalate crystals hybridized with surfactant cations have distinct layered packings due to the surfactants which can form lamellar structures. Introducing metal cations into such polyoxometalate-surfactant hybrid crystals is significant for the addition of specific functions. Here, polyoxomolybdate–surfactant hybrid crystals were synthesized as single crystals, and unambiguously characterized by X-ray structure analyses. Octamolybdate ([Mo8O26]4–, Mo8) and heterocyclic surfactant of 1-dodecylpyridinium (C12py) were employed. The hybrid crystals were composed of α-type and β-type Mo8 isomers. Two crystalline phases containing α-type Mo8 were obtained as pseudopolymorphs depending on the crystallization conditions. Crystallization with the presence of rubidium and cesium cations caused the formation of metal cation-introduced hybrid crystals comprising β-Mo8 (C12py-Rb-Mo8 and C12py-Cs-Mo8). The yield of the C12py-Rb-Mo8 hybrid crystal was almost constant within crystallization temperatures of 279–303 K, while that of C12py-Cs-Mo8 decreased over 288 K. This means that the C12py-Mo8 hybrid crystal can capture Rb+ and Cs+ from the solution phase into the solids as the C12py-Rb-Mo8 and C12py-Cs-Mo8 hybrid crystals. The C12py-Mo8 hybrid crystals could be applied to ion-capturing materials for heavy metal cation removal.

14

Wade, Colin, Nicolas Barrière, Lorraine Hanlon, Pierre Bastie, Gerard Fitzpatrick, Michael Jentschel, Gilles Roudil, and Peter Von Ballmoos. "Laue diffraction behaviour in silver mosaic crystals at several gamma-ray energies and orientations." Journal of Applied Crystallography 49, no. 2 (March 24, 2016): 606–15. http://dx.doi.org/10.1107/s1600576716002880.

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The Laue lens is an emerging technology that uses crystal diffraction to concentrate gamma-rays. The Darwin model describes diffraction in mosaic crystals at high energies (>50 keV) and is the basis for assessing the throughput of a Laue lens. While the Darwin model has been used successfully to describe binary alloys, it has shown inconsistencies when applied to diffraction with pure-metal crystals. This paper presents a systematic study of diffraction in pure-metal silver mosaic crystals and the performance of the Darwin model when applied to the data. Two cut silver crystals were tested at the Institute Laue–Langevin facility at three gamma-ray energies and at three different crystallographic orientations. The rocking curves were fitted using the Darwin model. A single Gaussian for the distribution of crystallite orientations leads to poor quality fits. A crystallite distribution that is the sum of two Gaussians gives improved fits. However, for each crystal, the Darwin model gives mosaicities and crystallite sizes that are not consistent with one another as a function either of energy or of crystallographic orientation, despite these being physical properties of the materials. Without an adequate model to describe diffraction in pure-metal crystals, either a Laue lens design must severely limit its catalogue of usable materials or each crystal in the design must be tested at the exact energy at which it is to be used. A more general theory to describe hard X-ray diffraction using pure-metal mosaic crystals, possibly involving a distribution of crystallite sizes, is therefore required.

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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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Chen, Chen, Xiao-Tong He, Dan-Li Hong, Jing-Wen Wang, Yang-Hui Luo, and Bai-Wang Sun. "Tuning the crystal structures of metal-tetraphenylporphines via a magnetic field." New Journal of Chemistry 42, no. 15 (2018): 12570–75. http://dx.doi.org/10.1039/c8nj01882k.

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In this work, two new single crystals of copper-tetraphenylporphine (Cu-TPP) (crystals 2 and 3), which were induced by external magnetic fields with strengths of 0.5 and 0.8 T, respectively, have been prepared and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis.

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Daeges, J., H. Gleiter, and J. H. Perepezko. "Superheating of metal crystals." Physics Letters A 119, no. 2 (December 1986): 79–82. http://dx.doi.org/10.1016/0375-9601(86)90418-4.

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Chen, Xin, Zhi-Yuan Yao, Chen Xue, Zhu-Xi Yang, Jian-Lan Liu, and Xiao-Ming Ren. "Novel isomorphism of two hexagonal non-centrosymmetric hybrid crystals of M(en)3Ag2I4 (M = transition metal Mn2+ or main-group metal Mg2+; en = ethylenediamine)." CrystEngComm 20, no. 3 (2018): 356–61. http://dx.doi.org/10.1039/c7ce02005h.

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For the first time, a main-group metal complex is used as a template for the formation of hybrid crystal structures and isomorphic hybrid crystals are obtained using transition and main-group metal complexes.

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Horichok, Ihor, Myroslava Shevchuk, Taras Parashchuk, and Mar’jan Galushchak. "INTRINSIC POINT DEFECTS OF SAMARIUM MONOSULPHIDE CRYSTALS IN METAL PHASE." Chemistry & Chemical Technology 11, no. 3 (August 28, 2017): 319–26. http://dx.doi.org/10.23939/chcht11.03.319.

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Wang, Zhang-Jie, Qing-Jie Li, Yi-Nan Cui, Zhan-Li Liu, Evan Ma, Ju Li, Jun Sun, et al. "Cyclic deformation leads to defect healing and strengthening of small-volume metal crystals." Proceedings of the National Academy of Sciences 112, no. 44 (October 19, 2015): 13502–7. http://dx.doi.org/10.1073/pnas.1518200112.

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When microscopic and macroscopic specimens of metals are subjected to cyclic loading, the creation, interaction, and accumulation of defects lead to damage, cracking, and failure. Here we demonstrate that when aluminum single crystals of submicrometer dimensions are subjected to low-amplitude cyclic deformation at room temperature, the density of preexisting dislocation lines and loops can be dramatically reduced with virtually no change of the overall sample geometry and essentially no permanent plastic strain. This “cyclic healing” of the metal crystal leads to significant strengthening through dramatic reductions in dislocation density, in distinct contrast to conventional cyclic strain hardening mechanisms arising from increases in dislocation density and interactions among defects in microcrystalline and macrocrystalline metals and alloys. Our real-time, in situ transmission electron microscopy observations of tensile tests reveal that pinned dislocation lines undergo shakedown during cyclic straining, with the extent of dislocation unpinning dependent on the amplitude, sequence, and number of strain cycles. Those unpinned mobile dislocations moving close enough to the free surface of the thin specimens as a result of such repeated straining are then further attracted to the surface by image forces that facilitate their egress from the crystal. These results point to a versatile pathway for controlled mechanical annealing and defect engineering in submicrometer-sized metal crystals, thereby obviating the need for thermal annealing or significant plastic deformation that could cause change in shape and/or dimensions of the specimen.

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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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Yu, Shimo, Xiang Wang, Xiuling Jiao, Cheng Li, and Dairong Chen. "Polyhedral metal–organic framework monolayer colloidal crystals with sharpened and crystal facet-dependent selectivity for organic vapor sensing." Journal of Materials Chemistry C 9, no. 16 (2021): 5379–86. http://dx.doi.org/10.1039/d1tc00810b.

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Polyhedral metal–organic framework monolayer colloidal crystals demonstrate sharpened and crystal facet-dependent selectivity for organic vapors by eliminating grain boundaries and randomly exposed crystal surfaces.

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Pengmanayol, S., and Tanakorn Osotchan. "Optical Properties of Metal Free and Metal Phthalocyanine by Molecular Band Calculation." Advanced Materials Research 55-57 (August 2008): 677–80. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.677.

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The optical properties of metal-free and metal phthalocyanine were calculated by using density functional theory with various metals including copper, zinc, cobalt, iron and manganese. The polymorphic form of these crystals was employed only for β from. The molecules were optimized with the symmetry of D4h. For the alignments of the molecule in the crystal structures of this polymorphic form which have not been reported in detail, the variation of total energy was examined as a function of the align angles. The align angle at minimum total energy was used for the band calculation. The density functional theory and plane-wave pseudopotential method were used to calculate the energy band structure and electron density of state. The calculated band structures of various metal phthalocyanines can be divided in two groups according to the peak wavelength of the maximum absorption. The first group with the peak wavelength at about 230 nm consists of β-CuPc, β-H2Pc, and β-MnPc while the wavelength of another group for β-CoPc, β-FePc, and β-ZnPc occurs at 350 nm. From the density of state calculation, it indicates that these two transitions originate from the different band and the ratio of the absorption between these states depending on the type of metal in phthalocyanine. The optical absorption was derived to examine the absorption spectra for various metal compositions while the variation in intrinsic electrical conductivity can be estimated from the shape of the band. The phonon and infrared spectra were also determined in order to investigate the vibration mode of molecule in the crystals

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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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Girard, Martin, Shunzhi Wang, Jingshan S. Du, Anindita Das, Ziyin Huang, Vinayak P. Dravid, Byeongdu Lee, Chad A. Mirkin, and Monica Olvera de la Cruz. "Particle analogs of electrons in colloidal crystals." Science 364, no. 6446 (June 20, 2019): 1174–78. http://dx.doi.org/10.1126/science.aaw8237.

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A versatile method for the design of colloidal crystals involves the use of DNA as a particle-directing ligand. With such systems, DNA-nanoparticle conjugates are considered programmable atom equivalents (PAEs), and design rules have been devised to engineer crystallization outcomes. This work shows that when reduced in size and DNA grafting density, PAEs behave as electron equivalents (EEs), roaming through and stabilizing the lattices defined by larger PAEs, as electrons do in metals in the classical picture. This discovery defines a new property of colloidal crystals—metallicity—that is characterized by the extent of EE delocalization and diffusion. As the number of strands increases or the temperature decreases, the EEs localize, which is structurally reminiscent of a metal-insulator transition. Colloidal crystal metallicity, therefore, provides new routes to metallic, intermetallic, and compound phases.

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D. S., Christy, Sahaya Shajan X., and Mahadevan C. K. "Study of Physico-Chemical Properties and Growth Dimension Augmentation of Barium Succinate Single Crystals Grown by Slow Evaporation Technique." Journal of Physical Science 33, no. 1 (April 25, 2022): 29–49. http://dx.doi.org/10.21315/jps2022.33.1.3.

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Slow evaporation method was adopted to grow barium succinate (BS) single crystals for the first time and diamond shape crystals were successfully synthesised with dimension 14 mm3 × 17 mm3 × 4 mm3. Single crystal x-ray diffraction studies show that the crystal system is monoclinic. Powder x-ray diffraction studies confirmed the crystallinity of the grown BS crystal. From energy dispersive x-ray spectroscopy (EDS) analysis the presence of barium metal was confirmed. The functional group of the BS crystal was confirmed from fourier transform infrared (FTIR) spectrum. The crystals were found to be hydrated and thermally stable up to 150°C. BS crystal possesses good transmittance in the wavelength range 250 nm–1200 nm and it is non-linear optical (NLO) active material. The BS crystals have mechanical softness and normal dielectric behaviour.

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Zhang, Wei Wen, Gang Guo, Yun Huang, and Zhi Huang. "Plastic Deformation of Nanometric Grinding Process for FCC Metal." Advanced Materials Research 154-155 (October 2010): 1336–41. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1336.

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This paper focuses on the simulations of nanometric grinding process on face centered cubic structure (FCC) single metal crystals (Cu, Ni) using Molecular dynamics. In order to analyze the plastic deformation of sample metals in nanometric grinding processes, we propose an approach using techniques of central symmetry parameters and neighbor changing ratios. The simulation results show that besides the normal dislocation defects, weak slipping defects locating on {111} crystal planes are found under the surface layer. In addition, the distribution of the neighbor changing ratio indicates that the nano grinding processes will likely cause the global plastic deformation in the surface layer.

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Mulijanto, Caroline Evania, Hong Sheng Quah, Geok Kheng Tan, Bruno Donnadieu, and Jagadese J. Vittal. "Curved crystal morphology, photoreactivity and photosalient behaviour of mononuclear Zn(II) complexes." IUCrJ 4, no. 1 (January 1, 2017): 65–71. http://dx.doi.org/10.1107/s2052252516019072.

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A dramatic effect of crystal morphology, photoreactivity and photosalient property is observed in a zinc(II) complex due to solvent effects and fluorine substitution at the backbone of the ligand. Of the two crystal forms with a 3-fluoro derivative, one yielded a curved morphology of single crystals and the second form shows photoreactivity in the solid state, whereas crystals of the 2-fluoro derivative pop during the [2 + 2] photocycloaddition reaction. This is the first report documenting curved single crystals of metal complexes obtained naturally during crystallization, although such bent crystals have been observed in extended solids naturally, or bent by mechanical force or by UV irradiation.

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Vasilyeva, Natalie, Marina Grigorieva, Alexander Antipin, Natalia Sorokina, and Alexey Voloshin. "Growth and structure of K2CoxNi(1-x)(SO4)2·6H2O mixed single crystals." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1029. http://dx.doi.org/10.1107/s2053273314089700.

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To date, crystals of Tutton salts with the general formula (M+)2M2+(SO4)2*6N2O (where M+- alkali metal or ammonium, M2+ - bivalent metal - Co2+, Ni2+) are used as a materials for ultraviolet (UV) filters. Only in recent year effort of ternary crystal growth has been taken. The main problem of mixed crystal growth from liquid solution is high level of the crystal inhomogeneity, which leads to generation of the elastic stress, inclusion trapping and micro- and macrocrack formation in the bulk crystal. For the first time the optically homogeneous mixed K2CoxNi(1 – x)(SO4)2 · 6H2O (KCNSH) large single crystals have been grown from solutions of different compositions by the temperature-reduction technique. Precise X-ray experiment of three mixed crystals was carried out by four-circle diffractometer CAD-4F and XcaliburS diffractometer with two-dimensional CCD detector at the room temperature. KCNSH crystals belong to the monoclinic space group P2(1)/c. Each Co2+ or Ni2+ ion is coordinated with six H2O molecules, forming a distorted octahedral (Co(H2O)6)2+ and (Ni(H2O)6)2+ unit. With increasing content of nickel ions in the crystal, the octahedral unit is narrowed and the unit cell volume is decreased. Chemical formulas refined using diffraction data are K2Co0.657Ni0.343(SO4)2·6H2O, K2Co0.226Ni0.774(SO4)2·6H2O and K2Co0.216Ni0.784(SO4)2·6H2O. Ratios of isomorphic cobalt and nickel components in the mixed crystals are conformed to data obtained by atomic emission spectroscopy. Effect of the Co2+ and Ni2+ ion ratio in KCNSH single crystal to crystal quality is considered.

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Lillo, Vanesa, and José Ramón Galán-Mascarós. "Transition metal complexes with oligopeptides: single crystals and crystal structures." Dalton Trans. 43, no. 26 (2014): 9821–33. http://dx.doi.org/10.1039/c4dt00650j.

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Choudhury, Tanushree H., Xiaotian Zhang, Zakaria Y. Al Balushi, Mikhail Chubarov, and Joan M. Redwing. "Epitaxial Growth of Two-Dimensional Layered Transition Metal Dichalcogenides." Annual Review of Materials Research 50, no. 1 (July 1, 2020): 155–77. http://dx.doi.org/10.1146/annurev-matsci-090519-113456.

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Transition metal dichalcogenide (TMD) monolayers and heterostructures have emerged as a compelling class of materials with transformative properties that may be harnessed for novel device technologies. These materials are commonly fabricated by exfoliation of flakes from bulk crystals, but wafer-scale epitaxy of single-crystal films is required to advance the field. This article reviews the fundamental aspects of epitaxial growth of van der Waals–bonded crystals specific to TMD films. The structural and electronic properties of TMD crystals are initially described along with sources and methods used for vapor phase deposition. Issues specific to TMD epitaxy are critically reviewed, including substrate properties and film-substrate orientation and bonding. The current status of TMD epitaxy on different substrate types is discussed along with characterization techniques for large-areaepitaxial films. Future directions are proposed, including developments in substrates, in situ and full-wafer characterization techniques, and heterostructure growth.

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Marukovich, E. I., and V. Yu Stetsenko. "Thermodynamic metal crystallization basics." Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), no. 2 (June 9, 2020): 8–11. http://dx.doi.org/10.21122/1683-6065-2020-2-8-11.

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On the basis of thermodynamic calculations it is shown that crystallization of metals is a thermodynamic process, which takes place mainly at constant temperature. The exception is crystallization at very high cooling rates of the metal melt when the released solidification heat is not enough to stabilize the crystallization temperature of the liquid metal. In crystallization, the specific interfacial surface energy of crystals is not a constant value, but is proportional to their dimensions (bend radius).Nanocrystals of crystallizing phases exist in the metal melt steadily. Metal crystallization aggregates nanocrystals and free metal melt atoms into microcrystals. Mechanism of dendritic crystallization of metals is proposed.

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Kousaka, Yusuke, Satoshi Iwasaki, Taisei Sayo, Hiroshi Tanida, Takeshi Matsumura, Shingo Araki, Jun Akimitsu, and Yoshihiko Togawa. "Chirality-controlled enantiopure crystal growth of a transition metal monosilicide by a floating zone method." Japanese Journal of Applied Physics 61, no. 4 (March 16, 2022): 045501. http://dx.doi.org/10.35848/1347-4065/ac4e2f.

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Abstract We performed a crystal growth to obtain chirality-controlled enantiopure crystals using a laser-diode-heated floating zone (LDFZ) method with a composition-gradient feed rod. It has been argued that the crystal handedness of TSi (T : transition metal) is fixed depending on T in the case of the ones grown by the conventional methods. We found that right-handed single crystals of CoSi and MnSi were grown from the composition-gradient feed rods that consist of FeSi–CoSi and FeSi–MnSi, respectively. The obtained CoSi and MnSi crystals inherit the chirality from the seed part of FeSi, which grows in a right-handed structure, and thus has the chirality opposite to that for the crystals in the literature. The LDFZ method with the feed rods with various combinations of TSi compounds enables flexible control of the chirality of TSi and will be useful for clarifying the interplay between crystalline chirality and chirality-induced physical responses.

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Chen, Lung-Chien, Kuan-Lin Lee, Kun-Yi Lee, Yi-Wen Huang, and Ray-Ming Lin. "Study of Metal–Semiconductor–Metal CH3NH3PbBr3 Perovskite Photodetectors Prepared by Inverse Temperature Crystallization Method." Sensors 20, no. 1 (January 5, 2020): 297. http://dx.doi.org/10.3390/s20010297.

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Numerous studies have addressed the use of perovskite materials for fabricating a wide range of optoelectronic devices. This study employs the deposition of an electron transport layer of C60 and an Ag electrode on CH3NH3PbBr3 perovskite crystals to complete a photodetector structure, which exhibits a metal–semiconductor–metal (MSM) type structure. First, CH3NH3PbBr3 perovskite crystals were grown by inverse temperature crystallization (ITC) in a pre-heated circulator oven. This oven was able to supply uniform heat for facilitating the growth of high-quality and large-area crystals. Second, the different growth temperatures for CH3NH3PbBr3 perovskite crystals were investigated. The electrical, optical, and morphological characteristics of the perovskite crystals were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy, and photoluminescence (PL). Finally, the CH3NH3PbBr3 perovskite crystals were observed to form a contact with the Ag/C60 as the photodetector, which revealed a responsivity of 24.5 A/W.

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Wardle, S. T., L. S. Lin, A. Cetel, and B. L. Adams. "Orientation imaging microscopy: Monitoring residual stress profiles in single crystals using an image-quality parameter, IQ." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 680–81. http://dx.doi.org/10.1017/s0424820100171134.

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Residual stresses are routinely calculated in polycrystalline materials from the residual strains determined by x-ray diffraction (XRD) analysis. Using XRD to determine residual stresses is a well-established technique, however it cannot be used for single crystals. This investigation develops a technique that readily monitors residual deformation profiles in single crystals. The technique is of particular interest to the aerospace industry as it enables the effectiveness of shot-peening single crystal turbine blades to be monitored.Electron Back-Scattered Patterns (EBSPs) can readily be obtained from electropolished single crystals using a scanning electron microscope (SEM) in spot mode. EBSPs from cold worked metals will be of poorer quality than EBSPs from undeformed metal. Likewise the EBSPs obtained from an electropolished section cut perpendicular to a shot-peened surface will show an increase in image quality with increasing distance from the worked surface (Fig. 1). This trend could easily be monitored in single crystals by quantifying the image quality of the associated EBSPs using orientation imaging microscopy (OIM).

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Savastano, Matteo, Valeria Monini, Carla Bazzicalupi, and Antonio Bianchi. "Bidimensional Polyiodide Netting Stabilized by a Cu(II) Macrocyclic Complex." Inorganics 10, no. 1 (January 13, 2022): 12. http://dx.doi.org/10.3390/inorganics10010012.

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Iodine-dense polyiodide phases are interesting materials for a number of potential uses, including batteries and solid-state conductors. The incorporation of transition metal cations is considered a promising way to enhance the stability, tune the properties, and influence the architecture of polyiodides. However, several interesting metals, including Cu(II), may suffer redox processes, which generally make them not compatible with the I2/I− redox couple. Herein L, a simple derivative of cyclen, is proposed as a Cu(II) ligand capable of protecting the +2 oxidation state of the metal even in the presence of polyiodides. With a step by step approach, we report the crystal structure of free L; then we present spectrophotometric verification of Cu(II) complex stability, stoichiometry, and formation kinetic in DMF solution, together with Cu(II) binding mode elucidation via XRD analysis of [Cu(L)Cl]ClO4∙CH3CN crystals; afterwards, the stability of the CuL complex in the presence of I− is demonstrated in DMF solution, where the formation of a Cu:L:I− ternary complex, rather than reduction to Cu(I), is observed; lastly, polyiodide crystals are prepared, affording the [Cu(L)I]2I3I5 crystal structure. This layered structure is highly peculiar due to its chiral arrangement, opening further perspective for the crystal engineering of polyiodide phases.

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Sano, Daisuke, and Soshu Kirihara. "Fabrication of Metal Photonic Crystals with Graded Lattice Spacing by Using Micro-Stereolithography." Materials Science Forum 631-632 (October 2009): 287–92. http://dx.doi.org/10.4028/www.scientific.net/msf.631-632.287.

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We designed micro-scale photonic crystal with or without graded lattice spacing composed of copper to control Terahertz (THz) waves. Designed structures were fabricated by using micro-stereolithography. By proper dewaxing and sintering process, pure copper photonic crystals were obtained. Transmission properties of THz waves propagating through the photonic crystals were measured by THz time-domain spectroscopy. Measured results showed good agreements with the simulated results.

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Makarov, Yu N., D. Litvin, A. Vasiliev, and S. Nagalyuk. "Sublimation Growth of 4 and 6 Inch 4H-SiC Low Defect Bulk Crystals in Ta (TaC) Crucibles." Materials Science Forum 858 (May 2016): 101–4. http://dx.doi.org/10.4028/www.scientific.net/msf.858.101.

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Recently, the wide bandgap semiconductors, especially silicon carbide (SiC), have become more important due to the unique electrical and thermophysical properties that make them applicable to a variety of electronic devices (Schottky and PiN diodes, JFETs, MOSFETs, etc.). For these applications, the crystals need to be manufactured with highest possible quality, both structural and chemical, at reduced cost. This requirement places rather extreme constraints on the crystal growth as the simultaneous goals of high quality and low cost are generally incompatible.Refractory metal carbide technology, particularly, tantalum carbide (TaC), was originally developed for application in highly corrosive and reactive environments. Yu. Vodakov [1] demonstrated for the first time advantages of use of refractory metal carbides for PVT growth of SiC and later AlN bulk crystals. In the present paper we discuss the effect of refractory metal on PVT growth of large diameter 4H SiC bulk crystals.

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Yeo, Hyun Ku, Jina Kang, Young Woo Park, Jung-Suk Sung, and Jae Young Lee. "Crystallization and preliminary X-ray diffraction analysis of the metalloregulatory protein DtxR fromThermoplasma acidophilum." Acta Crystallographica Section F Structural Biology and Crystallization Communications 68, no. 2 (January 26, 2012): 172–74. http://dx.doi.org/10.1107/s1744309111051700.

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The diphtheria toxin repressor (DtxR) is a metal-ion-dependent transcriptional regulator which regulates genes encoding proteins involved in metal-ion uptake to maintain metal-ion homeostasis. DtxR fromThermoplasma acidophilumwas cloned and overexpressed inEscherichia coli. Crystals of N-terminally His-tagged DtxR were obtained by hanging-drop vapour diffusion and diffracted to 1.8 Å resolution. DtxR was crystallized at 296 K using polyethylene glycol 4000 as a precipitant. The crystals belonged to the orthorhombic space groupP21212, with unit-cell parametersa= 61.14,b= 84.61,c= 46.91 Å, α = β = γ = 90°. The asymmetric unit contained approximately one monomer of DtxR, giving a crystal volume per mass (VM) of 2.22 Å3 Da−1and a solvent content of 44.6%.

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Suponitsky, Kyrill Yu, Ivan V. Fedyanin, Valentina A. Karnoukhova, Vladimir A. Zalomlenkov, Alexander A. Gidaspov, Vladimir V. Bakharev, and Aleksei B. Sheremetev. "Energetic Co-Crystal of a Primary Metal-Free Explosive with BTF. Ideal Pair for Co-Crystallization." Molecules 26, no. 24 (December 9, 2021): 7452. http://dx.doi.org/10.3390/molecules26247452.

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Co-crystallization is an elegant technique to tune the physical properties of crystalline solids. In the field of energetic materials, co-crystallization is currently playing an important role in the engineering of crystals with improved performance. Here, based on an analysis of the structural features of the green primary explosive, tetramethylammonium salt of 7-oxo-5-(trinitromethyl)-4,5,6,7-tetrahydrotetrazolo[1,5-a][1,3,5]triazin-5-ide (1), a co-former such as the powerful secondary explosive, benzotrifuroxan (BTF, 2), has been proposed to improve it. Compared to the original 1, its co-crystal with BTF has a higher detonation pressure and velocity, as well as an initiating ability, while the impact sensitivity and thermal stability remained at about the same level. Both co-formers, 1 and 2, and co-crystal 3 were characterized by single-crystal X-ray diffraction and their crystal packing was analyzed in detail by the set of approaches, including periodic calculations. In the co-crystal 3, all intermolecular interactions were significantly redistributed. However, no new types of intermolecular interactions were formed during co-crystallization. Moreover, the interaction energies of structural units in crystals before and after co-crystallization were approximately the same. A similar trend was observed for the volumes occupied by structural units and their densifications. The similar nature of the organization of the crystals of the co-formers and the co-crystal gives grounds to assert that the selected co-formers are an ideal pair for co-crystallization, and the invariability of the organization of the crystals was probably responsible for the preservation of some of their properties.

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Camara-Artigas, Ana, Marina Plaza-Garrido, Sergio Martinez-Rodriguez, and Julio Bacarizo. "New crystal form of human ubiquitin in the presence of magnesium." Acta Crystallographica Section F Structural Biology Communications 72, no. 1 (January 1, 2016): 29–35. http://dx.doi.org/10.1107/s2053230x15023390.

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Ubiquitin is a small globular protein that has a considerable number of lysine residues on its surface. This results in a high surface entropy that precludes the formation of crystal-packing interactions. To date, only a few structures of the native form of ubiquitin have been solved, and most of the crystals that led to these structures were obtained in the presence of different divalent metal cations. In this work, a new crystallographic structure of human ubiquitin solved from crystals grown in the presence of magnesium is presented. The crystals belonged to a triclinic space group, with unit-cell parametersa= 29.96,b = 30.18,c= 41.41 Å, α = 88.52, β = 79.12, γ = 67.37°. The crystal lattice is composed of stacked layers of human ubiquitin molecules with a large hydrophobic interface and a smaller polar interface in which the magnesium ion lies at the junction between adjacent layers in the crystal. The metal ion appears in a hexa-aquo coordination, which is key to facilitating the crystallization of the protein.

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Apkarian, R. P., and M. D. Gutekunst. "High-Resolution Topographic Imaging of Enamel Crystal Surfaces." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 188–89. http://dx.doi.org/10.1017/s0424820100103024.

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Previous interpretations of enamel crystal morphology have been handicapped by preparation techniques and the understanding of enamel crystals was derived from TEM and conventional SEM studies looking into lesion formation in enamel. Early studies focused on the demineralization and effects of mineralization on enamel structure. Enamel crystals were previously described as flattened hexagonal structures 100 μm long and 35-40 nm in diameter using conventional SEM and 47.3 nm in diameter using TEM. A methodology has been developed and employed in order to accurately image hydroxyapatite crystals in normal human teeth. The combination of an ultrathin coating of sputtered chromium (Cr) film and SE-I imaging herein provide topographic contrasts of crystal surfaces. Since the majority of the SE-I information should be produced close to the surface, the resultant image is specimen surface specific. Optimal metal coating thicknesses of low atomic number were utilized so that the generation of the SE-I signal contrast which occurs on the enamel crystal surface was used to form the image, thus avoiding image contrast contribution by electrons scattered in the metal coat.

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Abrahams, Brendan F., Nicholas J. FitzGerald, Timothy A. Hudson, Richard Robson, and Richard D. Shalders. "Metal Exchange within a Body-Centred Cubic Hydrogen-Bonded Network." Australian Journal of Chemistry 60, no. 1 (2007): 68. http://dx.doi.org/10.1071/ch06334.

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A hydrogen bonded network of composition Zn8(C4O7)4(H2O)12·hydrate was shown to undergo a single crystal to single crystal exchange process when crystals are immersed in a concentrated aqueous solution of Ni(ii). In the exchange process, half of the zinc(ii) centres are replaced by nickel(ii) centres. The process of metal ion exchange was monitored using IR spectroscopy. Crystal structures of the transformed crystal and the product generated from a direct synthetic approach are presented.

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Yang, Xue, Michel Giorgi, Hakim Karoui, Didier Gigmes, Virginie Hornebecq, Olivier Ouari, Anthony Kermagoret, and David Bardelang. "A single-crystal-to-single-crystal transformation affording photochromic 3D MORF crystals." Chemical Communications 55, no. 92 (2019): 13824–27. http://dx.doi.org/10.1039/c9cc07121k.

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Krause, Simon, Volodymyr Bon, Hongchu Du, Rafal E. Dunin-Borkowski, Ulrich Stoeck, Irena Senkovska, and Stefan Kaskel. "The impact of crystal size and temperature on the adsorption-induced flexibility of the Zr-based metal–organic framework DUT-98." Beilstein Journal of Nanotechnology 10 (August 20, 2019): 1737–44. http://dx.doi.org/10.3762/bjnano.10.169.

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In this contribution we analyze the influence of adsorption cycling, crystal size, and temperature on the switching behavior of the flexible Zr-based metal–organic framework DUT-98. We observe a shift in the gate-opening pressure upon cycling of adsorption experiments for micrometer-sized crystals and assign this to a fragmentation of the crystals. In a series of samples, the average crystal size of DUT-98 crystals was varied from 120 µm to 50 nm and the obtained solids were characterized by X-ray diffraction, infrared spectroscopy, as well as scanning and transmission electron microscopy. We analyzed the adsorption behavior by nitrogen and water adsorption at 77 K and 298 K, respectively, and show that adsorption-induced flexibility is only observed for micrometer-sized crystals. Nanometer-sized crystals were found to exhibit reversible type I adsorption behavior upon adsorption of nitrogen and exhibit a crystal-size-dependent steep water uptake of up to 20 mmol g−1 at 0.5 p/p 0 with potential for water harvesting and heat pump applications. We furthermore investigate the temperature-induced structural transition by in situ powder X-ray diffraction. At temperatures beyond 110 °C, the open-pore state of the nanometer-sized DUT-98 crystals is found to irreversibly transform to a closed-pore state. The connection of crystal fragmentation upon adsorption cycling and the crystal size dependence of the adsorption-induced flexibility is an important finding for evaluation of these materials in future adsorption-based applications. This work thus extends the limited amount of studies on crystal size effects in flexible MOFs and hopefully motivates further investigations in this field.

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Chen, Jing, Meng-Yao Chao, Yan Liu, Bo-Wei Xu, Wen-Hua Zhang, and David J. Young. "An N,N′-diethylformamide solvent-induced conversion cascade within a metal–organic framework single crystal." Chemical Communications 56, no. 44 (2020): 5877–80. http://dx.doi.org/10.1039/d0cc02420a.

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A two-dimensional metal–organic framework undergoes four-step single-crystal to single-crystals conversions, including a three-step DEF-induced cascade conversion to shuttle back to its original connectivity.

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Liu, Chong, and Nathaniel L. Rosi. "Ternary gradient metal–organic frameworks." Faraday Discussions 201 (2017): 163–74. http://dx.doi.org/10.1039/c7fd00045f.

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Gradient MOFs contain directional gradients of either structure or functionality. We have successfully prepared two ternary gradient MOFs based on bMOF-100 analogues, namely bMOF-100/102/106 and bMOF-110/100/102, via cascade ligand exchange reactions. The cubic unit cell parameter discrepancy within an individual ternary gradient MOF crystal is as large as ∼1 nm, demonstrating the impressive compatibility and flexibility of the component MOF materials. Because of the presence of a continuum of unit cells, the pore diameters within individual crystals also change in a gradient fashion from ∼2.5 nm to ∼3.0 nm for bMOF-100/102/106, and from ∼2.2 nm to ∼2.7 nm for bMOF-110/100/102, indicating significant porosity gradients. Like previously reported binary gradient MOFs, the composition of the ternary gradient MOFs can be easily controlled by adjusting the reaction conditions. Finally, X-ray diffraction and microspectrophotometry were used to analyse fractured gradient MOF crystals by comparing unit cell parameters and absorbance spectra at different locations, thus revealing the profile of heterogeneity (i.e. gradient distribution of properties) and further confirming the formation of ternary gradient MOFs.

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Yu, Jianyuan, Yingeng Wang, Yan Huang, Xiuwen Wang, Jing Guo, Jingkai Yang, and Hongli Zhao. "Structural and electronic properties of SnO2 doped with non-metal elements." Beilstein Journal of Nanotechnology 11 (September 3, 2020): 1321–28. http://dx.doi.org/10.3762/bjnano.11.116.

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Crystal structure and electronic properties of SnO2 doped with non-metal elements (F, S, C, B, and N) were studied using first-principles calculations. The theoretical results show that doping of non-metal elements cannot change the structure of SnO2 but result in a slight expansion of the lattice volume. The most obvious finding from the analysis is that F-doped SnO2 has the lowest defect binding energy. The doping with B and S introduced additional defect energy levels within the forbidden bandgap, which improved the crystal conductivity. The Fermi level shifts up due to the doping with B, F, and S, while the Fermi level of SnO2 doped with C or N has crossed the impurity level. The Fermi level of F-doped SnO2 is inside the conduction band, and the doped crystal possesses metallicity. The optical properties of SnO2 crystals doped with non-metal elements were analyzed and calculated. The SnO2 crystal doped with F had the highest reflectivity in the infrared region, and the reflectance of the crystals doped with N, C, S, and B decreased sequentially. Based on this theoretical calculations, F-doped SnO2 is found to be the best photoelectric material for preparing low-emissivity coatings.

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Shen, Kui, Lei Zhang, Xiaodong Chen, Lingmei Liu, Daliang Zhang, Yu Han, Junying Chen, et al. "Ordered macro-microporous metal-organic framework single crystals." Science 359, no. 6372 (January 11, 2018): 206–10. http://dx.doi.org/10.1126/science.aao3403.

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We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional–ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent–induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

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Klimm, Detlef, and Nora Wolff. "On Thermodynamic Aspects of Oxide Crystal Growth." Applied Sciences 12, no. 6 (March 8, 2022): 2774. http://dx.doi.org/10.3390/app12062774.

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Several metal oxide compounds, especially those containing metals possessing several valence states, are able to absorb or release oxygen under suitable thermodynamic conditions. Such behavior is found often in systems containing oxides of transition metals. It is important to note that the equilibrium oxidation level of those metal oxides can depend on the aggregation state, which may significantly impede crystal growth processes from the melt. If during the melt growth of such oxide crystals, the average valence state of the oxides is different in the molten and solid state, then crystallization is connected with the absorption of free oxygen from the ambient gas, or with the release of free oxygen into it. This phenomenon can be detected by simultaneous DTA/TG measurements and can deteriorate the stability of crystal growth. This holds especially if the average valence in the solid is smaller than in the melt, because oxygen release can lead to bubble formation at the crystallization front.

Journal articles on the topic 'Metal crystals'

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