Crystals

3395 KiB

Open AccessArticle

Crystal Structures, Thermal Analysis, and Dissolution Behavior of New Solid Forms of the Antiviral Drug Arbidol with Dicarboxylic Acids

by Alex N. Manin, Artem O. Surov, Andrei V. Churakov and German L. Perlovich

Crystals 2015, 5(4), 650-669; https://doi.org/10.3390/cryst5040650 - 04 Dec 2015

Cited by 20 | Viewed by 7721

Abstract

Salts of the antiviral drug arbidol (umifenovir) (Arb) with maleate (Mlc) and fumarate (Fum) anions have been obtained, and their crystal structures have been described. The crystal structure of arbidol maleate has been redetermined by single crystal [...] Read more.

Salts of the antiviral drug arbidol (umifenovir) (Arb) with maleate (Mlc) and fumarate (Fum) anions have been obtained, and their crystal structures have been described. The crystal structure of arbidol maleate has been redetermined by single crystal X-ray diffraction at 180K. A new arbidol cocrystal in zwitterion form with succinic acid (Suc) has also been found and characterized. The arbidol zwitterion was not previously seen in any of the drug crystal forms, and the [Arb + Suc] cocrystal seems to be the first found instance. Analysis of the conformational preferences of the arbidol molecule in the crystal structures has shown that it adopts two types of conformations, namely “open” and “closed” ones. Thermal stability of the arbidol salts and cocrystal have been analyzed by means of differential scanning calorimetry, thermogravimetric, and mass-spectrometry analysis. The dissolution study of the arbidol salts and cocrystal performed in aqueous buffer solutions with pH 1.2 and 6.8 has shown that both the salts and the cocrystal dissolve incongruently to form an arbidol hydrochloride monohydrate at pH 1.2 and an arbidol base at pH 6.8, respectively. The cocrystal reaches the highest solubility level in both pH 1.2 and pH 6.8 solutions. Full article

(This article belongs to the Special Issue Pharmaceutical Cocrystals)

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1281 KiB

Open AccessFeature PaperArticle

A New Method for the Synthesis of Heterospin Complexes

by Victor Ovcharenko, Olga Kuznetsova, Elena Fursova, Gаlinа Romаnenko and Artem Bogomyakov

Crystals 2015, 5(4), 634-649; https://doi.org/10.3390/cryst5040634 - 02 Dec 2015

Cited by 9 | Viewed by 4387

Abstract

The interaction of binuclear Co(II) pivalate [Сo₂(H₂O)Piv₄(HPiv)₄] with nitronyl nitroxide HL¹ (2-(2-hydroxy-5-nitrophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl) in organic solvents led to the formation of a pentanuclear heterospin complex [Co₅(Piv)₄L¹₄L²₂ [...] Read more.

The interaction of binuclear Co(II) pivalate [Сo₂(H₂O)Piv₄(HPiv)₄] with nitronyl nitroxide HL¹ (2-(2-hydroxy-5-nitrophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl) in organic solvents led to the formation of a pentanuclear heterospin complex [Co₅(Piv)₄L¹₄L²₂]. A nontrivial peculiarity of the complex is the presence of both the starting nitronyl nitroxide L¹ and its deoxygenated derivative imino nitroxide L² (HL²: 2-(2-hydroxy-5-nitrophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl) in its coordination sphere. Based on this, a new synthetic approach was developed, which suggests the use of both the starting radical and the product of its reduction in the reaction with the metal. The suggested approach is a new method for the synthesis of heterospin compounds, including those that cannot be obtained by other methods. It was shown that the reaction of Co(II) pivalate with a mixture of HL¹ and HL² can give a trinuclear heterospin complex [Co₃(Piv)₂L¹₂L²₂]. The replacement of Co(II) by Ni(II) completely suppresses the reduction of HL¹ into HL², and Ni(II) pivalate does not react with HL¹. The use of a known mixture of HL¹ and HL² in the reaction with [Ni₂(H₂O)Piv₄(HPiv)₄], however, led to the formation of a heterospin complex [Ni₃L¹L²₂(Piv)₃(HPiv)₃] also containing both nitronyl nitroxide and imino nitroxide. Full article

(This article belongs to the Special Issue High Spin Molecules)

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1702 KiB

Open AccessArticle

The Search for Hydrogen Stores on a Large Scale; A Straightforward and Automated Open Database Analysis as a First Sweep for Candidate Materials

by Joachim Breternitz and Duncan H. Gregory

Crystals 2015, 5(4), 617-633; https://doi.org/10.3390/cryst5040617 - 25 Nov 2015

Cited by 2 | Viewed by 5304

Abstract

The storage of hydrogen is considered as the bottleneck in the implementation of portable fuel cell power generating systems. The necessary experimental studies to discover and develop appropriate storage materials are always time-limited. We discuss herein the approach of an uncomplicated and accessible [...] Read more.

The storage of hydrogen is considered as the bottleneck in the implementation of portable fuel cell power generating systems. The necessary experimental studies to discover and develop appropriate storage materials are always time-limited. We discuss herein the approach of an uncomplicated and accessible computationally based analysis of database knowledge towards the identification of promising storage systems. The open access policy of the Crystallography Open Database (COD) invites researchers to grasp the opportunity to formulate targeted analyses of crystalline solids, unfettered by material resources. We apply such an approach to the initial evaluation of potential solid-state hydrogen stores, although the method could potentially be transferred to other material analysis tasks. Full article

(This article belongs to the Special Issue Crystalline Hydrogen Storage Materials)

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1020 KiB

Open AccessArticle

A New 1D Chained Coordination Polymer: Synthesis, Crystal Structure, Antitumor Activity and Luminescent Property

by Xi-Shi Tai and Hai-Ying You

Crystals 2015, 5(4), 608-616; https://doi.org/10.3390/cryst5040608 - 25 Nov 2015

Cited by 11 | Viewed by 4179

Abstract

A new 1D chained coordination polymer of Zn(II), {[Zn(L)₂(4,4′-bipy)]·(H₂O)}_n(1) (HL = N-acetyl-l-phenylalanine; 4,4′-bipy = 4,4′-bipyridine) has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. Theresults show that each [...] Read more.

A new 1D chained coordination polymer of Zn(II), {[Zn(L)₂(4,4′-bipy)]·(H₂O)}_n(1) (HL = N-acetyl-l-phenylalanine; 4,4′-bipy = 4,4′-bipyridine) has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. Theresults show that each asymmetric unit of Zn(II) complex belongs to monoclinic, space group P2₁ with a = 11.421(2) Å, b = 9.2213(17) Å, c = 15.188(3) Å,β = 106.112(3)°, V = 1536.7(5) Å³, Z = 2, Dc = 1.444 g·cm⁻³, µ = 0.857 mm⁻¹, F(000) = 696, and final R₁ = 0.0439, ωR₂ = 0.1013. The molecules form one-dimensional chained structure by its the bridging 4,4′-bipyridine ligands. The antitumor activities and luminescent properties of Zn(II) coordination polymer have also been investigated. Full article

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2341 KiB

Open AccessArticle

Influence of Boron on Initial Austenite Grain Size and Hot Deformation Behavior of Boron Microalloyed Steels

by Yong-liang Gao, Xiang-xin Xue and He Yang

Crystals 2015, 5(4), 592-607; https://doi.org/10.3390/cryst5040592 - 24 Nov 2015

Cited by 13 | Viewed by 5417

Abstract

The initial austenite grain size of boron microalloyed steel with three different amounts of boron (20, 40, and 60 ppm) was investigated under different heating temperatures (1150, 1100, and 1050 °C), and hot compression tests of samples in a wide range of temperature [...] Read more.

The initial austenite grain size of boron microalloyed steel with three different amounts of boron (20, 40, and 60 ppm) was investigated under different heating temperatures (1150, 1100, and 1050 °C), and hot compression tests of samples in a wide range of temperature (900–1100 °C) and strain rate (0.1–10 s⁻¹) were conducted. It was found that the initial austenite grain size increases with increasing temperature and boron content. The flow stress decreased with increasing boron content at lower strain rates. The flow stress constitutive equation of hot deformation was developed for the experimental steels; results showed that boron addition has the trend to reduce the hot deformation activation energy. The characteristic points of the flow curves were analyzed. Results revealed that the peak and critical stress decreased in response to an increase of boron content. The work-hardening behavior of both steels was investigated, and it was found that boron addition can decrease the work-hardening rate when strained at lower strain rates. On the contrary, peak and critical strains increased as boron content increased, indicating that boron has the ability to delay the onset of dynamic recrystallization. Full article

(This article belongs to the Special Issue Boron-Based (Nano-)Materials: Fundamentals and Applications)

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4672 KiB

Open AccessArticle

Liquid-Assisted Grinding to Prepare a Cocrystal of Adefovir Dipivoxil Thermodynamically Less Stable than Its Neat Phase

by Sungyup Jung, Insil Choi and Il Won Kim

Crystals 2015, 5(4), 583-591; https://doi.org/10.3390/cryst5040583 - 19 Nov 2015

Cited by 17 | Viewed by 6072

Abstract

Liquid-assisted grinding was employed to generate a cocrystal of adefovir dipivoxil (AD) and glutaric acid (GLU), which had not been successfully obtained through solution crystallization. The cocrystal formation was confirmed with powder X-ray diffraction, and its thermal stability and release behavior were studied [...] Read more.

Liquid-assisted grinding was employed to generate a cocrystal of adefovir dipivoxil (AD) and glutaric acid (GLU), which had not been successfully obtained through solution crystallization. The cocrystal formation was confirmed with powder X-ray diffraction, and its thermal stability and release behavior were studied through differential scanning calorimetry and dissolution experiments, respectively. The AD/GLU cocrystal was less stable than neat AD phase and the previously reported AD cocrystals with other dicarboxylic acids, such as suberic acid and succinic acid. This suggests that the intermolecular interactions of the AD/GLU cocrystal are probably weaker than the other crystal phases. The release behavior of the AD/GLU was comparable with the cocrystal with suberic acid. The current study verifies the effectiveness of the liquid-assisted grinding for the preparation of the thermodynamically less stable cocrystal phase. Full article

(This article belongs to the Special Issue Pharmaceutical Cocrystals)

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3446 KiB

Open AccessArticle

Enthalpies of Formation of Transition Metal Diborides: A First Principles Study

by Catherine Colinet and Jean-Claude Tedenac

Crystals 2015, 5(4), 562-582; https://doi.org/10.3390/cryst5040562 - 19 Nov 2015

Cited by 11 | Viewed by 5706

Abstract

The enthalpies of formation of transition metals diborides in various structures have been obtained from density functional theory (DFT) calculations in order to determine the ground state at T = 0 K and p = 0. The evolution of the enthalpies of formation [...] Read more.

The enthalpies of formation of transition metals diborides in various structures have been obtained from density functional theory (DFT) calculations in order to determine the ground state at T = 0 K and p = 0. The evolution of the enthalpies of formation along the 3D, 4D, and 5D series has been correlated to the considered crystal structures. In the whole, the calculated values of the enthalpies of formation of the diborides in their ground state are in good agreement with the experimental ones when available. The calculated values of the lattice parameters at T = 0 K of the ground state agree well with the experimental values. The total and partial electronic densities of states have been computed. Special features of the transition metal electronic partial density of states have been evidenced and correlated to the local environment of the atoms. Full article

(This article belongs to the Special Issue Intermetallics)

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1245 KiB

Open AccessArticle

Quantitative Evaluation of Photoinduced Bending Speed of Diarylethene Crystals

by Daichi Kitagawa, Chika Iwaihara, Hiroyasu Nishi and Seiya Kobatake

Crystals 2015, 5(4), 551-561; https://doi.org/10.3390/cryst5040551 - 06 Nov 2015

Cited by 28 | Viewed by 6289

Abstract

We investigated photoinduced crystal bending behavior of various photochromic diarylethenes. In all the diarylethene derivatives we used in this work, the relationship between the initial photoinduced bending speed and the crystal thickness was well explained by the easy-handled Timoshenkoʼs bimetal model. Moreover, we [...] Read more.

We investigated photoinduced crystal bending behavior of various photochromic diarylethenes. In all the diarylethene derivatives we used in this work, the relationship between the initial photoinduced bending speed and the crystal thickness was well explained by the easy-handled Timoshenkoʼs bimetal model. Moreover, we proposed a quantitative analysis method to reveal the relationship between the bending speed and the molecular structure of diarylethenes. These results provide the quantitative evaluation method of the photoinduced crystal bending speed. Full article

(This article belongs to the Special Issue Chiral Organic Crystal)

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3874 KiB

Open AccessArticle

Physiochemical Characterization of Iodine (V) Oxide Part II: Morphology and Crystal Structure of Particulate Films

by Brian K. Little, Samuel B. Emery and C. Michael Lindsay

Crystals 2015, 5(4), 534-550; https://doi.org/10.3390/cryst5040534 - 02 Nov 2015

Cited by 9 | Viewed by 7638

Abstract

In this study, the production of particulate films of iodine (V) oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with [...] Read more.

In this study, the production of particulate films of iodine (V) oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with electron microscopy, powder x-ray diffraction, and UV-visible absorption spectroscopy. Results indicate that sonicating iodine oxides in alcohol mixtures containing trace amounts of water decreases deposited particle sizes and produces a more uniform film morphology. UV-visible spectra of the pre-cast suspensions reveal that for some solvents, the iodine oxide oxidizes the solvent, producing I₂ and lowering the pH of the suspension. Characterizing the crystals within the cast films reveal their composition to be primarily HI₃O₈, their orientations to exhibit a preferential orientation, and their growth to be primarily along the ac-plane of the crystal, enhanced at higher spin rates. Spin-coating at lower spin rates produces laminate-like particulate films versus higher density, one-piece films of stacked particles produced by drop casting. The particle morphology in these films consists of a combination of rods, plates, cubes, and rhombohedra structure. Full article

(This article belongs to the Special Issue Energetic Materials)

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1160 KiB

Open AccessReview

Nano-Objects and Ions in Liquid Crystals: Ion Trapping Effect and Related Phenomena

by Yuriy Garbovskiy and Iryna Glushchenko

Crystals 2015, 5(4), 501-533; https://doi.org/10.3390/cryst5040501 - 02 Nov 2015

Cited by 124 | Viewed by 15310

Abstract

The presence of ions in liquid crystals is one of the grand challenges that hinder the application of liquid crystals in various devices, which include advanced 3-D and flexible displays, tunable lenses, etc. Not only do they compromise the overall performance of liquid [...] Read more.

The presence of ions in liquid crystals is one of the grand challenges that hinder the application of liquid crystals in various devices, which include advanced 3-D and flexible displays, tunable lenses, etc. Not only do they compromise the overall performance of liquid crystal devices, ions are also responsible for slow response, image sticking, and image flickering, as well as many other negative effects. Even highly purified liquid crystal materials can get contaminated during the manufacturing process. Moreover, liquid crystals can degrade over time and generate ions. All of these factors raise the bar for their quality control, and increase the manufacturing cost of liquid crystal products. A decade of dedicated research has paved the way to the solution of the issues mentioned above through merging liquid crystals and nanotechnology. Nano-objects (guests) that are embedded in the liquid crystals (hosts) can trap ions, which decreases the ion concentration and electrical conductivity, and improves the electro-optical response of the host. In this paper, we (i) review recently published works reporting the effects of nanoscale dopants on the electrical properties of liquid crystals; and (ii) identify the most promising inorganic and organic nanomaterials suitable to capture ions in liquid crystals. Full article

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1118 KiB

Open AccessArticle

Synthesis, Crystal Structure and DFT Studies of 8-chloro-3-((3-chlorobenzyl)thio)-[1,2,4]triazolo[4,3-a]pyridine

by Jin-Xia Mu, Ming-Yan Yang, Zhao-Hui Sun, Cheng-Xia Tan, Jian-Quan Weng, Hong-Ke Wu and Xing-Hai Liu

Crystals 2015, 5(4), 491-500; https://doi.org/10.3390/cryst5040491 - 02 Nov 2015

Cited by 18 | Viewed by 4417

Abstract

8-chloro-3-((3-chlorobenzyl)thio)-[1,2,4]triazolo[4,3-a]pyridine was synthesized and recrystallized from EtOH. The compound was characterized by ¹H NMR, ¹³C NMR, FTIR, MS, elemental analysis and X-ray diffraction. The compound was crystallized in the monoclinic space group P2(1)/c with a = 8.1992(5), [...] Read more.

8-chloro-3-((3-chlorobenzyl)thio)-[1,2,4]triazolo[4,3-a]pyridine was synthesized and recrystallized from EtOH. The compound was characterized by ¹H NMR, ¹³C NMR, FTIR, MS, elemental analysis and X-ray diffraction. The compound was crystallized in the monoclinic space group P2(1)/c with a = 8.1992(5), b = 21.7731(12), c = 7.8454(6) Å, α = 90, β = 108.421(7), γ = 90°, V = 1328.81 (15)Å³, Z = 4 and R = 0.0351. Theoretical calculation of the title compound was carried out with B3LYP/6-31G. The full geometry optimization was carried out by using the 6-31G basis set. The frontier orbital energy and atomic net charges were discussed. The experimental results of the compound have been compared with theoretical results and it was found that the experimental data shows good agreement with the calculated values. Full article

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1732 KiB

Open AccessReview

Role of Water Molecules to the Electronic States of M-DNA

by Kenji Mizoguchi and Hirokazu Sakamoto

Crystals 2015, 5(4), 475-490; https://doi.org/10.3390/cryst5040475 - 20 Oct 2015

Cited by 5 | Viewed by 6394

Abstract

Various kinds of roles of the water molecules in the electronic states of the complexes of metal ions (M) and deoxyribonucleic acid (DNA) are reviewed. Divalent metal ions M like Fe, Mn, Zn and so on, form Metal-DNA complexes (M-DNA) with each metal [...] Read more.

Various kinds of roles of the water molecules in the electronic states of the complexes of metal ions (M) and deoxyribonucleic acid (DNA) are reviewed. Divalent metal ions M like Fe, Mn, Zn and so on, form Metal-DNA complexes (M-DNA) with each metal ion between the bases of a base pair of DNA. The electronic states of the complexes depend on the species of ions in M-DNA. Metal ions in Fe-DNA and Mn-DNA possess 3d magnetic moments, but those in Zn-DNA do not. Interestingly, the magnetic property of the complexes, especially the magnetic interaction between the metal ions, is dominated by water molecules in the complexes. In Fe-DNA, the water molecules play a role of ligands for the iron ions, which controls the spin states of Fe3+, whereas they govern the magnetic interaction between the Mn2+ ions in Mn-DNA. In contrast, Zn-DNA has no 3d magnetic moment, but the water molecules dominate the bonding states of the Zn ions and the magnetic states of the Zn-DNA system. Full article

(This article belongs to the Special Issue High Spin Molecules)

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1235 KiB

Open AccessArticle

Synthesis and Molecular Structures of (E)-non-2-enoic Acid and (E)-dec-2-enoic Acid

by Marcel Sonneck, Tim Peppel, Anke Spannenberg and Sebastian Wohlrab

Crystals 2015, 5(4), 466-474; https://doi.org/10.3390/cryst5040466 - 16 Oct 2015

Cited by 2 | Viewed by 4657

Abstract

The molecular structures of (E)-non-2-enoic acid (C9) and (E)-dec-2-enoic acid (C10) are reported. The title compounds were crystallized by slow evaporation of ethanolic solutions at −30 °C. C9 crystallizes in the monoclinic space group P [...] Read more.

The molecular structures of (E)-non-2-enoic acid (C9) and (E)-dec-2-enoic acid (C10) are reported. The title compounds were crystallized by slow evaporation of ethanolic solutions at −30 °C. C9 crystallizes in the monoclinic space group P2₁/c and C10 in the triclinic space group P-1, each with 4 molecules in the unit cell. The unit cell parameters for C9 are: a = 10.6473(4) Å, b = 5.2855(2) Å, c = 17.0313(7) Å; β = 106.0985(10)° and V = 920.87(6) Å³. The unit cell parameters for C10 are: a = 4.1405(2) Å, b = 15.2839(6) Å, c = 17.7089(7) Å; α = 68.3291(11)°, β = 83.3850(13)°, γ = 85.0779(12)° and V = 1033.39(8) Å³. Full article

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1312 KiB

Open AccessArticle

Synthesis and Crystal Structure of a 1D Chained Coordination Polymer Constructed from Ca²⁺ and 2-[(E)-(2-Furoylhydrazono)methyl]benzenesulfonate

by Xi-Shi Tai and Xin Wang

Crystals 2015, 5(4), 458-465; https://doi.org/10.3390/cryst5040458 - 15 Oct 2015

Cited by 22 | Viewed by 4177

Abstract

A new Ca(II) coordination polymer, [{CaL₂·(H₂O)₂·2H₂O}]_n (1) (L = 2-[(E)-(2-furoylhydrazono)methyl]benzenesulfonate), has been obtained by one-pot method, and characterized by elemental analysis, IR spectrum, and X-ray single-crystal diffraction. The results showed that the [...] Read more.

A new Ca(II) coordination polymer, [{CaL₂·(H₂O)₂·2H₂O}]_n (1) (L = 2-[(E)-(2-furoylhydrazono)methyl]benzenesulfonate), has been obtained by one-pot method, and characterized by elemental analysis, IR spectrum, and X-ray single-crystal diffraction. The results showed that the Ca(II) coordination crystallizes in the orthorhombic space group with P2₁2₁2, a = 16.355(3) Å, b = 17.478(4) Å, c = 5.4549(11) Å, α =β = γ = 90.00°, V = 1559.3(5) Å³, Z = 2, Mr = 698.69, Dc = 1.488 g/cm³, T = 293(2) K, F(000) = 724, μ(MoKa) = 0.408 mm⁻¹, R = 0.0703 and wR = 0.1848. The Ca(II) ion is coordinated with four O atoms from two L ligands and two O atoms from two coordinated H₂O molecules, and generates a distorted octahedral geometry. The 1D chained structure of Ca(II) coordination polymer is constructed from the bridging of SO₃^– groups. The 3D network structure is formed by the hydrogen bonds and π-π interaction between 1D chains. Full article

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2731 KiB

Open AccessArticle

Laser Annealing for Gas-Dynamical Spraying of HA Coating upon a Titanium Surface

by Victor Saphronov and Igor Shishkovsky

Crystals 2015, 5(4), 447-457; https://doi.org/10.3390/cryst5040447 - 08 Oct 2015

Cited by 4 | Viewed by 5412

Abstract

Laser post-heating computer controlled detonation spraying (CCDS) and cold spray (CS) hybrid processes were proposed for fabrication of near sub micron structure coatings of hydroxyapatite (HA) + Ti system. Optical and SEM with energy dispersive X-ray analysis and comparative XRD phase analysis were [...] Read more.

Laser post-heating computer controlled detonation spraying (CCDS) and cold spray (CS) hybrid processes were proposed for fabrication of near sub micron structure coatings of hydroxyapatite (HA) + Ti system. Optical and SEM with energy dispersive X-ray analysis and comparative XRD phase analysis were used to evaluate microstructure. After those hybrid processes, no substantial variation in HA composition was noted by structural and phase examination. Nano-sized HA powders can be recommended for laser annealing CS (LaCS) process. Regimes of laser treatment optimal for increasing the adhesion between the HA and titanium coatings, providing more strength, ductility and decreasing of HA destruction in the coatings were determined. Full article

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3631 KiB

Open AccessArticle

Synthesis, Crystal and Electronic Structures of the Pnictides AE₃TrPn₃ (AE = Sr, Ba; Tr = Al, Ga; Pn = P, As)

by Stanislav S. Stoyko, Leonard H. Voss, Hua He and Svilen Bobev

Crystals 2015, 5(4), 433-446; https://doi.org/10.3390/cryst5040433 - 24 Sep 2015

Cited by 19 | Viewed by 5379

Abstract

The new ternary arsenides AE₃TrAs₃ (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr₃GaP₃ and Ba₃AlP₃ have been prepared by reactions of the respective elements at high temperatures. [...] Read more.

The new ternary arsenides AE₃TrAs₃ (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr₃GaP₃ and Ba₃AlP₃ have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr₃AlAs₃ and Ba₃AlAs₃ adopt the Ba₃AlSb₃-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr₃GaP₃ and Ba₃AlP₃. The compounds Sr₃GaAs₃ and Ba₃GaAs₃ crystallize with the Ba₃GaSb₃-type structure (Pearson symbol oP56, space group Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn₄ and GaPn₄ tetrahedra (Pn = pnictogen, i.e., P or As), separated by the alkaline-earth Sr²⁺ and Ba²⁺ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE²⁺]₃[Tr³⁺][Pn³⁻]₃, or rather [AE²⁺]₆[Tr₂Pn₆]¹²⁻, i.e., as Zintl phases. Full article

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1223 KiB

Open AccessArticle

Crystal Structures of Furazanes

by Thomas M. Klapötke, Philipp C. Schmid and Jörg Stierstorfer

Crystals 2015, 5(4), 418-432; https://doi.org/10.3390/cryst5040418 - 24 Sep 2015

Cited by 17 | Viewed by 6374

Abstract

Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA) and [...] Read more.

Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA) and BAM (Bundesanstalt für Materialforschung und -prüfung) methods. The standard enthalpies of formation were calculated for all compounds at the CBS-4M level of theory, and the energetic performance was predicted with the EXPLO5 V6.02 computer code. Full article

(This article belongs to the Special Issue Energetic Materials)

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Crystals, Volume 5, Issue 4 (December 2015) – 17 articles , Pages 418-669

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