Crystals

32 pages, 9354 KiB

Open AccessReview

Borates—Crystal Structures of Prospective Nonlinear Optical Materials: High Anisotropy of the Thermal Expansion Caused by Anharmonic Atomic Vibrations

by Rimma Bubnova^1,2,*, Sergey Volkov¹, Barbara Albert³ and Stanislav Filatov²

¹ Institute of Silicate Chemistry, Russian Academy of Sciences, Makarov Emb. 2, St. Petersburg 199034, Russia

² Department of Crystallography, Institute of Earth Sciences, St. Petersburg State University, University Emb. 7/9, St. Petersburg 199034, Russia

³ Eduard Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt, Alarich-Weiss-Str. 12, 64287 Darmstadt, Germany

Crystals 2017, 7(3), 93; https://doi.org/10.3390/cryst7030093 - 22 Mar 2017

Cited by 57 | Viewed by 10656

Abstract

In the present study the thermal structure evolution is reviewed for known nonlinear optical borates such as β-BaB₂O₄, LiB₃O₅, CsLiB₆O₁₀, Li₂B₄O₇, K₂Al [...] Read more.

In the present study the thermal structure evolution is reviewed for known nonlinear optical borates such as β-BaB₂O₄, LiB₃O₅, CsLiB₆O₁₀, Li₂B₄O₇, K₂Al₂B₂O₇, and α-BiB₃O₆, based on single-crystal and powder X-ray diffraction data collected over wide temperature ranges. Temperature-dependent measurements of further borates are presented for the first time: α-BaB₂O₄ (295–673 K), β-BaB₂O₄ (98–693 K), LiB₃O₅ (98–650 K) and K₂Al₂B₂O₇ (98–348 K). In addition to the established criteria for nonlinear optical (NLO) properties of crystals, here the role of the anisotropy and anharmonicity of the thermal vibrations of atoms is analysed as well as changes in their coordination spheres and the anisotropy of the thermal expansion of the crystal structure. Non-centrosymmetric borates, especially those that have NLO properties, often show distinct anisotropies for each cation in comparison to centrosymmetric borates. All considered NLO borates contain BO₃ triangles, which are the principal cause of the strong anisotropy of the thermal expansion. Full article

(This article belongs to the Special Issue Nonlinear Optical Crystals 2017—Commemorative Issue in Honor of Professor Chuangtian Chen on the Occasion of his 80th Anniversary)

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14 pages, 3457 KiB

Open AccessArticle

Two Organic Cation Salts Containing Tetra(isothiocyanate)cobaltate(II): Synthesis, Crystal Structures, Spectroscopic, Optical and Magnetic Properties

by Zheng Zhang¹, Junwei Xu², Sisi Yan², Yangli Chen², Yan Wang¹, Zhuo Chen^1,* and Chunlin Ni^2,*

¹ Department of Materials Science and Engineering, School of Aeronautics and Astronautics, Central South University, Changsha 410012, China

² College of Materials and Energy, Institute of Biomaterial, South China Agricultural University, Guangzhou 510642, China

Crystals 2017, 7(3), 92; https://doi.org/10.3390/cryst7030092 - 22 Mar 2017

Cited by 16 | Viewed by 5101

Abstract

Single crystals of two hybrid organic-inorganic molecular solids, benzyl pyridinium tetra(isothiocyanate)cobalt ([BzPy]₂[Co(NCS)₄]) (1) and benzyl quinolinium tetra(isothiocyanate)cobalt ([BzQl]₂[Co(NCS)₄]) (2), were grown using a slow evaporation growth technique at room temperature and [...] Read more.

Single crystals of two hybrid organic-inorganic molecular solids, benzyl pyridinium tetra(isothiocyanate)cobalt ([BzPy]₂[Co(NCS)₄]) (1) and benzyl quinolinium tetra(isothiocyanate)cobalt ([BzQl]₂[Co(NCS)₄]) (2), were grown using a slow evaporation growth technique at room temperature and their IR, UV-Vis, X-ray crystal structures, luminescence, and magnetism were reported. The crystal structural analysis revealed that two molecular solids crystallize in the monoclinic space group P2₁/c of 1 and P2₁/n of 2. The cations form a dimer through weak C–H···π/π···π interactions in 1 and 2, and the adjacent cation (containing N(6) atom) in 2 forms a columnar structure through π···π weak interactions between the quinoline and benzene rings, while the anions in 1 form a layer structure via short S···Co interactions. The anions (A) and cations (C) are arranged alternatively into a column in the sequence of ···A–CC–A–CC–A··· for 1, while the two anions and cationic dimer in 2 form an alliance by the C–H···π, C–H···S and C–H···N hydrogen bonds. A weak S···π interaction was found in 1 and 2. The two molecular solids show a broad fluorescence emission around 400 nm in the solid state at room temperature, and weak antiferromagnetic coupling behavior when the temperature is lowered. Full article

(This article belongs to the Section Crystal Engineering)

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10 pages, 16878 KiB

Open AccessArticle

Growth and Physical Properties of Sr_xCa_1−xCrO₃ Single Crystals

by Lipeng Cao^1,2, Aizi Jin^1,3,4, Changzhi Gu^1,3,4, Haiyang Bai^1,3,4, Youwen Long^1,3,4, Richeng Yu^1,3,4, Liqing Pan^2,5,* and Changqing Jin^1,3,4,*

¹ Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

² Department of Physics, University of Science and Technology Beijing, Beijing 100083, China

³ School of Physics, University of Chinese Academy of Sciences, Beijing 100190, China

⁴ Collaborative Innovation Center of Quantum Matter, Beijing 100190, China

⁵ College of Science, China Three Gorges University, Yichang 443002, China

Crystals 2017, 7(3), 91; https://doi.org/10.3390/cryst7030091 - 21 Mar 2017

Viewed by 5464

Abstract

Perovskites Sr_xCa_1−xCrO₃ attract much attention due to the controversy on the anomalous electronic state. In this study, we synthesized a series of Sr_xCa_1−xCrO₃ (0 ≤ x ≤ 1) single crystals under high pressure [...] Read more.

Perovskites Sr_xCa_1−xCrO₃ attract much attention due to the controversy on the anomalous electronic state. In this study, we synthesized a series of Sr_xCa_1−xCrO₃ (0 ≤ x ≤ 1) single crystals under high pressure and high temperature conditions with self-oxidization. The crystal structure was determined using X-ray diffraction (XRD). With the increase of x, the structure transformed from orthorhombic to tetragonal to cubic. Antiferromagnetism was observed except for SrCrO₃, and the T_N decreased with increased x. All samples demonstrated semiconductive behavior by electrical resistivity measurement. Full article

(This article belongs to the Special Issue Crystal Growth for Optoelectronic and Piezoelectric Applications)

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7 pages, 1677 KiB

Open AccessArticle

The Influence of Conductive Nanodomain Walls on the Photovoltaic Effect of BiFeO₃ Thin Films

by Zilong Bai, Yan Zhang, Huizhen Guo and Anquan Jiang^*

State Key Laboratory of ASIC & System, School of Microelectronics, Fudan University, Shanghai 200433, China

Crystals 2017, 7(3), 81; https://doi.org/10.3390/cryst7030081 - 21 Mar 2017

Cited by 2 | Viewed by 4416

Abstract

Two Planar Pt electrodes with an inter-electrode distance of about 100 nm were fabricated at the surface of BiFeO₃ thin films, which allow the manipulation of ferroelectric domain switching at nanoscale. This electrode configuration was pursued to study conductive domain-wall influence on [...] Read more.

Two Planar Pt electrodes with an inter-electrode distance of about 100 nm were fabricated at the surface of BiFeO₃ thin films, which allow the manipulation of ferroelectric domain switching at nanoscale. This electrode configuration was pursued to study conductive domain-wall influence on the photovoltaic current in BiFeO₃ thin films. Modulations of short-circuit photovoltaic current and hysteretic conductive switching behaviors were found in the above nanodevices, accompanied by the generation of the conductive domain walls connecting two gapped electrodes. Our technique provides a new method to configure ferroelectric domains, where the influence of the conductive domain walls on the photovoltaic effect is preeminent. Full article

(This article belongs to the Special Issue Multiferroics Crystals)

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8 pages, 2510 KiB

Open AccessArticle

X-ray Structures of Succinimidyl Halobenzoates

by Constantin Mamat¹

, Daniel Holger Weiß² and Martin Köckerling^2,*

¹ Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany

² Anorganische Festkörperchemie, Institut für Chemie, Universität Rostock, Albert-Einstein-Straße 3a, D-18059 Rostock, Germany

Crystals 2017, 7(3), 90; https://doi.org/10.3390/cryst7030090 - 20 Mar 2017

Cited by 1 | Viewed by 4982

Abstract

The crystal and molecular structures of five succinimidyl halobenzoates are reported. Corresponding derivatives with the respective halo-radionuclide (¹⁸F, ⁷⁶Br, ¹²³I/¹²⁴I/¹²⁵I/¹³¹I) were prepared and used for the radiolabeling of biologically active (macro-)molecules (peptides, proteins, [...] Read more.

The crystal and molecular structures of five succinimidyl halobenzoates are reported. Corresponding derivatives with the respective halo-radionuclide (¹⁸F, ⁷⁶Br, ¹²³I/¹²⁴I/¹²⁵I/¹³¹I) were prepared and used for the radiolabeling of biologically active (macro-)molecules (peptides, proteins, antibodies) under mild labeling conditions. All compounds were crystalized from petroleum ether/ethyl acetate mixtures. Full article

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9 pages, 1729 KiB

Open AccessArticle

Crystal Growth and Glass-Like Thermal Conductivity of Ca₃RE₂(BO₃)₄ (RE = Y, Gd, Nd) Single Crystals

by L. V. Gudzenko¹, M. B. Kosmyna¹, A. N. Shekhovtsov^1,*, W. Paszkowicz², A. Sulich², J. Z. Domagała², P. A. Popov³

and S. A. Skrobov³

¹ Institute for Single Crystals, NASU, Nauki Ave. 60, 61001 Kharkov, Ukraine

² Institute of Physics, PAS, Aleja Lotników 32/46, PL- 02668 Warsaw, Poland

³ Department of Exper. and Theor. Physics, Petrovsky Bryansk State University, Bezhitskaya Str. 14, 241036 Bryansk, Russia

Crystals 2017, 7(3), 88; https://doi.org/10.3390/cryst7030088 - 17 Mar 2017

Cited by 16 | Viewed by 5634

Abstract

Crystal growth and thermal properties of binary borates, Ca₃RE₂(BO₃)₄ (RE = Y, Gd, Nd), are considered promising crystals for laser applications. These single crystals were grown by the Czochralski method. The crystal and defect structure were [...] Read more.

Crystal growth and thermal properties of binary borates, Ca₃RE₂(BO₃)₄ (RE = Y, Gd, Nd), are considered promising crystals for laser applications. These single crystals were grown by the Czochralski method. The crystal and defect structure were characterized. Volumetric chemical methods without prior separation of the components were developed and applied for the determination of the dependence of chemical compositions of the crystals on the growth conditions. The thermal conductivity was investigated in the 50–300 K range. The character of the temperature dependence of thermal conductivity was found to be similar to that of glass. The possible reasons of the observed features of the thermal conductivity were analyzed. Full article

(This article belongs to the Special Issue Crystal Growth for Optoelectronic and Piezoelectric Applications)

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13 pages, 2170 KiB

Open AccessArticle

Application of the Improved Inclusion Core Model of the Indentation Process for the Determination of Mechanical Properties of Materials

by Boris A. Galanov, Yuly V. Milman^*

, Svetlana I. Chugunova, Irina V. Goncharova and Igor V. Voskoboinik

Institute for Problems of Materials Science of NASU, 3 Krzhizhanovky Str., 03680 Kiev, Ukraine

Crystals 2017, 7(3), 87; https://doi.org/10.3390/cryst7030087 - 16 Mar 2017

Cited by 21 | Viewed by 5192

Abstract

The improved Johnson inclusion core model of indentation by conical and pyramidal indenters in which indenter is elastically deformed and a specimen is elastoplastically deformed under von Mises yield condition, was used for determination of mechanical properties of materials with different types of [...] Read more.

The improved Johnson inclusion core model of indentation by conical and pyramidal indenters in which indenter is elastically deformed and a specimen is elastoplastically deformed under von Mises yield condition, was used for determination of mechanical properties of materials with different types of interatomic bond and different crystalline structures. This model enables us to determine approximately the Tabor parameter С = НМ/Y_S (where НМ is the Meyer hardness and Y_S is the yield stress of the specimen), size of the elastoplastic zone in the specimen, effective apex angle of the indenter under load, and effective angle of the indent after unloading. It was shown that the Tabor parameter and the size of elastoplastic deformation zone increase monotonically with the increase of the plasticity characteristic indentation test results significantly more informative. Full article

(This article belongs to the Special Issue Crystal Indentation Hardness)

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18 pages, 7052 KiB

Open AccessArticle

Strength of Alkane–Fluid Attraction Determines the Interfacial Orientation of Liquid Alkanes and Their Crystallization through Heterogeneous or Homogeneous Mechanisms

by Yuqing Qiu and Valeria Molinero^*

Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, UT 84112-0850, USA

Crystals 2017, 7(3), 86; https://doi.org/10.3390/cryst7030086 - 15 Mar 2017

Cited by 31 | Viewed by 8600

Abstract

Alkanes are important building blocks of organics, polymers and biomolecules. The conditions that lead to ordering of alkanes at interfaces, and whether interfacial ordering of the molecules leads to heterogeneous crystal nucleation of alkanes or surface freezing, have not yet been elucidated. Here [...] Read more.

Alkanes are important building blocks of organics, polymers and biomolecules. The conditions that lead to ordering of alkanes at interfaces, and whether interfacial ordering of the molecules leads to heterogeneous crystal nucleation of alkanes or surface freezing, have not yet been elucidated. Here we use molecular simulations with the united-atom OPLS and PYS alkane models and the mW water model to determine what properties of the surface control the interfacial orientation of alkane molecules, and under which conditions interfacial ordering results in homogeneous or heterogeneous nucleation of alkane crystals, or surface freezing above the melting point. We find that liquid alkanes present a preference towards being perpendicular to the alkane–vapor interface and more parallel to the alkane–water interface. The orientational order in the liquid is short-ranged, decaying over ~1 nm of the surface, and can be reversed by tuning the strength of the attractions between alkane and the molecules in the other fluid. We show that the strength of the alkane–fluid interaction also controls the mechanism of crystallization and the face of the alkane crystal exposed to the fluid: fluids that interact weakly with alkanes promote heterogeneous crystallization and result in crystals in which the alkane molecules orient perpendicular to the interface, while crystallization of alkanes in the presence of fluids, such as water, that interact more strongly with alkanes is homogeneous and results in crystals with the molecules oriented parallel to the interface. We conclude that the orientation of the alkanes at the crystal interfaces mirrors that in the liquid, albeit more pronounced and long-ranged. We show that the sign of the binding free energy of the alkane crystal to the surface, ΔG_bind, determines whether the crystal nucleation is homogeneous (ΔG_bind ≥ 0) or heterogeneous (ΔG_bind < 0). Our analysis indicates that water does not promote heterogeneous crystallization of the alkanes because water stabilizes more the liquid than the crystal phase of the alkane, resulting in ΔG_bind > 0. While ΔG_bind < 0 suffices to produce heterogeneous nucleation, the condition for surface freezing is more stringent, ΔG_bind < −2 γ_xl, where γ_xl is the surface tension of the liquid–crystal interface of alkanes. Surface freezing of alkanes is favored by their small value of γ_xl. Our findings are of relevance to understanding surface freezing in alkanes and to develop strategies for controlling the assembly of chain-like molecules at fluid interfaces. Full article

(This article belongs to the Special Issue Advances in Computer Simulation Studies on Crystal Growth)

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9 pages, 2628 KiB

Open AccessArticle

The Syntheses, Crystal Structure and Luminescence Properties of Cone-Like Octadentate Europium (III) Complexes with Four Short Alkoxy Substituents

by Tetsuji Moriguchi^1,*

, Satoshi Hirosaki¹, Venkataprasad Jalli¹, Akihiko Tsuge¹ and Kenji Yoza²

¹ Department of Applied Chemistry, Faculty of Engineering, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu 804-8550, Japan

² Japan Bruker AXS K.K, 3-9, Moriya-cho Kanagawaku, Yokohama 221-0022, Japan

Crystals 2017, 7(3), 85; https://doi.org/10.3390/cryst7030085 - 13 Mar 2017

Cited by 1 | Viewed by 4918

Abstract

Treatment of 1-(4′-methoxy or ethoxy phenyl)-4,4,4-trifluoro-1,3-butanedione with europium (III) chloride in the presence of piperidine resulted in the halide ligands exchange yielded new piperidinium tetrakis{1-(4′-methoxy or ethoxy phenyl)-4,4,4-trifluoro-1,3-butanedionato} europate (III) complexes 2a and 2b. Complexes 2a and 2b have been characterized by elemental [...] Read more.

Treatment of 1-(4′-methoxy or ethoxy phenyl)-4,4,4-trifluoro-1,3-butanedione with europium (III) chloride in the presence of piperidine resulted in the halide ligands exchange yielded new piperidinium tetrakis{1-(4′-methoxy or ethoxy phenyl)-4,4,4-trifluoro-1,3-butanedionato} europate (III) complexes 2a and 2b. Complexes 2a and 2b have been characterized by elemental analysis, 1H NMR spectroscopy, and FAB-MS, and their absolute structures were determined by single crystal X-ray diffraction analysis. The complexes 2a and 2b have the monoclinic space groups C2/c (No. 15, 4′-substituent = OCH3) and with P − 1 (No. 2, 4′-substituent = OC2H5), respectively. X-ray analysis results showed that eight coordinate structures of the complexes 2a and 2b have conelike structures, like calix[4]arenes, but their structures were slightly different due to the crystal packing and the existence of the solvent molecule. The complexes 2a and 2b exhibited identical, strong photoluminescence emissions in the solution phase. Full article

(This article belongs to the Special Issue Luminescent Properties of Lanthanoid Doped Crystals)

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12 pages, 10826 KiB

Open AccessArticle

A Structural Analysis of Spiropyran and Spirooxazine Compounds and Their Polymorphs

by Vanessa Kristina Seiler¹, Nikolay Tumanov²

, Koen Robeyns¹

, Johan Wouters², Benoit Champagne²

and Tom Leyssens^1,*

¹ Institute of Condensed Matter and Nanosciences (IMCN), Université catholique de Louvain, 1, Place Louis Pasteur, B-1348 Louvain-la-Neuve, Belgium

² Unité de Chimie Physique, Théorique et Structurale, UNamur, 61, rue de Bruxelles, B-5000 Namur, Belgium

Crystals 2017, 7(3), 84; https://doi.org/10.3390/cryst7030084 - 13 Mar 2017

Cited by 22 | Viewed by 8684

Abstract

In this work, crystal structures of commercially available photochromic compounds, i.e., spiropyrans and spirooxazines, were investigated by single-crystal X-ray diffraction. A total of five new structures were obtained via isothermal evaporation experiments under different conditions, namely 1,3,3-Trimethylindolino-benzopyrylospiran (I), 1,3,3-Trimethylindolinonaphtospirooxaxine (II), 1-(2-Hydroxyethyl)-3,3-dimethylindolino-6′-nitrobenzopyrylospiran (III), and [...] Read more.

In this work, crystal structures of commercially available photochromic compounds, i.e., spiropyrans and spirooxazines, were investigated by single-crystal X-ray diffraction. A total of five new structures were obtained via isothermal evaporation experiments under different conditions, namely 1,3,3-Trimethylindolino-benzopyrylospiran (I), 1,3,3-Trimethylindolinonaphtospirooxaxine (II), 1-(2-Hydroxyethyl)-3,3-dimethylindolino-6′-nitrobenzopyrylospiran (III), and 1,3,3-Trimethylindolino-8′-methoxybenzopyrylospiran (IVa and IVb). Since the basic structure of a spiropyran/-oxazine does not present typical hydrogen bond accepting and donating groups, this study illustrates the importance of additional functional groups connected to this kind of molecules to induce specific intermolecular interactions. Our results show that possible hydrogen bonding interactions are rather weak due to the high steric demand of these compounds. These results are supported by a search of the Cambridge structural database focused on related structures. Full article

(This article belongs to the Special Issue Thermo- and Photochromic Molecular Crystals)

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11 pages, 2403 KiB

Open AccessArticle

Growth of High Quality Al-Doped CsLiB₆O₁₀ Crystals Using Cs₂O-Li₂O-MoO₃ Fluxes

by Xianchao Zhu^1,2, Heng Tu¹, Ying Zhao¹ and Zhanggui Hu^1,*

¹ Key Lab of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Crystals 2017, 7(3), 83; https://doi.org/10.3390/cryst7030083 - 13 Mar 2017

Cited by 6 | Viewed by 5831

Abstract

Abstract: High quality and large size Al-doped CsLiB₆O₁₀ (CLBO) single crystals have been successfully grown by top-seeded solution growth (TSSG) technique using Cs₂O–Li₂O–MoO₃ fluxes. The advantages of this newly developed flux system were investigated by [...] Read more.

Abstract: High quality and large size Al-doped CsLiB₆O₁₀ (CLBO) single crystals have been successfully grown by top-seeded solution growth (TSSG) technique using Cs₂O–Li₂O–MoO₃ fluxes. The advantages of this newly developed flux system were investigated by viscosity measurements and growth experiments. Al-doped CLBO presents a very high transmittance in the visible region and the weak absorption values at 1064 nm along a and c axes are only 140 and 50 ppm/cm, respectively. The measured LIDT of Al-doped CLBO at λ = 1064 nm and τ = 5.0 ns is 5.10 GW/cm². Moreover, Al-doped CLBO exhibits an apparent enhancement of the hygroscopic nature in contrast with the undoped crystal as determined by the humidity experiments. Finally, a high fourth harmonic generation (FHG) conversion efficiency of 63% utilizing Al-doped CLBO has been achieved by a picosecond mode-locked Nd:YAG laser, the results also reveal that Al doping has no obvious impact on the FHG conversion efficiency. Full article

(This article belongs to the Special Issue Nonlinear Optical Crystals 2017—Commemorative Issue in Honor of Professor Chuangtian Chen on the Occasion of his 80th Anniversary)

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12 pages, 2869 KiB

Open AccessArticle

The Effects of ACRT on the Growth of ZnTe Crystal by the Temperature Gradient Solution Growth Technique

by Liying Yin^1,2,*, Wanqi Jie^1,2, Tao Wang^1,2, Boru Zhou^1,2, Fan Yang^1,2 and Ruihua Nan^1,3

¹ State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China

² Key Laboratory of Radiation Detection Materials and Devices, Ministry of Industry and Information Technology, Northwestern Polytechnical University, Xi’an 710072, China

³ Shaanxi Key Laboratory of Optoelectronic Functional Materials and Devices, Xi’an Technological University, Xi’an 710021, China

Crystals 2017, 7(3), 82; https://doi.org/10.3390/cryst7030082 - 13 Mar 2017

Cited by 10 | Viewed by 5055

Abstract

A finite element method is used here to simulate the temperature field, the thermosolutal convection, the solute segregation, and the non-isothermal phase transformation during the growth of ZnTe crystal via the temperature gradient solution growth technique (TGSG) with an accelerated crucible rotation technique [...] Read more.

A finite element method is used here to simulate the temperature field, the thermosolutal convection, the solute segregation, and the non-isothermal phase transformation during the growth of ZnTe crystal via the temperature gradient solution growth technique (TGSG) with an accelerated crucible rotation technique (ACRT). Three different trapezoid-wave ACRT sequences are proposed, and their effects are examined from the views of the constitutional supercooling and the mixing of the solution. The solution in front of the growth interface can be fully mixed only during the constant rotation stage of the ACRT when there is a clockwise Ekman flow. An inappropriate ACRT can produce excessively strong clockwise and counterclockwise Ekman flows, and this results in constitutional supercooling in front of the central part of the growth interface at the beginning of the stop stage and in front of the peripheral part at the end of the constant rotation stage. By adjusting the acceleration rate of the ampoule rotation, the appropriate Ekman flows can be obtained to well mix the solution and avoid the constitutional supercooling. An appropriate ACRT sequence is provided, which can facilitate the mixing of the solution, avoid constitutional supercooling, and improve the growth interface morphology. Full article

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10 pages, 8107 KiB

Open AccessArticle

Synthesis, Crystal Structures, and Properties of Two Coordination Polymers Built from Imidazolyl and Carboxylate Ligands

by Xing-Zhe Guo, Zhi-You Zhang, Zi-Long Li, Shan-Shan Shi and Shui-Sheng Chen^*

College of Chemistry & Chemical Engineering, Fuyang Normal University, Fuyang 236041, China

Crystals 2017, 7(3), 73; https://doi.org/10.3390/cryst7030073 - 10 Mar 2017

Cited by 6 | Viewed by 4784

Abstract

Two new two-dimensional (2D) layer coordination polymers—namely, [Cd(L)₂]_n (1) and [Co(L)₂(H₂O)]_n (2)—were synthesized by the reaction of corresponding metal salts with 3-(1H-imidazol-4-yl)benzoic acid (HL) incorporating 4-imidazolyl and [...] Read more.

Two new two-dimensional (2D) layer coordination polymers—namely, [Cd(L)₂]_n (1) and [Co(L)₂(H₂O)]_n (2)—were synthesized by the reaction of corresponding metal salts with 3-(1H-imidazol-4-yl)benzoic acid (HL) incorporating 4-imidazolyl and carboxylate functional groups, and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, and powder X-ray diffraction (PXRD). Complex 1 is a 2D network with (4, 4) topology, while 2 is a typical 6³-hcb topology net. Complex 1 exhibits intense light blue emission in the solid state at room temperature. Full article

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12 pages, 5075 KiB

Open AccessArticle

Interface Crystallization of Ceria in Porous Silica Films for Solar Applications

by Gundula Helsch^* and Joachim Deubener

Institute of Non-Metallic Materials, Clausthal University of Technology, Zehntnerstrasse 2A, D-38678 Clausthal-Zellerfeld, Germany

Crystals 2017, 7(3), 80; https://doi.org/10.3390/cryst7030080 - 8 Mar 2017

Cited by 1 | Viewed by 4770

Abstract

Antireflective (AR) coatings with photocatalytic activity for solar cover glasses are extensively investigated at present, mostly in multilayer systems including titania. In this study, bifunctional single coats from porous silica in combination with up to 33 mol % ceria were prepared by sol–gel [...] Read more.

Antireflective (AR) coatings with photocatalytic activity for solar cover glasses are extensively investigated at present, mostly in multilayer systems including titania. In this study, bifunctional single coats from porous silica in combination with up to 33 mol % ceria were prepared by sol–gel dip-coating on low-iron soda-lime float glass. After heat treatment for one hour at 350 °C, the coated glasses were characterized. Solar transmittance decreased with increasing ceria content, whereas photocatalytic activity increases. Crystallization of cubic ceria was detected by grazing incidence X-ray diffraction. Chemical depth profiling by secondary neutral mass spectrometry revealed the enrichment of cerium at the coating surface as well as at the interface to the glass substrate. Self-assembled ceria crystallization at the interfaces resulted in a three-layered mesostructure of the coating, which was verified by field-emission scanning electron spectroscopy. Cubic ceria crystals at the interface act as a barrier for the sodium diffusion from the substrate, which prevents the poisoning of the photocatalyst, while those crystals at the surface act as an electron donor for photooxidation processes, both enabling adequate photocatalytic activity. The triple-layer architecture with the sequence of high/low/high refractive index materials allows for optical interference sustaining the AR-function. Full article

(This article belongs to the Special Issue Crystallization of Sol-Gel Derived Glasses)

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8 pages, 2713 KiB

Open AccessArticle

Synthesis, Crystal Structure, Magnetic Property and Photo-Induced Coloration of a One-Dimensional Chain Complex

by Qingguo Meng

, Suqing Wang, Junhao Zhang, Rui Xun, Mingchao Chen and Jitao Lu^*

College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang 261061, China

Crystals 2017, 7(3), 77; https://doi.org/10.3390/cryst7030077 - 8 Mar 2017

Viewed by 4432

Abstract

A novel photoactive complex was constructed from two non-photoactive ligands and cobalt (II) ions. Upon ultra violet (UV) irradiation (365 nm), the color of complex 1 changes from orange to violet. The ESR spectrum indicates that the photoactive phenomenon of complex 1 originates [...] Read more.

A novel photoactive complex was constructed from two non-photoactive ligands and cobalt (II) ions. Upon ultra violet (UV) irradiation (365 nm), the color of complex 1 changes from orange to violet. The ESR spectrum indicates that the photoactive phenomenon of complex 1 originates from an intermolecular energy transfer between the H₅DDCPBA ligand and phenanthroline ligand. This photoactive complex shows high thermal stability according to the investigation of thermogravimetric analyses. In addition, the temperature dependence of magnetic susceptibilities for the orange complex 1 was also investigated systematically. Full article

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7 pages, 1868 KiB

Open AccessArticle

Cobalt-Substituted Seven-Layer Aurivillius Bi₈Fe₄Ti₃O₂₄ Ceramics: Enhanced Ferromagnetism and Ferroelectricity

by Zhiwei Lei^1,6, Tong Chen¹, Weigu Li¹, Min Liu^1,3,4,*, Wen Ge¹ and Yalin Lu^1,2,3,4,5,*

¹ CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China

² Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China

³ Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China

⁴ Hefei Physical Sciences and Technology Center, CAS Hefei Institutes of Physical Sciences, Hefei 230031, China

⁵ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China

⁶ Patent Examination Cooperation Sichuan Center of the Patent Office, Chengdu 610213, China

Crystals 2017, 7(3), 76; https://doi.org/10.3390/cryst7030076 - 8 Mar 2017

Cited by 12 | Viewed by 4946

Abstract

In this work, Aurivillius-phase Bi₈Fe_4-xCo_xTi₃O₂₄ (7-BFCT, 0 ≤ x ≤ 0.4) powders and ceramics were successfully prepared by the combination of citrate combustion and hot-press methods. X-ray diffraction (XRD) and high-resolution transmission electron [...] Read more.

In this work, Aurivillius-phase Bi₈Fe_4-xCo_xTi₃O₂₄ (7-BFCT, 0 ≤ x ≤ 0.4) powders and ceramics were successfully prepared by the combination of citrate combustion and hot-press methods. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) indicate a successful synthesis of the pure phase of the 7-BFCT ceramics, and all the samples showed a good seven-layer structure of the Aurivillius phase. Partial Fe substituted by Co was found to be effective to enhance both ferromagnetic and ferroelectric properties at room temperature, and the largest remnant magnetization (2M_r) of ~0.69 emu/g was revealed at the composition of x = 0.4. Zero field cooling and field cooling (ZFC-FC) magnetization measurement confirmed its magnetic transition occurring at a high temperature of ~750 K. Correspondingly, the enhanced ferroelectric properties of such Co-substituted ceramics were also investigated. Full article

(This article belongs to the Special Issue Multiferroics Crystals)

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8 pages, 2078 KiB

Open AccessArticle

Ferroelectric Liquid Crystal Dammann Grating by Patterned Photoalignment

by Fan Fan^1,2,*, Lishuang Yao², Xiaoqian Wang³, Liangyu Shi⁴, Abhishek K. Srivastava⁴, Vladimir G. Chigrinov⁴

, Hoi-Sing Kwok⁴ and Shuangchun Wen¹

¹ Key Laboratory for Micro-/Nano-Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha 410082, China

² State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China

³ Physics Department, East China University of Science and Technology, Shanghai 200237, China

⁴ Partner State Key Laboratory (PSKL) on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China

Crystals 2017, 7(3), 79; https://doi.org/10.3390/cryst7030079 - 6 Mar 2017

Cited by 24 | Viewed by 7000

Abstract

In this article, a ferroelectric liquid crystal (FLC) dammann grating (DG) is demonstrated based on the patterned photoalignment technology. By applying low electric field (10 V) on the FLC DG, the grating can switch between a diffractive state with 7 × 7 optical [...] Read more.

In this article, a ferroelectric liquid crystal (FLC) dammann grating (DG) is demonstrated based on the patterned photoalignment technology. By applying low electric field (10 V) on the FLC DG, the grating can switch between a diffractive state with 7 × 7 optical spots array and a non-diffractive state, depending on the polarity of electric field. The FLC DG shows very fast switching speed with switching on time and off time to be only 81 μs and 59 μs respectively. Comparing with other fast LC DGs such as the ones based on blue phase LC or dual-frequency LC, the switching speed of the proposed FLC DG is about one order faster, which provides great potential and perspective for the FLC DG to be applied in a broad range of optical applications such as optical communication and beam shaping. Full article

(This article belongs to the Special Issue Micro and Nano Patterned Substrates for Liquid Crystal Alignment)

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9 pages, 985 KiB

Open AccessArticle

Unexpected Au Alloying in Tailoring In-Doped SnTe Nanostructures with Gold Nanoparticles

by Samuel Atherton, Benjamin Steele and Satoshi Sasaki^*

School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK

Crystals 2017, 7(3), 78; https://doi.org/10.3390/cryst7030078 - 6 Mar 2017

Cited by 6 | Viewed by 4930

Abstract

Materials with strong spin-orbit interaction and superconductivity are candidates for topological superconductors that may host Majorana fermions (MFs) at the edges/surfaces/vortex cores. Bulk-superconducting carrier-doped topological crystalline insulator, indium-doped tin telluride (In-SnTe) is one of the promising materials. Robust superconductivity of In-SnTe nanostructures has [...] Read more.

Materials with strong spin-orbit interaction and superconductivity are candidates for topological superconductors that may host Majorana fermions (MFs) at the edges/surfaces/vortex cores. Bulk-superconducting carrier-doped topological crystalline insulator, indium-doped tin telluride (In-SnTe) is one of the promising materials. Robust superconductivity of In-SnTe nanostructures has been demonstrated recently. Intriguingly, not only 3-dimensional (3D) nanostructures but also ultra-thin quasi-2D and quasi-1D systems can be grown by the vapor transport method. In particular, nanostructures with a controlled dimension will give us a chance to understand the dimensionality and the quantum confinement effects on the superconductivity of the In-SnTe and may help us work on braiding MFs in various dimensional systems for future topological quantum computation technology. With this in mind, we employed gold nanoparticles (GNPs) with well-identified sizes to tailor In-SnTe nanostructures grown by vapor transport. However, we could not see clear evidence that the presence of the GNPs is necessary or sufficient to control the size of the nanostructures. Nevertheless, it should be noted that a weak correlation between the diameter of GNPs and the dimensions of the smallest nanostructures has been found so far. To our surprise, the ones grown under the vapor–liquid–solid mechanism, with the use of the GNPs, contained gold that is widely and inhomogeneously distributed over the whole body. Full article

(This article belongs to the Special Issue Topological Crystalline Insulators: Current Progress and Prospects)

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7 pages, 2739 KiB

Open AccessArticle

Synthesis, Crystal Structure and Catalytic Activity of a 1D Chained Ca(II) Coordination Polymer with 3,5-Bis(4-pyridylmethoxy)benzoate Ligand

by Li-Hua Wang¹, Xin Wang²

and Xi-Shi Tai^3,*

¹ College of Information and Engineering, Weifang University, Weifang 261061, China

² Department of Chemistry, Qinghai Normal University, Xining 810008, China

³ College of Chemistry and Chemical Engineering, Weifang University, Weifang 261061, China

Crystals 2017, 7(3), 72; https://doi.org/10.3390/cryst7030072 - 6 Mar 2017

Cited by 10 | Viewed by 4378

Abstract

A new 1D chained Ca(II) coordination polymer—namely, [CaL₂(H₂O)₂]_n (HL = 3,5-bis(4-pyridylmethoxy)benzoic acid)—was synthesized though the reaction of Ca(ClO₄)₂·4H₂O, 3,5-bis(4-pyridylmethoxy)benzoic acid and NaOH in H₂O/CH₃CH₂OH [...] Read more.

A new 1D chained Ca(II) coordination polymer—namely, [CaL₂(H₂O)₂]_n (HL = 3,5-bis(4-pyridylmethoxy)benzoic acid)—was synthesized though the reaction of Ca(ClO₄)₂·4H₂O, 3,5-bis(4-pyridylmethoxy)benzoic acid and NaOH in H₂O/CH₃CH₂OH (v:v = 1:2) solution. Its structure was determined by elemental analysis, infrared spectrum, and single-crystal XRD. Structural analyses show that each Ca(II) ion is eight-coordinated by six oxygen atoms of four 3,5-bis(4-pyridylmethoxy)benzoate ligands and two oxygen atoms of two coordinated H₂O molecules to form a square-antiprismatic CaO₈ polyhedron. The Ca(II) complex displays a 1D chained structure constructed by the bridging effect of the bidentate carboxyl group of 3,5-bis(4-pyridylmethoxy)benzoate ligand. The catalytic activity of the Ca-complex was tested for the preparation of propargylamine in the A³ coupling reaction. Full article

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8 pages, 5186 KiB

Open AccessArticle

The Effect of Trimethylaluminum Flow Rate on the Structure and Optical Properties of AlInGaN Quaternary Epilayers

by Dongbo Wang¹

, Gang Liu^2,*, Shujie Jiao^1,*, Lingping Kong², Teren Liu¹, Tong Liu³, Jinzhong Wang¹, Fengyun Guo¹, Chunyang Luan¹ and Zhenghao Li¹

¹ Department of Opto-Electronic Information Science, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

² Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China

³ Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123, China

Crystals 2017, 7(3), 69; https://doi.org/10.3390/cryst7030069 - 6 Mar 2017

Cited by 4 | Viewed by 5122

Abstract

In this work, a series of quaternary Al_xIn_yGa_1−x−yN thin films have been successfully achieved using metal organic chemical vapor deposition (MOCVD) method with adjustable trimethylaluminum (TMA) flows. Surface morphology and optical properties of Al_xIn_y [...] Read more.

In this work, a series of quaternary Al_xIn_yGa_1−x−yN thin films have been successfully achieved using metal organic chemical vapor deposition (MOCVD) method with adjustable trimethylaluminum (TMA) flows. Surface morphology and optical properties of Al_xIn_yGa_1−x−yN films have been evaluated. The indium segregation effect on the enhancement of UV luminescence emission in Al_xIn_yGa_1-x-yN films with increasing TMA flows was investigated. Our results shed some lights on future optical materials design and LED/LD applications. Full article

(This article belongs to the Special Issue Crystal Growth for Optoelectronic and Piezoelectric Applications)

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8 pages, 1647 KiB

Open AccessArticle

A Reversible Single-Crystal to Single-Crystal Thermal Phase Transformation of 3-(2-Bromo-4-(1-methylethyl)phenyl)-1,1-dimethyl urea

by Benson M. Kariuki^1,*

and Gamal A. El-Hiti^2,*

¹ School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK

² Cornea Research Chair, Department of Optometry, College of Applied Medical Sciences, King Saud University, P.O. Box 10219, Riyadh 11433, Saudi Arabia

Crystals 2017, 7(3), 75; https://doi.org/10.3390/cryst7030075 - 4 Mar 2017

Cited by 3 | Viewed by 4929

Abstract

3-(2-Bromo-4-(1-methylethyl)phenyl)-1,1-dimethylurea was synthesized and structurally characterized at 296 K, 200 K and 140 K. A reversible thermal phase transformation was observed at ~170–180 K. On cooling, the structure transforms from a monoclinic to a triclinic crystal system. The isopropyl group is disordered above [...] Read more.

3-(2-Bromo-4-(1-methylethyl)phenyl)-1,1-dimethylurea was synthesized and structurally characterized at 296 K, 200 K and 140 K. A reversible thermal phase transformation was observed at ~170–180 K. On cooling, the structure transforms from a monoclinic to a triclinic crystal system. The isopropyl group is disordered above the phase transition temperature but is ordered below the transition temperature. Full article

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10 pages, 4609 KiB

Open AccessArticle

Numerical Study of the Thermal and Flow Fields during the Growth Process of 800 kg and 1600 kg Silicon Feedstock

by Thi Hoai Thu Nguyen¹, Jyh Chen Chen^1,*, Chieh Hu¹, Chun Hung Chen², Yen Hao Huang³, Huang Wei Lin³, Andy Yu³, Bruce Hsu³, Michael Yang³ and Ray Yang³

¹ Department of Mechanical Engineering, National Central University, Jhongli 320, Taiwan

² Research and Development Division, GlobalWafers Co., Ltd., Hsinchu 300, Taiwan

³ Sino-American Silicon Products Inc., Zhunan 350, Taiwan

Crystals 2017, 7(3), 74; https://doi.org/10.3390/cryst7030074 - 3 Mar 2017

Cited by 6 | Viewed by 4777

Abstract

Two-dimensional (2D) transient numerical simulations are performed to investigate the evolution of the thermal and flow fields during the growth of multi-crystalline silicon ingots with two different silicon feedstock capacities, 800 kg and 1600 kg. The simulation results show that there are differences [...] Read more.

Two-dimensional (2D) transient numerical simulations are performed to investigate the evolution of the thermal and flow fields during the growth of multi-crystalline silicon ingots with two different silicon feedstock capacities, 800 kg and 1600 kg. The simulation results show that there are differences in the structure of the melt flow. In the 1600 kg case, there is a reduction in the concavity of the crystal-melt interface near the crucible wall and an increase in the convexity of the interface at higher solidification fractions. Moreover, the Voronkov ratios, which are indicative of the formation of defects, become lower during the solidification process. Full article

(This article belongs to the Special Issue Global Modeling in Crystal Growth)

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12 pages, 8604 KiB

Open AccessArticle

Enhanced Thermoelectric Properties of Graphene/Cu₂SnSe₃ Composites

by Degang Zhao^*

, Xuezhen Wang and Di Wu

School of Materials Science and Engineering, University of Jinan, Jinan 250022, China

Crystals 2017, 7(3), 71; https://doi.org/10.3390/cryst7030071 - 28 Feb 2017

Cited by 35 | Viewed by 6858

Abstract

Cu₂SnSe₃ material is regarded as a potential thermoelectric material due to its relatively high carrier mobility and low thermal conductivity. In this study, graphene was introduced into the Cu₂SnSe₃ powder by ball milling, and the bulk graphene/Cu [...] Read more.

Cu₂SnSe₃ material is regarded as a potential thermoelectric material due to its relatively high carrier mobility and low thermal conductivity. In this study, graphene was introduced into the Cu₂SnSe₃ powder by ball milling, and the bulk graphene/Cu₂SnSe₃ thermoelectric composites were prepared by spark plasma sintering. The graphene nanosheets distributed uniformly in the Cu₂SnSe₃ matrix. Meanwhile, some graphene nanosheets tended to form thick aggregations, and the average length of these aggregations was about 3 μm. With the fraction of graphene increasing, the electrical conductivity of graphene/Cu₂SnSe₃ samples increased greatly while the Seebeck coefficient was decreased. The introduction of graphene nanosheets can reduce the thermal conductivity effectively resulting from the phonon scattering by the graphene interface. When the content of graphene exceeds a certain value, the thermal conductivity of graphene/Cu₂SnSe₃ composites starts to increase. The achieved highest figure of merit (ZT) for 0.25 vol % graphene/Cu₂SnSe₃ composite was 0.44 at 700 K. Full article

(This article belongs to the Special Issue Materials Processing and Crystal Growth for Thermoelectrics)

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13 pages, 4471 KiB

Open AccessArticle

Effect of Diazotated Sulphonated Polystyrene Films on the Calcium Oxalate Crystallization

by Patricio Vásquez-Quitral¹, Javier Toledo Arana², Maria Cristina Miras², Diego Fernando Acevedo², Cesar Alfredo Barbero² and Andrónico Neira-Carrillo^1,*

¹ Department of Biological and Animal Sciences, School of Veterinary and Animal Sciences, University of Chile, Santiago, P.O. Box 2-15, Chile

² School of Sciences Exact, Physico-Chemical and Natural, National University of Rio Cuarto, Rio Cuarto, Cordoba, P.O. Box X5804BYA, Argentina

Crystals 2017, 7(3), 70; https://doi.org/10.3390/cryst7030070 - 28 Feb 2017

Cited by 5 | Viewed by 6345

Abstract

Pathological crystallization of calcium oxalate (CaOx) inside the urinary tract is called calculi or kidney stone (Urolithiasis). CaOx exhibits three crystalline types in nature: CaOx monohydrate COM, dihydrate COD and trihydrate COT. COD and COM are often found in urinary calculi, particularly COM. [...] Read more.

Pathological crystallization of calcium oxalate (CaOx) inside the urinary tract is called calculi or kidney stone (Urolithiasis). CaOx exhibits three crystalline types in nature: CaOx monohydrate COM, dihydrate COD and trihydrate COT. COD and COM are often found in urinary calculi, particularly COM. Langmuir monolayers, membrane vesicles, phospholipids’ micelles, among others, have been adopted as simplified biomimetic template-models to study in vitro the urolithiasis through CaOx. The nucleation and crystal growth of COM on self-assembled lipid monolayers have revealed that the negatively charged phosphatidylserine interface is a strong promoter of COM. Herein, we describe the synthesis and physicochemical characterization of diazotated sulphonated polystyrene films (DSPFs), prepared from various aminocompounds varying their polarity degree i.e., polar, non-polar and acidic DSPF derivatives. We also used these DSPFs as polymeric templates in crystallization experiments of CaOx in vitro. Images obtained by optical microscopy and scanning electron microscopy confirmed the precipitation of COM crystals on the DSPF surface. The employment of functionalized polymeric films as templates for CaOx crystallization represents a viable approach for understanding inorganic mineralization. Full article

(This article belongs to the Special Issue Membrane-Assisted Crystallization)

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11 pages, 8410 KiB

Open AccessArticle

Structures, Photophysical Properties, and Growth Patterns of Methylurea Coordinated Ni(II) and Mn(II) Complexes

by Wenting Wang^1,2, Zhihuang Xu², Liwang Ye², Genbo Su² and Xinxin Zhuang^2,*

¹ College of Chemistry, Fuzhou University, Fuzhou 350116, China

² Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China

Crystals 2017, 7(3), 68; https://doi.org/10.3390/cryst7030068 - 28 Feb 2017

Cited by 2 | Viewed by 7676

Abstract

Four coordinated complexes Mn_xNi_(1−x)(C₂H₆N₂O)₆SO₄ (x=0, 0.33, 0.75, 0.90) were synthesized and characterized. Single-crystal X-ray analysis revealed that the complexes belong to the trigonal crystal family, R-3c space group. Spiral and [...] Read more.

Four coordinated complexes Mn_xNi_(1−x)(C₂H₆N₂O)₆SO₄ (x=0, 0.33, 0.75, 0.90) were synthesized and characterized. Single-crystal X-ray analysis revealed that the complexes belong to the trigonal crystal family, R-3c space group. Spiral and terraced nucleus growth modes were observed by atomic force microscopy (AFM) in the crystals. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements showed their excellent thermostability until 200 °C. UV–vis spectra revealed that the transmission peaks of these crystals have a slight bathochromic shift compared to nickel sulfate hexahydrate (NSH), and the transmittance in the UV range increased as the proportion of Mn²⁺ increased. With their photophysical properties remaining similar, the much higher heat endurance is rendering these crystals better suitable for UV light filter (ULF) applications. Full article

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8 pages, 3259 KiB

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Single Crystal Growth of Multiferroic Double Perovskites: Yb₂CoMnO₆ and Lu₂CoMnO₆

by Hwan Young Choi, Jae Young Moon, Jong Hyuk Kim, Young Jai Choi^* and Nara Lee^*

Department of Physics and IPAP, Yonsei University, Seoul 120-749, Korea

Crystals 2017, 7(3), 67; https://doi.org/10.3390/cryst7030067 - 27 Feb 2017

Cited by 19 | Viewed by 8041

Abstract

We report on the growth of multiferroic Yb₂CoMnO₆ and Lu₂CoMnO₆ single crystals which were synthesized by the flux method with Bi₂O₃. Yb₂CoMnO₆ and Lu₂CoMnO₆ crystallize in a [...] Read more.

We report on the growth of multiferroic Yb₂CoMnO₆ and Lu₂CoMnO₆ single crystals which were synthesized by the flux method with Bi₂O₃. Yb₂CoMnO₆ and Lu₂CoMnO₆ crystallize in a double-perovskite structure with a monoclinic P2₁/n space group. Bulk magnetization measurements of both specimens revealed strong magnetic anisotropy and metamagnetic transitions. We observed a dielectric anomaly perpendicular to the c axis. The strongly coupled magnetic and dielectric states resulted in the variation of both the dielectric constant and the magnetization by applying magnetic fields, offering an efficient approach to accomplish intrinsically coupled functionality in multiferroics. Full article

(This article belongs to the Special Issue Multiferroics Crystals)

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16 pages, 3466 KiB

Open AccessArticle

Ni-Co Alloy and Multisegmented Ni/Co Nanowire Arrays Modulated in Composition: Structural Characterization and Magnetic Properties

by Miguel Méndez¹, Silvia González¹, Víctor Vega², Jose M. Teixeira¹, Blanca Hernando¹

, Carlos Luna³ and Víctor M. Prida^1,*

¹ Departamento de Física, Facultad Ciencias, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo, Asturias, Spain

² Laboratorio de Membranas Nanoporosas, Servicios Científico-Técnicos, Universidad de Oviedo, Campus El Cristo s/n, 33006 Oviedo, Asturias, Spain

³ Centro de Investigación en Ciencias Físico Matemáticas, Universidad Autónoma de Nuevo León (UANL), Av. Universidad S/N, San Nicolás de los Garza, 66455 Nuevo León, Mexico

Crystals 2017, 7(3), 66; https://doi.org/10.3390/cryst7030066 - 26 Feb 2017

Cited by 42 | Viewed by 8206

Abstract

Design of novel multisegmented magnetic nanowires can pave the way for the next generation of data storage media and logical devices, magnonic crystals, or in magneto-plasmonics, among other energy conversion, recovery, and storage technological applications. In this work, we present a detailed study [...] Read more.

Design of novel multisegmented magnetic nanowires can pave the way for the next generation of data storage media and logical devices, magnonic crystals, or in magneto-plasmonics, among other energy conversion, recovery, and storage technological applications. In this work, we present a detailed study on the synthesis, morphology, structural, and magnetic properties of Ni, Co, and Ni-Co alloy and multisegmented Ni/Co nanowires modulated in composition, which were grown by template-assisted electrodeposition employing nanoporous anodic aluminum oxide as patterned templates. X-ray diffraction, and scanning and high-resolution transmission electron microscopies allowed for the structural, morphological, and compositional investigations of a few micrometers long and approximately 40 nm in diameter of pure Ni and Co single elements, together with multisegmented Ni/Co and alloyed Ni-Co nanowires. The vibrating sample magnetometry technique enabled us to extract the main characteristic magnetic parameters for these samples, thereby evaluating their different anisotropic magnetic behaviors and discuss them based on their morphological and structural features. These novel functional magnetic nanomaterials can serve as potential candidates for multibit magnetic systems in ultra-high-density magnetic data storage applications. Full article

(This article belongs to the Special Issue Advance in Crystalline Thin Wires)

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10 pages, 5274 KiB

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A 130 GHz Electro-Optic Ring Modulator with Double-Layer Graphene

by Lei Wu, Hongxia Liu^*

, Jiabin Li, Shulong Wang^*

, Sheng Qu and Lu Dong

Key Laboratory for Wide Band Gap Semiconductor Materials and Devices of Education, School of Microelectronics, Xidian University, Xi’an 710071, China

Crystals 2017, 7(3), 65; https://doi.org/10.3390/cryst7030065 - 26 Feb 2017

Cited by 14 | Viewed by 9543

Abstract

The optical absorption coefficient of graphene will change after injecting carriers. Based on this principle, a high-speed double-layer graphene electro-optic modulator with a ring resonator structure was designed in this paper. From the numerical simulations, we designed a modulator. Its optical bandwidth is [...] Read more.

The optical absorption coefficient of graphene will change after injecting carriers. Based on this principle, a high-speed double-layer graphene electro-optic modulator with a ring resonator structure was designed in this paper. From the numerical simulations, we designed a modulator. Its optical bandwidth is larger than 130 GHz, the switching energy is 0.358 fJ per bit, and the driven voltage is less than 1.2 V. At the same time, the footprint of the proposed modulator is less than 10 microns squared, which makes the process compatible with the Complementary Metal Oxide Semiconductors (CMOS) process. This will provide the possibility for the on-chip integration of the photoelectric device. Full article

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10 pages, 229 KiB

Open AccessEditorial

Quo Vadis Quasicrystals?

by Enrique Maciá Barber

Departamento de Física de Materiales, Facultad Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain

Crystals 2017, 7(3), 64; https://doi.org/10.3390/cryst7030064 - 24 Feb 2017

Cited by 3 | Viewed by 5072

Abstract

This Special Issue aims at gaining a deeper understanding on the relationship between the underlying structural order and the resulting physical properties in aperiodic systems, including quasicrystalline and related complex metallic alloys, photonic quasicrystals, and other structures exhibiting long-range aperiodic order. This Special [...] Read more.

This Special Issue aims at gaining a deeper understanding on the relationship between the underlying structural order and the resulting physical properties in aperiodic systems, including quasicrystalline and related complex metallic alloys, photonic quasicrystals, and other structures exhibiting long-range aperiodic order. This Special Issue contains 12 papers which highlight recent developments in quasiperiodic crystal structure, photonic quasicrystals and related optical devices, the intrinsic electrical, thermal, and mechanical properties of icosahedral and decagonal metallic alloys, and the nature of chemical bonding in intermetallic compounds, from a multidisciplinary perspective. In light of the results presented in the contributions collected in this Special Issue, we can confidently expect that new insights into the interdisciplinary science of quasicrystals will be gained in the years to come, providing a sharper picture of their structures and related physical properties, and spurring further progress in practical issues related to both materials engineering science and nanotechnology. Full article

(This article belongs to the Special Issue Structure and Properties of Quasicrystals 2016)

62 pages, 8281 KiB

Open AccessReview

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

by Lijuan Wang^1,*, Liyao Zhang¹, Li Yue¹, Dan Liang², Xiren Chen³, Yaoyao Li¹, Pengfei Lu², Jun Shao³ and Shumin Wang^1,4,*

¹ Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Chang Ning Road, Shanghai 200050, China

² Beijing University of Posts and Telecommunications, Xitucheng Road, Haidian District, Beijing 100089, China

³ Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai 200083, China

⁴ Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg 458 93 58-34, Sweden

Crystals 2017, 7(3), 63; https://doi.org/10.3390/cryst7030063 - 24 Feb 2017

Cited by 82 | Viewed by 10495

Abstract

Dilute bismide in which a small amount of bismuth is incorporated to host III-Vs is the least studied III-V compound semiconductor and has received steadily increasing attention since 2000. In this paper, we review theoretical predictions of physical properties of bismide alloys, epitaxial [...] Read more.

Dilute bismide in which a small amount of bismuth is incorporated to host III-Vs is the least studied III-V compound semiconductor and has received steadily increasing attention since 2000. In this paper, we review theoretical predictions of physical properties of bismide alloys, epitaxial growth of bismide thin films and nanostructures, surface, structural, electric, transport and optic properties of various binaries and bismide alloys, and device applications. Full article

(This article belongs to the Special Issue Current and Future Directions in Crystal Growth by Molecular Beam Epitaxy (MBE))

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