Crystals

4841 KiB

Open AccessArticle

Stable Photocatalytic Paints Prepared from Hybrid Core-Shell Fluorinated/Acrylic/TiO₂ Waterborne Dispersions

by Audrey Bonnefond, Edurne González, José M. Asua, Jose Ramon Leiza, Eliana Ieva, Giulio Brinati, Serena Carella, Alessio Marrani, Alessandro Veneroni, John Kiwi, Cesar Pulgarin and Sami Rtimi

Crystals 2016, 6(10), 136; https://doi.org/10.3390/cryst6100136 - 24 Oct 2016

Cited by 16 | Viewed by 4718

Abstract

The contamination of air and water is one of the major concerns towards the development of a sustainable world in the 21st century. In this context many efforts are devoted to the design of photocatalytic paints able to degrade chemical and biological impurities [...] Read more.

The contamination of air and water is one of the major concerns towards the development of a sustainable world in the 21st century. In this context many efforts are devoted to the design of photocatalytic paints able to degrade chemical and biological impurities present in air and water. In this work, the photocatalytic activity of hybrid films formed from the blends of pure acrylic or core/shell fluorinated/acrylic waterborne dispersions and photocatalytic titanium dioxide (TiO₂) nanoparticle dispersions was first assessed. The films show photocatalytic activity (inactivation of the Escherichia coli bacteria under UV irradiation) at the substrate-film interface, but very reduced activity in the air-film interface due to the substantially lower amount of the TiO₂ nanoparticles in the vicinity of this interface. In a second step, the fluorinated/(meth)acrylic core-shell hybrid dispersions were used as binders in the formulation of waterborne photocatalytic paints and the stability of the paints, in terms of gloss retain and color change, was assessed during 5000 hours of accelerated weathering tests (QUV-B). Although a decrease in gloss retention and increased color change occurs during the first 1000 hours of exposure, no further change of these properties takes place, which is an excellent indication of stable photocatalytic paints. Full article

(This article belongs to the Special Issue Colloidal Nanocrystals: Synthesis, Characterization and Application)

► Show Figures

Graphical abstract

2522 KiB

Open AccessArticle

ZnO Micro- and Nanostructures Obtained by Thermal Oxidation: Microstructure, Morphogenesis, Optical, and Photoluminescence Properties

by Alejandro Escobedo-Morales, Rubén J. Aranda-García, Ernesto Chigo-Anota, Armando Pérez-Centeno, Antonio Méndez-Blas and Carlos G. Arana-Toro

Crystals 2016, 6(10), 135; https://doi.org/10.3390/cryst6100135 - 20 Oct 2016

Cited by 6 | Viewed by 5442

Abstract

ZnO micro- and nanostructures were obtained through thermal oxidation of Zn powders at high temperature under air atmosphere. A detailed study of the microstructure, morphology, optical, and photoluminescence properties of the generated products at different stages of thermal oxidation is presented. It was [...] Read more.

ZnO micro- and nanostructures were obtained through thermal oxidation of Zn powders at high temperature under air atmosphere. A detailed study of the microstructure, morphology, optical, and photoluminescence properties of the generated products at different stages of thermal oxidation is presented. It was found that the exposure time has a strong influence on the resulting morphology. The morphogenesis of the different ZnO structures is discussed, and experimental parameters for fabricating ZnO tetrapods, hollow, core-shell, elongated, or rounded structures by thermal oxidation method are proposed on the basis on the obtained results. Notoriously, the crystal lattice of the ZnO structures has negligible residual strain, although, the density of point defects increases when the thermal treatment is extended; as consequence, their visible luminescence upon UV excitation enhances. Full article

► Show Figures

Graphical abstract

4303 KiB

Open AccessArticle

Spectroscopy, Crystal and Molecular Structures of New 4-Acylpyrazolone Dinitrophenylhydrazones

by Omoruyi G. Idemudia and Eric C. Hosten

Crystals 2016, 6(10), 127; https://doi.org/10.3390/cryst6100127 - 19 Oct 2016

Cited by 7 | Viewed by 4148

Abstract

Still looking at the development of new materials with unique properties and taking advantage of the nucleophilic properties of amines to form stable azomethines, dinitrophenylhydrazine was reacted with 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one and then with 4-propyl-5-methyl-2-phenyl-pyrazol-3-one to get 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Empp-Dh) and 4-propyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Pmpp-Dh), respectively, [...] Read more.

Still looking at the development of new materials with unique properties and taking advantage of the nucleophilic properties of amines to form stable azomethines, dinitrophenylhydrazine was reacted with 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one and then with 4-propyl-5-methyl-2-phenyl-pyrazol-3-one to get 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Empp-Dh) and 4-propyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Pmpp-Dh), respectively, via a simple condensation reaction in a one-pot synthesis system. Careful interpretations of results from elemental analysis, mass and NMR spectroscopy were in agreement with single-crystal X-ray diffraction data. Reported Schiff bases in their single-crystal solid state exist in imine keto tautomer form, each crystallizing in a monoclinic crystal system, with a space group of C2/c (No. 15) in Empp-Dh and P21/c (No. 14) in Pmpp-Dh. They have extensive intra- and inter-molecular hydrogen as well as C–H···π-ring interactions. Full article

► Show Figures

Graphical abstract

2137 KiB

Open AccessArticle

A Heterobimetallic 2-D Coordination Polymer [Na₂(Cu₂I₂(2pyCOO)₄)(H₂O)₄]_n (2pyCOO⁻=picolinate) within a 3-D Supramolecular Architecture

by Anis A. Kamari, Rosenani A. Haque and Mohd R. Razali

Crystals 2016, 6(10), 96; https://doi.org/10.3390/cryst6100096 - 18 Oct 2016

Cited by 2 | Viewed by 3711

Abstract

A heterobimetallic 2-D coordination polymer, [Na₂(Cu₂I₂(2pyCOO)₄)(H₂O)₄]_n (1) (2pyCOO=picolinate) was synthesized and characterized. The complex was also structurally characterized using single X-ray diffraction studies that revealed the complex 1 [...] Read more.

A heterobimetallic 2-D coordination polymer, [Na₂(Cu₂I₂(2pyCOO)₄)(H₂O)₄]_n (1) (2pyCOO=picolinate) was synthesized and characterized. The complex was also structurally characterized using single X-ray diffraction studies that revealed the complex 1 having a vertex symbol of 4.8² which corresponds to fes topology. Together with hydrogen bonds and interdigitating π···π interactions, these thus facilitate the formation of 3-D supramolecular network. The nitrogen gas absorption amount of 1 at 77 K shows a small volume of N₂ sorption isotherm with a small Langmuir and a Brunauer-Emmett-Teller (BET) surface area indicating that the heterobimetallic 3-D supramolecular of 1 exhibits a very weak ability of adsorbing gas. Full article

(This article belongs to the Special Issue Crystal Structure of Complex Compounds)

► Show Figures

Graphical abstract

1662 KiB

Open AccessArticle

Synthesis and Crystal Structures of Two New Oxaspirocyclic Compounds

by Jinhe Jiang and Wulan Zeng

Crystals 2016, 6(10), 134; https://doi.org/10.3390/cryst6100134 - 18 Oct 2016

Cited by 7 | Viewed by 3150

Abstract

Two new oxaspirocyclic compounds, 8-(4-(dimethylamino)benzylidene)-6,10-dioxaspiro[4.5]decane-7,9-dione (1) and 8-(4-hydroxybenzylidene)-6,10-dioxaspiro[4.5]decane-7,9-dione (2) have been synthesized and their structures determined by single crystal X-ray crystallography. Compound 1, C₁₇H₁₉NO₄, belongs to the monoclinic system, space group P21/c [...] Read more.

Two new oxaspirocyclic compounds, 8-(4-(dimethylamino)benzylidene)-6,10-dioxaspiro[4.5]decane-7,9-dione (1) and 8-(4-hydroxybenzylidene)-6,10-dioxaspiro[4.5]decane-7,9-dione (2) have been synthesized and their structures determined by single crystal X-ray crystallography. Compound 1, C₁₇H₁₉NO₄, belongs to the monoclinic system, space group P21/c with a = 6.2554(13) Å, b = 14.605(3) Å, c = 16.265(3) Å, β = 95.97(3)°, V = 1477.9(5) Å³, Z = 4, D_c = 1.354 g/cm³, F(000) = 640, μ(MoKa) = 0.097 mm⁻¹, the final R = 0.0570 and wR = 0.1667. Compound 2, C₁₅H₁₄O₅, is also of the monoclinic system, space group P21/c with a = 10.739(2) Å, b = 18.348(4) Å, c = 6.7799(14) Å, β = 104.20(3)°, V = 1295.1(5) Å³, Z = 4, D_c = 1.407 g/cm³, F(000) = 608, μ(MoKa) = 0.106 mm⁻¹, the final R = 0.0568 and wR = 0.1739. Some C–H···O intra- and intermolecular hydrogen bonds and π··· π stacking interactions are both observed in the two lattice structures. The difference between them is that one type of C–H···π supramolecular interaction (1) and one type of O–H···O intermolecular hydrogen bond (2) are observed. Full article

► Show Figures

Figure 1

3645 KiB

Open AccessArticle

Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods

by Brener R. C. Vale, Fernanda O. Silva, Melissa S. Carvalho, Ellen Raphael, Jefferson L. Ferrari and Marco A. Schiavon

Crystals 2016, 6(10), 133; https://doi.org/10.3390/cryst6100133 - 15 Oct 2016

Cited by 5 | Viewed by 6453

Abstract

We conducted a comparative synthesis of water-soluble CdTe/CdS colloidal nanocrystalline semiconductors of the core/shell type. We prepared the CdS shell using two different methods: a one-pot approach and successive ionic layer adsorption and reaction (SILAR); in both cases, we used 3-mercaptopropionic acid (MPA) [...] Read more.

We conducted a comparative synthesis of water-soluble CdTe/CdS colloidal nanocrystalline semiconductors of the core/shell type. We prepared the CdS shell using two different methods: a one-pot approach and successive ionic layer adsorption and reaction (SILAR); in both cases, we used 3-mercaptopropionic acid (MPA) as the surface ligand. In the one-pot approach, thiourea was added over the freshly formed CdTe dispersion, and served as the sulfur source. We achieved thicker CdS layers by altering the Cd:S stoichiometric ratio (1:1, 1:2, 1:4, and 1:8). The Cd:S ratios 1:1 and 1:2 furnished the best optical properties; these ratios also made the formation of surface defects less likely. For CdTe/CdS obtained using SILAR, we coated the surface of three differently sized CdTe cores (2.17, 3.10, and 3.45 nm) with one to five CdS layers using successive injections of the Cd²⁺ and S^2– ions. The results showed that the core size influenced the optical properties of the materials. The deposition of three to five layers over the surface of smaller CdTe colloidal nanocrystals generated strain effects on the core/shell structure. Full article

(This article belongs to the Special Issue Colloidal Nanocrystals: Synthesis, Characterization and Application)

► Show Figures

Graphical abstract

3988 KiB

Open AccessArticle

Synthesis, Crystal Structure, and Luminescent Properties of New Zinc(II) and Cadmium(II) Metal-Organic Frameworks Based on Flexible Bis(imidazol-1-yl)alkane Ligands

by Marina Barsukova, Tatiana Goncharova, Denis Samsonenko, Danil Dybtsev and Andrei Potapov

Crystals 2016, 6(10), 132; https://doi.org/10.3390/cryst6100132 - 13 Oct 2016

Cited by 23 | Viewed by 5936

Abstract

New metal-organic frameworks (MOFs) based on zinc and cadmium ions, terephthalic acid, and flexible ligands 1,5-bis(imidazol-1-yl)pentane or 1,6-bis(imidazol-1-yl)hexane were prepared and characterized by X-ray diffraction, thermorgavimetric analysis and IR spectroscopy. The imidazolyl ligands were prepared by a new robust procedure involving the reaction [...] Read more.

New metal-organic frameworks (MOFs) based on zinc and cadmium ions, terephthalic acid, and flexible ligands 1,5-bis(imidazol-1-yl)pentane or 1,6-bis(imidazol-1-yl)hexane were prepared and characterized by X-ray diffraction, thermorgavimetric analysis and IR spectroscopy. The imidazolyl ligands were prepared by a new robust procedure involving the reaction between imidazole and 1,5-dibromopentane or 1,6-dibromohexane in a superbasic medium (KOH in DMSO). MOFs based on 1,5-bis(imidazol-1-yl)pentane had diamond topology (dia) and are triply interpenetrated. Ligands with longer spacer 1,6-bis(imidazol-1-yl)hexane, terephthalate ions and zinc(II) ions formed five-fold interpenetrated metal-organic framework also with dia topology, while cadmium(II) ions with the same ligands formed eight-connected uninodal net with a very rare self-penetrated topological type ilc and a point symbol 4²⁴.5.6³. The influence of the chemical composition of MOFs on their photoluminescent properties is investigated and discussed in detail. Full article

(This article belongs to the Special Issue Crystallography of Functional Materials)

► Show Figures

Graphical abstract

1784 KiB

Open AccessCommunication

Synthesis, Structure, and Magnetic Properties of New Spin Crossover Fe(II) Complexes Forming Short Hydrogen Bonds with Substituted Dicarboxylic Acids

by Takumi Nakanishi and Osamu Sato

Crystals 2016, 6(10), 131; https://doi.org/10.3390/cryst6100131 - 13 Oct 2016

Cited by 13 | Viewed by 4251

Abstract

We synthesized new Fe(II) compounds consisting of [Fe(L)₂] (HL: 2-Acetylpyridine isonicotinoylhydrazone) and dicarboxylic acids. Single crystal analysis shows that short hydrogen bonds are formed between [Fe(L)₂] and dicarboxylic acids. The hydrogen bonding interactions between metal complexes and dicarboxylic acids [...] Read more.

We synthesized new Fe(II) compounds consisting of [Fe(L)₂] (HL: 2-Acetylpyridine isonicotinoylhydrazone) and dicarboxylic acids. Single crystal analysis shows that short hydrogen bonds are formed between [Fe(L)₂] and dicarboxylic acids. The hydrogen bonding interactions between metal complexes and dicarboxylic acids are complemented by π-π interactions, forming two-dimensional network structures. Magnetic properties show that the Fe(II) compounds exhibit gradual spin crossover behavior around room temperature and a T_1/2 value is dependent on the halogen substituent on the dicarboxylic acids. Full article

(This article belongs to the Section Biomolecular Crystals)

► Show Figures

Graphical abstract

6349 KiB

Open AccessArticle

Study of Dislocations in the Minicrystallized Regions in Multicrystalline Silicon Grown by the Directional Solidification Method

by Nan Chen, Shenyu Qiu, Jianhua Huang, Guoping Du and Guihua Liu

Crystals 2016, 6(10), 130; https://doi.org/10.3390/cryst6100130 - 12 Oct 2016

Cited by 3 | Viewed by 4114

Abstract

Directionally solidified multicrystalline silicon (mc-Si)-based solar cells have dominated the global photovoltaic market in recent years. The photovoltaic performance of mc-Si solar cells is strongly influenced by their crystalline defects. The occurrence of minicrystallization results in much smaller grain size and, therefore, a [...] Read more.

Directionally solidified multicrystalline silicon (mc-Si)-based solar cells have dominated the global photovoltaic market in recent years. The photovoltaic performance of mc-Si solar cells is strongly influenced by their crystalline defects. The occurrence of minicrystallization results in much smaller grain size and, therefore, a larger number of grain boundaries in mc-Si ingots. Dislocations in the minicrystallized regions have been rarely investigated in the literature. In this work, optical microscopy was used to investigate dislocations in the mincrystallized regions in mc-Si ingots grown by the directional solidification method. The distribution of dislocations was found to be highly inhomogeneous from one grain to another in the mincrystallized regions. High inhomogeneity of dislocation distribution was also observed in individual grains. Serious shunting behavior was observed in the mc-Si solar cells containing minicrystallized regions, which strongly deteriorates their photovoltaic properties. The shunting was found to be highly localized to the minicrystallized regions. Full article

(This article belongs to the Special Issue Crystal Dislocations)

► Show Figures

Graphical abstract

1193 KiB

Open AccessLetter

Dynamic Tuning and Memory Switching of Defect Modes in a Hybrid Photonic Structure

by Hsiao-Tsung Wang, Po-Chang Wu, Ivan V. Timofeev, Victor Ya. Zyryanov and Wei Lee

Crystals 2016, 6(10), 129; https://doi.org/10.3390/cryst6100129 - 10 Oct 2016

Cited by 3 | Viewed by 4013

Abstract

We propose a memorable and electrically tunable photonic device by infiltrating a dual-mode chiral-doped dual-frequency liquid crystal (LC) as the central defect layer in a one-dimensional photonic crystal (PC). According to the transmission properties of this structure, the wavelength tunability of defect modes [...] Read more.

We propose a memorable and electrically tunable photonic device by infiltrating a dual-mode chiral-doped dual-frequency liquid crystal (LC) as the central defect layer in a one-dimensional photonic crystal (PC). According to the transmission properties of this structure, the wavelength tunability of defect modes is obtained by manipulating the LC layer in the dynamic mode due to the electrically controlled birefringence effect. Moreover, the switching between two memorable states, the splay and π-twist states, creates two distinct sets of defect modes at null voltage. The spectral characteristics of this device ensure its potential application as an energy-efficient multichannel wavelength filter. Full article

(This article belongs to the Section Liquid Crystals)

► Show Figures

Figure 1

1603 KiB

Open AccessArticle

Single Crystal Growth of URu₂Si₂ by the Modified Bridgman Technique

by Andrew Gallagher, William L. Nelson, Kuan Wen Chen, Tiglet Besara, Theo Siegrist and Ryan E. Baumbach

Crystals 2016, 6(10), 128; https://doi.org/10.3390/cryst6100128 - 02 Oct 2016

Cited by 5 | Viewed by 7040

Abstract

We describe a modified Bridgman growth technique to produce single crystals of the strongly correlated electron material URu₂Si₂ and its nonmagnetic analogue ThRu₂Si₂. Bulk thermodynamic and electrical transport measurements show that the properties of crystals produced [...] Read more.

We describe a modified Bridgman growth technique to produce single crystals of the strongly correlated electron material URu₂Si₂ and its nonmagnetic analogue ThRu₂Si₂. Bulk thermodynamic and electrical transport measurements show that the properties of crystals produced in this way are comparable to those previously synthesized using the Czochralski or conventional molten metal flux growth techniques. For the specimens reported here, we find residual resistivity ratios

R R R

=

ρ_{300 K}

/

ρ_{0}

as large as 116 and 187 for URu₂Si₂ and ThRu₂Si₂, respectively. Full article

(This article belongs to the Special Issue Correlated Electron Crystals)

► Show Figures

Figure 1

3656 KiB

Open AccessFeature PaperArticle

Phosphorus SAD Phasing for Nucleic Acid Structures: Limitations and Potential

by Joel M. Harp, Pradeep S. Pallan and Martin Egli

Crystals 2016, 6(10), 125; https://doi.org/10.3390/cryst6100125 - 01 Oct 2016

Cited by 3 | Viewed by 5221

Abstract

Phasing of nucleic acid crystal diffraction data using the anomalous signal of phosphorus, P-SAD, at Cuk_α wavelength has been previously demonstrated using Z-DNA. Since the original work on P-SAD with Z-DNA there has been, with a notable exception, a conspicuous absence of [...] Read more.

Phasing of nucleic acid crystal diffraction data using the anomalous signal of phosphorus, P-SAD, at Cuk_α wavelength has been previously demonstrated using Z-DNA. Since the original work on P-SAD with Z-DNA there has been, with a notable exception, a conspicuous absence of applications of the technique to additional nucleic acid crystal structures. We have reproduced the P-SAD phasing of Z-DNA using a rotating-anode source and have attempted to phase a variety of nucleic acid crystals using P-SAD without success. A comparison of P-SAD using Z-DNA and a representative nucleic acid, the Dickerson-Drew dodecamer, is presented along with a S-SAD using only two sulfurs to phase a 2’-thio modified DNA decamer. A theoretical explanation for the limitation of P-SAD applied to nucleic acids is presented to show that the relatively high atomic displacement parameter of phosphorus in the nucleic acid backbone is responsible for the lack of success in applying P-SAD to nucleic acid diffraction data. Full article

(This article belongs to the Special Issue Nucleic Acid Crystallography)

► Show Figures

Graphical abstract

3516 KiB

Open AccessReview

Morphological and Structural Control of Organic Monolayer Colloidal Crystal Based on Plasma Etching and Its Application in Fabrication of Ordered Gold Nanostructured Arrays

by Guangqiang Liu and Weiping Cai

Crystals 2016, 6(10), 126; https://doi.org/10.3390/cryst6100126 - 26 Sep 2016

Cited by 12 | Viewed by 7533

Abstract

The organic monolayer colloidal crystals, which are usually prepared by self-assembling, could be used as templates, due to their interstitial geometry, for the periodically arranged nanostructured arrays, which have important applications in many fields, such as photonic crystals, information storage, super-hydrophobicity, biological and [...] Read more.

The organic monolayer colloidal crystals, which are usually prepared by self-assembling, could be used as templates, due to their interstitial geometry, for the periodically arranged nanostructured arrays, which have important applications in many fields, such as photonic crystals, information storage, super-hydrophobicity, biological and chemical sensing. Obviously, the structures of the obtained arrays mainly depend on those of the templates. However, the self-assembled monolayer colloidal crystal is exclusive in structure and for its hexagonal close-packed colloidal arrangement, leading to the limitation of the monolayer colloidal crystal as the template for the nanostructured arrays. Therefore, structural diversity is important in order for colloidal crystals to be used as the templates for various nanostructured arrays. Recently, there have been some reports on the morphological and structural manipulation of the organic monolayer colloidal crystals. In this review article, we focus on the recent progress in morphological and structural manipulation of polystyrene monolayer colloidal crystals based on plasma etching, and its application in the fabrication of the ordered gold nanostructured arrays with different structures, mainly including close-packed monolayer colloidal crystal and its transferrable property; structural manipulation based on plasma etching; and fabrication of gold nanostructured arrays based on varied monolayer colloidal crystals as template. Full article

(This article belongs to the Special Issue Colloidal Crystals)

► Show Figures

Figure 1

4956 KiB

Open AccessReview

Quantum Simulation of a 2D Quasicrystal with Cold Atoms

by Nicolas Macé, Anuradha Jagannathan and Michel Duneau

Crystals 2016, 6(10), 124; https://doi.org/10.3390/cryst6100124 - 23 Sep 2016

Cited by 15 | Viewed by 5463

Abstract

We describe a way to obtain a two-dimensional quasiperiodic tiling with eight-fold symmetry using cold atoms. One can obtain a series of such optical tilings, related by scale transformations, for a series of specific values of the chemical potential of the atoms. A [...] Read more.

We describe a way to obtain a two-dimensional quasiperiodic tiling with eight-fold symmetry using cold atoms. One can obtain a series of such optical tilings, related by scale transformations, for a series of specific values of the chemical potential of the atoms. A theoretical model for the optical system is described and compared with that of the well-known cut-and-project method for the Ammann–Beenker tiling. The relation between the two tilings is discussed. This type of cold atom structure should allow the simulation of several important lattice models for interacting quantum particles and spins in quasicrystals. Full article

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

► Show Figures

Figure 1

3649 KiB

Open AccessArticle

Numerical and Experimental Study of Optoelectronic Trapping on Iron-Doped Lithium Niobate Substrate

by Michela Gazzetto, Giovanni Nava, Annamaria Zaltron, Ilaria Cristiani, Cinzia Sada and Paolo Minzioni

Crystals 2016, 6(10), 123; https://doi.org/10.3390/cryst6100123 - 23 Sep 2016

Cited by 31 | Viewed by 4547

Abstract

Optoelectronic tweezers (OET) are a promising technique for the realization of reconfigurable systems suitable to trap and manipulate microparticles. In particular, dielectrophoretic (DEP) forces produced by OET represent a valid alternative to micro-fabricated metal electrodes, as strong and spatially reconfigurable electrical fields can [...] Read more.

Optoelectronic tweezers (OET) are a promising technique for the realization of reconfigurable systems suitable to trap and manipulate microparticles. In particular, dielectrophoretic (DEP) forces produced by OET represent a valid alternative to micro-fabricated metal electrodes, as strong and spatially reconfigurable electrical fields can be induced in a photoconductive layer by means of light-driven phenomena. In this paper we report, and compare with the experimental data, the results obtained by analyzing the spatial configurations of the DEP-forces produced by a 532 nm laser beam, with Gaussian intensity distribution, impinging on a Fe-doped Lithium Niobate substrate. Furthermore, we also present a promising preliminary result for water-droplets trapping, which could open the way to the application of this technique to biological samples manipulation. Full article

(This article belongs to the Special Issue Lithium Niobate Crystals)

► Show Figures

Figure 1

2774 KiB

Open AccessCommunication

Self-Assembly Kinetics of Colloidal Particles inside Monodispersed Micro-Droplet and Fabrication of Anisotropic Photonic Crystal Micro-Particles

by Ming-Yu Zhang, Ke Xu, Jian-Hong Xu and Guang-Sheng Luo

Crystals 2016, 6(10), 122; https://doi.org/10.3390/cryst6100122 - 23 Sep 2016

Cited by 15 | Viewed by 7282

Abstract

A new microfluidic approach to preparing anisotropic colloidal photonic crystal microparticles is developed and the self-assembly kinetics of colloidal nanoparticles is discussed. Based on the “coffee ring” effect in the self-assembly process of colloidal silica particle in strong solvent extraction environment, we successfully [...] Read more.

A new microfluidic approach to preparing anisotropic colloidal photonic crystal microparticles is developed and the self-assembly kinetics of colloidal nanoparticles is discussed. Based on the “coffee ring” effect in the self-assembly process of colloidal silica particle in strong solvent extraction environment, we successfully prepared anisotropic photonic crystal microparticles with different shapes and improved optical properties. The shapes and optical properties of photonic crystal microparticles can be controlled by adjusting the droplet size and extraction rate. We studied the self-assembly mechanism of colloidal silica particles in strong solvent extraction environment, which has potential applications in a variety of fields including optical communication technology, environmental response, photo-catalysis and chromic material. Full article

(This article belongs to the Special Issue Colloidal Crystals)

► Show Figures

Graphical abstract

1974 KiB

Open AccessArticle

A High Laser Damage Threshold and a Good Second-Harmonic Generation Response in a New Infrared NLO Material: LiSm₃SiS₇

by Ni Zhen, Leyan Nian, Guangmao Li, Kui Wu and Shilie Pan

Crystals 2016, 6(10), 121; https://doi.org/10.3390/cryst6100121 - 23 Sep 2016

Cited by 20 | Viewed by 4935

Abstract

A series of new infrared nonlinear optical (IR NLO) materials, LiRe₃MS₇ (Re = Sm, Gd; M = Si, Ge), have been successfully synthesized in vacuum-sealed silica tubes via a high-temperature solid-state method. All of them crystallize in the non-centrosymmetric space [...] Read more.

A series of new infrared nonlinear optical (IR NLO) materials, LiRe₃MS₇ (Re = Sm, Gd; M = Si, Ge), have been successfully synthesized in vacuum-sealed silica tubes via a high-temperature solid-state method. All of them crystallize in the non-centrosymmetric space group P6₃ of the hexagonal system. In their structures, LiS₆ octahedra connect with each other by sharing common faces to form infinite isolated one-dimensional _∞[LiS₃]_n chains along the 6₃ axis. ReS₈ polyhedra share edges and corners to construct a three-dimensional tunnel structure with _∞[LiS₃]_n chains located inside. Remarkably, LiSm₃SiS₇ shows promising potential as one new IR NLO candidate, including a wide IR transparent region (0.44–21 μm), a high laser damage threshold (LDT) (3.7 × benchmark AgGaS₂), and a good NLO response (1.5 × AgGaS₂) at a particle size between 88 μm and 105 μm. Dipole-moment calculation was also used to analyze the origin of NLO responses for title compounds. Full article

(This article belongs to the Special Issue Nonlinear Optical Crystals)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Crystals, Volume 6, Issue 10 (October 2016) – 17 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI