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10 pages, 19713 KiB

Open AccessArticle

Morphology Transition of ZnO Nanorod Arrays Synthesized by a Two-Step Aqueous Solution Method

by Guannan He, Bo Huang, Zhenxuan Lin, Weifeng Yang, Qinyu He and Lunxiong Li

Crystals 2018, 8(4), 152; https://doi.org/10.3390/cryst8040152 - 30 Mar 2018

Cited by 7 | Viewed by 4911

ZnO nanorod arrays (ZNAs) with vertically-aligned orientation were obtained by a two-step aqueous solution method. The morphology of the ZnO nanorods was regulated by changing the precursor concentration and the growth time of each step. ZnO nanorods with distinct structures, including flat top, [...] Read more.

ZnO nanorod arrays (ZNAs) with vertically-aligned orientation were obtained by a two-step aqueous solution method. The morphology of the ZnO nanorods was regulated by changing the precursor concentration and the growth time of each step. ZnO nanorods with distinct structures, including flat top, cone top, syringe shape, and nail shape, were obtained. Moreover, based on the X-ray diffraction (XRD) and the transmission electron microscope (TEM) analysis, the possible growth mechanisms of different ZnO nanostructrues were proposed. The room-temperature PL spectra show that the syringe-shaped ZNAs with ultra-sharp tips have high crystalline quality. Our study provides a simple and repeatable method to regulate the morphology of the ZNAs. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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8 pages, 2002 KiB

Open AccessArticle

Room Temperature Solid State Synthesis, Characterization, and Application of a Zinc Complex with Pyromellitic Acid

by Rong-Gui Yang, Mei-Ling Wang, Ting Liu and Guo-Qing Zhong

Crystals 2018, 8(2), 56; https://doi.org/10.3390/cryst8020056 - 24 Jan 2018

Cited by 11 | Viewed by 4846

Abstract

The complex [Zn₂(btca)(H₂O)₄] was synthesized with 1,2,4,5-benzenetetracarboxylic acid (H₄btca) and zinc acetate as materials via a room-temperature solid state reaction. The composition and structure of the complex were characterized by elemental analyses (EA), Fourier transform [...] Read more.

The complex [Zn₂(btca)(H₂O)₄] was synthesized with 1,2,4,5-benzenetetracarboxylic acid (H₄btca) and zinc acetate as materials via a room-temperature solid state reaction. The composition and structure of the complex were characterized by elemental analyses (EA), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and thermogravimetric (TG) analysis. The index results of X-ray powder diffraction data showed that the crystal structure of the complex belonged to monoclinic system with cell parameters a = 9.882 Å, b = 21.311 Å, c = 15.746 Å, and β = 100.69°. In order to expand the application of the complex, the nanometer zinc oxide was prepared by using the complex as a precursor, and the effect of the thermal decomposition temperature on the preparation of the nanometer zinc oxide was studied. The results showed that the grain size of zinc oxide gradually grew with the increase of the pyrolysis temperature, the obtained nanometer zinc oxide was spherical, and the diameter of the particles was about 25 nm. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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22 pages, 12592 KiB

Open AccessArticle

Crystal Chemistry of Zinc Quinaldinate Complexes with Pyridine-Based Ligands

by Barbara Modec

Crystals 2018, 8(1), 52; https://doi.org/10.3390/cryst8010052 - 19 Jan 2018

Cited by 10 | Viewed by 7310

Abstract

Substitution of methanol in [Zn(quin)₂(CH₃OH)₂] (quin⁻ denotes an anionic form of quinoline-2-carboxylic acid, also known as quinaldinic acid) with pyridine (Py) or its substituted derivatives, 3,5-lutidine (3,5-Lut), nicotinamide (Nia), 3-hydroxypyridine (3-Py-OH), 3-hydroxymethylpyridine (3-Hmpy), 4-hydroxypyridine (4-Py-OH) and [...] Read more.

Substitution of methanol in [Zn(quin)₂(CH₃OH)₂] (quin⁻ denotes an anionic form of quinoline-2-carboxylic acid, also known as quinaldinic acid) with pyridine (Py) or its substituted derivatives, 3,5-lutidine (3,5-Lut), nicotinamide (Nia), 3-hydroxypyridine (3-Py-OH), 3-hydroxymethylpyridine (3-Hmpy), 4-hydroxypyridine (4-Py-OH) and 4-hydroxymethylpyridine (4-Hmpy), afforded a series of novel heteroleptic complexes with compositions [Zn(quin)₂(Py)₂] (1), [Zn(quin)₂(3,5-Lut)₂] (2), [Zn(quin)₂(Nia)₂]·2CH₃CN (3), [Zn(quin)₂(3-Py-OH)₂] (4), [Zn(quin)₂(3-Hmpy)₂] (5), [Zn(quin)₂(4-Pyridone)] (6) (4-Pyridone = a keto tautomer of 4-hydroxypyridine), and [Zn(quin)₂(4-Hmpy)₂] (7). In all reactions, the {Zn(quin)₂} structural fragment with quinaldinate ions bound in a bidentate chelating manner retained its structural integrity. With the exception of [Zn(quin)₂(4-Pyridone)] (6), all complexes feature a six-numbered coordination environment of metal ion that may be described as a distorted octahedron. The arrangement of ligands is trans. The coordination sphere of zinc(II) in the 4-pyridone complex consists of only three ligands, two quinaldinates, and one secondary ligand. The metal ion thereby attains a five-numbered coordination environment that is best described as a distorted square-pyramid (τ parameter equals 0.39). The influence of substituents on the pyridine-based ligand over intermolecular interactions in the solid state is investigated. Since pyridine and 3,5-lutidine are not able to form hydrogen-bonding interactions, the solid state structures of their complexes, [Zn(quin)₂(Py)₂] (1) and [Zn(quin)₂(3,5-Lut)₂] (2), are governed by π···π stacking, C–H∙∙∙π, and C–H∙∙∙O intermolecular interactions. With other pyridine ligands possessing amide or hydroxyl functional groups, the connectivity patterns in the crystal structures of their complexes are governed by hydrogen bonding interactions. Thermal decomposition studies of novel complexes have shown the formation of zinc oxide as the end product. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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6 pages, 2843 KiB

Open AccessArticle

Observations on Nanoscale Te Precipitates in CdZnTe Crystals Grown by the Traveling Heater Method Using High Resolution Transmission Electron Microscopy

by Boru Zhou, Wanqi Jie, Tao Wang, Zongde Kou, Dou Zhao, Liying Yin, Fan Yang, Shouzhi Xi, Gangqiang Zha and Ziang Yin

Crystals 2018, 8(1), 26; https://doi.org/10.3390/cryst8010026 - 10 Jan 2018

Cited by 7 | Viewed by 5728

Abstract

Te precipitates in CdZnTe (CZT) crystals grown by the traveling heater method (THM) are investigated using high-resolution transmission electron microscopy (HRTEM). The results show that in THM-grown CZT crystals, Te precipitates are less than 10 nm in size—much smaller than those in Bridgman-grown [...] Read more.

Te precipitates in CdZnTe (CZT) crystals grown by the traveling heater method (THM) are investigated using high-resolution transmission electron microscopy (HRTEM). The results show that in THM-grown CZT crystals, Te precipitates are less than 10 nm in size—much smaller than those in Bridgman-grown CZT. They have hexagonal structure and form a coherent interface with zinc blend structure CZT matrix in the orientation relationship

{[\bar{1} 12]}_{M} / / {[0001]}_{P}

and

{(1 \bar{1} 1)}_{M} / / {(\bar{1} 100)}_{P}

. A ledge growth interface with the preferred orientation along the

{[1 \bar{1} 1]}_{M}

and

{[110]}_{M}

was found near Te precipitates. The growth and nucleation mechanism of Te precipitates are also discussed. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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4906 KiB

Open AccessArticle

Synthesis, Crystal Structure and Luminescent Properties of 2D Zinc Coordination Polymers Based on Bis(1,2,4-triazol-1-yl)methane and 1,3-Bis(1,2,4-triazol-1-yl)propane

by Evgeny Semitut, Taisiya Sukhikh, Evgeny Filatov, Alexey Ryadun and Andrei Potapov

Crystals 2017, 7(12), 354; https://doi.org/10.3390/cryst7120354 - 29 Nov 2017

Cited by 8 | Viewed by 4576

Abstract

Two new two-dimensional zinc(II) coordination polymers containing 2,5-thiophenedicarboxylate and bitopic ligands bis(1,2,4-triazol-1-yl)methane (btrm) or 1,3-bis(1,2,4-triazol-1-yl)propane (btrp) were synthesized. Synthesized compounds were characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction, and thermal analysis. Crystal structures of coordination polymers were determined and their structural [...] Read more.

Two new two-dimensional zinc(II) coordination polymers containing 2,5-thiophenedicarboxylate and bitopic ligands bis(1,2,4-triazol-1-yl)methane (btrm) or 1,3-bis(1,2,4-triazol-1-yl)propane (btrp) were synthesized. Synthesized compounds were characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction, and thermal analysis. Crystal structures of coordination polymers were determined and their structural peculiarities are discussed. The differences in structural features, thermal behavior, and luminescent properties are discussed. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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5698 KiB

Open AccessArticle

Stuck in Our Teeth? Crystal Structure of a New Copper Amalgam, Cu₃Hg

by Jonathan Sappl, Ralph Freund and Constantin Hoch

Crystals 2017, 7(12), 352; https://doi.org/10.3390/cryst7120352 - 24 Nov 2017

Cited by 3 | Viewed by 5852

Abstract

We have synthesized a new Cu amalgam, the Cu-rich phase Cu

_{3}

Hg. It crystallizes with the Ni

_{3}

Sn structure type with a hexagonal unit cell (space group P6

_{3}

/mmc , a = 5.408(4) Å, c = 4.390(3) Å) [...] Read more.

We have synthesized a new Cu amalgam, the Cu-rich phase Cu

_{3}

Hg. It crystallizes with the Ni

_{3}

Sn structure type with a hexagonal unit cell (space group P6

_{3}

/mmc , a = 5.408(4) Å, c = 4.390(3) Å) and shows some mixed occupancy of Cu on the Hg site, resulting in a refined composition of Cu

_{3.11}

Hg

_{0.89}

. This is the first example of an amalgam with the Ni

_{3}

Sn structure type where Hg is located mainly on the Sn site. Cu

_{3}

Hg might be one of the phases constituting dental amalgams and therefore has major relevance, as well as the only Cu amalgam phase described so far, Cu

_{7}

Hg

_{6}

with the

γ

-brass structure. It occurs as a biphase in our samples. Thermal decomposition of Cu amalgam samples in a dynamic vacuum yields nanostructured copper networks, possibly suitable for catalytic applications. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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4352 KiB

Open AccessArticle

The Mixed-Metal Oxochromates(VI) Cd(Hg^I₂)₂(Hg^II)₃O₄(CrO₄)₂, Cd(Hg^II)₄O₄(CrO₄) and Zn(Hg^II)₄O₄(CrO₄)—Examples of the Different Crystal Chemistry within the Zinc Triad

by Matthias Weil

Crystals 2017, 7(11), 340; https://doi.org/10.3390/cryst7110340 - 06 Nov 2017

Cited by 3 | Viewed by 4522

Abstract

The three mixed-metal oxochromates(VI) Cd(Hg^I₂)₂(Hg^II)₃O₄(CrO₄)₂, Cd(Hg^II)₄O₄(CrO₄), and Zn(Hg^II)₄O₄(CrO₄) were grown under hydrothermal [...] Read more.

The three mixed-metal oxochromates(VI) Cd(Hg^I₂)₂(Hg^II)₃O₄(CrO₄)₂, Cd(Hg^II)₄O₄(CrO₄), and Zn(Hg^II)₄O₄(CrO₄) were grown under hydrothermal conditions. Their crystal structures were determined from single-crystal X-ray diffraction data. The crystal-chemical features of the respective metal cations are characterised, with a linear coordination for mercury atoms in oxidation states +I and +II, octahedral coordination spheres for the divalent zinc and cadmium cations and a tetrahedral configuration of the oxochromate(VI) anions. In the crystal structures the formation of two subunits is apparent, viz. a mercury-oxygen network and a network of cadmium (zinc) cations that are directly bound to the oxochromate(VI) anions. An alternative description of the crystal structures based on oxygen-centred polyhedra is also given. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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11379 KiB

Open AccessArticle

Morphological and Crystallographic Characterization of Primary Zinc-Rich Crystals in a Ternary Sn-Zn-Bi Alloy under a High Magnetic Field

by Lei Li, Chunyan Ban, Ruixue Zhang, Haitao Zhang, Minghui Cai, Yubo Zuo, Qingfeng Zhu, Xiangjie Wang and Jianzhong Cui

Crystals 2017, 7(7), 204; https://doi.org/10.3390/cryst7070204 - 06 Jul 2017

Cited by 6 | Viewed by 4051

Abstract

Due to the unique capacity for structural control, high magnetic fields (HMFs) have been widely applied to the solidification process of alloys. In zinc-based alloys, the primary zinc-rich crystals can be dendritic or needle-like in two dimensions. For the dendritic crystals, their growth [...] Read more.

Due to the unique capacity for structural control, high magnetic fields (HMFs) have been widely applied to the solidification process of alloys. In zinc-based alloys, the primary zinc-rich crystals can be dendritic or needle-like in two dimensions. For the dendritic crystals, their growth pattern and orientation behaviors under HMFs have been investigated. However, the three-dimensional crystallographic growth pattern and the orientation behaviors of the needle-like primary zinc-rich crystals under a high magnetic field have not been studied. In this work, a ternary Sn-Zn-Bi alloy was solidified under different HMFs. The above-mentioned two aspects of the needle-like primary zinc-rich crystals were characterized using the Electron Backscattered Diffraction (EBSD) technique. The results show that the primary zinc-rich crystals are characterized by the plate-shaped faceted growth in three dimensions. They grow in the following manner: spreading rapidly in the {0001} basal plane with a gradual decrease in thickness at the edges. The application of HMFs has no effect on the growth form of the primary zinc-rich crystals, but induces their vertical alignment. Crystallographic analysis indicates that the vertically aligned primary zinc-rich crystals orient preferentially with the c-axis perpendicular to the direction of the magnetic field. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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7175 KiB

Open AccessArticle

Elastic, Mechanical and Phonon Behavior of Wurtzite Cadmium Sulfide under Pressure

by Melek Güler and Emre Güler

Crystals 2017, 7(6), 164; https://doi.org/10.3390/cryst7060164 - 04 Jun 2017

Cited by 22 | Viewed by 5907

Abstract

Cadmium sulfide is one of the cutting-edge materials of current optoelectronic technology. Although many theoretical works are presented the for pressure-dependent elastic and related properties of the zinc blende crystal structure of cadmium sulfide, there is still some scarcity for the elastic, mechanical, [...] Read more.

Cadmium sulfide is one of the cutting-edge materials of current optoelectronic technology. Although many theoretical works are presented the for pressure-dependent elastic and related properties of the zinc blende crystal structure of cadmium sulfide, there is still some scarcity for the elastic, mechanical, and phonon behavior of the wurtzitic phase of this important material under pressure. In contrast to former theoretical works and methods used in literature, we report for the first time the application of a recent shell model-based interatomic potential via geometry optimization computations. Elastic constants, elastic wave velocities, bulk, Young, and shear moduli, as well as the phonon behavior of wurtzite cadmium sulfide (w-CdS) were investigated from ground state to pressures up to 5 GPa. Calculated results of these elastic parameters for the ground state of w-CdS are approximately the same as in earlier experiments and better than published theoretical data. Our results for w-CdS under pressure are also reasonable with previous calculations, and similar pressure trends were found for the mentioned quantities of w-CdS. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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3637 KiB

Open AccessArticle

Theoretical Analysis of Elastic, Mechanical and Phonon Properties of Wurtzite Zinc Sulfide under Pressure

by Melek Güler and Emre Güler

Crystals 2017, 7(6), 161; https://doi.org/10.3390/cryst7060161 - 04 Jun 2017

Cited by 16 | Viewed by 4949

Abstract

We report for the first time the application of a mixed-type interatomic potential to determine the high-pressure elastic, mechanical, and phonon properties of wurtzite zinc sulfide (WZ-ZnS) with geometry optimization calculations under pressures up to 12 GPa. Pressure dependency of typical elastic constants, [...] Read more.

We report for the first time the application of a mixed-type interatomic potential to determine the high-pressure elastic, mechanical, and phonon properties of wurtzite zinc sulfide (WZ-ZnS) with geometry optimization calculations under pressures up to 12 GPa. Pressure dependency of typical elastic constants, bulk, shear, and Young moduli, both longitudinal and shear wave elastic wave velocities, stability, as well as phonon dispersions and corresponding phonon density of states of WZ-ZnS were surveyed. Our results for the ground state elastic and mechanical quantities of WZ-ZnS are about experiments and better than those of some published theoretical data. Obtained phonon-related results are also satisfactory when compared with experiments and other theoretical findings. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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Review

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29 pages, 20352 KiB

Open AccessReview

Perplexing Coordination Behaviour of Potentially Bridging Bipyridyl-Type Ligands in the Coordination Chemistry of Zinc and Cadmium 1,1-Dithiolate Compounds

by Edward R. T. Tiekink

Crystals 2018, 8(1), 18; https://doi.org/10.3390/cryst8010018 - 04 Jan 2018

Cited by 37 | Viewed by 6999

Abstract

The X-ray structural chemistry of zinc and cadmium 1,1-dithiolates (for example, xanthate, dithiophosphate and dithiocarbamate) with potentially bridging bipyridyl-type ligands (for example, 4,4′-bipyridine) is reviewed. For zinc, the xanthates and dithiophosphates uniformly form one-dimensional coordination polymers, whereas the zinc dithiocarbamates are always zero-dimensional, [...] Read more.

The X-ray structural chemistry of zinc and cadmium 1,1-dithiolates (for example, xanthate, dithiophosphate and dithiocarbamate) with potentially bridging bipyridyl-type ligands (for example, 4,4′-bipyridine) is reviewed. For zinc, the xanthates and dithiophosphates uniformly form one-dimensional coordination polymers, whereas the zinc dithiocarbamates are always zero-dimensional, reflecting the exceptional chelating ability of dithiocarbamate ligands compared with xanthates and dithiophosphates. For cadmium, one-dimensional coordination polymers are usually found, reflecting the larger size of cadmium compared with zinc, but zero-dimensional aggregates are sometimes found. Steric effects associated with the 1,1-dithiolate-bound R groups are shown to influence supramolecular aggregation and, when formed, polymer topology in order to reduce steric hindrance; the nature of the bipyridyl-type ligand can also be influential. For the dithiocarbamates of both zinc and cadmium, in instances where the dithiocarbamate ligand is functionalised with hydrogen bonding potential, extended supramolecular architectures are often formed via hydrogen bonding interactions. Of particular interest is the observation that the bipyridyl-type ligands do not always bridge zinc or cadmium 1,1-dithiolates, being monodentate instead, often in the presence of hydrogen bonding. Thus, hydroxyl-O–H^…N(pyridyl) hydrogen bonds are sometimes formed in preference to M←N(pyridyl) coordinate-bonds, suggesting a competition between the two modes of association. Full article

(This article belongs to the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury)

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