Dimensional Compound Research Articles

Colloidal Synthesis of γ-MnS Nanorods with Uniform Controlled Size and Pure ⟨002⟩ Growth Direction.

One dimensional (1D) compound semiconductor nanostructures have unique anisotropic optical, electrical, and physical properties. Synthesis of large scale 1D nanostructures with pure crystallographic growth direction by a colloidal route and finding an easy method to prove it were significant for further exploring their unique anisotropic properties. Additionally, MnS is one of the most important optoelectronic and magnetic semiconductors. Herein, the large scale γ-MnS nanorods with completely pure ⟨002⟩ growth direction were first synthesized and convinced by solid evidence using the X-ray diffraction method. Compared with the standard diffraction pattern of γ-MnS powder, the ⟨002⟩ oriented long γ-MnS nanorods showed only the (100),(110), (200), and (210) peaks while other diffraction peaks disappeared. This study opened a door for the synthesis of the 1D colloidal nanostructures with pure crystallographic growth direction at large scale, benefiting the manufacture of a novel apparatus based on their anisotropic properties.

Novel Eu-MOF-based mixed matrix membranes and 1D Eu-MOF-based ratiometric fluorescent sensor for the detection of metronidazole and PA in water

Metal organic framework-based mixed matrix membranes and ratiometric fluorescent sensors have received significant attention in application of sensing. Herein, a two-dimensional europium-based metal organic frameworks, [Eu(L-N2)2·(L-Cl4)1.5·H2O] (CUST-506). (L-Cl4 = 2,3,5,6-tetrachloroterephthalic acid, L-N2 = 1,10-phenanthroline) has been synthesized and characterized. Then, by immobilizing water-stable CUST-506 into agarose hydrogels, the Eu-MOF-based mixed matrix membranes (CUST-506-based MMMs) were successfully prepared. The CUST-506-based MMMs exhibit not only the integrity and the metronidazole, picric acid (PA) sensing nature of Eu-MOF powder, but also excellent processability. Moreover, the Eu-MOF-based MMMs show distinguished water-stability. More interestingly, during the hydrothermal synthesis process, through anchoring the formic acid into the framworks to break the symmetrical coordination environment of the CUST-506, a one dimensional (1D) compound {[Eu(L-N2)·(L-Cl4)0.5(COOH)·2H2O]·(L-Cl4)0.5}(CUST-507) with two emission centers from Eu3+-based centers and free L-Cl4 molecules is generated. CUST-507 displayes a unique ability of auto-calibration effect based on the dual emission mechanism and sensitive sensing of metronidazole and picric acid. This work highlights a simple fabrication strategy for MOF-based mixed matrix membranes and overcomes the environmental interference for ratiometric fluorescent sensor.

Field-temperature induced dimensionality crossover in Ca3Co2O6 spin system

Quasi-one dimensional spin chain compound, Ca3Co2O6, undergoes field and temperature induced dimensionality crossover at about 25 K from one-dimension to three-dimensionally correlated state. It is shown that interplay of intrachain and interchain couplings with thermal energy in this infinite spin chain system is responsible for this phenomenon. It is established from the measurement of temperature dependent magnetic susceptibility and field dependence of magnetization along different crystallographic axes of the single crystal. Further, the effect of chain truncation on dimensionality crossover has been studied to substantiate the role of these interactions in this phenomenon. Reduction of chain length causes decrease of the effective intrachain coupling strength without affecting the interaction of neighbouring chains significantly. As a result, the propensity of dimensional crossover is found to be weaker in the broken chain compared to the longer chain.

Magnetic correlations in subsystems of the misfit [Ca2CoO3]0.62[CoO2] cobaltate

[Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$], a two dimensional misfit metallic compound, is famous for its rich phases accessed by temperature, $i.e.$ high temperature spin-state transition, metal-insulator transition (MIT) at intermediate temperature ($\sim$ 100 K) and low temperature spin density wave (SDW). It enters into SDW phase below T$_{MIT}$ which becomes long range at 27 K. Information on the independent role of misfit layers (rocksalt/Ca$_2$CoO$_3$ \& triangular/CoO$_2$) in these phases is scarce. By combining a set of complementary macroscopic (DC magnetization and resistivity) and microscopic (neutron diffraction and X-ray absorption fine structure spectroscopy) measurements on pure (CCO) and Tb substituted in the rocksalt layer of CCO (CCO1), magnetic correlations in both subsystems of this misfit compound are unraveled. CCO is found to exhibit glassiness, as well as exchange bias (EB) effects, while CCO1 does not exhibit glassiness, albeit it shows weaker EB effect. By combining local structure investigations from extended X-ray absorption fine structure (EXAFS) spectroscopy and neutron diffraction results on CCO, we confirm that the SDW arises in the CoO$_2$ layer. Our results show that the magnetocrystalline anisotropy associated with the rocksalt layer acts as a source of pinning, which is responsible for EB effect. Ferromagnetic clusters in the Ca$_2$CoO$_3$ affects SDW in CoO$_2$ and ultimately glassiness arises.

Bulky 9-phenylfluorene fuctionalized 2,6-bis(N-carbazolyl)- pyridine with high triplet energy level as host for blue thermally activated delayed fluorescence devices

A new 9-phenylfluorene functionalized 2,6-bis(N-carbazolyl)-pyridine compound 2,6-bis(3-(9-phenyl-fluoren- 9-yl)-carbazol-9-yl)pyridine (2,6-PFCzPy) with large steric hindrance and high triplet energy level has been successfully prepared by introducing 3-(9-phenyl-fluoren-9-yl)-carbazole unit into the 2,6-position of pyridine group via Ullmann reaction. Cyclic voltammetry (CV) was used to study the electrochemical properties of the compound and obtain HOMO (−5.85 eV), LUMO (−2.09 eV), and energy gap (Eg, 3.57 eV). The 2,6-CzPy-based compound was employed as host to fabricate blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) for the first time with the maximum EQEs of 6.2% at the doping concentration as high as 30%. The electroluminescent (EL) spectra show almost no changes along with the driving voltage ranging from 5.1 to 15.1 V at high doping concentration, which indicates the 2,6-CzPy-based three dimensional bulky compound could successfully suppress the excimer emission of the guest in high doping ratio.

Ground state and low-temperature magnetism of the quasi-two-dimensional honeycomb compound InCu2/3V1/3O3

We report a combined $^{115}$In NQR, $^{51}$V NMR and $\mu$SR spectroscopic study of the low-temperature magnetic properties of InCu$_{2/3}$V$_{1/3}$O$_3$, a quasi-two dimensional (2D) compound comprising in the spin sector a honeycomb lattice of antiferromagnetically coupled spins $S=1/2$ associated with Cu$^{2+}$ ions. Despite substantial experimental and theoretical efforts, the ground state of this material was has not been ultimately identified. In particular, two characteristic temperatures of about $\sim 40$ K and $\sim 20$ K manifesting themselves as anomalies in different magnetic measurements are discussed controversially. A combined analysis of the experimental data complemented with theoretical calculations of exchange constants enabled us to identify below 39 K an ``intermediate'' quasi-2D static spin state. This spin state is characterized by a staggered magnetization with a temperature evolution that agrees with the predictions for the 2D XY model. We observe that this state gradually transforms at 15 K into a fully developed 3D antiferromagnetic N\'eel state. We ascribe such an extended quasi-2D static regime to an effective magnetic decoupling of the honeycomb planes due to a strong frustration of the interlayer exchange interactions which inhibits long-range spin-spin correlations across the planes. Interestingly, we find indications of the topological Berezinsky-Kosterlitz-Thouless transition in the quasi-2D static state of the honeycomb spin-1/2 planes of InCu$_{2/3}$V$_{1/3}$O$_3$.

Enhanced magneto dielectric effect on oxygen annealed geometrically frustrated spin-chain compound: Ca3Co2O6

In the present work we report on the magneto dielectric studies of oxygen annealed, one dimensional compound Ca3Co2O6. The magnetic and electrical properties were studied on the polycrystalline samples prepared by conventional solid state reaction method and annealed in oxygen atmosphere. The magnetization versus temperature curve shows paramagnetic behavior up to 30 K and interesting magnetic transitions below that temperature. A dielectric anomaly around 15 K was observed. The change in dielectric constant between 75 K and 100 K is not intrinsic and is due to the grain boundary contributions in the polycrystalline sample. Our results predict that annealing at oxygen atmosphere improve the physical properties of calcium cobaltates which are promising materials for magnetoelectric applications.

Image Hiding Technology Based on Low Dimensional Compound Chaos Algorithm

Image Hiding Technology Based on Low Dimensional Compound Chaos Algorithm

Layered semiconductor EuTe4 with charge density wave order in square tellurium sheets

We report a novel quasi-two dimensional compound of EuTe4 hosting charge density waves (CDW) instability. The compound has a crystallographic structure in a orthorhombic space group Pmmn (No.59) with cell parameters a = 4.6347(2){\AA}, b = 4.5119(2){\AA}, c = 15.6747(10){\AA} at room temperature. The pristine structure contains consecutive near-square Te sheets separated by corrugated Eu-Te slabs. Upon cooling, the compound experiences a phase transition near 255 K. X-ray crystallographic analysis and transmission electron microscopy (TEM) measurements reveal strong structural distortions in the low temperature phase, showing a superstructure with a periodic formation of Te-trimers in the monolayer Te sheets, yielding evidence for the formation of CDW order. The charge transport properties show a semiconducting behavior in the CDW state. Density functional theory calculations reveals a Fermi surface nesting driven instability with a nesting vector in good agreement with the one observed experimentally. Our finding provides a promising system for the study of CDW driven 2D semiconducting mechanisms, which would shed a new light on exploring novel 2D semiconductors with collective electronic states.

Titanosilicate Sitinakite Compound As a Low-Potential Anode for Sodium-Ion Battery

Sodium-ion batteries (SIBs) have been considered as a promising candidate for large-scale energy storage applications, because of the low cost of sodium element and a broad choice of cathode materials which do not contain the expensive raw materials. However, a lack of promising anode materials still hinders the development of SIBs technology. Herein, we for the first time report a one dimensional tunnel-structure titanosilicate sitinakite compound with an ideal formula of Na1.68H0.32Ti2O3SiO4·1.76H2O employed as a new type anode material in SIBs. This material can deliver a reversible capacity of 110 mAh g-1 at a current density of 20 mA g-1 and with an average working voltage of 0.4 V vs. Na+/Na. The structure changes of this material during discharge/charge processes were investigated by using in-situ laboratory X-ray diffraction. The results indicated that sodium insertion proceeds via a topotactic intercalation pathway. We also identified pre-dehydration as an effective avenue to further improve the capacity of Na1.68H0.32Ti2O3SiO4·1.76H2O anode (reversible capacity of 131 mAh g-1 at a current density of 20 mA g-1 after pre-dehydration process). In addition, cation Nb doped Na1.68H0.32Ti2O3SiO4·1.76H2O compounds have been synthesized and systematically investigated the electrochemical performances in SIBs. Reference [1] Liu, Y.; Xia, Y., Na1.68H0.32Ti2O3SiO4·1.76H2O as a Low-Potential Anode Material for Sodium-Ion Battery. ACS Applied Energy Materials 2018, doi:10.1021/acsaem.8b01412.

Renormalization group analysis for the quasi-one-dimensional superconductor BaFe2S3

Motivated by the discovery of superconductivity in the two-leg, quasi-one dimensional ladder compound, BaFe$_2$S$_3$ we present a renormalization group study of electrons moving on a two leg, two orbital ladder, subjected to Hubbard repulsion $U$ and Hund's coupling $J$. In our calculations, we adopt tightbinding parameters obtained from ab-initio studies on this material. At incommensurate filling, the long wavelength analysis displays four phases as a function of $0 \leq J/U <1$. We show that a fully gapped superconductor is stabilized at sufficiently large Hund's coupling, the relative phases at the three Fermi points are "+,-,-". By contrast, when the system is tuned to half filling, Umklapp scattering gives rise to Mott insulating phases. We discuss the general implications of our study for the broad class of iron-based superconductors.

Multidimensional compound Poisson distributions in free probability

Inspired by Speicher's multidimensional free central limit theorem and semicircle families, we prove an infinite dimensional compound Poisson limit theorem in free probability, and define infinite dimensional compound free Poisson distributions in a non-commutative probability space. Infinite dimensional free infinitely divisible distributions are defined and characterized in terms of their free cumulants. It is proved that for a sequence of random variables, the following three statements are equivalent: (1) the distribution of the sequence is multidimensional free infinitely divisible; (2) the sequence is the limit in distribution of a sequence of triangular trays of families of random variables; (3) the sequence has the same distribution as that of $$\left\{ {a_1^{\left( i \right)}:i = 1,2 \ldots } \right\}$$ of a multidimensional free Levy process $$\left\{ {\left\{ {a_t^{\left( i \right)}:i = 1,2 \ldots } \right\}:t \geqslant 0} \right\}$$ . Under certain technical assumption, this is the case if and only if the sequence is the limit in distribution of a sequence of sequences of random variables having multidimensional compound free Poisson distributions.

Crystal growth, magnetic property and phase transition of the zigzag-chain antiferromagnet FeNbO4

We report crystal growth, magnetic properties and electron spin resonance (ESR) study of the one dimensional zigzag-chain compound FeNbO4. The single crystals were grown by the flux method using Na2WO4·12H2O and Na2W2O7 as the flux. Magnetic susceptibility and specific heat data show an antiferromagnetic ordering below 44 K. High-field magnetization data reveal a spin-flop transition at 12 T when magnetic field is applied along the magnetic easy axis. Multi-frequency ESR study on the single crystals reveal three resonance modes which can be understood by the molecule-field theory. Using a simple model with easy-axis type anisotropy, we estimate that the anisotropy field HA and the exchange field HE are 2.67 T and 27 T, respectively. The zero-frequency resonance field at 11 T corresponds to the spin-flop transition, demonstrating a close correlation between the high-field magnetization and the ESR spectra.

Synthesis and Analysis of TiS3 Nanoribbons

Nowadays ,there are a variety of nanoscale materials that scientists around the whole world try to find out specific nanoscale materials which they can truly apply to the industry and the academic.community. Therefore, finding cheap, non-toxic and accessible materials which can actually apply to the industry is being my core target. One-dimensional materials including nanowires, nanobelts, nanoribbons, nanotubes and nanorods that have been attracting a great research in the last few years. These materials have been demonstrated to exhibit superior electrical, optical, mechanical and thermal properties. One-dimensional materials also become the focus of intensive research due to their unique applications in mesoscopic physics and fabrication of nanoscale devices. One-dimensional nanostructures provide convenient system to investigate the dependence of electrical and thermal transport or mechanical properties on dimensionality and size reduction. Furthermore, they are also play an important role as both interconnects and functional units in fabricating electronic, optoelectronic, electrochemical and electromechanical devices with nanoscale dimensions. Metal sulfides exhibit very interesting properties in the fields of energy conversion and storage. Concerning energy conversion, many of them (FeS2, TiS3, MoS2…) show suitable band gap energy and optical properties to be used in photovoltaic systems and photo-electrochemical hydrogen generation. Furthermore, they exhibit 2D-layered structures with the possibility to develop peculiar nano-morphologies such as nanotubes, nanoplates and nanoribbons These materials can be used as nanotransistors because of their optoelectronic properties as well as potential hydrogen stores. Among all metal sulfides, TiS3 is the transition metal trichal-cogenides and quasi-one dimensional semiconductor with outstanding electronic, optoelectronic properties and easy to get. The direct optical band gap of ≈1 eV, high sensitivity and ultrahigh optical responsivities (≈3000 A/W) make them an ideal material for optoelectronic applications. Moreover, TiS3 has large surface area owing to its considerable (001) plane that TiS3 can be applied to the energy storage or hydrogen storage1~2. In this work, titanium based sulfides TiS3 one-dimensional nanostructures (nanoribbons) have been synthesized by chemical vapor deposition (CVD) method in the two-zone heating furnace. Ti and S powder as the precursors of CVD method, which were put into quartz tube and sealed by spray gun. First of all, Ti and S powders were placed between first zone furnace and second zone furnace. Second, formation of sulfides were produced by heating the quartz tube up to 700 ºC. for 40 minutes and held 20 minutes at setting temperature in vacuum. The quartz tube was cooled to 580 ºC for 2 days. The morphology, component, grain size, thickness, length and crystal structure of Ti-sulfides were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and raman spectrum respectively. According to the analyses, X-ray diffraction (XRD) patterns of titanium sulfureted of TiS3 sample at room temperature shows the strongest peak of preferential orientation on the (001) plane but still exhibits strong peak of S of preferential orientation on the (222) plane and strong peak of TiS2 of preferential orientation on the (001) plane. Beyond expectation, there are a lot of TiS2 exhibited which will be the significant influence of the purity of TiS3 nanoribbons. According to literatures, this accident occurs since the decomposition of TiS3 nearly below the eutectic point. The scanning electron microscopy (SEM) images of TiS3 samples with 100 μm in length, 0.5~2 μm in width and 100~200 nm in thickness are observed for TiS3. Furthermore, energy dispersive X-ray spectrometry (EDS) for the synthetized sample that the composition is uniform in agreement with the formation of single phase. The S/Ti ratio of TiS3 ratio is 2.96. Finally , the raman spectrum of every peak of TiS3 sample completely corresponds to the correct position. After doing these analyses, TiS3 nanoribbons are doing analyses of optical and electrical properties and apply to the lithium batteries. Reference: G. Gorlova, V.Ya. Pokrovskii, S.G. Zybtsev, A.N. Titov and V.N. Timofeev. Features of the Conductivity of the Quasi One Dimensional Compound TiS3 Journal of Experimental and Theoretical Physics, 2010, 111, 298–303. Tao, Y.; Wu, X.; Zhang, Y.; Dong, L.; Zhu, J.; Hu, Z. (2008). "Surface-assisted synthesis of microscale hexagonal plates and flower-like patterns of single-crystalline titanium disulfide and their field-emission properties". Crystal Growth and Design. 2990–2994

Formation of the S = 1 paramagnetic centers in the bond-diluted spin-gap magnet (C4H12N2)(Cu2Cl6)

Recently found quasi-two dimensional metalloorganic compound (C4H12N2)(Cu2Cl6) (abbreviated PHCC) is an example of a spin-gap magnet. Its ground state is a nonmagnetic singlet separated from the triplet excitations by an energy gap of approximately 1 meV. This compound allows partial substitution of chlorine ions by bromine, which results in the modulation of the affected exchange bonds. We have found by means of electron spin resonance spectroscopy that this doping results in the formation of the gapless S = 1 paramagnetic centers. These centers can be interpreted as triplet excitations trapped in a potential well created by doping.

(Invited) Band Gap Engineering and Optoelectronic Performance of Indium Gallium Arsenide Nanobelts

Low dimensional III-V compound semiconductors, such as GaAs, InAs, and their ternary alloys, exhibit unique optical and electronic properties. Their abilities of efficient carrier transport, light emission, and detection means they can be used in integrated transistors, lasers, light-emitting diodes, and detectors for infrared communications [1-3]. Very recently, intense research has been directed toward the fabrication and application of the III-V nanoplates/sheets owing to their realization of multiterminal electronic devices such as Hall bars, quantum point contacts, and so forth. However, the influence of growth condition on the formation of these nanostructures is still unclear. Furthermore, these nanoplates/sheets generally suffer from small and irregular morphology, demonstrating the difficulties in the controlled growth. Importantly, realizing the continuously tunable composition and heterojunction of these nanostructures remains great challenges, particularly for the technologically important InGaAs. It's well known that InGaAs is of great interest for high-performance device in electronics and optoelectronics [4,5]. Unfortunately, the transistors and photodetectors based on low dimensional InGaAs nanostructures still need improvement due to their low on/off ratio, poor photoresponsivity, and so on. To address these problems, we have realized the controlled growth of high-quality single-crystal InGaAs nanobelts with fully tunable composition/bandgap via an orientation selective vapor growth. Density functional theory calculations reveal that the surface energy variation induced by the chemical potential of arsenic (μ As) is critical for the formation of these nanobelts. When configured into transistors, the InGaAs nanobelt devices exhibit impressive electrical properties with the turn on/off ratio of 2×107, better than any value reported for a InGaAs nanowire device to date. The broadband phototransistor (covering 405-1,550 nm) were further fabricated with an ultrahigh photoresponsivity of >8000 A/W and an external quantum efficiency of >106 %, both of which are much higher than those of all the reported InGaAs nanowire photodetectors. These results suggest that the novel InGaAs nanobelts may open up new opportunities for various applications in integrated electronics, optoelectronics, and quantum electronics.

Ultrasound-Assisted Synthesis of Novel Nano 3D Supramolecular Lead(II) Metal–Organic Coordination System: A New Precursor to Produce Nano Lead Oxide

Novel nanorods of a lead(II) 3D metal–organic coordination system {[Pb(μ2-NO3)4].(hmta)2.H2O}n (1) (hmta = hexamethylenetetramine) were synthesized by a sonochemical method. The new nanostructure was characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, elemental analysis, and thermogravimetric analysis. The single-crystal X-ray structure shows that 1 is a three dimensional (3D) coordination compound. This is further self-assembled into a 3-D supramolecular structure by weak directional intermolecular interactions. The coordination number of the Pb(II) ions is eight (PbO8). PbO nanoparticles were obtained by the thermolysis of 1 at 180 °C using oleic acid as a surfactant. The average diameter of the nanoparticles was estimated by the Scherrer equation to be 30 nm. The morphology and size of the prepared PbO samples were also observed using SEM.

Boussinesq-Type Modeling of Sediment Transport and Coastal Morphology

A two horizontal dimensional compound model is developed to simulate coastal sediment transport and bed morphology evolution due to wave action. The wave module is a higher-order Boussinesq-type model. The bed load in the surf zone is computed from an advanced semi-empirical formula while the suspended load can be calculated through the solution of the advection-diffusion equation for the sediment or alternatively from a simplified formula. The estimation of the sediment transport in the swash zone is based on the ballistic theory. The unified sediment transport module is valid under combined waves and currents including the wave asymmetry and phase-lag effects. The bathymetry is updated through the sediment conservation equation and the morphological accelerator factor technique accounts for extended simulation time. The model is validated against a number of short-term tests in one horizontal dimension. The response is generally good with most of the morphological features being reproduced in the cross-shore direction. A comparison between various sediment transport formulae and a sensitivity analysis are also performed illustrating the need for inclusion of the phase-lag effects.

Synthesis, structure and physical properties of a low dimensional compound

The crystal structure of (μ3-oxo)hexakis(cyanoacetato-κO,O′)(cyanoacetato-κO)diaquatriiron(III) cyanoacetic acid shows the formation of trinuclear complexes in a hydrogen-bond network that bonds all the molecules in a 3D arrangement. For this complex, within whose clusters the whole magnetic interaction takes place, 57Fe Mössbauer spectroscopy shows that the Fe cations are in the S=5/2 state in the temperature range 2–295K. The asymmetric broadening of the absorption peaks below 80K is consistent with strong antiferromagnetic interactions between the metal spins. The magnetization measurements also show the antiferromagnetic character of the spin ensemble and an ST=1/2 magnetic ground state typical of triangular systems with similar J between Fe-Fe pairs.

Exact Traveling Wave Solutions for the (1 + 1)-Dimensional Compound KdVB Equation via the Novel (G'/G)-Expansion Method

In this work, while applying a new and novel (G'/G)-expansion version technique, we identify four families of the traveling wave solutions to the (1 + 1)-dimensional compound KdVB equation. The exact solutions are derived, in terms of hyperbolic, trigonometric and rational functions, involving various parameters. When the parameters are tuned to special values, both solitary, and periodic wave models are distinguished. State of the art symbolic algebra graphical representations and dynamical interpretations of the obtained solutions physics are provided and discussed. This in turn ends up revealing salient solutions features and demonstrating the used method efficiency.