Dimensional Compound Research Articles

On the Coordination Behaviour of the hmta Toward Alkali Metal Cations in Presence of Perchlorate Anions

The lithium and sodium perchlorate coordination compounds with hexamethylenetetramine of general formulas: [Li(H2O)4]+•2hmta•ClO4 − (1) and [Na(ClO4)(H2O)(hmta)]n (2) have been synthesized, characterised by elemental and thermal analysis, IR spectroscopy and X-ray crystallography. The compound 2 is a rare three dimensional hybrid compound. The obtained compounds are air stable at room temperature and well soluble in water. As a result of the different electronic properties of the ions, the compounds differ considerably in the molecular structure and consequently in the properties. The studied compounds exhibit opposite placement of both hmta molecules and perchlorate ions: in an outer and inner coordination sphere, respectively, for 1 and 2. The thermal and spectroscopic properties were correlated with the studied compounds molecular structure. The two novel coordination compounds {namely [Li(H2O)4]+•2hmta•ClO4 − and [Na(ClO4)(H2O)(hmta)]n}, of which one is a rare three dimensional hybrid compound, have been synthesized and characterised by: elemental and thermal analysis, IR spectroscopy and X-ray crystallography.

Magnetic Order in the Frustrated Ising Quasi-One Dimensional Compound NaCo(acac)3∙ Benzene

We report the results of susceptibility, magnetization curve, and specific heat measurements on single crystals of NaCo(acac)3 ∙ benzene, which forms a triangular lattice on the ab-plane with Ising ferromagnetic chains along the c-axis. We found a long-range order below 62 mK by specific heat measurement, a steplike increase in susceptibility at this temperature, and a plateau of one-third of the full moment in the M–H curve at 20 mK. We also observed a spin relaxation that obeys the Arrhenius law in the ordered state. The existence of a partially disordered antiferromagnetic state is discussed on the basis of the results.

Temporal and spatial instability of a compound jet in a surrounding gas

Droplet generated from the rupture of a compound liquid jet can be used to produce encapsulated droplets which have applications in a wide variety of industrial processes. In this paper, we examine the instability of a two dimensional axisymmetric inviscid compound jet falling vertically downwards in a surrounding gas under the influence of gravity. The steady state equations are derived using an asymptotic method and the linear instability, including temporal and spatial instability, is determined using a multiple scales approach. The results are analysed to investigate how the gas-to-shell density ratio affects key features of the jet including theoretical breakup lengths.

Fast Adaptive Image Encryption using Chaos by Dynamic State Variables Selection

new image encryption scheme based on high dimensional compound chaotic systems is proposed in this paper. Common chaotic image encryption, will perform encryption algorithm on pixels one by one which make the process slower, in this paper we called logistic map to choose and encrypt appropriate number of pixels makes the algorithm swifter and much more reliable by enlarging the key length.

Exact travelling wave solutions of the (3+1)-dimensional mKdV-ZK equation and the (1+1)-dimensional compound KdVB equation using the new approach of generalized G ′ / G $\left (\boldsymbol { {G^{\prime }/G}} \right )$ -expansion method

In this paper, the new generalized ( $G^{\prime } /G)$ -expansion method is executed to find the travelling wave solutions of the (3+1)-dimensional mKdV-ZK equation and the (1+1)-dimensional compound KdVB equation. The efficiency of this method for finding exact and travelling wave solutions has been demonstrated. It is shown that the new approach of generalized ( ${G}^{\prime }/G)$ -expansion method is a straightforward and effective mathematical tool for solving nonlinear evolution equations in applied mathematics, mathematical physics and engineering. Moreover, this procedure reduces the large volume of calculations.

Modeling of Ordered-Disordered Transition in Two Dimensional Binary Compound: Monte Carlo Simulation of Interface Characteristic

In this study, Monte Carlo simulations were used to investigate the ordered-disordered transition behavior of a two dimensional binary compound represented by Ising spins on square lattice. The spin exchange Kawasaki algorithm was use to update the system. With varying the system temperature and adhesive interaction strength, while keeping the cohesive interaction fixed, the system morphologies were investigated via the cluster (of the same spin) forming and the interface/surface area of the cluster. The results show that ferro-favorable systems exist only two large clusters (of the two binary species) at low temperatures. However, with increasing the temperature, the clusters reduce in size while their interface/surface area grows, becomes maximum and drop. This is due to the competitive effect between energy minimization by reducing the cluster size and the thermodynamic kinetic energy in diffusing Ising spins into random fashion. In addition, by increasing the adhesive interaction strength, even the ferro-type cluster forms, the cluster becomes smaller due to the introduction of anti-bonding between spins caused by stronger adhesive interaction. Diagrams of these phenomena which displays relationship among adhesive interaction, temperature, and the cluster of the same spin characteristic as well as the interface/surface area were given. These diagrams can be used as guides in enhancing the topic in acquiring desired applications having parts made from binary compound in which the interface characteristic is important.

Performance analysis of a dielectric based 3D building integrated concentrating photovoltaic system

The use of concentrating photovoltaic systems (CPV) in building integration has spurred towards the development of newer products, which have the potential to offer the convenience of pleasing architecture and day lighting along with simultaneous production of clean energy. This paper addresses the energy transformations and the expected energy output of a low concentrating photovoltaic system designed to have a geometric concentration of 3.6×. The optical element used is a three dimensional Cross Compound Concentrator (3DCCPC) made from clear polyurethane material. Small sized silicon solar cells based on the Laser Grooved Buried Contact (LGBC) technology having an absorber area of 1cm2 are utilised in the system. Both experimental and numerical analyses are performed confirming the optical, electrical and thermal performance of the system. While performing the optical analysis the concentrator was found to have a maximum optical efficiency of 73.4%. A maximum power ratio of 2.67 was observed when comparing the electrical output of the concentrator unit with a non-concentrating counterpart. The effects of non-uniformity caused by the use of the concentrator are analysed. The non-uniformity of flux distribution showed an average drop of 2.2% in the Isc values which is again reflected in the overall power output. Manufacturing defects like the cell and concentrator misalignments are addressed and their impact on the overall performance are verified by numerical simulations. The operating temperature of the solar cells was found to have a parasitic effect on the overall performance of the system. A maximum temperature of 332K was observed in the solar cell at 0° incidence and a incoming radiation of 1000W/m2 which brings down the overall power production by 14.6%. Finally, the expected system output over a given time period is presented showing the strengths and weakness while employing such a system.

Charge-orbital-lattice coupling effects in theddexcitation profile of one-dimensional cuprates

We identify dd-excitations in the quasi-one dimensional compound Ca$_2$Y$_2$Cu$_5$O$_{10}$ using resonant inelastic x-ray scattering. By tuning across the Cu L$_3$-edge, we observe abrupt shifts in the dd-peak positions as a function of incident photon energy. This observation demonstrates orbital-specific coupling of the high-energy excited states of the system to the low-energy degrees of freedom. A Franck-Condon treatment of electron-lattice coupling, consistent with other measurements in this compound, reproduces these shifts, explains the Gaussian lineshapes, and highlights charge-orbital-lattice renormalization in the high energy d-manifold.

The Analysis of Corporate Bond Valuation under an Infinite Dimensional Compound Poisson Framework

This paper analyzes the firm bond valuation and credit spread with an endogenous model for the pure default and callable default corporate bond. Regarding the stochastic instantaneous forward rates and the firm value as an infinite dimensional Poisson process, we provide some analytical results for the embedded American options and firm bond valuations.

Effect of a Gaussian white noise on the charge density wave dynamics in a one dimensional compound

The effect of a white Gaussian noise (WGN) on the charge density wave (CDW) dynamics properties of a one-dimensional conductor is studied numerically in the weak pinning limit. In agreement with a recent experimental work on the charge density wave conductor K0.3MoO3, the addition of a Gaussian noise affects the CDW dynamics of the system. The results are discussed in the context of CDW dislocations.

Spin fluctuations with two-dimensional XY behavior in a frustratedS=12square-lattice ferromagnet

The spin dynamics of the layered square-lattice vanadate Pb2VO(PO4)2 is investigated by electron spin resonance at various magnetic fields and at temperatures above magnetic ordering. The linewidth divergence towards low temperatures seems to agree with isotropic Heisenberg-type spin exchange suggesting that the spin relaxation in this quasi-two dimensional compound is governed by low-dimensional quantum fluctuations. However, a weak easy- plane anisotropy of the g factor points to the presence of a planar XY type of exchange. Indeed, we found that the linewidth divergence is described best by XY-like spin fluctuations which requires a single parameter only. Therefore, ESR-probed spin dynamics could establish Pb2VO(PO4)2 as the first frustrated square lattice system with XY-inherent spin topological fluctuations.

Exergy analysis on solar heat collection of three-dimensional compound parabolic concentrator

This study presents a thermal model for the optimum design of the three–dimensional compound parabolic concentrator (CPC) considering the maximisation of exergy delivery. The model in this study has been validated by comparing the computed collector temperature with the measured one. A good agreement has been confirmed. The optimum temperatures of the collector and the thermal medium are calculated. Reduction of heat loss from the collector to ambient air can enhance the maximum exergy, but it is accompanied by shift of the optimum temperature. The heat extraction process has been examined by assuming that it is composed of two steps of heat flow: the first from the collector to the medium and the second from the medium to the final objective. The analysis shows how the exergy efficiency varies in response to the design change in the second step and where the overall optimised design can be found in a diagram between heat transfer coefficient and temperature.

Spin trimers in Ca3Cu2Ni(PO4)4

The nature of spin trimer and 3d spin dynamics in Ca3Cu2Ni(PO4)4 is studied using 31P NMR measurements. The data are obtained by replacing one of the Cu ions by a Ni ion in the one dimensional spin trimer compound Ca3Cu3(PO4)4. The NMR spectrum suggests the presence of two types of magnetically inequivalent phosphorous atoms, as in the parent compound. This reveals the presence of only one type of trimer, Cu2-Ni-Cu2, rather than of three types, Cu2-Cu1-Cu2, Cu2-Cu1-Ni and Ni-Cu1-Ni, as indicated by neutron scattering. Hence, the ground state of Ca3Cu2Ni(PO4)4 appears to be a quintet. These results also explain the magnetic susceptibility behavior, which indicates no reduction in the net spin of the trimer in Ca3Cu2Ni(PO4)4, as expected for JNi-Cu = −0.85 meV compared to the value JCu-Cu = −4.74 meV derived from neutron scattering. The spin lattice relaxation rate suggests that the three magnon mediated scattering process dominant in Ca3Cu3(PO4)4 is reduced in Ca3Cu2Ni(PO4)4.

Crossover from coherent to incoherent scattering in spin-orbit dominated Sr2IrO4

Strong spin-orbit interaction in the two dimensional compound Sr2IrO4 leads to the formation of Jeff=1/2 isospins with unprecedented dynamics. In Raman scattering a continuum attributed to double spin scattering is observed. With higher excitation energy of the incident Laser this signal crosses over to an incoherent background. The characteristic energy scale of this cross over is identical to that of intensity resonance effects in phonon scattering. It is related to exciton-like orbital excitations that are also evident in resonant X-Ray scattering. The crossover and evolution of incoherent excitations are proposed to be due to their coupling to spin excitations. This signals a spin-orbit induced entanglement of spin, lattice and charge degrees of freedoms in Sr2IrO4.

Sonochemical Synthesis and Characterization of A Nano-Rod Lead(II) Supramolecular, Three Dimensional Coordination Compound: New Precursor to Produce Pure Phase Nano-Sized Lead(II) Oxide

Nanorods of a lead(II) supramolecular three-dimensional (3D) coordination compound, [Pb(tfpb)2]n (1) (Htfpb = 4,4,4-trifluoro-1-phenyl-1,3-butanedione), was prepared by the sonochemical method. The new nano-structure was characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. A single-crystal structure of the compound showed that the coordination number of Pb(II) is eight with six O-donor atoms from the tfpb ligand and two F-donors from anionic ligands. The 3D supramolecular structure of 1 is realized by weak directional C–F···F–C and π–π stacking interactions. After calcination of nano-sized 1 at 500 °C, pure phase nano-sized lead(II) oxide is produced.

Density of states, magnetic and transport properties of Nd doped two dimensional perovskite compound Sr2CoO4

Structures, transport, magnetic properties, and first principle calculation results will be reported for the two dimensional layered structured perovskite compounds Sr2-xNdxCoO4 (x = 0.5, 0.75, 1, 1.25). Structure refinement results revealed that these compounds crystallized in K2NiF4-type structures with space group I4/mmm. The temperature dependence of resistivity showed semiconductor like behavior for these samples. It was found that the lattice parameter c decreases as the doping level x increases. The compounds exhibited a paramagnetic to ferromagnetic transition at temperatures of about 170, 125 K for the x = 1 and 0.75 samples, respectively. The temperature dependence of resistivity for the samples can be well fitted by the 2D variable hoping (VRH) model ρ = ρo exp(T0/T)1/3 (where ρo is a material specific characteristic conductance, with unit Ω−1, T0 is a material specific characteristic temperature in K) over the whole measured temperature range. First principles calculations indicated that the Nd doped Sr2CoO4 compounds show high spin polarization.

Structural analysis and photoluminescence properties of low dimensional lanthanide tetracyanometallates

The synthesis of a number of lanthanide tetracyanometallate (TCM) compounds have been carried out by reaction of Ln3+ nitrate salts and potassium tetracyanometallates in solvent systems containing dimethylsulfoxide and water. These reactions result in the isolation of three distinct structure types: (1) monoclinic [Ln(DMSO)4(H2O)3M(CN)4](M(CN)4)0.5·2H2O (Ln=Eu, Tb and M=Pd, Pt), (2) orthorhombic {La(DMSO)3(H2O)2(NO3)M(CN)4}∞·H2O (M=Pd, Pt), and (3) orthorhombic {Ln(DMSO)3(H2O)(NO3)M(CN)4}∞ (Ln=Tb and M=Pd, Pt; Ln=Er, Yb and M=Pt) in the form of single crystals. Single-crystal X-ray diffraction has been used to investigate their structural features. Structure type 1 is a zero dimensional ionic compound with a M/Ln ratio of 1.5:1. It contains coordinated as well as uncoordinated [M(CN)4]2− (M=Pd, Pt) anions and features relatively long platinophilic interactions. Structure types 2 and 3 differ quite drastically from structure type 1, but they are very similar to each other. Both of the latter are one-dimensional in nature due to chains containing linkage of Ln3+ coordination spheres with trans-bridging [M(CN)4]2− anions. These coordination polymers both have a M/Ln ratio of 1:1, a lack of platinophilic interactions, and incorporation of a bidentate NO3− for charge balance. Photoluminescence properties for select Eu3+ and Tb3+ compounds have been investigated. They show characteristic absorption and emission for the Ln3+ ions, but no significant influence of the tetracyanometallate anions.

A new three dimensional proton transfer compound including citric acid and 2,4,6-triamine-1,3,5-triazine: synthesis, characterization and X-ray crystal structure

A new three dimensional proton transfer compound, (tataH) 2 (citH).2H 2 O (I) was synthesized from the reaction of citric acid (citH 3 ), and 2,4,6-triamino-1,3,5-triazine (tata). The characterization was performed using elemental analysis, IR spectroscopy, and single crystal X-ray structure determination. The crystal structure of the title compound consists of bis-2,4,6-triamino-1,3,5-triazin-1-ium cations, hydrogen citrate, and lattice water molecules. Intermolecular O-H•••O, N-H•••O, and N-H•••N hydrogen bonding interactions stabilize the crystal structure. The hydrogen bonds distances range from of 1.781 to 2.088 A. The π-π stacking (centroid-centroid ranges 3.410-3.504 A) between two aromatic rings of tata moieties can play an essential role in the creation and stabilization of the title crystalline network.

Crystal water induced alteration of magnetic exchange interactions

Cuprates show an intimate interplay between the crystal structure and their magnetism, particularly with respect to frustration and dimensionality. On the other hand, it is a widespread belief that crystal water has just a moderate and quantitative influence to the magnetic properties of these compounds caused by the modification of interatomic distances. In contrast, the hydration of CuCl2 leads to a dramatic change in magnetic behaviour and ground state. While CuCl2·2H2O is a classic example for a three-dimensional antiferromagnet (TN 4.3 K) [1] with small exchange couplings, CuCl2 is a quasi-one dimensional chain compound that exhibits long-range order at T 24 K [2].

Limit theorems for the number of solutions of a system of random linear equations belonging to a given set

We investigate the asymptotic behaviour of the distribution of the number ξ( B ) of the solutions of a system of homogeneous random linear equations Ax = 0 (the T × n matrix A is composed of independent random variables a i , j uniformly distributed on a set of elements of a finite field K ) which belong to some given set B of non-zero n -dimensional vectors over the field K . We consider the case where, under a concordant growth of the parameters n , T → ∞ and variations of the sets B 1 , . . . , B s such that the mean values converge to finite limits, the limit distribution of the vector (ξ( B 1 ), ... , ξ( B s )) is an s -dimensional compound Poisson distribution. We give sufficient conditions for this convergence and find parameters of the limit distribution. We consider in detail the special case where B k is the set of vectors which do not contain a certain element k ∈ K .