Materials Physics and Chemistry(TRANSFERRED)

Abstract The so-called piezoelectric ceramics are piezoelectric polycrystals, a functional ceramic material capable of converting mechanical energy and electric energy from each other. It belongs to inorganic nonmetallic materials. So far, the most widely used piezoelectric ceramic materials have both good piezoelectricity and ferroelectricity through the substitution and doping in a wide range to adjust its properties to meet the different needs of zirconium titanium lead (PZT) and its composite materials. Piezoelectric materials are also one of the many piezoelectric materials, accounting for about 1/3 of the entire functional ceramic materials. It is mainly used for transducers, sensors, resonators and drives.

Abstract With the extensive application of electromagnetic resources in the information industry, electromagnetic interference has caused many hazards. Polymer-based electromagnetic shielding composite material as a new type of material has good shielding effect on the electromagnetic wave. This paper mainly introduces the types of polymer-based electromagnetic shielding composite materials and the performance evaluation method of shielding materials.

Abstract

Photonic crystals are a major discovery in physics and have an important influence on our present life. The biggest feature of the photonic crystals is it has bandgap which can block photons of a certain frequency, thus affecting the photon movement. This effect is like the influence of the semiconductor body on electrons. Therefore, research and discovery of the photonic crystal is a broad prospect, people has large expectation on the photonic crystal. The emergence of photonic crystals makes it possible for the miniaturization and integration of some aspects of information technology. Study of structure able to determines characteristics, thus the discovery of the photonic crystal structure and function will lay the foundation for the study of its application, in this paper, the study is focus on the research of material absorption of photonic crystal on Transverse Magnetic (TM) wave band. Firstly, the basic knowledge and principle of photonic crystal are introduced. Then, the research was carried out to study the effect of characteristic matrix method on photon crystal TM energy wave through designed experiments and analyzed by computer software.

 

Abstract This paper describes the development of carbon-based composites, and describes the synthesis and application of four carbon-based composites of graphene, carbon nanotubes, fullerenes and graphite.

Abstract Chalcone compounds have a wide range of biological activities. In this paper, nine kinds of novel chalcone compounds were synthesized by using transacrylone derivatives and anthrone as raw materials. The effects of different catalysts and solvents on the yield of the products were investigated. The optimal catalyst was DABCO. The optimum solvent was dichloromethane with the highest yield of 71.6%. On this basis, the effect of the co - catalyst on the yield was investigated. The yield was increased to 89.9%.

Abstract In this paper, the influence of the microstructure of a metal on the breakdown mechanism of diodes with a Schottky barrier is studied. It is shown that in electronic processes occurring in the contact between a metal and a semiconductor, the metal plays a very active role and is a more important contact partner than a semiconductor. Unlike the known mechanisms of breakdown of diodes (avalanche, tunnel and thermal), another mechanism is proposed in this paper - the geometric mechanism of the reverse current flow of Schottky diodes made using a metal with a polycrystalline structure. The polycrystallinity of a metal transforms a homogeneous contact into a complex system, which consists of parallel-connected multiple elementary contacts having different properties and parameters.

Abstract In recent years, the numbers of patents have been devoted to the development of rough pipes. The technique theoretical settlement determine of factor of hydraulic resistance for round pipes with rough walls is developed on the basis of a principle of a superposition of complete viscosity in turbulent a layer mainly distinguished from the existing theories. The received results of account for the extended range of determining parameters much distinguished from appropriate given for round pipes with turbulizers, specify a level и intensification of heat exchange.

Abstract

Hexagonal tungsten trioxide (h-WO₃) nanoflakes have been synthesized by a hydrothermal approach using L-lysine as the shape directing agent. The influence of hydrothermal reaction time and L-lysine content on the morphology of h-WO₃ was investigated. The experimental results showed that the nanoflake morphology could be achieved at higher concentration of L-lysine. Based on the evolution of nanoflake morphology as a function of hydrothermal duration, a “dissolution-crystallization-Ostwald ripening” growth mechanism has been proposed. The electrochemical performance of h-WO₃ nanoflakes has also been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that h-WO₃ modified glassy carbon electrode (GCE) showed lower charge transfer resistance and enhancement in peak current attributed to the enrichment in electroactive surface area and faster electron transfer kinetics at h-WO₃ modified GCE.

Abstract

As the products are being used widely in almost part of Daily life, antibacterial textile products gain more importance. The necessity of antibacterial agents used due to the importance given to today's health and alternative products provided by natural routes has also revealed the necessity of this context. This work focuses on the usage of propolis as an antibacterial agent. On the other hand, it is aimed to gather information on the use of propolis for the purpose of giving antibacterial properties to textile materials.

Abstract The paper proposes a scientifically grounded - principally new approach to managing the fundamental parameters of the basic material of electronic engineering as like silicon. The essense of the proposed approach is that the formation of binary elementary cells in the silicon lattice involving elements III (B, Al, Ga, Zn) and V (P, As, Sb) groups in the form of Si2GaAs, Si2GaSb, etc., taking into account electrical and chemical parameters of these impurity atoms, as well as their diffusion parameters in Si, are determined by the most suitable pairs of atoms of groups III and V that allow obtaining silicon with the necessary composition and structure of binary elementary cells, as well as their more complex associations, up to the formation of nanocrystals of semiconductor connections AIIIBV. It is shown that by controlling the composition and structure, as well as the concentration of binary elementary cells, it is possible to significantly expand the spectral sensitivity of silicon, both in the IR and hλ > Eg directions. The formation of nanoclusters of AIIIBV semiconductor compounds in the silicon lattice significantly changes the emissivity of the material. It is established that the successive diffusion of elements of groups III and V in silicon and additional low-temperature annealing under certain thermodynamic conditions makes it possible to ensure the maximum participation of the impurity atoms introduced in the formation of binary elementary cells. It is shown that silicon with binary elementary cells involving atoms of groups III and V is a new class of semiconductor material with unique functionality for modern optoelectronics and photoenergetics.

Abstract In this study, new theoretical conceptions have been developed about an impurity segregation mechanism at the time of alloy solidification considering present microvolumes with different chemical compositions during alloy solidification. It has been concluded that this conception allows to establish and optimize technologic parameters that influence the production of the main types of macroheterogeneity. The derived model conceptions have confirmed the final condition of real continuous casting billets by using the advanced analyzing methods.

Abstract In this work, a mixture of ZnO and CeO2 powders are subjected to a milling procedure to monitor the mechanical alloying processes. ZnO-CeO2 powders have been milled during 10 to 60 hours, and have been characterized by X-ray diffraction (XRD), UV-Vis absorption, Raman and photoluminescence spectroscopies, in order to study the present phases, the tensional state of material and particle sizes. The evolution of the phases present with the time of milling, and the possible changes in the lattice parameter will help us to estimate the efficiency of the grinding process for obtaining Ce doped ZnO.

Abstract Nanoporous Nickel has been prepared by electrodeposition using non-ionic surfactant based liquid crystalline template under optimized processing conditions. Physico-chemical properties of Nanoporous nickel is systematically characterized through XRD, SEM and AFM analyses. Comparison of electrocatalytic activity of Nanoporous nickel with smooth nickel was interrogated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) analyses. Distinctly enhanced electrocatalytic activity with improved surface poisoning resistance related to Nanoporous nickel electrode towards methanol oxidation stems from unique Nanoporous morphology. This Nanoporous morphology with high surface to volume ratio is highly beneficial to promote active catalytic centers to offer readily accessible Pt catalytic sites for MOR, through facilitating mass and electron transports.

Abstract

Polycrystalline cuprous oxide (P-Cu2O) films are deposited on Cu substrates for various (0.2, 0.3 and 0.4 mbar) oxygen pressures (OP) by thermal evaporator. The XRD pattern shows the development of Cu (200), Cu2O (200) and Cu2O (311) diffraction planes which confirms the deposition of P-Cu2O films. The intensity of Cu2O (200) and Cu2O (311) planes is associated with the increase of OP. The crystallite size and microstrains developed in (200) and (311) planes are found to be 19.31, 21.18, 11.32 nm; 22.04, 23.11, 12.08 nm and 0.113, 0.103, 0.193; 0.099, 0.096, 0.181 with increasing OP respectively. The d-spacing and lattice constant are found to be 0.210, 0.128 nm and 0.421, 0.425 nm respectively. The bond length of P-Cu2O film is found to be 0.255 nm. The crystallites/unit area of these planes is found to be 12.21, 7.46, 45.16 nm-2 and 8.21, 5.75, 37.16 nm-2 respectively. The texture coefficients of these planes are found to be 1.22, 1.26, 1.11 and 0.78, 0.74 and 0.56 with increasing OP respectively. The O and Cu contents are found to be 5.31, 5.92, 6.94 wt % and 83.01, 82.44, 80.65 wt % respectively. The thickness and growth rate of P-Cu2O films are found to be 87.9, 71.9, 65.5 nm and 17.6, 14.2, 13.1 (nm min-1) with increasing OP respectively. The SEM microstructures reveal the formations of patches of irregular shapes, rounded nano-particles, clouds of nano-particles and their distribution depend on the increasing OP. The refractive index and energy band gap of P-Cu2O films are found to be 1.96, 1.89, 1.92 and 2.47, 2.44 and 2.25 eV with increasing OP respectively.

Abstract An α, α′-dipyridyl adduct of a complex compound hexaaquatribenzene-1,2,4,5-tetracarbonatotetra iron (III) with porous structure was synthesized for the first time. According to the results of elemental, X-ray, IR-spectroscopic and differential-thermal analyses the individuality, chemical formula, thermal destruction, and form of coordination of acidic anion and dipyridyl were established. During interaction of a complex compound with dipyridyl, it completely loses all crystallization molecule of water resulting in a compound with a chemical formula of Fe4(C6H2(COO)4)3(dpy)2(dipyridyl). Using the identification of diffraction pattern the parameters of lattice cell of the complex compound were determined.

Abstract In this paper, standard SS304 austenitic stainless steel and SS430 ferritic steel cylindrical rods were fabricated by friction welding process by varying the frictional pressure and forge pressure in order to understand the effect of process parameter.   The tensile strength and Vickers micro hardness tests were conducted for each fabricated joints to evaluate the mechanical properties of the welded specimen. It was found that sample S5 with friction pressure of 90 MPa and forging Pressure of 120 MPa has the high tensile strength value of 637 MPa and 372HV at the interface region. A detailed microstructural analysis were performed at the interface to reveal interconnecting of dissimilar metals.