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The electric forces are the main factor responsible for the characteristic jet path and stretching in electrospinning. The distribution of the electric field determines the quality of the electrospinning. In this paper, a glass flywheel nozzle is designed, and a ring electrode and a capacitor are added between the nozzle and the receiving plate. Theoretical calculations prove the feasibility of the design. The finite element analysis software COMSOL Multiphysics5.0 is used for electric field simulation. The effect of the voltage across the ring electrode and capacitor on the electric field was studied. It is found that when the ring electrode is connected to 10 kV voltage and the voltage across the capacitor is 5 kV, the uniformity of the electric field is significantly improved, which provides a reference for the future optimization of the electrostatic spinning electric field. [ABSTRACT FROM AUTHOR]

The electrochemical performances of microsupercapacitors depend on the electrode materials. And graphene quantum dots are a very ideal electrode materials. In particular, nitrogen or oxygen doping is beneficial to enhance the Faraday reaction kinetics and improve the interfacial wettability of the carbon electrode and electrolyte solution. In this paper, nitrogen and oxygen co-doped graphene quantum dots were used as electrode materials and the electrode film was prepared by a modified liquid-air interface self-assembly method. The microsupercapacitors had high electrochemical characteristics including the area capacitance which was 98 μF cm−2, the energy density which was 0.014 μWh cm−2, the power density which was 51.07 μW cm−2 and the excellent time constant which was 0.12 ms. Meanwhile, the capacitance retention rate was 97.3% after 10,000 cycles. [ABSTRACT FROM AUTHOR]

Strength quality can reflect the physical quality, strength forging plays a positive role to maintain a strong body and abundant energy. The transmission system of traditional fitness equipment, such as electric treadmill and bicycle fitness device, are difficult to achieve the force training effect of simulating the rapid change of resistance like wind gust change and slope change automatically according to the pre-programmed curve changes in real time or speed. Combined with the current situation and existing problems of fitness equipment at home and abroad, this paper develops a self-generating power generation and electromagnetic damping control system that does not require external power supply, also has intelligent charge and discharge function, which can adjust the resistance output in real time. The system, which takes permanent magnetic synchronous generator as the resistance source, can replace the complex mechanical resistance structure and some electric resistance structure, and is widely used in the fitness equipment such as treadmill and bicycle trainer. [ABSTRACT FROM AUTHOR]

This paper reports a low-cost method for the preparation of AgInS2 thin films on conductive glass. The AgInS2 thin films were prepared by electrodeposition method after sulfurization at 400 °C for 1 h in N2 atmosphere. AgInS2 was successfully prepared using nitrate, sodium citrate and sodium thiosulfate as raw materials. The experimental results show that a good AgInS2 film can be obtained when the deposition potential is −1.0 V and the deposition time is 30 min. The AgInS2 film with chalcopyrite and tetragonal phase structure can be prepared under different deposition temperatures and different pH conditions, and the pH has a greater influence on the phase of AgInS2. The composition of the AgInS2 film prepared by sulfurization after electrodeposition basically accords with the stoichiometric ratio. [ABSTRACT FROM AUTHOR]

In this paper, potassium sodium niobate lead-free piezoelectric thin films were prepared by sol-gel method. The electric domain structure and optical band gap of the thin films were regulated by doping Mn. It is found that Mn doping increases the grain size and density of KNNLT piezoelectric film surface. In addition, Mn doping can regulate the electric domain of thin films. Increasing Mn doping concentration can regulate the size and distribution of electric domain, and the ratio of 71° electric domain increases with the increase of doping concentration. The results show that the optical band gap decreases gradually with the increase of doping amount when the annealing temperature is 650 °C. The lowest optical band gap reaches 3.426 eV, and is lower than the undoped KNNLT films. [ABSTRACT FROM AUTHOR]

This paper studies the application of zinc oxide semiconductor nanomaterials in the printing process, including (1) photolithography technology (2) microcontact technology (3) screen printing (4) inkjet writing technology commonly used in daily life. Among them, the screen printing and lithography technology are analyzed in detail, and the use process and specific process of the two methods are introduced. In the process of preparing zinc oxide into ink, not only the method and process are introduced in detail, but also chemical formulas and examples are listed. In the experiment on ZnO, it can be objectively analyzed that the evaporation characteristics of the organic solvent of the ZnO semiconductor nanomaterials determine the characteristics of the carrier, which leads to the uneven quality of the formed printed film. If the solvent evaporates quickly, the paint will gradually evaporate the water in it during printing to increase the viscosity of the slurry. [ABSTRACT FROM AUTHOR]

As one of the new high-performance products, the ferroelectric liquid crystal light valve has entered people's daily lives and has been widely used. Because of its excellent characteristics, it is widely used in various aspects such as industry and commerce. This paper adopts an experimental analysis method and data analysis method, and aims to break through the existing image acquisition methods by studying ferroelectric liquid crystal light valve film and high-speed image acquisition system, and develop an image acquisition system with faster speed and high-quality performance. According to the experimental results, the system can meet the functional requirements and technical indicators proposed by the design and can operate safely and stably, achieving the expected effect of the design. [ABSTRACT FROM AUTHOR]

Titanium alloy Ti-5553 has the advantages of high strength and corrosion resistance, but its high cutting temperature and chemical activity in the machining process reduce its surface integrity. In this paper, the effect of surface integrity on fatigue life is analyzed in terms of surface morphology, microstructure, and residual stresses through liquid nitrogen cryogenic and dry cutting Ti-5553 experiments. The results show that the surface roughness parameter Ra and Sq both show a trend of decreasing and then increasing under the same cutting parameters. Under cryogenic cutting effectively improves surface integrity and extends the fatigue life of the specimen. [ABSTRACT FROM AUTHOR]

Friedel's salt is a common hydrate of cement concrete in chloride environment, and the change of its performance will affect the performance of cement paste and the safety of concrete structure. In order to study the properties and morphological characteristics of Friedel's salt, Friedel's salt is prepared by reaction of C3A with chlorine salt and chemical synthesis in this paper. The expansibility and stability of Friedel's salt are studied by XRD, SEM, TG-DTG and FTIR. The results show that the higher the curing temperature is, the faster the reaction rate is, the expansion degree is 0.3 and the density is 2.087 g/cm3. Friedel's salt is more stable in alkaline environment, and the greater the pH value is, the more stable the Friedel's salt is. Under dry heat curing, Friedel's salt is gradually decomposed with the increase of temperature, and the Friedel's salt prepared by C3A and chlorine salt is completely decomposed at 500 °C, and the Friedel's salt prepared by chemical method is completely decomposed at 600 °C. Under damp heat curing, Friedel's salt is gradually decomposed with the increase of temperature, and it is not completely decomposed at 100 °C. [ABSTRACT FROM AUTHOR]

Compared with traditional secondary batteries such as lithium-ion batteries, lithium-sulfur batteries have a higher theoretical specific capacity (1675 mAh/g) and energy density (2600 Wh/kg), so they are regarded as the most promising one of the lithium batteries. However, it also has problems such as volume expansion during the reaction, poor conductivity of sulfur, serious "shuttle effect" caused by poly-sulfides, and slow electrochemical reaction kinetics. In this paper, a two-step hydrothermal method was used to synthesize CNTs-MoS2/SnO2 composite materials. We assembled CNTs/MoS2 materials, CNTs/SnO2 materials and CNTs-MoS2/SnO2 composite materials into batteries and tested their electrochemical performance. The experimental results show that the CNTs-MoS2/SnO2 composite material has a more significant catalytic effect and a stronger adsorption capacity. The first-lap discharge specific capacity reaches 1369.9 mAh/g at a rate of 0.1 C, and the Coulomb efficiency can reach more than 98%after 150 cycles at 0.2 C. Its excellent performance is due to the synergistic inter-action of p-type semiconductor metal sulfide MoS2 and n-type semiconductor metal oxide SnO2, and the p-n heterojunction interface formed by the two promotes ion and the transmission rate of electrons. [ABSTRACT FROM AUTHOR]

Passivation is carried out on the basis of low chromium or no chromium. This paper has prepared a nontoxic passivation agent suitable for building door and window hardware. Its formula is sodium molybdate, cobalt nitrate, phytic acid, sodium citrate, phosphoric acid sodium. The content of each component was determined by the single variable factor experiment method, the corrosion resistance was measured by electrochemical workstation, the surface morphology and coating thickness of the passive film were observed and analyzed by JSM-6380LA scanning electron microscope (SEM), and the German Brook D8 Advance diffractometer was used. The composition of the passivation film was analyzed, and the corrosion resistance of the passivation film was tested in a salt spray test box. Finally, the optimal formula of the chromium-free blue and white passivation agent was sodium molybdate 40 g/L, sodium phosphate 20 g/L, sodium citrate. 15 g/L, phytic acid 10 ml/L, cobalt nitrate 1.5 g/L, PH value 1-2, passivation time 8–20 s. The prepared passivation used this nontoxic passivation agent can reaches 72 h in the neutral salt spray test. This work provides a new idea for the development of nontoxic passivation agent, and it has potential commercial value [ABSTRACT FROM AUTHOR]

In this paper, the shaft parts of failed machine tools were treated by laser cladding, and the shaft surface of 45# steel matrix was repaired. The microstructure, hardness and corrosion resistance of the cladding layer and quenched phase transformation zone were analyzed by metallographic microscope, Vickers microhardness tester, and friction and wear tester. The laser cladding layer was tested by friction and wear tester. The results showed that the friction coefficient of laser cladding layer was only 0.58, and it fluctuated slightly. The corrosion resistance of laser cladding layer was obviously increased. [ABSTRACT FROM AUTHOR]

With the application of higher and higher power density IC in power driver circuits, an efficient modeling method of thermal design and heat dissipation is desired. In this paper, the printed circuit board (PCB) heat dissipation without heat-sink is discussed. Firstly, the thermal resistance of PCB thermal via array is analytically modeled. Then, the optimal via diameter and number are found in a limited area for minimum thermal resistance. Secondly, the radial temperature distribution is analyzed and a method of designing a proper copper pad for heat dissipation under the design power is posed. Finally, computational fluid dynamics (CFD) simulations are developed to verify the posed model and method. [ABSTRACT FROM AUTHOR]

Energy issues have always been one of the most concerned issues in the world. To solve the problem of building energy consumption, the future development of building energy-saving projects is more meaningful. This article aims to study the application of the parameter tester based on ferroelectric ceramics in building energy-saving projects. This paper proposes to use the orthogonal test method to elaborate and accurately calculate the energy-saving projects of green buildings and calculate the annual energy-saving rate and load rate of green buildings, to achieve real building energy conservation and reduce energy consumption. The comparative analysis method is used to conduct strict calculation and analysis of the four specific energy-saving systems in the enclosure structure, such as doors and windows, external wall insulation, roof, and sunshading, to more clarify the advantages and disadvantages of each component in the enclosure structure place. According to the experimental data of this article, under the premise that the energy saving rate of this article fully meets the national requirements exceeds 50%, in this model, in terms of the full life cycle cost, the cost of using the worst solution can be reduced by 614,900 yuan compared with the cost of the best solution. [ABSTRACT FROM AUTHOR]

CFRP/Ti laminated materials are widely used in key parts of aircraft such as skin and wing, but the common problem of the two kinds of difficult to machine materials is particularly prominent tool wear, which seriously affects the quality of parts. In this paper, an experimental study was carried out on the milling of CFRP/Ti laminates with diamond coating unit edge tool. By combining theoretical analysis and experiment, the surface morphology and the change law of cutting force of CFRP/Ti laminates under different tool wear conditions were obtained. The results show that abrasive wear is the main mechanism in CFRP cutting zone, while adhesive wear is the main wear mechanism in the titanium alloy cutting zone, accompanied by the mixture of abrasive, oxidation and diffusion. With the tool wear aggravating, the milling force gradually increases and accompanied by irregular fluctuations. [ABSTRACT FROM AUTHOR]

The LiFePO4 with olivine structure has become one of the most popular cathode materials for lithium-ion batteries due to its absolute superiority of safety, environment-friendly, inexpensive. In this paper, Fe3(PO4)2 and Li2CO3 were used as raw materials, meanwhile graphite powder or glucose as reducing agent to prepare the LiFePO4 cathode materials via carbothermal reduction method. The effects of molar ratio of lithium to iron, calcination temperature, calcination time, C% and the different C resource on the phase, morphology and electrochemical properties of the products were investigated. The experimental results showed that when the molar ratio of LiFePO4 was 1.05, the calcination temperature at 750 °C for 3 h, and graphite powder or glucose content 5%, the pure olivine structure LiFePO4 sample was obtained, the particle size of which was about 2 ∼ 5 μm with good dispersibility. The prepared sample was assembled as CR2032 Button Battery for electrochemical performance. The charge-discharge capacity was close to the theoretical capacity of 170mAh/g, the efficiency was more than 99% and high-rate capacity retention was maintained at 96.5%, respectively. The overall electrochemical performance of LiFePO4 was excellent. [ABSTRACT FROM AUTHOR]

In this paper, the projection method, the stereographic method and the spherical map method are used to calculate the spatial angle of the parts with the oblique hole in the numerical control machining center. At the same time, the calculation principle and method of the spatial double deflection angle hole system in the numerical control machining center are studied.The projection method is used to analyze the spatial angle relation of Φ10 holes in milling. V spherical method and H spherical method are used to calculate the positioning angle and the orientation angle. The spatial angle of a valve body part in milling Φ12 space inclined hole is calculated by using the stereographic method, and the positioning angle and the orientation angle are calculated by using the V spherical graph method and the H spherical graph method.The calculation results show that the spatial angles obtained by the above methods are the same, which verifies the correctness and the feasibility of the calculation method. [ABSTRACT FROM AUTHOR]

In this paper, nanostructured Cu2O thin films were prepared on glass substrates by magnetron sputtering. The effects of the O2/Ar ratio and sputtering power on the preparation of Cu2O thin films were investigated. In order to verify its morphology and phase, we use scanning electron microscope and X-ray diffraction to test. The first principle is used to calculate the crystal structure of Cu2O, and the optical properties and electronic structure of Cu2O are calculated. Our structure shows that Cu2O is a direct band gap material with 2.144 eV. It has good absorption capacity in the ultraviolet region and high transmittance in the visible region, which is consistent with the experimental results. It can be used as an ideal electrode material for solar cells. [ABSTRACT FROM AUTHOR]

Nanometer cemented carbide has a wide range of applications and prospects in the fields of machinery, metallurgy and industrial mold, based on its excellent mechanical performance. During the fabrication of WC-Co cemented carbide, the grains have high potential to grow up, how to manufacture the nano-cemented carbides with excellent comprehensive mechanical properties remains challenging. This paper demonstrates that the WC-10Co nano-cemented carbide combining with carbon nanotubes can realize enhanced the mechanical properties of nanomaterials. Ultra nanometer indentation tests are conducted to detect the hardness and elastic modulus of the nano-WC-10Co-CNT composite material. The key figure of merit of the CNT composite nano-material and its ability to refine the grains and to enhance the comprehensive performance are proved. We also envision that when the doping amount of CNT reaches to 0.7%, the performance of the nano CNT composite cemented carbide will degrade due to the exiting of free carbon. [ABSTRACT FROM AUTHOR]

In this paper, we provide the adsorption behavior of lysozyme on the inverse colloidal crystal (ICC) membrane under different parameters (such as temperature, pH value, adsorption time). Besides, this also studied lysozyme adsorption behavior by changing the Hydroxyethyl methacrylate (HEMA) ratio of the ICC membrane. Furthermore, we found that ICC membranes containing Hydroxyethyl methacrylate have significantly improved lysozyme adsorption than ICC membranes without Hydroxyethyl methacrylate. With the increasing lysozyme concentration, the ICC membrane containing 50% HEMA showed an excellent selective adsorption effect. At the same time, we describe the adsorption mechanism of lysozyme on the ICC membrane containing HEMA. Finally, after ten adsorption-desorption cycles on the ICC membrane, the membranes adsorption effect on lysozyme has not significantly decreased. [ABSTRACT FROM AUTHOR]

The instantaneous cutting contact relationship between tool and workpiece is changing with the change of curvature profile of open blade impeller. This leads to a strong nonlinear characteristic of the dynamic cutting load change during the machining of this type of parts, which affects the machining accuracy of the blade. This paper proposes a method to predict the machining error of ball-end milling under dynamic load. This method considers the influence of the curvature change of blade profile. Based on the analysis of the instantaneous cutting contact of complex surface in ball-end milling, a prediction model of the instantaneous undeformed cutting thickness of ball-end milling under the influence of surface curvature changes is constructed. Based on this model, the correction of the prediction model of machining complex surface milling force is realized. The prediction of the machining error when the complex surface is thin-walled impeller is processed under dynamic load. Finally, the effectiveness and accuracy of the method are verified through ball-end milling experiments. The research can provide guidance for the control and compensation of milling machining errors of complex-shaped thin-walled open blade. [ABSTRACT FROM AUTHOR]

Information about vibrating objects can be obtained by vibration measurements. Piezoelectric sensors made by piezoelectric ceramics, quartz, or organic piezoelectric materials, e. g. polyvinylidene fluoride (PVDF) have been adopted by many researchers to measure vibrations. Among these piezoelectric materials, PVDF has attracted much attention for its excellent properties such as outstanding chemical resistance, high thermal stability, low permitivities, low acoustic impedances, flexibility and membrane forming properties. In this paper, PVDF is introduced in brief. In addition, this paper briefly reviews the use of PVDF films as sensors for vibration measurement in the areas of portable medical detections, structural health monitoring, mechanical equipment vibration measurements and other applications. Meanwhile, some cases which have good low-frequency performances or novel features in structures will be especially introduced to provide helpful experiences for future applications. In the end, a spiral-shaped PVDF cantilever and a double-clamped PVDF beam of two piezoelectric energy harvesters are mentioned to provide ideas for reducing the resonant frequencies and enhancing the output signals of PVDF vibration sensors respectively. The idea of how to enhance the output signals of PVDF sensors for low frequency vibration measurements may be helpful to the development of geophone. [ABSTRACT FROM AUTHOR]

This paper reviews wearable and unconstrained systems based on PVDF sensors in physiological signals monitoring. Since using wearable and unconstrained biomedical sensor systems for health monitoring is convenient and efficient, and piezoelectric polyvinylidene fluoride (PVDF) film has the advantages as flexibility, wide frequency response, low cost, easiness to fabricate, biocompatibility and light weight, many studies have focused on the PVDF film as sensors of wearable and unconstrained systems. Utilizing a modular design concept, the processing circuit of systems can be reorganized to implement different functions, so as to match different medical applications. This paper reviews key ideas and performance of the reported wearable and unconstrained systems based on PVDF sensors in physiological signals monitoring and the modular design concept. The various existing state of art practices of the wearable and unconstrained systems with PVDF sensors in measurement of physiological signals are also reviewed. And an outlook of the future about wearable and unconstrained systems with PVDF sensors in physiological signals monitoring is given. [ABSTRACT FROM AUTHOR]

In the present paper the phenomena predicted in [2] for substances with FE and AFE phases coexisting is experimentally shown for Pb(Mg 1/3 Nb 2/3 )O 3 and Pb(B′ 1/2 B′′ 1/2 )O 3 -type compounds. Special attention is paid to analysis of their phase diagrams. The influence of external factors on the properties of these substances is considered. It is shown that all peculiarities in the behaviour of the substances in question are described on the basis of phase transitions between FE and AFE states. [ABSTRACT FROM AUTHOR]

To find out the effect of the rare earth doping element Holmium (Ho) on CuInS2 thin films, various studies have been carried out and the results have been reported in this paper. The PL study shows that intensity of doped film is more than undoped film. The PL emission peak appears at 570–580 nm. SEM images of CIS:Ho (4 ml) film shows agglomeration on the surface. Both synthesized film of CuInS2 appears to be amorphous in nature with chalcopyrite structure as clear from XRD. Hall measurement and optical studies were also performed. [ABSTRACT FROM AUTHOR]

The paper presents the results of studying the polarization properties of solid solutions ceramics, including sodium and calcium niobates at room temperature and frequency f = 50 Hz. Three classification regions of the dielectric hysteresis loops formation were identified. The nature of observed effects formations was determined. [ABSTRACT FROM AUTHOR]

The paper presents a calculation of doping concentration profile in a two-layer barium titanate film, one of the layers of which contains lanthanum impurity. The theoretically predicted distributions were experimentally verified. Influence of the doping profile on the magnitude of the electrocaloric (EC) response of ferroelectric films is assessed by numerical simulation. It is demonstrated that at the same La concentration, the magnitude of the EC effect can change by 40% due to the distribution of the lanthanum concentration in the structure. The results obtained allow optimizing the technological process to ensure the required characteristics of ferroelectric thin films. [ABSTRACT FROM AUTHOR]

The paper provides information on the growth of SrTiO3/Si (001) (STO/Si) and 0.5BiFeO3–0.5PbFe0.5Nb0.5O3/SrTiO3/Si (001) (BFO-PFN/STO/Si) composite heterostructures. BFO–PFN/STO/Si composite thin films were deposited on Si substrate by RF-cathode sputtering using STO as buffer layer for textured growth. The use of STO enhanced the orientation for the perovskite phase growth of the BFO–PFN films, which was confirmed by XRD. It was shown that the BFO–PFN layer in the BFO–PFN/STO/Si heterostructures suffered a strain and thus their physical properties were modified. The optical properties of the STO/Si pseudo-substrate were studied in detail. [ABSTRACT FROM AUTHOR]

This paper presents a study of microstructure and dielectric properties of solid solutions of (1-х)BiFeO3 − x/2 PbFe1/2Nb1/2O3 − x/2 PbFe2/3W1/3O3 system with x = 0.05 ÷ 0.50 using X-ray diffraction analysis. Phase diagram of the studied system at room temperature is obtained. Critical influence of oxygen defects and liquid phase on formation of structure and microstructure of the samples is detected. Relaxor nature ε′′/ε0 for the studied solid solutions is demonstrated dealing with occurrence of Maxwell-Wagner's relaxation due to movement of oxygen vacancies. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the dielectric response in single crystals of barium strontium niobate doped with thulium of various concentrations. It is shown that the dielectric permittivity increases with increasing concentration of thulium. For as-grown samples the dispersion of the permittivity is observed in the frequency region of 106 Hz. The dependence is not observed for the samples polarized under DC field. For all the samples studied, the switched polarization increases and the coercive field decreases under action of an AC field. [ABSTRACT FROM AUTHOR]

In this paper, thin films are considered within the framework of the Ising model with a depolarizing field. In the existing works, the depolarizing field is considered to be proportional to the polarization, but it is not suitable for polydomain films. According to our approach, the depolarizing field energy is calculated as the difference between the energy of dipole-dipole interactions in a bulk sample and a thin film. Stripe domains with neutral and charged walls can appear in the considered model. We also studied domain structures arising in films of different thicknesses with increasing temperature and depolarizing field value. [ABSTRACT FROM AUTHOR]

This paper presents an L-shaped piezoelectric energy harvester (PEH) constructed by adding a cylindrical rigid body at the end of the horizontal cantilever. The theoretical model of the presented system is established. The correctness of the model is verified by testing performance and comparing the results. The effects of several key parameters on the output power and the optimal size parameters are deduced by simulation for the harvester. The presented harvester has a maximum power output of 533.9 μW under the resonant frequency of 15 Hz when the excitation acceleration is 0.2 g and optimal load resistance is 100 kΩ. [ABSTRACT FROM AUTHOR]

In this paper, thick film antiferroelectric ceramics (1-x)(Pb0.97La0.02)(Zr0.46Sn0.48Ti0.06)O3-xH3BO3 ((1-x)PLZST-xH3BO3, x = 0–0.025) were prepared by solid state sintering and tape-casting method. The effects of boron-doping on the microstructure, dielectric properties and energy storage properties of (1-x)PLZST-xH3BO3 ceramics were investigated. Appropriate boron-doping can improve the stability of antiferroelectric phase, delay phase transition and increase saturation polarization strength. Compared with the undoped PLZST thick films, the maximum polarization intensity increased by 1.9 times and the residual polarization decreased by 37%. When x = 0.020, the maximum recoverable energy storage density is 2.74 J/cm3, and the energy storage efficiency is 88.12%. [ABSTRACT FROM AUTHOR]

This paper discusses the approach to formulate mathematical model (MM) for synthesis of any ceramic and to decide reliability of density measurement. In the research of basic science, the majority of operations are still executed manually which needs to be focused and develop a mathematical relation which simulate the real input and output data directly. The advantages and limitations of the developed mathematical models are identified and the models are classified in terms of range of application and goals. In this study, a generalized experimental data based model developed to simulate the contemporary techniques for the purpose of study, compression, inducing generalized approach for the mathematical model of ceramic synthesis. The findings indicate that the topic understudy is of great importance, as no such approach of experimental data based mathematical simulation is adopted for the formulation of synthesis of ceramics so far. Thus the results of this experimental research would be useful to industry for manufacturing of multilayer capacitors. [ABSTRACT FROM AUTHOR]

Due to the promising prospects of near-ultraviolet excitation of single-substrate white LED phosphors, a series of Ba3BP3O12:Eu3+,Dy3+ single white emitting phosphors were prepared by the conventional high temperature solid-state method in this article. This paper systematically studied the crystal structure, microscopic morphology, energy transfer mechanism and emission spectrum of the sample, and analyzed the effects of different temperature, holding time, charge compensator and rare earth ion doping on the luminescence performance of the sample. The CIE color coordinates were also calculated. The results show that Ba3BP3O12:Eu3+,Dy3+ phosphor can be used as a luminescent material on a near-ultraviolet excited white light LED. [ABSTRACT FROM AUTHOR]

In the present paper, Nd, Nb co-doped La2Mo2O9 system is investigated to understand phase transition, ionic conductivity and dielectric relaxation phenomenon. X-ray diffraction study confirms order-disorder phase transition by disappearance of peak splitting of (231) in co-doped LMX system, which is associated with monoclinic phase and is observed for LMX-Pure at around 2θ = 47–48°. In co-doped system, two dielectric relaxation peaks are observed, which are associated with diffusion process between O(1)-O(2) and O(1)-O(3) oxygen ion ←→ vacancies sites, while diffusion process O(1)-O(3) is supposed to be occurred in parent system having single relaxation peak. Thus dielectric relaxation phenomenon indicates phase transition is proceeding with static-to-dynamic disorder transition. Electric modulus data are revealed to ascertain correlation of relaxation dynamics and oxy-ion conductivity in co-doped LMX system. The extracted data of activation energy of oxy-ion conductivity at intermediate temperature range (500–700 °C) of co-doped samples is found relatively lower than that of the parent sample. The study reveals that incorporation of Nd, Nb co-doped in LMX system successfully suppress the phase transition and enhanced ionic conductivity at intermediate temperature range and found suitable as electrolytes for intermediate temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

In this paper, studies of structural, microstructural and electrical properties of calcium, tin, and selenium modified bismuth sodium titanate (Bi0.5Na0.5TiO3) compound with a general chemical formula (Bi0.45Na0.45Ca0.1) (Ti0.9Sn0.05 Se0.05) O3, synthesized by a high-temperature mixed oxide reaction method, have been discussed. Analysis of room temperature X-ray diffraction data confirms the formation of perovskite single-phase compound with rhombohedral symmetry. The surface morphology of the sample exhibits the uniform distribution of grains of varying size. Studies of the electrical parameters (dielectric, impedance and conductivity) of the material, collected at various temperatures (75–375 °C) in a wide frequency range (1 kHz–1MHz) have provided its conduction and relaxation behavior. The electric field dependent current density (J-E) characteristics suggest the Ohmic behavior while the field dependent polarization (P-E loop) confirms the ferroelectric nature of the studied material. [ABSTRACT FROM AUTHOR]

MnO2 added potassium sodium niobate (KNN) electroceramics were prepared by conventional double sintering ceramic route. The samples prepared have the compositional formula K0.5Na0.5NbO3+ (x)MnO2 where x = 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt% and 25 wt% is the amount of MnO2 added. The sintering of the samples was done using the microwave sintering technique. Pre-sintering was done at 850 °C for 20 min. Different sintering conditions may results in KNNs with varied properties. The studies of the structural properties of the prepared samples were done by X-ray diffraction (XRD) technique. It has been found that addition of MnO2 to KNNs and sintering at 1000 °C for 20 min and at 1050 °C for 10 min showed all the KNNs crystallization in tetragonal phase with nearly similar structural parameters. The electrical properties such as dielectric constant, dielectric loss and ac conductivity of the prepared samples were investigated using an impedance analyzer. The room temperature frequency variation of electrical properties showed a dispersive behavior for all the samples. The temperature variation of the dielectric properties showed an increase with the increase of temperature. The results of the various measurements are discussed in the paper. [ABSTRACT FROM AUTHOR]

A comparative analysis of structural and immittance characteristics of bismuth and antimony based fourfold layered perovskites BaBi4-xSbxTi4O15 (x = 1–4), synthesized by high temperature mixed oxide method are reported in this paper. The room temperature XRD data shows single phase orthorhombic crystal system for all the compounds with some variation in lattice parameters. Mostly uniformly and homogeneously distributed grains with a smaller number of voids are observed over pallet surface in SEM micrographs which exposes the good quality of the samples. Immittance spectroscopy indicates the influence of bulk and bulk boundary in the resistive and capacitive properties of the materials. The bulk resistance is found to be very small for when Bi is completely substituted by S band behaves as a good conductor. Negative temperature coefficient of resistance characteristics is observed from the impedance analysis, which confirm the semiconductor characteristics of the materials within the experimental range of temperature. Non-Debye type of relaxation mechanism is seen from the Nyquist plots. From the modulus spectroscopy, the higher capacitive properties are observed at lower temperature. The charge carriers in the samples have long-range as well as short-range ordering which are confirmed from complex impedance and modulus study of the studied samples. [ABSTRACT FROM AUTHOR]

In this paper, we report that the DC electrical conductivity is a very interesting property which provides important information about mechanism in solid. The CdS–B2O3 glasses of different composition were prepared in the laboratory. The conductivity was measure in the temperature 308–473 K. A plot of log σ versus 1/T is drawn for various compositions. From this it observed that electrical conductivity increases linearly with temperature which shows Arrhenius nature for different composition of CdS–B2O3. Activation energy for all samples is laying in the range 0.29–0.82 eV which decreases with mol% of CdS. The decrease in conductivity for greater B2O3 concentrations may be due to reduced segmental motion. The temperature dependence conductivity shows percolative behavior and a clear cross over from Vogel–Tamman–Fulcher to Arrhenius behavior. The adiabatic and non-adiabatic hopping conduction is checked by drawing a plot of log σ versus activation energy at fixed temperature. [ABSTRACT FROM AUTHOR]

Li- Co-Y ferrites having the general formula Li0.495Co0.01YxFe2.485-xO4 where x ranges from 0.00 to 0.25 in steps of 0.05 were synthesized by chemical sol-gel auto combustion method. The sol-gel derived nanoferrite powders were initially heated at 300 °C for 1 h. The powders were then processed, shapped and heated at 1000 °C for 1 h using conventional furnace. The structural properties were studied using X-ray diffraction (XRD) technique and Fourier Transform Infrared (FTIR) Spectroscopy. The studies confirmed the formation of single phase with spinel structure in all the sol-gel synthesized ferrites. Scanning Electron Microscopy (SEM) studied the microstructure of the samples and found the formation of well defined grains. Vibrating Sample Magnetometer (VSM) measured the magnetic hysteresis properties of the prepared ferrites and found that saturation magnetization decreased but coercivity increased with Y3+ substitution. The results of the measurements obtained have been discussed in the paper. [ABSTRACT FROM AUTHOR]

In this article, the behavior of pyroelectric coefficient and spontaneous polarization with temperature have been studied for pure (LG), 0.5 wt% (LG1) and 1 wt% (LG2) lanthanum doped lead germanate (Pb5Ge3O11) single crystals. These crystals were grown by method of controlled cooling of the melt. The pyroelectric coefficient of grown crystals was measured over a temperature range 40–300 °C, which shows a change in sign negative to positive for LG and LG1 while for LG2 it shows only negative sign for a said temperature range. The observed results of pyroelectricity and spontaneous polarization in pure and doped materials are discussed. The comparative study of room temperature values of pyroelectric coefficient measured by various methods, spontaneous polarization and figure of merit is presented in this paper. [ABSTRACT FROM AUTHOR]

Multilayer of Cadmium Sulphide (CdS) and Bismuth-doped Zinc Oxide (ZnO:Bi) is a direct band gap material, capable of use as a window layer material for silicon solar cells. With tuneable energy band gaps (2.41–2.71 eV)the ZnO:Bi/CdS window multilayer can allow for absorption of a wider range of wavelengths. This paper presents the varied number of ZnO:Bi/CdS multilayers and its effect on the optical properties. Samples were prepared using 3–11 layers of CdS and 3 layers of ZnO:Bi. Optical and structural properties were investigated through techniques including UV-Vis, XRD and FTIR analysis. Trends in energy band gaps were visible in relation to the number of layers used. The ZnO:Bi/CdS window layer demonstrated good absorption/transmission properties that make it a potential way of improving existing solar cell technology. Due to the high transmission rates, wavelengths of light (> Energy band gap of 1.1 eV) harnessed by Si cells, would not be hindered, while absorption of high energy photons (UV-Visible) can be improved on bulk Si solar cells. [ABSTRACT FROM AUTHOR]

In this research paper, we report the dielectric and electric investigation of series of dielectric ceramics samples with structural formula Ba2-xRe4+2x/3Ti8O24(where Re = Sm and La and x = 0.0, 0.2, 0.4 and 0.6). The dielectric parameters (i.e. dielectric constant and loss tangent) and ac conductivity are measured with impedance analyzer. This paper is presented to compare the effect of samarium and lanthanum doping on the properties of barium titanate. The research work concludes that lanthanum doping has more favorable effect on the properties. This paper also presents impedance analysis and V-I characteristics of all the samples. This is concluded that these properties are strongly dependent on frequency, temperature and composition. The investigation reports almost constant value of dielectric constant and very low loss tangent at lower temperatures. [ABSTRACT FROM PUBLISHER]

Optical second harmonic generation (SHG), which is sensitive to the symmetry breaking, provides a powerful experimental technique for investigation of ferroic materials, i.e. ferroelectrics, magnetics, and multiferroics. A far-field confocal microscopy provides three-dimensional imaging of an order parameter of ferroics with a spatial resolution up to diffraction limit of a probing wavelength. In this paper, we discuss general important consideration regarding SHG microscopy and show new imaging techniques for ferroelectric and magnetic domains and switching, bio-inspired ferroelectrics, as well as femtosecond laser annealed ferroelectric microstructures. [ABSTRACT FROM PUBLISHER]

Energy harvesting using cantilever based piezoelectric structure is most popular for harvesting electrical energy from ambient vibrations. Attempts are also made to increase the harvester power by means of tailoring the structural parameters of the cantilever beam. This paper presents a non-uniform beam based energy harvester associated with a piezoelectric patch to achieve higher power by means of tailoring the width of beam linearly with positive tapering ratio towards its free end. It is also proposed to introduce a rectangular and trapezoidal cavity in the uniform thickness-width tapered energy harvesters to further maximise the harvester voltage. The mode shapes and fundamental natural frequency of proposed energy harvesters are obtained analytically by using Euler-Bernoulli beam theory and its free vibration solution is analysed by using Bessel functions. The performance of the proposed energy harvesters is demonstrated through both analytical and experimental implementation. It is shown that the inclusion of the rectangular and trapezoidal cavity in the harvester beam significantly affects the output voltage due to the change in the neutral axis of beam. The effects of variation in thickness of rectangular and trapezoidal cavity on the mode frequencies, harvester voltage and power are determined analytically. From the results of analytical model and experimentation, it is concluded that width tapered beam increases the harvester voltage by 16.33% as compared to the energy harvester considered with uniform cantilever beam. Among all the energy harvesters projected during this paper, the maximum voltage is produced from the width tapered beam with trapezoidal cavity. The experimental results are in close agreement with the results obtained from the analytical model. [ABSTRACT FROM AUTHOR]

At the present work, we have studied high-intensity ultrasound fields of standing cylindrical waves, generated by cylindrical piezoelectric transducer with radial polarization in its internal volume filled by liquid. The paper is focused on the study of length-extensional and thickness vibrational modes of cylindrical piezoelectric transducer. We have performed the finite-element simulations of standing cylindrical waves formation inside the cylindrical transducer filled with a liquid by those oscillation modes of piezoelectric cylinder using ANSYS software package and compared effectiveness of different regimes of standing waves generation. [ABSTRACT FROM AUTHOR]

In a semi-review paper, the fundamentals of the vibronic (pseudo Jahn-Teller) theory of ferroelectricity in perovskite crystals of ABO3 type, its main achievements and significant applications, are given. The theory is derived from first principles. First, the pseudo Jahn-Teller effect (PJTE) is introduced and shown to be the only source of polar instability that triggers the spontaneous polarization of the crystal. The driving force of the PJTE is added covalency by distortion, which is essentially of local (chemical) origin. Then, the earlier more qualitative, but physical transparent results in application of the PJTE theory to ABO3 perovskites are presented, followed by the rigorous formulation in terms of Greens' functions theory. The form of the adiabatic potential energy surface (APES) for the metal B sites with eight equivalent minima, obtained analytically, is confirmed by DFT calculations, and its parameter numerical values were estimated for BaTiO3. It explains the occurrence of the three ferroelectric and one paraelectric phases, and order-disorder transitions between them as due to temperature dependent gradual overcome of the consecutive barriers between its eight equivalent minima. The theoretical treatment of the phase transitions is carried out in the mean-field approximation yielding near-to-experimental Curie temperatures. An important further development of this theory was reached more recently, for the first time revealing the role of spin in ferroelectric polarization of perovskites with the electronic dn configuration of the B ion. It was shown that, subject to the PJTE, not only d0 configurations may be unstable to produce ferroelectricity ("the d0 mystery"), but some other specific dn configurations with unpaired electrons may be dipolar active too, the crystal being thus both magnetic and ferroelectric (multiferroic). The necessary conditions for such multiferroicity are formulated for the whole n = 0,1,...10 variety of perovskites, and it is shown to be different in the two (or more) possible spin arrangements of the same ion, high-spin or low-spin for n = 3, 4, ...7. In conditions of spin crossover this leads to a magnetic-ferroelectric crossover that can be manipulated by external perturbations, including electric magnetization, already realized experimentally. A novel chapter is opened in application of the vibronic PJTE theory to important problems of materials science by analyzing the interaction of the ferroelectric perovskites with external perturbations. For the paraelectric phase of BaTiO3 with local dynamic-polar instability, any external electric field, strain, or stress violates the equivalency of the eight minima of the APES, quenching the polar dynamics, thus contributing an orientational polarization (like in polar liquids). It increases the permittivity, flexoelectricity, electrostriction, and external pressure effects by several orders of magnitude, confirmed experimentally. The theory explains also the formation of polar nanoregions and laxor properties in the paraelectric phase as due to the "local drops formation" when two phases may coexist locally (which is not possible in displacive theories where the formation of a polarized phase requires long-range interaction). A significant part of the paper is devoted to discussion and comparison of the vibronic PJTE theory of ferroelectricity with other theories and empirical data. It is shown that a series of experimentally observed specific properties of perovskite ferroelectrics encounter fundamental difficulties in attempt to explain their origin by means of displacive theories. This is related to the B ion being (instantly) polar displaced along the trigonal axis in all the phases, the order-disorder character of the phase transitions, the role of the spin of the B ion in the ferroelectric polarization, the strong dependence of ferroelectricity and multiferroicity on the chemical composition, the giant effects in interaction with external perturbations, the formation of polar nanoregions in nonpolar phases leading to relaxor behavior, etc. All these unique properties of perovskite ferroelectrics follow directly from the vibronic (PJTE) theory. [ABSTRACT FROM AUTHOR]

An adaptive energy harvesting system for high voltage piezoelectric generators is presented in this paper. Maximum power point tracking scheme is applied in the adaptive system. Low-power-consumption schemes are applied in the control system and harvesting circuit. A self-startup circuit is also applied to the system. Theoretical analysis was explored to determine optimal parameters for the harvesting system. Experiments were done to verify the theoretical analysis. The experimental results show that the harvesting system can achieve an efficiency of 17.5 ∼ 73.3% for piezoelectric generator with a peak open-circuit voltage of 6 ∼ 20 V. And the harvesting system can be self-powered from low input power as 25 μW. The average power consumption of the microcontroller can be low as 3.5 μW. [ABSTRACT FROM AUTHOR]