Using the method of extracting a series resistance from a p-n diode current-voltage characteristics developed earlier, parameters of low-temperature non-ohmic conduction in bases of two types of silicon diodes have been studied. In the diode of the first type, with finite value of impurity ionization energy, low-temperature impurity breakdown in the diode base is accompanied by hysteresis of its conduction; in the diode of the second type, the impurity breakdown occurs in soft form. In the pre-breakdown region, the results obtained for the diodes of both types, agree completely with existing picture of non-ohmic hopping conduction in spite of significant space inhomogeneity of the diode structures and non-equilibrium character of the transport in them. In the post-breakdown region, the certain peculiarities are available. For the first time the activationless hopping conduction has been revealed in crystalline silicon.

An analytical method is proposed to address, the effects of geometry variations in piezoelectric bimorph actuators and the theory is applied to an actuator with an exponential tapered shape. Through five different examples, it is demonstrated, through theoretically calculated electric admittance spectra, that for a fixed length, the resonant frequency can be tailored by changing the tapering rate of the actuator. The theoretical predictions were also experimentally verified and excellent agreement was found. Our theoretical model provides a conventional tool for design optimization of such tapered bimorph actuators.

We report on a modified bulk heterojunction (BHJ) solar cell in which a nanohybridized composition of lead sulfide (PbS) colloidal quantum dots (QDs) and multiwall carbon nanotubes (MWCNTs) were incorporated into a standard regioregular poly(3-hexylthiophene) (rr-P3HT):phenyl-C61-butyric acid methyl ester (PCBM) blend. This hybrid ((P3HT:PCBM):PbS-QD/MWCNT) solar cell exhibits an increased power conversion efficiency (PCE) of 3.40% as compared to that of 2.57% from a controlled P3HT:PCBM standard BHJ solar cell fabricated under similar experimental conditions. The 32% increase in efficiency is effectively attributed to the extended quantum-dot-sensitization in the near-infrared (NIR) due to the absorbance of QDs/CNTs in the spectral range from 700 nm to 1450 nm. The strong conjugation, controlled coupling and nanohybridization of QDs/CNTs played an important role towards the improvement of PCE since it is proposed that excitons generated in the QDs can be efficiently dissociated at the QD/CNT interface by transferring the electrons to the CNTs followed by holes transfer to the P3HT. In this ternary blend, the staggered energy band alignment between P3HT and the QDs allows both electrons and holes transfer from the QDs to the PCBM and the P3HT, respectively. Subsequently, the dissociated carriers have been efficiently transported by the CNTs and P3HT to favorable respective electrodes.

In the present work, we study the dielectric behavior of various ternary mixtures composed of epoxy resin (RE), of one of three different titanates (barium titanate, BaTiO3; calcium titanate, CaTiO3; magnesium titanate, MgTiO3) respectively with one of three oxides (calcium oxide, CaO; manganese dioxide, MnO2; zinc oxide, ZnO) using time domain reflectometry (TDR). The different composites are mixed at room temperature in different volume fractions keeping the epoxy resin at a constant volume fraction. Several mixture combinations are studied to see the oxides influence on the titanates dielectric behavior in the range from DC to 10 GHz. This is done through the experimental determination of the dielectric constant εs. A noticeable effect has been recorded at the low frequency and which consists of an increase of this dielectric permittivity when growing the volume fraction of manganese dioxide. One meaningful point of this study is the lowest static conductivity value (8.017 × 10−3/(Ωm)) being reached with an incursion of 7.5% of MnO2 in a ternary mixture composed of RE, MgTiO3 and MnO2. In addition, the behavior obtained experimentally has been validated by the Lichtenecker modified model. This study interest lies on an application of these materials in microelectronics and particularly in telecommunication components manufacturing.

A facile generic strategy of solid-state reaction under air atmosphere is employed to prepare LiNi0.8Co0.15Al0.05O2 layer structure micro-sphere as cathodes for Li-ion batteries. The impurity phase has been eliminated wholly without changing the R-3m space group of LiNi0.8Co0.15Al0.05O2. The electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathodes depend on the sintering step, temperature, particle size and uniformity. The sample pre-sintered at 540 °C for 12 h and then sintered at 720 °C for 28 h exhibits the best electrochemical performance, which delivers a reversible capacity of 180.4, 165.8, 154.7 and 135.6 mAhg−1 at 0.2 C, 1 C, 2 C and 5 C, respectively. The capacity retention keeps over 87% after 76 cycles at 1 C. This method is simple, cheap and mass-productive, and thus suitable to large scale production of NCA cathodes directly used for lithium ion batteries.

Using the discrete ordinate method, we solve the equations of phonon radiative transfer for thin films analytically, and deduce closed-form expressions for three thermophysical properties including the phonon intensity, heat flux density and effective phonon thermal conductivity. These analytical expressions provide a fast and convenient way to analyze heat conduction behavior in thin films, and thus allowing us to comprehend how the film thickness and bulk phonon mean free path affects the thermophysical properties. Also we extend these expressions from thin films to one period of superlattices, and demonstrate that adjusting the thickness ratio of two layers can control its effective phonon thermal conductivity.

Mn(II) ions doped NaCaAlPO4F3 phosphor was synthesized by using solid state reaction method. The prepared sample was characterized by various spectroscopic techniques such as powder XRD, SEM with EDS, Optical absorption, electron paramagnetic resonance (EPR) and photoluminescence. From powder XRD, the average crystallite size was calculated about 46 nm. SEM images showed the irregular shaped entities present in the sample. Optical absorption spectrum gave the absorption bands in UV-VIS region which are the characteristic of Mn(II) ions in octahedral symmetry. The room temperature EPR spectrum exhibited a six weak hyperfine splitting lines centered at g = 2.0. Photoluminescence spectrum showed the emission peaks in visible region, from yellow to red with an excitation wavelength of 465 nm. From the emission spectral data, the CIE chromaticity coordinates were also calculated as (x = 0.661, y = 0.338).

The energy leakage rate of Rayleigh wave generated by a laser pulse applied on a fluid-solid interface was analyzed. Data were presented for different fluid-solid interfaces based on the overall solution of wave motion, which was obtained by using finite element method. The results show that the energy leakage rate increases linearly with the increase of acoustic impedance ratio of the fluid and solid material, and that the increase in acoustic impedance matching of those two materials will be able to increase the acoustic leakage of Rayleigh wave and the excitation efficiency of leaky Rayleigh wave.

A systematic current annealing treatment to achieve a high magnetoimpedance (MI) response in CoFeSiB amorphous ribbons is demonstrated. After current annealing in the present of air, although transverse permeability can increase but because of a significant surface oxidization, condition to reach a high MI response cannot be achieved. Additionally, this process leads to asymmetric MI response. In this paper, the effect of mechanical polishing of samples after current annealing is studied. We show a significant MI change by removing the hard magnetic phase on sample surface after current annealing. Results are useful and promising to be employed to reach high MI response for sensing applications.

A theoretical model for the frequency response of magnetoelectric (ME) effect in thin cylindrical piezoelectric-magnetostrictive composites is presented by using constitutive and elastodynamic equations. The calculated results show that there is a resonant enhancement peak of ME voltage coefficient in the electromechanical resonance region and the ME voltage coefficient at resonance frequency exceeds that at low frequency by one or two orders of magnitude. The resonance frequency is predicted to increase with decreasing average diameter D̅$ \bar{D}$ and increasing thickness of magnetostrictive layer tM of the cylindrical composite, which is in good agreement with the experimental results reported in literatures. The corresponding resonance ME voltage coefficient increases with increasing tM , but reaches to a peak value and then decreases with increasing D̅$ \bar{D}$. It is indicated that the ME effect of trilayered cylindrical composite is less than that of bilayered one, possibly due to its symmetric structure. Under clamped condition, the resonance frequency will shift to a very high value for both trilayered and bilayered cylindrical composites, while the ME effect has different performance, enhanced in bilayered but suppressed in trilayered cylindrical composite. Our model shows that one can obtain strong ME effect and proper resonance frequency by selecting suitable materials, optimizing its geometry structure and varying mechanical boundary conditions for the cylindrical composite structure

This study is carried out to establish a correlation between optical absorbance and track density in CR-39 detectors exposed to different fluences of D-T (14 MeV) neutrons. This can be useful in estimating the neutron fluence and hence the dose without involving the tedious track counting procedure, especially when the track density is extremely high. Variation in the optical properties is studied using UV-VIS-NIR (ultraviolet-visible-near infrared) spectroscopic technique. The neutron-induced recoil tracks are developed by chemical etching and the track density is determined. The optical transmission spectra are obtained for pristine and neutron irradiated detectors before and after etching. A linear relationship is obtained between the track density and the optical absorbance with increasing neutron fluence. Another objective of this work is to study the effect of etching on the optical properties such as transmittance and absorbance of irradiated CR-39 detectors. The optical properties are found to be changing due to the development of tracks in the detector.

Rare earth gadolinium oxide film has been studied by X-ray absorption fine structure (XAFS) at Gd L3-edge and energy electron loss spectroscopy (EELS) spectroscopies. XAFS data showed that the nearest Gd coordination shells consist of six oxygen atoms at ~2.308(2) Å and six gadolinium atoms at ~3.57(2) Å corresponding to Gd2O3 with a space group of Ia-3. EELS analysis of the film revealed excitations at the energies of 14.2, 19.9 eV which are due to electron transition from the valence band to the conductive one; excitations at the energies of 22.2–23.5 eV originated from valence electrons plasmon oscillations (bulk plasmons); and the excitation at 5.5 eV resulted from the electron transition at defects. When the photon energy changed from 1.5 to 5.0 eV the refractive index increased from 1.92 to 2.15.

We consider illumination systems and mathematical algorithms for determination of the anisotropy and topographical features of an illuminated surface from its reflection images. As a particular example we study determination of the fiber orientation of paper surface. We also consider illumination systems with multiple light sources, and introduce optimization algorithms that exploit different spectral bands of these light sources. We show that a system of three light sources, e.g., a blue, green and red LED placed in a regular triangular form, efficiently prevents distortion of the above features. It is also easy to implement in applications, e.g., of the paper industry. We furthermore show that a pentagonal illumination system would be even better. However, in this case a five-colour photographic system and the corresponding light sources would be needed.

In this study, the effect of a dense compression nitrogen plasma flow on a microstructure and the elemental and phase compositions of a “tantalum layer-silicon substrate” system is investigated. Predeposited tantalum thin films (∼2 μm thick) on Si(1 1 1) and Si(1 0 0) substrates were exposed to a single plasma pulse or to a series of pulses. The power density absorbed by the target, plasma pulse duration and discharge current were 1.2 GW/m2, 100 μs and 80 kA, respectively. The temperature field distribution and its time evolution were approximately simulated. SEM and EDX analyses revealed the presence of tantalumrich domains consisting of nano-sized particles and spherical multilevel structures. X-ray diffraction analysis showed the formation of crystalline hexagonal tantalum-rich silicides and tantalum nitride. A mechanism explaining the structural changes and phase transformation of the Ta/Si system is proposed.

We characterize and employ a light transmission technique to measure the dispersivity of a solute in the flow of a neutrally-buoyant non-Brownian spherical particle suspension in a Hele-Shaw cell (parallelplate axial flow). Particle radii (a) were 20 and 40 μm, the particle bulk volume fraction ϕbulk was 0.2, and the cell aperture was 420 ± 10 μm. In each displacement experiment a suspension with a colouring solute displaces a transparent one at constant flow rates ranging from 0.721 to 0.928 mL/min (corresponding to solute Péclet numbers (Pes) between 350 and 450). A reference measurement, identical to the displacement ones but without particles in the flow (ϕbulk = 0), were performed in the same experimental assembly for comparison purposes. A light calibration related the transmitted intensity I to the solute concentration c for each combination of ϕbulk and a. The time variation of the solute concentration was found to be well-fitted by the solution of the advection-dispersion equation (ADE) in the range of Pes studied, and consequently a dispersion coefficient D and a dispersivity ld of the solute were measured.

Investigation the multibody contact-sliding occurred at atomic discrete contact spot will play an important role in determine the origin of tribology behavior and evaluates the micro-mechanical property of nanomaterials and thus optimizing the design of surface texture. This paper carries out large scale parallel molecular dynamics simulation on contact-sliding at atomic scale to uncover the special physical essence. The research shows that some kind of force field exists between nanodot pair and the interaction can be expressed by the linear combination of exponential function while the effective interaction distance limited in 1 angstrom for nanodot with several tens of nanometer diameter. The variation tendency about the interaction force between nanodot array is almost the same between nanodot pairs and thus the interaction between two nanodot array can be characterized by parallel mechanical spring. Multibody effect which dominates the interaction between atoms or molecules will gradually diminish with the increasing of length scales.