In present work we report that the observation of Meyer Neldel rule and crystallization rate constant stability of Se93-x Zn2Te5Inx (0 ≤x≤ 10) chalcogenide glasses. A strong correlation has been observed between the pre-exponential factor (K 0) and activation energy of crystallization (E c). Such a strong correlation between K 0 and E c indicates that the presence of compensation effect under the non-isothermal crystallization processes. Further, obtained results also demonstrate that the crystallization rate constant stability is higher at 6 at.wt.% of indium.

This article provides an extensive outlook of different types of piezoelectric actuated micro-pumps published in the literature recently. We start by reminding the reader about the conventional operating parameters used to quantify the capabilities of these devices. After this introductory stage, we describe and classify the most prominent micro-pump's geometries found with piezoelectric actuation. At this point we identify the parameters given previously for each pump in order to establish a subsequent discussion in which the trends of different families are compared. Specific attention is given to the particularities of each case namely: flow rates and backpressures.

Phase pure perovskite structure (1-x)Pb(Zr1/2Ti1/2)O3-xPb(Ni1/3Nb2/3)O3 (PZT-PNN, x = 0.05-0.40) ferroelectric ceramics were prepared by conventional solid-state reaction method via the columbite precursor technique. The PZT-PNN ceramics sintered at 1225 °C for 2 h exhibit rather homogenous microstructure and high relative density. With the increase of the Pb(Ni1/3Nb2/3)O3 (PNN) content, the crystal structure of PZT-PNN changes gradually from tetragonal perovskite structure to rhombohedral one, where the morphotropic phase boundary (MPB) composition locates at a region of x = 0.15-0.20 determined by X-ray diffraction (XRD) and dielectric measurements. Furthermore, the dielectric response peaks of PZT-PNN also changes from narrow, sharp and almost frequency independent peaks of normal ferroelectrics to broad, diffused and apparent frequency dependent peaks of relaxor ferroelectrics, accompanied by the decrease of the temperature of dielectric maximum (T m ) with the increase of the PNN content. PZT-PNN with the MPB composition exhibits integral excellent electrical properties, where 0.80PZT-0.20PNN exhibits the maximum value of dielectric constant ε m 26750 at 280.6 °C, the remanent polarization P r is 25.17 µC/cm2, coercive field E c is 5.82 kV/cm, and piezoelectric constant d 33 reaches 281 pC/N.

The effect of Cu additive on the dielectric relaxation of two binary Se-Te glassy systems, comparing the properties of a-Se75Te25, a-Se85Te15 and a-Se75Te15Cu10 alloys has been reported. The temperature and frequency dependence of dielectric parameters in Glassy Se75Te25, Se85Te15 and Se75Te15Cu10 alloys are studied by measuring capacitance and dissipation factor in the frequency range (1 kHz-5 MHz) and temperature range (300-350 K). A Debye like relaxation of dielectric behavior has been observed. A comprehensive study on the relaxation mechanism revealed that the presence of grains and grain boundaries across the pallet thickness is the basic relaxation process. A detailed analysis shows that the observed dielectric loss is in agreement with the Guintini's theory of dielectric dispersion based on two electron hopping over a potential barrier and is applicable in the present case. Dielectric constant (ε’), dielectric loss (ε”), loss tangent (δ) and capacitive reactance (X c ) are found highly frequency and temperature dependent. Dependence of these dielectric parameters over the metallic impurity Cu, has also been found in the present glassy system and has been discussed in terms of electronegativity difference between the elements used in making the aforesaid glassy system.

Cu doped cadmium sulfide (CdS:Cu) nanoparticles were prepared with a wet chemical synthesis by mixing the reactants in a double distilled water solvent. Thioglycerol (TG) was employed as the capping agent and also as the reaction catalyst. Properties of the particles were investigated using UV absorption; photoluminescence spectroscopy (PL) and X-ray diffraction analysis (XRD). The particle size of the prepared CdS:Cu nanoparticles was estimated to be about 4 nm. The XRD pattern of CdS:Cu nanoparticles reveals a hexagonal crystal structure at room temperature. Variation of the TG concentration does not shift the position of the excitonic peak in the absorption spectrum but the PL intensity increases as the TG concentration is increased. The PL intensity decreases with increasing Cu concentration.

Hybrid organic-inorganic heterostructures have been produced using the conducting polymer PEDOT:PSS and three types of semiconductor single crystals, i.e., high-ohmic and low-ohmic cadmium sulphide (CdS, n-type semiconductor) and low-ohmic cadmium telluride (CdTe, p-type semiconductor). A photovoltaic (PV) response was observed upon light illumination of both CdS/PEDOT:PSS and CdTe/PEDOT:PSS heterojunctions. Photocurrent spectra unequivocally evidenced the main contribution of band-band transitions of inorganic crystals to the PV response, and current-voltage measurements indicated that band bending due to a depleting region at the surface of the crystals takes place. The suggested band bending was consistent with the model of the vacuum level alignment only at the interface of the low-ohmic CdS crystal and the polymer, which results in formation of a Schottky barrier responsible for the PV response. However, the analogous band bending for high-ohmic CdS and p-type CdTe crystals could be associated only with the Fermi level pinning regime at the semiconductor interfaces.

In this study, both the intersubband optical absorption coefficients and the refractive index changes in triple quantum well (TQW) with different well shapes for different barrier widths is theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband transitions and the energy levels in triple quantum well can importantly be modified and controlled by the barrier width. By considering the variation of the energy differences, it should point out that by increasing barrier width we can obtain a blue or red shift in the intersubband optical transitions. The sensitivity to the barrier width of the absorption coefficient and the refractive index changes can be used in various optical semiconductor device applications.

In this work, we investigate the emission of the nano-hole array in an ultrathin silver film at infrared regime. It is shown that when the incident light illuminates the nano-hole array, the localized surface plasmons are excited and serve as electric dipoles. The emission of the nano-hole array presents a strong directivity. The maximum radiation is located at infrared regime, and it can be tuned by the period of the nano-hole array, the incidence angle and the polarization of the excitation light. These findings extend our understandings of optical property of metallic nano-structures and provide a unique way to achieve infrared antenna arrays, which may achieve potential applications in photovoltaics and telecommunication.

The stability, structural, elastic, electronic and optical properties of perovskite hydrides BaLiH3 and SrLiH3 were investigated by the density functional theory. The calculated lattice parameters are in well agreement with previous calculation and experimental data. The energy band structure, density of states, born effective charge and Mulliken charge population were obtained. BaLiH3 and SrLiH3 present an indirect band gap of 2.23 eV and 1.86 eV at equilibrium. The top of the valence band reflects the s electronic character for both structures. Furthermore, the absorption spectrum, refractive index, extinction coefficient, reflectivity, energy-loss spectrum and dielectric function were calculated. The origin of the spectral peaks was interpreted based on the electronic structure. The static dielectric constant and static refractive index are proportional to the fundamental indirect band gap.

AlGaN/GaN high electron mobility transistors (HEMTs) with sapphire (Al2O3) substrates reveal anomalies like kink effect, current collapse, hysteresis phenomena on I ds -V ds and I ds -V gs . These parasitic effects can be attributed to the presence of traps in the hetero-structure. Deep defects analysis was performed by conductance deep level transient spectroscopy (CDLTS) under drain pulse. Four electron traps have been detected with activation energy and capture cross-section of 2.62 eV, 1.18 eV, 0.97 eV, 0.48 eV, σ n = 2.4 × 10-17 cm2 and σ n = 2.37 × 10-14 cm2, σ n = 2 × 10-12 cm2 and σ n = 4.67 × 10-14 cm2 respectively. The localisation and the identification of these traps have occurred and a correlation between defects and parasitic effects has been discussed.

Ba2Ca(BO3)2: Eu2+ green phosphors were prepared by sol-gel process. The crystallization processes of the phosphor precursors were characterized by X-ray diffraction (XRD) and thermogravimetric analysis (TG). The photoluminescence (PL) results showed that this phosphor was efficiently excited by ultraviolet (UV)-visible light in the wavelength range from 300 to 500 nm and emitted intensely green light with a broad peak at around 520 nm, causing in to exhibit a bright green emission. The critical quenching concentration of Eu2+ in Ba2Ca(BO3)2: Eu2+ phosphor was about 0.10 mol. Based on the experimental results, it is identified that the dipole-dipole interaction in the mechanism of concentration quenching of Eu2+ in the Ba2Ca(BO3)2: Eu2+ phosphor. The CIE of the optimized sample was calculated (x, y) = (0.23, 0. 63).

GaAs nanocrystallites are elaborated by electrochemical etching of n+ type GaAs substrates. Photoluminescence (PL) and atomic force microscope (AFM) images analysis are used to study the porous layers obtained with different etching times. Two kind of quantum confinement due to the formation of two nanostructures of different sizes are observed from room temperature photoluminescence (RTPL) spectra. The surface topography and the density of grains of the porous GaAs (π-GaAs) samples are investigated using the AFM technique. AFM images showed that the structure of films was nanocrystalline with a grain size close to 7 nm, this was confirmed by photoluminescence spectroscopy (PL) and the effective mass theory.

This work presents the use of molecular dynamics (MD) and the code of Dl_Poly, in order to study the structure of fluoride glass after melting and quenching. We are realized the processing phase liquid-phase, simulating rapid quenching at different speeds to see the effect of quenching rate on the operation of the devitrification. This technique of simulation has become a powerful tool for investigating the microscopic behaviour of matter as well as for calculating macroscopic observable quantities. As basic results, we calculated the interatomic distance, angles and statistics, which help us to know the geometric form and the structure of PbF2. These results are in experimental agreement to those reported in literature.

We demonstrate a very stable silver-coated mirror exploiting novel MgO/SiO2 double layers. It was found that the MgO/SiO2 protective layer provides a good adhesion and protection to the silver surface. Using epoxy-Ti(40 nm)-Ag(60 nm)-MgO(5~10 nm)-SiO2(25 nm) mirror structures, we achieved over 95% reflectivity and observed a minimal degradation in reflectance even after severe environmental tests.

In this paper, a new calculation approach is developed and applied, for the first time, to different dielectric scales using the thermal step method (TSM). The thermal aspect of the approach concerns insulating materials from nano to macro-scales. The theoretical approach is based on the ballistic-diffuse transport taking into account the relaxation time of heat phonons and their effects on the trapped space charges. These effects are revealed on the temporal evolution of the induced image charges that constitute the electrical signal of the thermal step method. The temperature distributions and the TSM induced image charges are obtained by applying the numerical finite element method, the Newmark direct integration, the mean value theorem and the composite Simpson approximation. In a first step, the results of the temperature distributions are validated with those obtained by Boltzmann and Chen models for nano-polyethylene sample. In a second step, our approach is validated with TSM previous works using the Fourier's model for space charge characterizations in the micro and macro-dielectrics. The validated results of the TSM induced image charges for micro and macro-scales show good agreements, and prove that our approach is a consistent tool to be applied in space charge characterizations for different dielectric scales.

Structural, optical and nanomechanical properties of nanocrystalline Zinc Telluride (ZnTe) films of thickness upto 10 microns deposited at room temperature on borosilicate glass substrates are reported. X-ray diffraction patterns reveal that the films were preferentially oriented along the (1 1 1) direction. The maximum refractive index of the films was 2.74 at a wavelength of 2000 nm. The optical band gap showed strong thickness dependence. The average film hardness and Young's modulus obtained from load-displacement curves and analyzed by Oliver-Pharr method were 4 and 70 GPa respectively. Hardness of (1 1 1) oriented ZnTe thin films exhibited almost 5 times higher value than bulk. The studies show clearly that the hardness increases with decreasing indentation size, for indents between 30 and 300 nm in depth indicating the existence of indentation size effect. The coefficient of friction for these films as obtained from the nanoscratch test was ~0.4.

Here, large-scale ordered periodic silicon pillar arrays were prepared using nanosphere lithography. And, the diameter and the density of nanopillar arrays are determined by the initial diameter of polystyrene (PS) spheres. In our experiment, the nanopillar has a diameter of approximately 50 nm, and the density of silicon pillar is 6×109/cm2. This array shows a field emission property with a low turn-on field of 9.8 V μm-1 at a current density of 10 μA cm-2. And the field enhancement factor is about 560. The Fowler-Nordheim plot obtained is linearly dependent, indicating that the emission current arises from the F-N tunnelling effect.

ZnSe nanorods are grown by varying the amount of reducing agent Sodium borohydride and keeping the amount of zinc chloride, selenium powder constant. The samples are characterized using electron diffraction techniques. Simultaneously optical absorption, photoluminescence and longtime photorelaxation of these samples are studied at room temperature. An increase in band gap is observed in each case as compared to bulk ZnSe. Also the formation of nanorods is found to be favourable at particular ratio of reducing agent. An attempt is made to explain the growth and correlate the structural, optical and electrical properties.

The present paper reports the study of a porous silicon based microcavity for a potential chemical sensing application using tris-(8-hydroxyquinoline) aluminum (Alq3) molecules. Porous silicon based planar microcavity was first designed and fabricated using the electrochemical etching technique. Photoluminescence emission of a single porous silicon layer after immersion in an Alq3 solution was first carried out in order to verify that the Alq3 molecules were bound to the porous surface. A wide green band centered at 519 nm, typical of a nano-structured Alq3 film, was observed. Reflectivity measurements of the porous silicon microcavity were then performed for different aluminum concentrations of the Alq3 solution. The microcavity device showed a good sensibility for the Alq3 molecules and an important shift of the microcavity photonic resonance was observed. This device might be considered for a potential aluminiun sensing application.

The temperature distribution in dentin under pulse Er:YAG laser radiation has been studied and simulated, analytically. For this reason we considered heat deposited in dentin due to laser radiation. The heat conduction equation has been solved and the temperature distribution has been obtained. The obtained results then have been used for dentin and discussed. Based on the simulation, the temperature rise to 40.5 K for 300 mJ and 21 pulses which have very good consistency with the experiment.