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In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm2with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm2, reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.

In this work, n-type porous silicon (n-PS) was fabricated via photoelectrochemical etching (PECE) method with different etching current densities, including 5, 10, 15, 20, and 25 mA/cm2 at constant concentration of HF about 20%. The suspension mixture of standard copper oxide nanoparticles (CuO-NPs) was prepared by dissolving 0.2 g of CuO powder in 100-ml ethanol. Then, CuO-NPs were deposited on n-PS surface employing the drop-casting method. X-ray diffraction and scanning electron microscope techniques proved the cubic crystal phase with porous morphology. The current–voltage (J-V) measurements were conducted in the dark and under illumination with different intensities for n-PS and CuO/PS samples. To evaluate the photodetector-sensing performance, the responsivity (Rλ), detectivity (D), and the quantum efficiency (Q.E) tests were performed for all samples at room temperature. All results showed that the CuO-NPs on the n-PS surface lead to increase Rλ, D, and Q.E compared with n-PS-only sample.

RuO2–ZnO nanocomposite with high adsorption ability of Pb(II) was productively fabricated through mediated pectinose solution. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDS), pore and surface area characteristics (BET), and Fourier transforms infrared (FTIR) results showed the formation of Ru-doped ZnO with new RuO2 rutile phase. The removal kinetics process was fitted with the pseudo-second-order model. Nevertheless, the adsorption rate is possibly governed by the Pb(II) ions intra-particular diffusion. The average diameter of the nanocomposite was about 32 nm. The fabricated nanopowders have a rapid adsorption equilibrium time of 40 min and excellent competence for Pb(II) ion elimination (184.5 mg g−1).

Thin films of CuPc of various thicknesses (150,300 and 450) nm have been deposited using pulsed laser deposition technique at room temperature. The study showed that the spectra of the optical absorption of the thin films of the CuPc are two bands of absorption one in the visible region at about 635 nm, referred to as Q-band, and the second in ultra-violet region where B-band is located at 330 nm. CuPc thin films were found to have direct band gap with values around (1.81 and 3.14 (eV respectively. The vibrational studies were carried out using Fourier transform infrared spectroscopy (FT-IR). Finally, From open and closed aperture Z-scan data non-linear absorption coefficient and non-linear refractive index have been calculated respectively using He-Ne laser which have beam waist of (24.2 μm), wave-length of (632.8 nm) and Rayleigh thickness was 2.9 mm.

Electronic properties including (bond length, energy gap, HOMO, LUMO and density of state) as well as spectroscopic properties such like infrared, Raman scattering, force constant, reduced mass and longitudinal optical mode as a function of frequency are based on size and concentration of the molecular and nanostructures of aluminum nitride ALN, boron nitride BN and AlxB7-XN7 as nanotubes has calculated using Ab –initio approximation method dependent on density functional theory and generalized gradient approximation. The geometrical structure are calculated by using Gauss view 05 as a complementary program. Shows the energy gap of ALN, BN and AlxB7-XN7 as a function of the total number of atoms , start from smallest molecule to reached to Nano structure wurtzoid, wurtzoid2c and triwurtzoid, these values are compared with the experimental bulk value of ALN and BN (6.2 eV and 6.4 eV) respectively. Longitudinal optical mode frequency, force constant and reduced mass are presented which are agreement with experimental results.

The electronic and spectroscopic properties of ZnO nanostructures were evaluated by ab-initio density functional theory and generalized gradient approximation calculations combined with many-body, all calculations using Gaussian 09 program. These electronic properties including energy gap, density of state and bond length were calculated, also the spectroscopic properties like infrared and Raman scattering, force constant and reduced mass were calculated and compared with longitudinal optical mode of vibration. The geometrical structure of ZnO molecules and wurtzoids nanostructures were studied with the help of using Gauss view 05 program. The energy gaps of cyclohexane, Wurtzoid, wurtzoid2C and tri-wurtzoid are (4.48, 3.35, 3.4 and 3.096 eV) respectively, these values agreement with experimental values for ZnO wurtzite bulk (3.3 eV). As well as, the Spectroscopic study of IR and Raman scattering, force constant, and reduced mass as a function of frequencies showed an agreement with the experimental results.

Hybrid bilayer heterojunction Zinc Phthalocyanine (ZnPc) thin-film P-type is considered as a donor active layer as well as the Zinc Oxide (ZnO) thin film n-type is considered as an acceptor with (Electron Transport Layer). In this study, using the technique of Q-switching Nd-YAG Pulsed Laser Deposition (PLD) under vacuum condition 10-3 torr on two ITO (Indium Tin Oxide) and (AL) electrodes and aluminum, is used to construct the hydride bilayer photovoltaic solar cell heterojunction (PVSC). The electrical properties of hybrid heterojunction Al/ZnPc/ZnO/ITO thin film are studied. The results show that the voltage of open circuit (V_oc=0.567V), a short circuit (I_sc=36 ?A), and the fill factor (FF) of 0.443. In addition, the conversion efficiency of (n=3.4%) is recorded with Xenon lamp with an intensity 235mw/cm2 .

Hybrid organic Copper phthalocyanine (CuPc) –inorganic Cadmium Sulfide (CdS), double layered structures were deposited on glass substrate at different thickness using Pulsed Laser Deposition (PLD) with Q-Switching Nd: YAG laser with energy (240,500 mJ) at (25 Celsius) and within vacuum conditions of (10-3 torr). The photoluminescence (PL) is showing that the CdS quenches emissions from CuPc indicating the carrier transfer to the CdS. Also, the CuPc/CdS hybrid structures have the capability for various absorptions as can be seen in the ultraviolet-visible absorption researches and the charge carrier extractions from PL analysis have been adequate for the solar cell applications. FT-IR spectra have been specified for CdS and CuPc.

In this work, ultra-sensors of chemical solvents vapor were fabricated for chloroform, n-Hexane and Ethanol via modified porous silicon (PS) surface by the reduction of graphene oxide (rGO) layer. The rGO was conducted by electrochemical exfoliation of graphite electrodes with electrolyte solution at PH = 4.6. Then porous silicon (PS) was prepared by employing electrochemical etching (ECE) method using silicon (Si) p-type at different etching current density J = 2, 4 and 6 mA/cm2with constant HF concentration of 15%, and time of etching of 15 min. The reduction graphene oxide competition with PS was studied as vapors organic sensor, morphological, structural, and surface bond configuration were characterized by Atomic Force Microscopic (AFM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) respectively, then the Photoluminescence (PL) quenching was measured by using sensor test system with three types of organic chemical solvents n-Hexane, chloroform and ethanol with nitrogen gas mixing, where they were prepared for testing humidity sensor towards the different organic solvents. The results revealed that the reduction graphene oxide layer on surface of PS lead to intensity increase of the PL, and modified the quality of PS sensor for chemical vapor.

III-V zinc-blende AlP, AlAs semiconductors and their alloy Aluminum Arsenide phosphide Al AsxP1-x ternary nanocrystals have been investigated using Ab- initio density functional theory (Ab-initio-DFT) at the generalized-gradient approximation (GGA) level with STO-3G basis set coupled with large unit cell method (LUC). The dimension of crystal is found around (1.56 – 2.24) nm at a function of increasing the sizes (8, 16, 54, 64) with different concentration of arsenide (x=0, 0.25, 0.5, 0.75 and 1) respectively. Gaussian 03 code program has been used throughout this study to calculate some of the physical properties such as the electronic properties energy gap, lattice constant, valence and conduction band as well as density of state. Results show that the lattice constant increases with the increasing in the arsenide concentration in the alloy. The total energy, cohesive energy, electron affinity and ionization potential as well as ionicity for these concentrations have been reported.

Thin films of Nickel Phthalocyanine have been prepared by evaporation technique for (50 - 350 nm) of thickness. XRD studies show that the thin films have single crystalline structure for low thicknesses with (100) orientation and the crystallite size increased with increased thickness. Also from the AFM technique for NiPc films, the roughness was determined and the grain size increases with increasing of thickness from except at thickness 350 nm. The studies of electrical properties, morphology and orientations of the crystallites are important to understand and predict the nature of the films and essential for their successful applications in solar cell and sensors. The electrical properties of these films were studied with different thickness, NiPc has three activation energy. Carrier’s concentration and mobility was calculated. Hall measurements showed that all the films are p-type.

Ni-Phthalocyanine thin films were thermally evaporated with different substrate temperatures (300 - 450) K on (silicon wafer, glass) substrates. The chemical bonds of NiPc powder were investigated by FTIR spectrum, which introduce good information for NiPc bonds and their locations. The optical properties have been studied by UV-Visible, and Photoluminescence (PL) Spectra. The NiPc thin films have direct gap for all samples. The values of energy gap which is calculated by PL spectra are lower than those calculated by Tauc equation. It is found there are three activation energies, the mobility and concentration of carriers have been measured and, the NiPc films are p-type. P-NiPc/n-Si HJ solar cell was fabricated at substrates temperatures (300, 400) K. From I-V and C-V characteristic, abrupt junction has been found, photovoltaic characteristics have been observed with Voc of (0.335 - 0.415) V, and Isc of (2.77 - 4.26) μA, and the efficiency of (3.08 - 5.03)% at room temperature and substrate temperature (300, 400 K) and under illumination of 55 mW/cm2 using Halogen lamp. Ideality factors of the junction increase from (0.61 - 0.73) and barrier height increases from 2.53 eV to 3.69 eV while shunt resistance decreases from 3.76 KΩ to 2.59 KΩ and series resistance decreases slightly from 0.24 KΩ to 0.23 KΩ. The fill factor decreases from 0.46 to 0.4 with the increase of substrate temperature.

In this work chemical vapor sensors for Ethanol, chloroform and n-Hexane were fabricated by porous silicon (PS). PS samples were prepared by electrochemical etching (ECE) method with different current density J = 2, 4 and 6 mA/cm2 and etching time 15 min and HF concentration 15%. Ordered porous silicon p-type (111) is thoroughly studied as an The structure, chemical composition and surface bond configuration of PS layer has been characterized by X-ray diffraction (XRD), Atomic Force Microscopic (AFM) and a Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence (PL) quenching measurement were conducted using mixture nitrogen gas and vapor of n-Hexane, chloroform and ethanol, where prepared to test the sensor response towards the chemical organic solvents. The results refer to the PS surface is good sensing for chemical vapor. It's were also found that a higher PL quenching value for Ethanol compared with the value of n-Hexane and chloroform vapors.

Electronic structure and vibrational characteristics of GaAlN wurtzoids at the molecular-nanoscale limit are investigated. The investigated properties include energy gap, vibrational properties, and phase stability against transition to GaAlN diamondoids. At the molecular-nanoscale limit, wurtzite GaAlN nanocrystals are represented by wurtzoids. The properties of GaAlN molecules and nanocrystals as a function of Ga and Al contents are shown. The results show that the energy gap depends on size, shape and surface conditions. Molecules with hydrogen passivated surface have wide energy gap while bare molecules have smaller energy gaps. On the other hand, vibrational longitudinal optical mode of bare molecules experiences a redshift after surface hydrogen passivation with smaller vibrational reduced masses and force constant at a given frequency. Differences between GaAlN two limits (GaN and AlN) are explained by the existence of d orbitals in Ga atoms. Calculated Gibbs free energy of atomization show the stability of wurtzoids against transition to the diamondoids at the molecular-nanoscale limit for both bare and hydrogen passivated cases.

Nanocomposites have the potential to produce very selective, stable, and sensitive sensors. Nanocomposites porous structures have a larger surface area for gas molecule adsorption. In this paper, the high quality gas sensor was prepared by modified porous layer of silicon (PS) with a thin layer of carbon nanotube (CNTs) and carbon nanotube doped with zinc oxide (ZnO) nanoparticles (70–30)% respectively. PS samples were created using the photoelectrochemical etching method (PECE), for N-type silicon (Si) wafer with resistivity of (1.5–4) Ω cm and a thickness (580 ± 0.25) μm. Three etching current densities were employed for prepare PS layers 12, 24, and 30 mA/cm2, while, the hydrofluoric acid HFc concentration of 40% and etching time was about 10 min. The Structure characteristics, morphological features, and surface chemical bond formation of all PS and (MWCNTs-ZnO/PS) samples were examined using X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and Transition Electron Microscope (TEM). All PS and MWCNTs-ZnO/PS samples were applied as ethanol gas sensors at room temperature. The results revealed that CNTs-ZnO/PS had the highest sensitivity to ethanol gas at etching current density 30 mA/cm2, reaching about (2.004984) at a concentration of 500 ppm. Fusion of CNTs-ZnO leads to the emergence of new properties and unique effects, and as a result of the excellent sensing ability of carbon nanotubes in detecting different gases at room temperature, Used in the manufacture of highly selective gas sensors that operate at room temperature. The Interest of this article return to study the effect of extremely high surface to volume ratio (increasing surface area), and ease composition and compatibility with modern silicon microelectronics manufacturing technologies.

Hybrid perovskite solar cells (PSCs) have introduced as a good revolution photovoltaic to meet the green world energy demands. The crystallinity improvement of PSCs is a practical approach to improve the efficacy of PSCs. Double cation formamidinium (FA)/methylammonium (MA) PSCs were fabricated by using a simple sequential deposition process. The mesoporous titanium dioxide (TiO2) layers with 200 nm thickness were used as the electron transport layer (ETL). It was observed that with changing the FA/MA precursor temperature could achieve more desirable perovskite films for photovoltaic applications. Our measurements show that with pre-heating of FA/MA solution at 55 °C the defects on the perovskite layer are well passivated. Besides, the perovskite with better crystallinity and smooth morphology, and the defect-free surface was achieved. It is delightful that perovskite with 55 °C reveals stronger photon absorption and better charge collection. Using the pre-heating approach, a redshift in edge absorption of the perovskite films was observed, indicating a better light-harvesting phenomenon in the corresponding perovskite films. Through optimization of the pre-heating temperature of FA/MA solution, a champion PCE of 13.77% was yielded for PSCs higher than of 10.05% one for pre-heating. Also, modified mixed cation devices revealed higher stability behavior in atmospheric conditions than the reference devices.

Incredible progress in the efficiency of hybrid perovskite solar cells (PSCs) has nominated perovskites as a promising light-harvesting for new-generation photovoltaic devices. Additive engineering in PSCs is a valid and straightforward method to increase the surface quality of perovskite films. Herein, we prepared mixed cation of cesium (Cs)/formamidinium (FA)/methylammonium (MA) PSCs via an air-processed sequential deposition method. Acetonitrile (ACN) was used as an effective additive to improve the surface properties of perovskite layer. Our measurements demonstrated that with the incorporation of ACN in the FAI/MABr/MACl precursor surface defects on the perovskite film well passivated, and consequently, crystal grain size increased. A PCE of 15.64% was achieved for ACN-based PSCs higher than of 13.06% one for without additive devices. Additionally, ACN-containing devices showed a lower hysteresis effect as compared to the control devices. Most importantly, ACN additive based PSCs showed more stable behavior in ambient air, thermal, and humidity stability tests. This work introduces a simple approach for the fabrication of high-performance perovskite materials in ambient air.

In the present paper, Copper Phthalocyanine (CuPc) thin films were deposited on glass and silicon substrate by thermal evaporation and pulsed laser deposition (PLD) methods. CuPc thin films prepared at different annealing temperatures (298, 323, 348, 373, 423 K) respectively. The structure and surface morphology of CuPc in powder and thin films forms prepared by two methods were studied using Energy dispersive X-ray (EDX), X-ray florescence (XRF), X-ray diffraction (XRD), Atomic force microscope (AFM), and Scanning electron microscope (SEM). It showed that there was a change and enhancement in the crystallinity and surface morphology due to change in the annealing temperature (Ta). The purpose of our work is to find the optimal temperature for which the film produces best structural properties for CuPc thin film to produce organic field effect transistor. Analysis of X-ray diffraction patterns of CuPc in powder form showed that it had an α-poly-crystalline phase with monoclinic structure, with preferentially oriented (100) plane transform to β-single crystalline morestable structure at different annealing temperatures.

In this research, the nanoparticles of gold (AuNPs) was used for doping graphene (rGO) nanocomposites, then deposted on porous silicon (PS) for high sensitivity of chemical vapors sensor such as n-Hexane, Ethanol, and chloroform. The graphite electrodes were used for the production of rGO by electrochemical exfoliation method. The pulsed Nd:YAG laser system with 1064 nm of wavelength, and laser energy of 400 mJ for 600 pulses was used for AuNPs preparation. Then the electrochemical etching (ECE) system was used for prepared PS with the variation of etching current densities: 2, 4 and 6 mA/cm2 for 15 min etching time. The comparison of rGO:AuNPs/PS with PS surface was studied for a chemical vapors sensor. The X-ray diffraction (XRD), Atomic Force Microscopic (AFM), Scannin electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were performed for studying the Structural, morphological and surface bond configuration respectively and the UV–vis spectrophotometer applied for calculating transmittance ratio of hybrid materials. The Photoluminescence (PL) test was conducted for all samples using PL system on the three kinds of organic chemical solvents, by mixing with gas of nitrogen, in which prepared for using as the sensor of organic vapors. All results showed that the hybrid doping of rGO:AuNPs layers on the PS surface lead to rise of PL peak, and modify the PS feature as organic chemical vapor sensor.

Reactions at the molecular and nanoscale for the formation of ZnCdS wurtzoids are calculated and compared to the experiment. The related electronic and vibrational properties that relate to the variation of the compound constituents are discussed. The change of the energy gap is mostly due to the variation of the highest occupied molecular orbital (HOMO) energy level. The vibrational longitudinal optical mode values of ZnCdS is not entirely confined between CdS and ZnS limits because of the ZnS surface activity. Gibbs and enthalpy of formation of ZnCdS wurtzoids are less than their bulk values because of molecular and nano-size surface effects. The entropy and heat capacity show a high pairing effect in which even number of Zn atoms has higher absolute entropy values and lower heat capacity. The natural bond orbital analysis shows that most of the properties mentioned above are due to relative inertness of Cd with respect to the Zn atom.

Raw materials are anisotropic and heterogeneous in nature, and recovering their conductivity is of utmost importance to the oil, aerospace and medical industries concerned with the identification of soils, reinforced fibre composites and organs. Due to the ill-posedness of the anisotropic inverse conductivity problem certain simplifications are required to make the model tracktable. Herein, we consider such a model reduction in which the conductivity tensor is orthotropic with the main diagonal components independent of one space variable. Then, the conductivity components can be taken outside the divergence operator and the inverse problem requires reconstructing one or two components of the orthotropic conductivity tensor of a two-dimensional rectangular conductor using initial and Dirichlet boundary conditions, as well as non-local heat flux over-specifications on two adjacent sides of the boundary. We prove the unique solvability of this inverse coefficient problem. Afterwards, numerical results indicate that accurate and stable solutions are obtained.

In this work, a novel zigzag edge toothed log-periodic antenna (ZETLPA) placed over Hilbert curve Graphene AMC is proposed for frequency band (0.1 –10) terahertz. The bandwidth and operating frequency bands of the antenna have changed by varying the applied DC voltage source. This leads to change the chemical potential of the Graphene and hence changing its surface conductivity. The antenna radiating element of the ZETLPA is made from gold patch placed on Hilbert curve shape Graphene AMC. An Exponential taper is employed for the matching process over the antenna bandwidth. The antenna simulated by CST 2016 package (Computer Simulation Technology). The results show that 100 % of the bandwidth obtained (S 11 < −10 dB) when the chemical potential of the Graphene equal to 1eV. A zigzag edges TLP is used to increase the antenna arms lengths and reduce the return losses to a minimum level as possible over the required frequency band.

In this research work PVA:xAl (0.01 ≤ x ≤ 0.05) based solid polymer composites have been prepared by solution cast technique. The transmittances of the samples are decreased with increasing Al powder concentration. The absorption spectra of the samples are shifted to higher wavelengths which indicate their importance for shielding. The increase of absorption intensity in UV region was observed. The clear shift of absorption edge upon the addition of Al powder content indicated the decrease of energy band gap. The increase of extinction coefficient at high wavelengths for the samples containing Al powder revealed the loss of photon energy. The refractive indexes of the doped samples are increased compared to that of pure PVA. The linear relationship between the refractive index and volume fraction indicates a good dispersion of Al powder in PVA host polymer. The direct optical band gap measured from the plot of (αhυ)2 versus photon energy (hυ) showed a decreasing trend with increase of Al content. The Urbach energy was found to increase with increasing aluminum concentration. The complex optical dielectric functions were used to determine the type of electron transition.

In this study, the fabrication and characterization of capacitive humidity sensors using cobalt-phthalocyanine (CoPc) as the active material were presented. Thin films of CoPc were deposited by drop casting on glass substrates with pre-deposited aluminum electrodes to form Al/CoPc/Al surface-type humidity sensors. The effect of humidity on the electrical properties of the CoPc film was investigated by measuring capacitance and resistance of the samples at four different frequencies of the applied voltage. It was observed that the capacitance of the sensor increased while the resistance decreased with raising the relative humidity. It was also found that the values of capacitance and resistance decreased with increasing frequency. The optical absorption spectra and optical band gap energy of CoPc films were measured. The structure of CoPc powder and thin films has been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Results of XRD studies show that the film structure is polycrystalline with the monoclinic structure while thin films have a peak for annealing temperatures with (100) orientation. Also, the surface morphology (grain size and roughness) for CoPc films have been studied by AFM.

Humidity is the one of physical quantities that widely measured and is of very important in a many fields. In this paper, the ultra sensor of humidity was created using modified porous layer of silicon (PS), by thin films of reduction graphene oxide sheets (rGO). The electrochemical method was applied to exfoliation electrodes of graphite for preparing rGO sheets in peeling solution Acidic about PH = 4.6. p-type of Silicon waver (Si) was used for formulating PS samples using electrochemical etching (ECE) process. three etching current density 2, 4 & 6 mA/cm2 were used and fixed the other parameters such as Hydrofluoric acid HFc concentration was 15%, and time of etching about 15 min. All the samples of PS and rGO/PS were tested as humidity sensor. the structure characteristic, morphological properties and surface chemical bonds configuration were described by X-ray diffraction (XRD)و Scanning electron microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) consequently, also the Photoluminescence (PL) tests were conducted by using system of sensor test, the measurements of PL in a controlled humidity atmosphere (mixing gas of Nitrogen with humidity (vapor of water) were performed for examining the sensor response to the water vapor. The results showed that all samples revealed that the PL intensities were increased while rGO sheets deposited on the surface layer of PS, and improved the sensitivity of PS as humidity sensor.

In this work, ZnS structure change from the molecular size of ZnS Wurtzite to obtain on longitudinal mode vibrational properties for both IR and Raman intensities and other features of vibration like forces constant and reduced masses for bare and H-passivation to ZnS Wurtzoids nanostructures. The vibrational modes represented by Longitudinal optical (LO) of structures as nanoscale with H-passivated (Hp) shifted to red shift inverse the bare of ZnS shift to blue with respect to ZnS bulk. The theoretical study of ZnS as nanotubes using Ab-initio density functional theory (ADFT) and comparison with experimental results, all calculations done in program Gaussian 09. At nanoscale properties, the nanostructure of ZnS different from at bulk or molecule limit to there are dangling bonds in the clusters at their surface.

The thin films of Nickel Phthalocyanine (NiPc) on glass substrates were prepared by vacuum evaporation at different substrates temperatures (300, 325, 350, 400, 450) K. The structure and surface morphology of NiPc in powder and thin film forms (265 nm) were studied using X-ray diffraction and atomic force microscope (AFM), and showed that there was a change and enhance in the crystallinity and surface morphology due to change in the substrates temperatures. Analysis of X-rays diffraction patterns of NiPc in powder form showed that it had an α-polycrystalline phase with monoclinic system with lattice constants a = 1.513 nm, b = 0.462 nm, c = 2.03 nm and β = 123.46°. Thermal evaporation of NiPc at different substrates temperatures led to β-crystalline films oriented preferentially to the (100) plane with different substrate temperatures. The mean crystallite size increased with substrates temperatures from 300 K to 450 K. This result was supported by AFM measurements, which exhibited a relatively larger grain size.

The electronic structure of III-V zinc blend Gallium Phosphide nanocrystals is investigated using ab-initio density functional theory coupled with large unit cell for the core and surface parts. Two kinds of cells are investigated: multiple Bravais and multiple primitive cells. The results show that both energy gap and valence band width depend on the shape of the nanocrystal. Results also revealed that most electronic properties converge to some limit as the size of the large unit cell increases. Furthermore, the results have shown that the cohesive energy is decreasing with increasing size of nanocrystals. The core part is more degenerate, with larger energy gap and smaller valance and conduction bands than the surface.

The La 0.7 Ca 0.25 Sr 0.05 MnO 3− δ □ δ compounds were prepared by the solid-state reaction with 0.00⩽ δ ⩽0.15. X-ray diffraction, electrical and magnetic measurements were performed to examine the effect of the oxygen deficiency on the physical properties of these compounds. It was found that these samples crystallize in an orthorhombic structure and present a ferromagnetic behaviour for δ ⩽0.1. For δ =0.125 and 0.15, the structure becomes rhombohedral and the magnetization curves reveal the presence of an antiferromagnetic character. The electrical study indicates the existence of a transition from the metallic phase to the semiconductor one for δ =0 and 0.05. When increasing δ , the measures of the resistivity show the presence of semiconductor behaviour only. Oxygen deficiency modifies also the electrical transport properties delineating an electronic phase boundary between metal and semiconducting phase. Finally, oxygen deficiency affects the coupling between magnetism and transport properties, i.e., the double exchange of electrons between ferromagnetically coupled Mn ions.

Over the decades there have been several papers on the coloration of cotton-based textiles. The number of articles dealing with the processing of cotton, including preparation, dyeing, and finishing, may be in the thousands. An investigation of the possible causes of problems occurring in the coloration of textiles revealed that a comprehensive review of case studies and scientific analysis would be a welcome addition to the already rich pool of knowledge in this area.

Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM), energy-dispersive X-ray florescence analysis (EDS), optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4 : 1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment.

In this paper, we present the magnetocaloric effect of Sr vacancies in La 0.7 Sr 0.3− x □ x MnO 3 compounds with x =0 and 0.05. From the magnetic measurements as function of temperature and magnetic applied field, we have discovered a large magnetic entropy change (Δ S M ) at Curie temperature. Δ S M is found to reduce for La 0.7 Sr 0.25 □ 0.05 MnO 3 sample (−1.78 J/kg K for x= 0 and 1.60 J/kg K for x =0.05 under magnetic field change μ 0 Δ H= 2 T). This reduction is accompanied by a decrease of the Curie temperature ( T C = 374 and 366 K for x =0 and 0.05, respectively). These results show that these materials are potential candidates for magnetic refrigerants working in above room temperature.

The aim of this paper is to investigate microstrip multilayer antenna using computer simulation technology (CST-2010) simulation. In this way, improvement bandwidth of the patch antenna is increased by using multiple layer dielectric substrates. It is known that bandwidth of microstrip antenna is small and varies directly with the size of the patch, increasing size of patch to improve bandwidth makes it large. Thus to overcome the bandwidth limitation without increasing antenna size, a patch on multiple layer scheme has been designed to reduce the effective dielectric constant. This ensures that bandwidth increases greatly while size is not change. Performance parameters like bandwidth and reflection loss have been evaluated and compared with that obtained from single layer substrates. Results suggest considerable improvement in bandwidth using the proposed patch antenna design on multi layered substrate. The designed patch has a size of 8∗8∗2 mm3 and gives a bandwidth and gain of 920 MHz and gain 2.8 dB at 5.491GHz.

Two series of mixes lying in the field of celsian BaO·Al 2 O 3 ·2SiO 2 in the ternary system BaOAl 2 O 3 SiO 2 were investigated. These compositions were obtained using 35 to 60% barite together with either clay and feldspar or clay, feldspar and quartz. The amount of unreacted BaSO 4 was determined by chemical means. The effect of barite addition on physical properties, reversible linear thermal expansion and modulus of rupture of the produced bodies was verified. Results showed that 35 to 40% barite was consumed in the reaction with other constituents forming celsian BaO·Al 2 O 3 ·2SiO 2 and sanbornite BaO·2SiO 2 . Higher additions of barite left unreacted BaSO 4 as a constituent of the fired product. Unreacted barite increased the bulk density, 2.2–2.9 g/cm 3 , raised the linear thermal expansion coefficient, 4.2–8.5 10 −6 /°C, between 20–1000°C and lowered the modulus of rupture, 450-180 kg/cm 2 .

Summary Differential thermal analysis curves were obtained for a Portland cement paste and a fl-dicalcium silicate paste (β-C2S paste), by heating in vacuo and in air up to 1,200°C. The vacuum thermograms of both pastes showed a first single endotherm at 140 to 143°C which is mainly characteristic for the decomposition of tobermorite gel. For the Portland cement paste, this includes also the decomposition of the smaller amounts of aluminate hydrated salts. A second peak which appeared at 360 to 385°C is due to the decomposition of calcium hydroxide. Thermograms obtained by heating in air differ considerably from those obtained in vacuo. The first endothermal effect which mainly characterizes the decomposition of the tobermorite gel showed more than one peak; and the temperature, shape and area of the peaks are all affected by heating in air. These effects may be due to the reversibility of the reaction and to the liability of the dehydrated products to be rehydrated at an accelerated rate in the presence of air. At high temperatures, DTA in vacuo seems to be a useful technique for resolving some peaks which apparently are fused into a single effect in the air thermogram.

The completely decarbonized ash residue of rice hulls was mixed with 15% hydrated lime and subjected to different conditions of hydrothermal treatments. Results showed that a calcium silicate hydrate probably an ill defined form of tobermorite, is the main component of the cured samples together with small residual amounts of hydrated silica and lime. The products obtained showed reasonable values of apparent porosity, bulk density and water absorption as well as high compressive strength. These properties became more improved on treating the materials at higher steam pressure, a case which is probably connected with the formation of a more well defined form of tobermorite at such condition.

The effect of certain whiteware constituents clay, quartz, feldspar or alumina on the dissociation of barite was studied by thermogravimetric analysis of two series of powder mixes. In addition discs of the powders were semi-dry-pressed and their weight loss determined. The dissociation process of barite is influenced by two reactions which occur with increasing temperature. A solid state reaction occurs at 600°C in the presence of all additions and results in a slight loss in weight. The products of this superfacial reaction hinder reaction between the barite grains and quartz until 1000°C is reached. In the case of clay, this reaction proceeds slowly up to 1200°C. A second reaction starts at 1250°C where a liquid phase is present, accelerating the dissociation process. Alumina appears inert even at 1250°C. Only 50.4% of the original amount of barite in the mixes reacted with the clay and even less reacted with feldspar and quartz. The main crystalline phases detected were barite together with sanbornite or mullite and celsian.