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We report the study of high-pressure phases of YN and ScN compounds, using a recent version of the full potential linear muffin-tin orbital (FPLMTO)method, which enables an accurate treatment of the interstitial regions. The local density approximation (LDA) was used for the exchange and correlation energy density functional. Calculations are given for lattice parameters, bulk modulus and its first derivatives in different structures.Under compression, we found that ScN transforms from NaCl-type structure (B1) to Beta-Sn-type (A5) at a pressure of around301.3GPa, with a direct energy gap at Γ of about 0.108eV. This transition B1 to A5 takes place at a lower pressure than the well-known transition NaCl-type structure (B1) to CsCl-type structure (B2) (found here to be 412GPa). Our calculations also show that YN transforms from B1 to B2 at a pressure of around198.5GPa. [ABSTRACT FROM AUTHOR]

The knowledge of the electrical properties of materials is inevitable in surface technologies, such as microtechnology, corrosion, etc. Concerning the surface phenomena, the work function represents the main property. It was developed by Lord Kelvin and it corresponds to the contact potential difference between two surfaces of materials. In this project, the data acquisition of Kelvin Probe System (KPS) was performed after sequential tests in electronic computing and physical fields in order to acquire the work function of conductor and semiconductor materials. This system has revealed the great importance of controlling the support voltage Vb calculating the capacitor applied to the Metal-Insulator-Semiconductor (MIS) structure in order to measure the surface potential of the semiconductors. Some problems were solved during the assembly of the system and the pertinent frequency of 50 Hz was suitably adjusted. However, the conversion of current-voltage was not carried out in KPS due to the insensitivity of the amplifiers on hand. To understand this difficulty in signal experimental study, we have used a calculation by a Fortran code. The latter has confirmed that the signal of Kelvin probe is a very weak amplitude of the order of pico-volts. Because of the available measuring devices whose sensitivity is much lower than the signal itself, on the other hand, these results justify the experimental steps. [ABSTRACT FROM AUTHOR]

This paper reports the effect of Fe incorporation on structural and electro-optical properties of ZnO thin films prepared by spin coating techniques. The Fe/Zn nominal volume ratio was 7 % in the solution. X-ray diffraction patterns of the films showed that doped incorporation leads to substantial changes in the structural characteristics of ZnO films. All the films have polycrystalline structure, with a preferential growth along the ZnO (002) plane. The crystallite size was calculated using a well-known Scherrer’s formula and found to be in the range of 22-17 nm. The highest average optical transmittance value in the visible region was belonging to the Fe doped ZnO film. The results of the Raman scattering confirmed the observations of XRD and UV-Vis analysis techniques by the appearance of these occupancies at Zn+2 sites. These results are explained theoretically and are compared with those reported by other workers. The results of Hall measurement of ZnO and ZnO:Fe thin films reveal a high electron concentration around 1016 cm–3 and low mobility 2.6 cm2/Vs. All as-grown samples show ambiguous carrier conductivity type (p-type and ntype) in the automatic Van der Pauw Hall measurement. A similar result has been observed in Li-doped ZnO and in As-doped ZnO films by other groups before. However, by characterizing our samples whit XPS, we have demonstrated that the ambiguous carrier type n in intended our ZnO films is not intrinsic behavior of the samples. It is due to the persistent photoconductivity effect in ZnO. [ABSTRACT FROM AUTHOR]

This work deals with the synthesis, characterization of mixed oxides of metals and their applications as catalysts. The synthesized ferrite solid solution of formula Fe2Zn1 – xCuxO4 has been prepared from ground frost. The purity of the samples has been verified by X-Ray Diffraction (XRD). The characterizations of samples have been carried out using Fourier Transform InfraRed Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Refinement of lattice parameters of the solid solution has been elaborated from the basic compound NiFe2O4 indexing in a cubic unit cell of space group Fd3m. The trend of the diffraction lines shows that the structure was well crystallized, and there indeed a complete solid solution of cubic symmetry was formed. The SEM micrograph reveals that the samples are presented in the form of nanometer sized crystallites; the samples are in the form of fragments of different sizes in the Cu-Zn mixture. The results show the nanometric size of the grains varying between 90 and 130 nm. These newly elaborated materials have been applied as catalysts for heterogeneous reaction of oxidation of phenolic compounds; subject of investigations in the presence of hydrogen peroxide. The degradation products were analyzed by High Performance Liquid Phase Chromatography (HPLC). The obtained results showed powerful catalytic character of these oxides to completely degrade phenol. [ABSTRACT FROM AUTHOR]

Zinc sulfide (ZnS) is important II-VI semiconductors material for the development of various modern technologies and photovoltaic applications. ZnS thin film was prepared by using chemical spray pyrolysis technique. The starting solution is a mixture of 0.1 M zinc chloride as source of Zn and 0.05 M thiourea as source of S. The glass substrate temperature was varied in the range of 300 °C-400 °C to investigate the influence of substrate temperature on the structure, chemical composition, morphological and optical properties of ZnS films. The DRX analyses indicated that ZnS films have polycrystalline cubic structure with (111) preferential orientation and grain size varied from 25 to 60 nm, increasing with substrate temperature. The optical properties of these films have been studied in the wavelength range 300-2500 nm using UV-VIS spectro-photometer. The ZnS films has a band gap of 3.89 eV-3.96 eV. [ABSTRACT FROM AUTHOR]