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Abstract: We prepared multilayers of superlattice thin film system with 50 periodic alternating nano-layers of semiconducting half-Heusler β-Zn4Sb3 and skutterudite CeFe2Co2Sb12 compound thin films using ion beam assisted deposition (IBAD) with Au layers deposited on both sides as metal contacts. The deposited multilayer thin films have alternating layers about 5nm thick. The total thickness of the multilayer system is 275nm. The superlattices were then bombarded by 5MeV Si ion at six different fluences to form nano-cluster structures. The film thicknesses and composition were monitored by Rutherford backscattering spectrometry (RBS) before and after MeV ion bombardment. We have measured the thermoelectric efficiency, Figure of Merit ZT, of the fabricated device by measuring the cross plane thermal conductivity by the 3rd harmonic (3ω) method, the cross plane Seebeck coefficient, and the electrical conductivity using the van der Pauw method before and after the MeV ion bombardments. We reached the remarkable thermoelectric Figure of Merit results at optimal fluences. [Copyright &y& Elsevier]

Abstract: Lithium niobate crystals with various dopents, such as Fe (0.3wt%), Mn (0.1wt%) and Eu (1wt%) ions have been successfully grown using the Czochralski technique. The crystals have been cut in suitable sizes and polished. It is essential to know the concentration and location of dopants in the crystal lattice in order to improve the crystal growth parameters to grow large crystals of LiNbO3 with known impurities. Using Li(p,α) nuclear reaction profile the Li in LiNbO3 crystal was located. Using Rutherford backscattering spectrometry (RBS), the dopants and their concentration as a function of depth were measured. Using channeling, both RBS channeling and (p,α) channeling the lattice location of impurities and the location of Li in the doped crystal could be identified. The energy of the incident protons is maintained at 1.0MeV to avoid neutron production. [Copyright &y& Elsevier]

Abstract: Heavy metals and metalloid ions are found in environmental matrices. The most toxic are lead, cadmium and mercury. These three heavy metals have no biological function and are toxic at all concentrations. Lead is one of the most insidious heavy metals and is introduced into the environment by many different means. It persists in both urban and rural settings, being found in paint chips, pottery, crystal and pharmaceutical and nutritional products. The analysis of heavy elements such as lead in soil is of particular importance [W.T. Sturges, R.M. Harrison, Sci. Total Environ. 44 (3) (1985) 225; M.L. Lepow, L. Bruckman, M. Gillette, S. Markowitz, R. Robino, J. Kapish, Environ. Res. 10 (3) (1975) 415; A.E. Daniels, J.R. Kominsky, P.J. Clark, J. Hazard. Mater. B 87 (2001) 117; G. Hutter, D. Moshman, J. Hazard. Mater. 40 (1995) 1]. In preparing the methods for lead detection in paint, we have used Rutherford backscattering spectrometry (RBS) in order to study the type and amount of heavy metal content in paint samples collected at various sites in the historic campus at A&M University (AAMU). We will show the results of our study with emphasis on comparison of what we learned about presence of lead in paints using our ion beam methods compared with the analysis of lead in paints using cyclic voltammetry. [Copyright &y& Elsevier]

Abstract: In this work we are investigating the structural evolution of tungsten carbide films deposited on silicon carbide (SiC) substrates as a function of temperature. We used thermal evaporation and tungsten carbide (WC) powder as a starting material to produce the thin layer deposition on semi-insulating silicon carbide (6H). Our intended applications are for devices working at 800°C; therefore, our investigations are carried out at 1h intervals of time the samples spent at this temperature. We used Rutherford backscattering spectrometry (RBS) for measuring the stoichiometry and depth profile, atomic force microscopy (AFM) and scanning electron microscopy (SEM) to monitor the surface morphology change, and optical measurements (Raman and optical absorption spectroscopy) to monitor the eventual apparition and evolution of chemically-induced defects of the SiC crystalline lattice. [Copyright &y& Elsevier]

Abstract: Zinc oxide films are deposited at 300K, on SiO2 quartz or glass and glassy polymeric carbon (GPC), by RF magnetron sputtering using zinc oxide target. The stoichiometry of the deposited oxide was determined by Rutherford backscattering spectrometry (RBS) and the optical band gap by optical absorption measurements. Ion irradiation with 5MeV Si ions was performed to enhance the nucleation process of ZnO islands on the SiO2 surface. The first results show that the stoichiometry of ZnO layers is 1 to 1 and the band gap is 3.3eV. Ion bombardment led to a needle-like surface of the ZnO layer, quite different from the effect of annealing of similar samples. Optical properties and surface morphology of Si bombarded ZnO films were analyzed and compared with ZnO annealed films. [Copyright &y& Elsevier]