Analytical and experimental study of electrical conductivity in the lithium tantalate nonstoichiometric structure

We have been interested to experimental and analytical studies of ionic conductivity of nonstoichiometric LiTaO3 solid solutions. Theoretical approach combined with lithium and tantalate vacancy models has been performed. A comparative study between the calculated and measured values is presented taking into account the temperature and composition effects on the conductivity.We have been interested to experimental and analytical studies of ionic conductivity of nonstoichiometric LiTaO3 solid solutions. Theoretical approach combined with lithium and tantalate vacancy models has been performed. A comparative study between the calculated and measured values is presented taking into account the temperature and composition effects on the conductivity

Association between knowledge, risk behaviours, and testing for sexually transmitted infections among men who have sex with men: findings from a large online survey in the United Kingdom.

OBJECTIVES: In the UK, men who have sex with men (MSM) bear a disproportionate sexually transmitted infection (STI) burden. We investigated MSM's STI knowledge; whether their STI testing behaviour met national guidelines (annually if sexually active; 3-monthly if engaging in STI risk behaviours); and the relationship between STI testing in the last 3 months, STI knowledge and STI risk behaviours by HIV status. METHODS: Sexually active (in the last year) men aged > 15 years who were UK residents and were recruited from gay-orientated online dating platforms completed an anonymous online survey about STI knowledge, STI risk behaviours, and STI testing (March-May 2017). This included 11 true statements about STIs. Respondents scored 1 for each statement they 'knew', with those scoring < 6 overall treated as having 'poor' STI knowledge. Descriptive and multivariable analyses were conducted, separately by HIV status, to test our hypothesis and calculate adjusted odds ratios (AORs) with 95% confidence intervals (CIs). RESULTS: Compared to HIV-positive men (n = 489), the proportion of HIV-negative/unknown-status men (n = 3157) with 'poor' STI knowledge was significantly higher (46.4% versus 22.9% for HIV-positive men) and the proportion with STI testing in the last 12 months was lower (71.6% versus 87.2%, respectively). In the last 3 months, 56.9% of HIV-negative/unknown-status and 74.1% of HIV-positive men reported STI risk behaviours, of whom 45.8% and 55.1%, respectively, had been tested for STIs during this time. Among HIV-negative/unknown-status men, those reporting STI risk behaviours were more likely (AOR 1.52; 95% CI 1.26-1.84) and those with poor STI knowledge less likely (AOR 0.73; 95% CI 0.61-0.89) to have been tested during the last 3 months. However, neither factor was independently associated with 3-monthly testing among HIV-positive men. CONCLUSIONS: Improving STI knowledge, especially among HIV-negative/unknown-status men, and promoting frequent STI testing among men engaging in STI risk behaviours are vital to address the poor sexual health of MSM

Effect of Al-doped on physical properties of ZnO Thin films grown by spray pyrolysis on SnO

Transparent conducting thin films of aluminum-doped zinc oxide (ZnO:Al) have been deposited on SnO2:F/glass by the chemical spray technique, starting from zinc acetate (CH3CO2)2Zn.2H2O and aluminum chloride AlCl3. The effect of changing the aluminum-to-zinc ratio y from 0 to 3 at.%, has been thoroughly investigated. It was found that the optical and electrical properties of Al doped ZnO films improved with the addition of aluminum in the spray solution until y=2%. At this Al doping percentage, the thin layers have a resistivity equal to 4.1 × 10−4 Ω.cm and a transmittance of about 90 % in the region [600-1000] nm. XRD patterns confirm that the films have polycristalline nature and a wurtzite (hexagonal) structure which characterized with (100), (002) and (101) principal orientations. The undoped films have (002) as the preferred orientation but Al doped ones have (101) as the preferred orientation. Beyond y= 1%, peak intensities decrease considerably

Structure, surface composition, and electronic properties of CuInS2 and CuIn(1-x)AlxS2

International audienceCuInS2 and CuIn(1-x)AlxS2 thin films have been deposited on different substrates using the spray pyrolysis technique at 320 degreesC. X-ray diffraction, atomic force microscopy, and scanning electron microscopy were used to characterize the structure of the films; the surface compositions of the films were studied by Auger electrons spectroscopy and energy dispersive spectrometry (EDS), the work function and the photovoltage by the Kelvin method. Using these techniques, we have specified the effect of the nature of the substrate, its surface morphology, and the introduction of small amounts of Al in the layer on the properties of the films. The best crystallized composition of CuInS2 was obtained for deposits on pyrex. This was improved by the introduction of Al atoms. The work function differences (phi(material)-phi(probe)) for CuInS2 and CuIn(1-x)AlxS2 deposited on pyrex were equal to -350 meV and to -400 meV, respectively. Putting Al atoms in the film increases phi(m) (by about 50 meV) and induces the formation of a negative surface barrier. The best composition was obtained for CuInS2 deposited on SnO2 and annealed. Auger studies shows that the concentration of S and C elements increased when the samples were annealed under a vacuum, whereas the concentration of Cu, In, and O decreased. In the case of CuInS2 grown on pyrex, the introduction of Al increases the O, S, and Cl concentrations and reduces Cu and C concentrations. Analysis of the film compositions by EDS gives the following concentrations [Cu]=24.270%, [In]=24.487%, [S]=46.670%, and [Cl]=4.573%. (C) 2002 American Institute of Physics

Structural and Morphological studies of CuIn(1−x)AlxS2 deposited by spray on various substrates

AbstractStructural properties of CuIn(1−x)AlxS2 layers obtained by spray pyrolysis on various substrates were studied using X Ray Diffraction, Atomic Force Microscopy and Scanning electron microscopy. The concentration of Al in the spray solution, represented by the ratio z (z=[Al3+]/[In3+]), was varied from 0 to 3.2%. The different substrates are: glass, ZnO/glass, SnO2/glass, ZnO/SnO2/glass and In2S3/Glass. All the layers were deposited by spray. The ZnO used in the substrates was doped with indium. The concentration of indium in the ZnO sprayed solution is [In]/[Zn]=3%.The X-ray diffraction spectra revealed that, different values of the ratio z, the CuIn(1−x)AlxS2 thin films were well crystallized in the tetragonal structure of the CuInS2 material with the privileged orientation (112) whatever the substrate.The surface topography of the CuIn(1−x)AlxS2 thin films, deduced from the Atomic Force Microscopy, proved that the grain size in the top of the layers depends both on the z value and on the substrate.The Auger analysis has been done in order to get information on the surface layer composition, the measurement show that the surface chemical composition where improved by annealing.In this work the performances of the solar cell CuIn(1−x)AlxS2(p)/CuInS2(p)/In2S3(n)/ZnO, realized with optimized value of Al concentration, is also presented

Analytical and experimental study of electrical conductivity in the lithium tantalate nonstoichiometric structure

We have been interested to experimental and analytical studies of ionic conductivity of nonstoichiometric LiTaO 3 solid solutions. Theoretical approach combined with lithium and tantalate vacancy models has been performed. A comparative study between the calculated and measured values is presented taking into account the temperature and composition effects on the conductivity. I