Bismuth Oxide Thin Films for Optoelectronic and Humidity Sensing Applications

Bismuth oxide thin films still prove attractive to both scientists and engineers due to their semiconducting behavior, large energy bandgap and high refractive index, despite their often complex structure, both polymorphic and polycrystalline. We present here a summary and a comparison of the morpho-structural and optical properties of such films prepared through three physical vapor deposition (PVD) techniques on several types of substrates kept at different temperatures. Thermal vapor deposition, thermal oxidation in air and pulsed laser deposition are discussed as largely used PVD methods. It is proved that the physical properties of the bismuth oxide thin films can be tailored by changing the substrate nature and its temperature during the deposition process in a way even more relevant than even the chosen deposition method. Thus, bismuth oxide thin films with energy bandgaps ranging from the infrared up to near-ultraviolet can be obtained, depending on their structure and morphology. High refractive index of the films can be also attained for specific spectral ranges. When deposited on certain conductive substrates, the films have much lower electrical resistance and even became sensitive to water vapor. Therefore, humidity sensing and optoelectronic applications of the analyzed bismuth oxide thin films can be easily found and used in both science and technology

CLOUD COVER AND INTERPLANETARY MAGNETIC FIELD: POSSIBLE RELATIONSHIP

Solar energy is the main driver of the climate on Eart, thus the variation of solar activity may affect climate variability via changes in irradiation, energetic particles, cosmic ray flux or solar wind parameters. Solar wind is characterized by speed, magnetic and electric fields, flow pressure, particle flux, dynamic pressure, with various effects on atmospheric processes. One of these is the formation and evolution of clouds which play a crucial role in the terrestrial climate, since they induce cooling or warming effects, depending on their heights and composition. Possible relationship between solar activity and cloud cover variability are lately the subject of various studies, but no clear conclusion exists due to contradictory results obtained so far. This article studies the possible relationship between mean cloud cover and the interplanetary magnetic field at global scale, as well as geographical/regional characteristics for the 1984 – 2009 period, i. e. for solar cycles 22-23, when satellite observations are available at global scale and on a continuous basis. The study also shows the seasonal dependence and is made for different cloud height and composition, i. e. for low/middle/high and liquid/ice types of clouds

Correlation Studies between Sol Aging Time and Substrate Dipping Time Parameter and Optical Properties of Cobalt Oxide Layers

Cobalt oxide films represent an important class of materials which are characterized with good electrochemical, catalytic and optical properties [1]. Many articles proved that so

Preparation and Characterization of Tin Oxide Thin Films

Tin oxide (SnO) thin films were prepared onto glass substrates by thermal evaporation under vacuum. The substrate temperature was kept constant at 300 K during the film growth. The structural studies using transmission electron microscopy (TEM) analysis showed that the SnO thin films have a polycrystalline and tetragonal crystal structure with preferential orientation of (110) planes parallel to the substrate. Optical transmission and reflection spectra, at normal incidence, in the spectral range 300-1100 nm, are investigated. The optical properties of SnO thin films were determined. The optical energy band gap, Eg, has been estimated from the absorption coefficient values using Tauc’s procedure. It is found that the SnO thin films exhibit direct band gap

Clouds and the Near-Earth Environment: Possible Links

Climate variability is a hot topic not only for scientists and policy-makers, but also for each and every one of us. The anthropogenic activities are considered to be responsible for most climate change, however there are large uncertainties about the magnitude of effects of solar variability and other extraterrestrial influences, such as galactic cosmic rays on terrestrial climate. Clouds play an important role due to feedbacks of the radiation budget: variation of cloud cover/composition affects climate, which, in turn, affects cloud cover via atmospheric dynamics and sea temperature variations. Cloud formation and evolution are still under scientific scrutiny, since their microphysics is still not understood. Besides atmospheric dynamics and other internal climatic parameters, extraterrestrial sources of cloud cover variation are considered. One of these is the solar wind, whose effect on cloud cover might be modulated by the global atmospheric electrical circuit. Clouds height and composition, their seasonal variation and latitudinal distribution should be considered when trying to identify possible mechanisms by which solar energy is transferred to clouds. The influence of the solar wind on cloud formation can be assessed also through the ap index - the geomagnetic storm index, which can be readily connected with interplanetary magnetic field, IMF structure. This paper proposes to assess the possible relationship between both cloud cover and solar wind proxies, as the ap index, function of cloud height and composition and also through seasonal studies. The data covers almost three solar cycles (1984-2009). Mechanisms are looked for by investigating observed trends or correlation at local/seasonal scal

Effect of substrate temperature on bismuth oxide thin films grown by pulsed laser deposition

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Clouds blown by the solar wind

In this letter we investigate possible relationships between the cloud cover (CC) and the interplanetary electric field (IEF), which is modulated by the solar wind speed and the interplanetary magnetic field. We show that CC at mid–high latitudes systematically correlates with positive IEF, which has a clear energetic input into the atmosphere, but not with negative IEF, in general agreement with predictions of the global electric circuit (GEC)-related mechanism. Thus, our results suggest that mid–high latitude clouds might be affected by the solar wind via the GEC. Since IEF responds differently to solar activity than, for instance, cosmic ray flux or solar irradiance, we also show that such a study allows distinguishing one solar-driven mechanism of cloud evolution, via the GEC, from others

Wastewater assessment in Galatz city during 2015-2016

Due to the industrialization and urbanization a great quantity of wastewater is produced every day. It is important to monitor the wastewater quality and to determine if it is safe to discharge it in to the environment.In this study, wastewater quality in Galatz city, from Romania, was evaluated. The wastewater generally comes from domestic activities and from industry. We were monitored wastewater which enters in the treatment station of the city.In order to monitor the wastewater quality, some physical and chemical parameters were determined according to standard methods. The analyzed chemical parameters were: ammonium (mg/l), total nitrogen (mg/l), sulphides and hydrogen sulphide (mg/l), total phosphorus, total dispersed solids (TDS), total solids in suspension (TSS)(mg/l), chemical oxygen demand (COD)(mg O2/l) and pH. As physical parameters was studied only conductivity. These data were collected during February 2015–February 2016. The physico-chemical parameters were determinated each month during this period

BISMUTH OXIDE THIN FILMS DEPOSITED ON SILICON THROUGH PULSED LASER ABLATION, FOR INFRARED DETECTORS

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