Thin films of Barium Strontium Titanate (BST) have been fabricated using Pulse Laser Deposition (PLD) technique. Two stoichiometries of BaxSr1-xTiO3 with x=0.5 and x=0.7 are deposited on well cleaned quarts substrates in high vacuum chamber with oxygen pressure of 0.13mbar at 700˚C. XRD pattern shows perovskite structure of the films. Energy Dispersive X-ray (EDX) is used to determine the element concentration of both the films. Transmittance spectra of UV characterization shows decrement in transparency of the film as Barium (Ba) concentration increase and sharp cut-offs are observed at the band edge. Refractive Index (n), absorption coefficient (α), extinction coefficient (k), optical conductivity (σ) and optical band gap (Eg) are derived from UV-Vis spectroscopy. The calculated parameters for Ba0.5Sr0.5TiO3 and Ba0.7Sr0.3TiO3 are presented in this work. The present work also includes study of BST thin films as gas sensors.
The group II-IV nanoparticles have excellent semiconducting properties having a possibility of tuning it by changing the size, shape and precursors. This makes them an ideal candidate for their applications in the field of science and technology. Amongst several semiconductor nanoparticles, zinc sulphide (ZnS) nanoparticles are promising material because of chemical stability, low toxicity and better optical properties. Introducing transition metal impurities in ZnS nanoparticles further improves the physical properties like optical and magnetic. The synthesis and optical properties of transition metal doped ZnS nanoparticles with varying doping percentage is reported. The doping of ZnS with the transition metal with variable doping concentration improves the luminescence in comparison of pure ZnS. The photoluminescence spectrum has a single major peak at 780nm, and the intensity increases with the type and concentration of the impurity but at higher concentration the luminescence is quenching. This paper tries to give a comprehensive study of photoluminescence of ZnS nanoparticles doped with different transition metal with varying concentration.
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