Shivaji University

About: Shivaji University is a education organization based out in Kolhāpur, Maharashtra, India. It is known for research contribution in the topics: Thin film & Scanning electron microscope. The organization has 3078 authors who have published 5295 publications receiving 115397 citations.

Temperature influence on morphological progress of Ni(OH)2 thin films and its subsequent effect on electrochemical supercapacitive properties

Abstract: The temperature dependent morphological evolution and its effect on the electrochemical supercapacitive properties of Ni(OH)2 thin films have been systematically investigated. A temperature dependent growth mechanism model is proposed for the changes in microstructure. Different nanostructures of Ni(OH)2 thin films such as nanoplates, stacked nanoplates, nanobelts and nanoribbons have been fabricated by varying the deposition temperature. An X-ray diffraction study discloses the orientations of different nanostructures and the formation of nanocrystalline β-Ni(OH)2. Further, these Ni(OH)2 nanostructures demonstrate excellent surface properties like uniform surface morphology, good surface area, pore volume and uniform pore size distribution. The electrochemical supercapacitive properties of Ni(OH)2 nanostructures have been investigated by cyclic voltammetry, charge–discharge and electrochemical impedance spectroscopy techniques. The electrochemical studies of the Ni(OH)2 samples show an obvious influence of surface properties on the pseudocapacitance. The maximum specific capacitance of 357 F g−1 was evaluated for nanoplates at a scan rate of 5 mV s−1. Furthermore, all these Ni(OH)2 samples show good long-term cycling performances in KOH electrolyte. The Ragone plots ascertain good power and energy densities of all Ni(OH)2 nanostructured samples. Subsequently, electrochemical impedance measurements for the different nanostructures of Ni(OH)2 electrodes are assessed indicating that the Ni(OH)2 nanoplates structured electrodes are suitable for good capacity electrochemical supercapacitors.

Band gap shift, structural characterization and phase transformation of CdSe thin films from nanocrystalline cubic to nanorod hexagonal on air annealing

Abstract: Cadmium selenide (CdSe) thin films were deposited on a glass substrate using the chemical bath deposition method at room temperature. The films were deposited using cadmium acetate as a Cd2+ ion source and sodium selenosulfate as a Se2? ion source. The 'as-deposited' CdSe thin films are red in colour and specularly reflective. The 'as-deposited' CdSe layers grew with nanocrystalline cubic phase along with some amorphous phase present, with an optical band gap 'Eg' of 2.3 eV and electrical resistivity of the order of 105?106 ? cm. The 'as-deposited' film is annealed in air at 673 K for 4 h and the effect of annealing on structural, morphological, optical and electrical properties is studied. It is worth noting that after annealing, metastable nanocrystallite cubic phase transforms into stable well crystalline hexagonal phase and films show a 'redshift' of '0.6 eV' in their optical band gap 'Eg'. After annealing, the crystallites' size increases from 45 ? to 180 ?, which results in a decrease in electrical resistivity. These changes have been attributed to the crystallite size dependent properties of CdSe semiconductor thin films.