Xavier Sahaya Shajan

Aerogels are 3-D nanostructures of non-fluid colloidal interconnected porous networks consisting of loosely packed bonded particles that are expanded throughout its volume by gas and exhibit ultra-low density and high specific surface area. Aerogels are normally synthesized through a sol–gel method followed by a special drying technique such as supercritical drying or ambient pressure drying. The fascinating properties of aerogels like high surface area, open porous structure greatly influence the performances of energy conversion and storage devices and encourage the development of sustainable electrochemical devices. Therefore, this review describes on the applications of inorganic, organic and composite aerogel nanostructures to dye-sensitized solar cells, fuel cells, batteries and supercapacitors accompanied by the significant steps involved in the synthesis, mechanism of network formation and various drying techniques.

A new type of lithium enriched cathode material Li (Li_0.05Ni_0.6Fe_0.1Mn_0.25)O₂ was synthesized by sol-gel method with citric acid as a chelating agent. The structural and morphological studies were systematically investigated through X-ray diffraction, SEM with EDS, FT-IR and Raman analyses. The crystallite size of the Li (Li_0.05Ni_0.6Fe_0.1Mn_0.25)O₂ cathode material was found to be 45 nm thereby leads to the feasible movement of lithium ion all through the material. FT-IR spectroscopy was used to confirm the metal-oxygen interaction in the prepared cathode material. The electrical properties of the Li (Li_0.05Ni_0.6Fe_0.1Mn_0.25)O₂ cathode material were studied by impedance and dielectric spectral analyzes. Li (Li_0.05Ni_0.6Fe_0.1Mn_0.25)O₂ showed a maximum ionic conductivity of 10^-6 S/cm at ambient temperature.

Semi‐organic single crystals of barium ‐ calcium succinate have been grown by the slow evaporation solution growth technique for the first time with reasonable size. It illustrate like a routine growth methodologies and characterization but many applications demand crystals with greater flexibility and it can able to control and alter the properties of the single crystal. One of the useful approaches is to prepare hybrid crystals, their properties are different from the single component crystals. In this context the present work is considered. Crystal structure, chemical composition and thermal stability of the five grown crystals have been determined by carrying out single crystal X‐ray diffraction, FTIR spectroscopic, atomic absorption spectroscopic and thermogravimetric analyses. The grown crystals have been characterized optically, mechanically and electrically by carrying out optical transmittance, photoluminescence, second harmonic generation efficiency, microhardness and electrical (both AC and DC) measurements. Results obtained in the present study indicate the possibility of growing single phased mixed crystals with the end members being non‐isomorphous and with tuned thermal, optical, mechanical and electrical properties.