Brief Summary of Research Experience

« Ph. D. Title: Nanostructured Materials and Their Composites for Energy Storage Device Applications

Overview of the research:

The energy storage devices, such as batteries and electrochemical capacitors, are gaining a wide importance to meet the future energy demands. Electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors are further divided as electrochemical double layer capacitors and pseudocapacitors based on their internal mechanisms of storage/delivery. Both electrode and electrolyte properties are equally important in controlling the performance of these devices. The large surface area, high electrical conductivity, controllable pore size with respect to electrolyte molecules are the some important electrode parameters, whereas high decomposition voltage, high dielectric conductivity, better stability, fast storage/high deliver response, low cost and environmental compatibility are the required properties of electrolytes. Worldwide a lot of research has been focused to achieve the superior specific capacitance and better stability of ECs by controlling both electrode and electrolyte properties. However, the performance of these devices still falls well below the expected level for many of the modern applications.

In our research work [1] Graphene coated on poly urethane foam will act as an electrode material for supercapacitors. [2] A series of linear thiol molecules are chosen to bind on the electrode surface to constitute the electrochemical capacitors. Modified electrodes shows the significant enhancement in specific capacitance values when compared with the untreated electrodes. [3] Deposition of silver nanoparticles and copper sulfide nanoparticles on cellulose paper to create high conducting, high surface area, flexible and light weight electrodes for the constitution of supercapacitors. These electrodes exhibited the high specific capacitance. [4] Similarly silver on foam showed the high specific surface area and the high specific capacitance. [5] Metal oxides and metal sulfides are the emerging materials for supercapacitors. Further research has been carried out with CdO, SnO₂ (on glass as a substrate) and CuS (on cellulose paper) as an electrode for supercapacitors which exhibited the high specific capacitance value with the reported research articles.

« M. Phil – Title: Study of AC mobility in semiconductors

Overview of the research:

In my dissertation work of M. Phil I have concentrated on theoretical work physics, in that I have calculated AC mobility in compound semiconductors like GaAs, GaN, InSb, these elements are also called III-IV compounds. In my dissertation I have discussed about transport properties of these compound semiconductors and calculated mobility for all scattering phenomenon using theoretical formula for mobility.

I have discussed Boltzmann transport equation in AC field and its solution in relaxation time approximation, all the different scattering mechanisms and their relaxation times & about Mathiessens rule. I have calculated average relaxation time, derived mobility expression and relaxation time for three compound semiconductors within the range of 1 x 10⁸ to 1 x 10¹³ of frequency.

Conclusion is that “The effect of polar optic phonon vibrations is greater than the effect of acoustic phonon vibrations, the contribution of relaxation time in mobility due to polar optic phonon scattering is greater than any other scattering mechanisms”. From my thesis I may be able to find many practical applications, like in semiconductor devices. Presently research work is going on in North Carolina USA they invented a semiconductor device called “HEMT – stands for High Electron Mobility Transistor” using GaAs and GaN compound semiconductors.

« M. Sc Project - Title: Study of Color Centre in Alkyl Halides

Overview of project:

The experiment for color centre in alkali halides, we studied about defects in solids. This causes color formation in crystal. We did experiment for KBr, in that we used spherical shaped glass tube for keeping K and Br, we evacuated the tube, after we sealed it with the help of glass blower. Next we have heated in oven of asbestos pipe for 400˚ C over night. We collected the sample. We analyzed the yellow colored sample by UV spectrum. We calculated Gaussian distribution and frequency at which range absorption takes place.