Day 1 :
A P Pathak
University of Hyderabad, India
Keynote: Nano Science and Nano Technology research using Ion Beams, Lasers and gamma radiations
Anand P Pathak, a Ph.D. from Indian Institute of Technology, Kanpur in 1971, is a Fellow of National Academy of Sciences India (NASI) F N A Sc, IOP (London) F Inst P, C Phys. He is member of International Committee, ICACS and IBA. He was Chair ICACS20 and IBA2007. He is an Associate Editor of REDS. His postdoctoral appointments were in AERE, Harewell and CEA France. He was Physics faculty at University of Hyderabad 1977-2011 where he also served as Dean, school of Physics during 1992-1996. He was CSIR Emeritus Scientist till Dec 2016 and currently NASI Senior Scientist Platinum Jubilee Fellow at University of Hyderabad He was Guest faculty in IIIT (RGUKT) Basar, and Sikkim University, Gangtok. He was Distinguished Research Scientist at CSIRO Australia, Humboldt Fellow in Germany, Chair Professor in Mexico etc. His research interests are ion solid interactions and ion beam and Laser studies of nano-materials. He has 327 publications in international journals.
Swift heavy ion beams, Lasers and Gamma Radiations have been used to synthesize and modify nanostructures of elemental as well as compound semiconductors. Subsequent characterization is done by using XRD, Raman and TEM. An overview of the dependence of the resulting new class of nano-materials on energy and fluence of the initial swift heavy ions and Lasers will be presented. These external radiations modify the electronic and optical properties of nanostructures (quantum wells, quantum dots and nanowires). Some applications of these studies in Nanotechnology in general and opto-electronic devices in particular along with their relevance in energy research as well as biosciences, will also be discussed during this Webinar on the theme Innovative Methodology and Modern Advances in Materials Science & Engineering.
King Fahd University of Petroleum and Minerals, Saudi Arabia
Keynote: Improving water barrier and mechanical properties of epoxy with nanoclays
Dr. Merah is a professor in the Mechanical Engineering Department at King Fahd University of Petroleum and Minerals. He obtained his Ph.D. in Mechanical Engineering from Ecole Polytechnique of Montreal and his MSc and BSc from the University of Tulsa, OK, USA. His research work in multidisciplinary design, fracture mechanics and materials synthesis and characterization has been largely funded by industry and national and international research organizations and institutions. He has contributed more than 170 scholarly publications and 15 US patents. His research outcome and excellence in teaching have been recognized by a number of national and international awards.
Statement of the Problem: Epoxy resins have an attractive combination of stiffness, strength, high heat distortion temperature, creep resistance, thermal, and environmental stability. This makes them one of the most applied thermoset polymers for fiber reinforced structures and anticorrosion coatings. However, epoxies’ affinity to water results in moisture uptake that degrades the functional, structural, and mechanical properties of epoxy-based composites and coatings. Absorbed liquid molecules act as efficient plasticizers for cured epoxy systems thereby reducing strength, stiffness, and glass transition temperatures. Several researchers have shown that proper mixing of clay nanocomposites with epoxy reduces its water uptake and helps improve its mechanical, thermal and physical properties. The purpose of this work is to show what optimum parameters can lead to proper clay dispersion and distribution of nanoclays in epoxy matrix. Methodology: Two mixing techniques, high shear mixing (HSM) and ultra-sonication, were used, at different mixing speeds and times, to disperse different clay loadings (1-10wt%) in diglycidyl ether of bisphenol A (DGEBA) epoxy matrix. Four types of organically-modified montmorillonite clays are investigated, namely; monomers: I.30E, I.28E, and Cloisites C10A, and C15A. Findings: The results showed that optimal clay dispersion was obtained with 1.0wt% to 2.0wt% of I.30E and C10A clays, using HSM at the optimum speed and mixing time of 6000 rpm and 60 min, respectively. These, with a degassing temperature, around 100˚C lead to the synthesis of nanocomposites with a disorder-intercalated and exfoliated morphologies that reduced the diffusion constant of epoxy by more than 50% and maximum water uptake by more than 20%. Conclusion & Significance: The reduction in water uptake improved the glass transition temperature and the mechanical properties of the pristine polymer. These improvements are mainly due to the tortuosity effect, where water molecules have to move around clay layers during diffusion in nanocomposites.
- Physics and Chemistry of Materials | Materials Science and Engineering
Kathmandu University, Nepal
Title: Electronic structure calculation of graphene by formulating a relativistic tight-binding approximation model
Rohin Sharma is a graduate student of physics at Kathmandu University who recently graduated with a MSc. degree in Physics. He has a research background and interest in condensed matter theory and computational material science. He has done several research involving investigating materials properties using first principle calculation methods, namely the plane wave dft codes of Quantum espresso. The work presented here is his most recent work which was part of his thesis work for the achievement of the master’s degree. The work presents a theoretical framework that is used to accurately build the Hamiltonian matrix of the system. He is currently working as a research assistant in Phutung Research Institute doing experimental optical research on the nano-photonic waveguides and Raman scattering.
A non-perturbative relativistic Tight-Binding (TB) approximation method applicable to crystalline material immersed in a magnetic field was developed in 2015. To apply this method to any material in a magnetic field, the electronic structure of the material in absence of the magnetic field must be calculated. In this study, we present the relativistic TB approximation method for graphene in a zero magnetic field. The Hamiltonian and overlap matrix is constructed considering the nearest neighbouring atomic interactions between the s and p valence orbitals, where the relativistic hopping and overlap integrals are calculated using the relativistic version of the Slater-Koster table. The method of constructing the Hamiltonian and overlap matrix and the resulting energy-band structure of graphene in the first Brillouin zone is presented in this paper. It is found that there is an appearance of a small band-gap at the k points (also known as the spin-orbit gap) due to the relativistic effect, whose magnitude is 25 $mu$eV.
Bhabha Atomic Research Centre, India
Title: Process intensification and optimization for sonocrystallisation of uranium peroxide
Shrishma Paik is currently working in the field of nuclear technology on separation and recovery of uranium from different sources. Her development area involves intensification of process of uranium by precipitation as well as solvent extraction by novel techniques and minimization of waste volume during uranium refining process.
Peroxide precipitation is an emerging process in nuclear technology and one of the well-known methods for production of first intermediate uranium compound before uranium bearing fuel production. Though the conventional method of precipitation is practiced worldwide, it suffers from the limitation of non-uniform particle formation and lesser control over particle growth and size. Hence there is always a scope to study the effect of novel technique for process intensification. Application of ultrasound or sonochemical technique is one of the techniques which can intensify the crystallization event to a large extent by the impact of its cavitational process imparting micro mixing, enhanced mass transfer and the effect of additional spontaneous nucleation. It also facilitates in enhancing the crystal shape and size with better consistency and can control physical and morphological characteristics of the powder in several ways. Here, study was carried out for establishing important process parameters namely uranium cocn and temperature for ultrasonic precipitation compared to conventional methods in laboratory scale with an ultrasound horn at 35 KHz. Uranyl nitrate with 30% hydrogen peroxide was used for the reaction in 1 liter scale. No appreciable difference in the phases has been found from the XRD study. However a more homogeneous, regular and smooth crystalline appearance is observed in sonochemical precipitation route compared to conventional route under SEM study at 100 g/L uranium with 60ºC temperature. The crystal shape is rhombohedra with a spherical aggregation in comparison to needle shaped crystals in conventional route. Significant improvement is also seen in specific surface area and tap density of the prepared powder in sononchemical route. The powders obtained from this novel technique are having recovery more than 99.9% w.r.t. uranium. The purity of the synthesized powder also meets the specification of nuclear grade quality. Overall, the sonochemical method of precipitation of uranium peroxide is a fast, simple, convenient and intensifying technique imparting appreciable morphology and physical characteristics over the conventional precipitation process.