Research

Increasing demand for energy and pollutant free environment has led to continuous investigation of leading-edge technological products with high energy efficient performance. Thermoelectric materials, which enable direct conversion between thermal and electrical energy, based on Seebeck and Peltier effects are being actively considered for a variety of energy harvesting and thermal management applications. The efficiency of thermoelectric materials is measured by a dimensionless figure of merit ZT =S^2σT /(κ_L + κ_e ), where S is the Seebeck coefficient, σ is the electrical conductivity, T is the temperature, and κ_L and κ_e are the phononic and electronic contributions to the thermal conductivity, respectively. As the fabrication of technological products has to be cost effective, the thermoelectric materials should be available at low price, high stability with respect to temperature and give sufficient output. Therefore, for enhancing ZT , proper material selection, optimization of their thermoelectric properties is necessary. Optimization of the properties can be done by developing bulk materials by alloying, doping or by preparing nanostructured materials by reducing the grain size of the materials, hence giving higher ZT. In our group we are working on computational prediction of novel thermoelectric materials by using Density functional theory (DFT) , BoltzTraP2 ( An open source code for solving Boltzmann Transport equation for electron) , Phonopy ( Phonon calculation) and homemade code.

Conventional electronic devices involve manipulation of charge degree of freedom of electron. Irrespective of tremendous advancement in this field, there are challenges like device speed, miniaturization, non-volatility, integration density and power consumption. To surpass or overcome these traditional shortcomings , another intrinsic property of electron i.e. spin can be exploited in integration with traditional charge-based devices. This has begun a new era of spintronics or spin-electronics. This rather new research field of spintronics is currently being explored rigorously due to its huge potential for development of new spin based devices free from conventional boundaries. Applications of spintronics include nonvolatile memories, detectors, sensors and spin-based junctions and amplifiers. For successful implementation of electron spin in practical devices generation, manipulation and detection of spin in materials are three basic processes that are to be handled. For realization and fabrication of spintronic devices, we need unprecedented materials that relies on magnetism rather than flow of current through charge of electron. In our group, we are working on finding interesting magnetic properties with or without spin orbit coupling in ternary chalcogenides studying the correlation effects with density functional theory calculations which are useful for spintronic devices.

In the last few decades, intense research and development efforts have been devoted to energy harvesting technologies, which utilize the wasted energy such as vibrations, heat, wind and water into electrical energy for low-power devices. Piezoelectric materials can be electrically polarized under an externally applied strain and can be deformed by an applied voltage that is, they undergo electromechanical coupling which is crucial for sensing, actuating and energy harvesting. Piezoelectricity is only possible in materials which have non-centrosymmetric structure. Many materials which are not piezoelectric in their bulk form become piezoelectric when reduced to a single atomic layer as they lack inversion symmetry in the monolayer form. Moreover, 2D materials are strong, flexible and easy to be integrated with conventional integrated circuits or micro-electromechanical systems. Piezoelectric materials find their application in bio-medical and smart health devices too. We are working on theoretically predicting the novel piezoelectric materials by using density functional theory (DFT) to expand the pool of these materials for more cost-effective and performance-effective choices.

Hyperthermia therapy has been considered as an alternate treatment method for cancer therapy due to the physical and physiological side effects present in the conventional cancer treatment methods such as drug, surgery, chemotherapy, and radiotherapy. There are many modes of hyperthermia available such as whole body hyperthermia, radiofrequency capacitance hyperthermia, and phased-array microwave hyperthermia. However, these methods have their own limitations like invasive, tissue non-specific, heating above the physiological temperature, heating surrounding cells. The ideal hyperthermia should be non-invasive, tissue-specific, precise localization of thermal energy, and high intensity heating. In our combined experimental and theoretical method, we are working on high intensity ultra sound based hyperthermia and hyperthermia by AC magnetic field. We are working on theoretical modeling on the mechanism of ultrasound or magnetic energy transfer to heat energy in a Nano-particulate system.

Nanofluids are the suspension of solid nanoparticles in the liquid medium. Nanofluids show extraordinary stability as compared to the microfluids due to their smaller size. The larger surface to volume ratio of the nanoparticles in nanofluids lead to more interaction with the solvent molecules at the interface. Due to the interesting nature of the nanofluids, it has been focused for many applications in diverse fields such as mechanical, electrical, optical, heat transfer and biomedical engineering. Heat transfer using nanofluids is one of the recent research interests being focused by many researchers due to the anomalous thermal properties of nanofluids. In our group we are working on experimental method and theoretical modelling of thermal transport mechanism through nanofluids.