Research

Thermal Engineering Stream 

Major Area of research Energy Materials/ Energy Engineering

Expert in the ferroelectric/piezoelectric ceramics materials synthesis by solid-state reaction method and expert in materials characterization techniques like SEM, AFM, dielectric and ferroelectric measurements, impedance spectroscopy, electrocaloric, piezoelectric, pyroelectric studies. Research interest in Ferroelectric/Piezoelectric ceramics materials for energy harvesting, cooling, storage applications experimental and theoretical modeling.

Google Scholar

https://scholar.google.co.in/citations?user=ZyXuyHMAAAAJ&hl=en

The ability of ferroelectric materials to successfully combine physical and electrical stimulus has resulted into a number of novel applications ranging from sensors, transducers, and random access memory (RAM) to integrated health monitoring systems. However their applications in energy devices are not well explored. These materials have high dielectric constant and have strong electric-thermal –mechanical coupling. These features are desirable for electrical energy storage and waste thermal/mechanical energy harvesting devices, respectively. I have been working on engineering and scientific aspects of ferroelectric materials in view of high energy density capacitors, waste (thermal and mechanical energy harvesting) and solid state refrigeration applications. As briefly explained below.

 Waste Energy Harvesting

Electrical energy generation (from waste energy) is currently a topic of intense interest because of the growing energy demands of society and as a means to create autonomous and self-powered systems. For example, applications for energy harvesting devices include battery-free wireless sensor networks that do not require maintenance or replacement, with typical power requirements in mW range. Piezoelectric and pyroelectric effects are promising phenomena for harvesting waste mechanical and thermal energies. These effects are being used for sensing and actuator purposes. However, their applications in energy harvesting are relatively unexplored. In this direction various lead-free ferroelectric (pyroelectric and piezoelectric) materials can be fabricated and tested for energy harvesting view points. Finite element method-based studies were also performed in view of optimizing device parameters. 

Solid State Cooling Materials and Methods 

There is a great interest in seeing the development of new solid-state refrigeration technologies. In part, this is driven by a desire to replace the existing vapor-compression cycle technologies, which are notoriously inefficient, with new refrigeration devices that operate near the Carnot limit. A second motivation for the development of solid-state cooling is the creation of new microscale refrigeration devices that can be deployed within larger devices, e.g., cooling on a chip. The traditional approach to solid-state refrigeration employs the Peltier effect for thermoelectric devices. In recent years, there has been interest in developing new approaches including devices based on the giant magnetocaloric, the giant electrocaloric, and mechanocaloric effects in various classes of materials.

Dielectric Materials for High Energy Density Capacitors                       

 The storage of electrical energy is important for devices ranging from cell phones to electric vehicles. Capacitors provide a way of storing energy that can be both rapidly charged and discharged. Present capacitors have relatively limited energy storage capacities on the order of kilowatt hours per unit volume or kilogram. Generally, these high energy density capacitors are made from electrolytic and polymer technologies, which suffer from problems such as lower energy density and are volumetrically inefficient. Also, under elevated operating temperatures, electrolytic capacitors are prone to evaporation of the electrolyte solution. The high energy-storage capacity in capacitors can be achieved by using materials with high dielectric constants along with a large dielectric breakdown strength. Usually, high dielectric constants are associated with ferroelectric/anti-ferroelectric materials due to dipole polarizations and, hence, these materials have been extensively investigated for use as electrostatic capacitors. 

 Looking for Piezotronic Applications

 The research work wants to explores a novel way of tailoring the electromechanical properties, which has not been attempted earlier and is aimed towards ZnO for sensing and energy conversion applications. This work also explores simulation and experimental study of ZnO as energy generator for powering suitable NEMS/MEMS devices. Further, I also aim to explore the theoretical modelling of these effects. Additionally, I have also explored a relatively new phenomenon (flexoelectric effect) in ZnO for I-V potential and energy conversion. Moreover flexoelectric dependency on various parameters such as stress application direction, electrode and substrate will also be undertaken. The main scientific goal of this research plan is to develop ZnO nanorods/nanowires for tuning the I-V characteristics by mechanical confinement and explore potential application as nanogenerators for energy conversion, which will open up new avenues of research in the field of developing functional materials with novel properties.

"Developmentof Porous Lead-Free Ceramics for Temperature-Independent Pyroelectric Performance and Waste Energy Harvesting

Science and Engineering Research Board (SERB)  Amount of Rs. 2375790