A5023536469- Advanced Thermoelectric Materials and Devices
- Mechanical and Optical Resonators
- Carbon Nanotubes in Composites
- Thermal properties of materials
- Machine Learning in Materials Science
- Thermal Expansion and Ionic Conductivity
- Force Microscopy Techniques and Applications
- Nanotechnology research and applications
- Field-Flow Fractionation Techniques
- Advanced Thermodynamics and Statistical Mechanics
- Solid-state spectroscopy and crystallography
- Physics of Superconductivity and Magnetism
- Phase-change materials and chalcogenides
- Advanced Thermodynamic Systems and Engines
Jawaharlal Nehru Centre for Advanced Scientific Research
2019-2025
Indian Institute of Technology Kharagpur
2011-2017
Understanding the mechanism that correlates phonon transport with chemical bonding and solid-state structure is key to envisage develop materials ultralow thermal conductivity, which are essential for efficient thermoelectrics barrier coatings. We synthesized thallium selenide (TlSe), comprised of intertwined stiff weakly bonded substructures exhibits intrinsically lattice conductivity (κL) 0.62-0.4 W/mK in range 295-525 K. Ultralow κL TlSe a result its low energy optical modes strongly...
Understanding the correlations of both local and global structures with lattice dynamics is critical for achieving low thermal conductivity (κlat ) in crystalline materials. Herein, we demonstrate cationic off-centring within rock-salt structure AgSbSe2 by using synchrotron X-ray pair distribution function analysis unravel origin its ultralow κlat ≈0.4 W mK-1 at 300 K. The cations are locally off-centered along crystallographic ⟨100⟩ direction about ≈0.2 Å, which averages out as on scale....
Seeking new and efficient thermoelectric materials requires a detailed comprehension of chemical bonding structure in solids at microscopic levels, which dictates their intriguing physical properties. Herein, we investigate the influence local structural distortion on properties TlCuS, layered metal sulfide featuring edge-shared Cu-S tetrahedra within Cu2S2 layers. While powder X-ray diffraction suggests average crystallographic symmetry with no CuS4 tetrahedra, synchrotron pair distribution...
Abstract The consequences of broken long‐range atomic arrangement in glasses or amorphous solids are reflected the temperature dependence lattice thermal conductivity (κ lat ). However, appearance glassy ultralow κ a crystalline solid with high electrical transport like metal is unusual but can have remarkable impact on thermoelectric performance material. Here, an ultra‐high demonstrated maximum figure merit, zT ≈ 2.7 (≈2.92 Dulong–Petit heat capacity) via achieving along significant ball...
Phononic coupling can have a significant role in friction between nanoscale surfaces. We find frictional dissipation per atom carbon nanotube (CNT) oscillators to depend significantly on interface features such as contact area, commensurability, and by end-capping of the inner core. perform large-scale phonon wavepacket MD simulations study 250 nm long (10,10) outer tube cores four different geometries. Five polarizations known dominant roles thermal transport are selected, transmission...
Using phonon wave packet molecular dynamics simulations, we find that anomalous longitudinal acoustic (LA) mode scattering in low to moderate energy ranges is responsible for initiating thermophoretic motion carbon nanotube oscillators. The repeated of a single LA near the ends inner provides net unbalanced force that, if large enough, initiates thermophoresis. By applying coherent pulse on outer tube, which generalizes packet, are able achieve thermophoresis oscillator. We also nature...
Friction in carbon nanotube (CNT) oscillators can be explained terms of the interplay between low frequency mechanical motions and high vibrational modes sliding surfaces. We analyze single mode phonon wave packet dynamics CNT based oscillators, with cores either stationary or moderate velocities, study how various individual phonons travel through outer CNT, interact inner nanostructure, undergo scattering. Two acoustic (longitudinal transverse) one optical (flexural optical) are found to...
Effect of vacancy and Stone–Wales defects on the oscillatory behavior (5,5)/(10,10) carbon nanotube-based oscillator are studied using NVE molecular dynamics simulations. Results show that reduce stability oscillators. single defect is very small, whereas considerably reduces thereby damping oscillations quickly. Further increase in density causes a monotonic decrease oscillator. In all cases initial temperature (1 300 K) had almost no effect oscillation stability.
Abstract Understanding the correlations of both local and global structures with lattice dynamics is critical for achieving low thermal conductivity ( κ lat ) in crystalline materials. Herein, we demonstrate cationic off‐centring within rock‐salt structure AgSbSe 2 by using synchrotron X‐ray pair distribution function analysis unravel origin its ultralow ≈0.4 W mK −1 at 300 K. The cations are locally off‐centered along crystallographic direction about ≈0.2 Å, which averages out as on scale....
There are various potential applications in which carbon nanotubes (CNTs) may be subjected to bending a cantilevered configuration leading buckling turn affect their electrical, electronic as well load bearing properties. Using atomistic simulations, we study and post-buckling behavior of six single-walled CNTs cantilever loading (i.e., flexure addition shear axial compression). Starting with small kinks on the compression side corresponding locations high strain energy density, ripples form...