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Ranita Basu

Bio: Ranita Basu is an academic researcher from Bhabha Atomic Research Centre. The author has contributed to research in topics: Thermoelectric effect & Seebeck coefficient. The author has an hindex of 13, co-authored 47 publications receiving 691 citations. Previous affiliations of Ranita Basu include Indira Gandhi Centre for Atomic Research.

Papers published on a yearly basis

Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors present an overview on the various aspects of device development i.e. from synthesis of high ZT thermoelectric materials to issues & design aspects of the TEG.

224 citations

Journal ArticleDOI
TL;DR: In this article, the highest value of thermoelectric figure-of-merit (ZT) ∼1.84 at 1073 K for n-type SiGe nanostructured bulk alloys was achieved.
Abstract: Silicon germanium alloys (Si80Ge20) have been used in thermoelectric generators for deep space missions to convert radioisotope heat into electricity. This work demonstrates the highest value of thermoelectric figure-of-merit (ZT) ∼1.84 at 1073 K for n-type SiGe nanostructured bulk alloys, which is 34% higher than the reported record value for n-type SiGe alloys. The optimized samples exhibit a Seebeck coefficient of ∼284 μV K−1, resistivity of ∼45 μΩ m and thermal conductivity of ∼0.93 W m−1 K−1 at 1073 K. The main contributing factor for the enhanced ZT is very low and almost temperature independent thermal conductivity, which overcomes the low power factor of the material. Significant reduction of the thermal conductivity is caused by the scattering of low, medium and high wavelength phonons by atomic size defects, dislocations, and grain boundaries that are present due to the formation of nanocrystalline grains in the bulk material.

139 citations

Journal ArticleDOI
TL;DR: In this article, a new class of thermoelectric (AgCrSe2)0.5 nano-composites is reported, which naturally consists of phonon scattering centers in a multiscale hierarchical fashion, i.e., atomic scale disorder, nanoscale amorphous structure, natural grain boundaries due to layered structure and mesoscale grain boundaries/interfaces.
Abstract: Recent studies have shown that thermoelectric materials exhibit a high figure-of-merit if it consists of hierarchically organized microstructures that significantly lower the lattice thermal conductivity without any appreciable change in the power factor. Here, we report a new class of thermoelectric (AgCrSe2)0.5(CuCrSe2)0.5 nano-composites synthesized via the vacuum hot pressing of a mixture of the constituents, which naturally consists of phonon scattering centers in a multiscale hierarchical fashion, i.e. atomic scale disorder, nanoscale amorphous structure, natural grain boundaries due to layered structure and mesoscale grain boundaries/interfaces. The presence of a natural hierarchical architecture of different length scales in the composite samples is confirmed by scanning electron and transmission electron microscopy. Detailed characterization reveals that in the composite samples there is a slight migration of Cu into the Ag site. Composite samples exhibit extremely low thermal conductivity ∼2 mW cm−1 K−1 at 773 K, which is nearly one third of the pure AgCrSe2 and CuCrSe2. The composite samples exhibit a high ZT ∼ 1.4 at 773 K, which is attributed to the scattering of heat carrying phonons of all wavelengths via the natural hierarchical architecture of the material. The ease of synthesis of such high performance (AgCrSe2)0.5(CuCrSe2)0.5 nanocomposites with a natural hierarchical architecture offers a promise for replacing conventional tellurides.

77 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reported a very high ZT ∼ 1 at 773 K. This unusual combination of thermoelectric properties for CuCrSe2 suggests that it is an ideal example of the phonon glass and electron crystal approach.
Abstract: The efficient conversion of heat into electricity using a thermoelectric approach requires high performance materials with the thermoelectric figure of merit ZT ≥ 1. Here we report on bulk CuCrSe2, which exhibits a very high ZT ∼ 1 at 773 K. The titled compound exhibits an electrical resistivity of ∼2.8 mΩ cm, a Seebeck coefficient of ∼160 μV K−1, together with very low thermal conductivity ∼7 mW cm−1 K−1 at 773 K. The very low thermal conductivity of bulk CuCrSe2 is attributed to phonon scattering by various sources such as (i) superionic Cu ions between the CrSe2 layers, (ii) nanoscale precipitates in the bulk and (iii) natural grain boundaries due to the layered structure of the material. This unusual combination of thermoelectric properties for CuCrSe2 suggests that it is an ideal example of the phonon glass and electron crystal approach.

75 citations

Journal ArticleDOI
TL;DR: In this article, the authors reported a thermoelectric figure-of-merit (ZT ) of 1.81 (at 1100 K) in p-type SiGe alloys (that is ~34% higher as compared to earlier best reported ZT value) by intentional incorporation of metallic yttrium silicide nano-inclusions.

67 citations


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Journal ArticleDOI
TL;DR: This review describes the recent advances in designing high-performance bulk thermoelectric materials and highlights the decoupling of the electron and phonon transport through coherent interface, matrix/precipitate electronic bands alignment, and compositionally alloyed nanostructures.
Abstract: There has been a renaissance of interest in exploring highly efficient thermoelectric materials as a possible route to address the worldwide energy generation, utilization, and management. This review describes the recent advances in designing high-performance bulk thermoelectric materials. We begin with the fundamental stratagem of achieving the greatest thermoelectric figure of merit ZT of a given material by carrier concentration engineering, including Fermi level regulation and optimum carrier density stabilization. We proceed to discuss ways of maximizing ZT at a constant doping level, such as increase of band degeneracy (crystal structure symmetry, band convergence), enhancement of band effective mass (resonant levels, band flattening), improvement of carrier mobility (modulation doping, texturing), and decrease of lattice thermal conductivity (synergistic alloying, second-phase nanostructuring, mesostructuring, and all-length-scale hierarchical architectures). We then highlight the decoupling of th...

1,469 citations

Journal ArticleDOI
TL;DR: In this paper, the physical and chemical properties of various thermoelectric materials are reviewed and strategies for improving the performance of materials are proposed, along with an insight into semiconductor physics.

499 citations

Journal Article
TL;DR: In this paper, a theory for the enhancement of the thermoelectric properties of semiconductor materials with metallic nanoinclusions is presented, which is based on the concept of band bending at metal/semiconductor interfaces as an energy filter for electrons.
Abstract: Based on the concept of band bending at metal/semiconductor interfaces as an energy filter for electrons, we present a theory for the enhancement of the thermoelectric properties of semiconductor materials with metallic nanoinclusions. We show that the Seebeck coefficient can be significantly increased due to a strongly energy-dependent electronic scattering time. By including phonon scattering, we find that the enhancement of $ZT$ due to electron scattering is important for high doping, while at low doping it is primarily due to a decrease in the phonon thermal conductivity.

485 citations

Journal ArticleDOI
TL;DR: In this article, the inherent relationship between the structural characteristics and the thermoelectric performance of tin selenide (SnSe) is discussed, including the thermodynamics, crystal structures, and electronic structures.

389 citations

Journal ArticleDOI
TL;DR: In this paper, the authors summarise the recent progress in bulk thermoelectric (TE) materials and summarize the recently achieved enhancements in the TE performance encompassing the use of electronic band structure engineering, lattice phon...
Abstract: Thermoelectric (TE) materials facilitate direct heat-to-electricity conversion. The performance of a TE material is characterised by its figure of merit zT (=S2 σT/κ) that depends on both electronic transport properties, i.e. the Seebeck coefficient S and the electrical conductivity σ, and on thermal transport properties, i.e. the thermal conductivity κ of a material. The intrinsically counter-correlated behaviour between electronic and thermal transport properties makes the enhancement of zT a very challenging task. In the past 10 years, the zTs in bulk TE materials have been significantly enhanced due to intensive exploratory efforts, the discovery of new physical phenomena and effects, and applications of advanced synthesis methods. In this review, we summarise the recent progress in bulk TE materials. After the introduction of fundamental principles of thermoelectricity, the recently achieved enhancements in the TE performance encompassing the use of electronic band structure engineering, lattice phon...

380 citations