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Author

Rinkle Juneja

Other affiliations: Oak Ridge National Laboratory
Bio: Rinkle Juneja is an academic researcher from Indian Institute of Science. The author has contributed to research in topics: Phonon & Thermal conductivity. The author has an hindex of 9, co-authored 18 publications receiving 213 citations. Previous affiliations of Rinkle Juneja include Oak Ridge National Laboratory.

Papers
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Journal ArticleDOI
TL;DR: In this article, a n-type bulk cubic AgBiS2 exhibits ultralow thermal conductivity, which is essential for thermal barrier coating and thermoelectric energy conversion.
Abstract: Crystalline materials with ultralow thermal conductivity are essential for thermal barrier coating and thermoelectric energy conversion. Nontoxic n-type bulk cubic AgBiS2 exhibits exceptionally low...

60 citations

Journal ArticleDOI
TL;DR: In this article, low thermal conductivity materials are crucial for applications such as thermoelectric conversion of waste heat to useful energy and thermal barrier coatings, on the other hand, high thermal conduc...
Abstract: Low thermal conductivity materials are crucial for applications such as thermoelectric conversion of waste heat to useful energy and thermal barrier coatings. On the other hand, high thermal conduc...

57 citations

Journal ArticleDOI
TL;DR: In this paper, two distinct stacking orders in ReS2 were identified without ambiguity and their influence on vibrational, optical properties and carrier dynamics were investigated with atomic resolution scanning transmission electron microscopy (STEM).
Abstract: Two distinct stacking orders in ReS2 are identified without ambiguity and their influence on vibrational, optical properties and carrier dynamics are investigated. With atomic resolution scanning transmission electron microscopy (STEM), two stacking orders are determined as AA stacking with negligible displacement across layers, and AB stacking with about a one-unit cell displacement along the a axis. First-principles calculations confirm that these two stacking orders correspond to two local energy minima. Raman spectra inform a consistent difference of modes I & III, about 13 cm-1 for AA stacking, and 20 cm-1 for AB stacking, making a simple tool for determining the stacking orders in ReS2 . Polarized photoluminescence (PL) reveals that AB stacking possesses blueshifted PL peak positions, and broader peak widths, compared with AA stacking, indicating stronger interlayer interaction. Transient transmission measured with femtosecond pump-probe spectroscopy suggests exciton dynamics being more anisotropic in AB stacking, where excited state absorption related to Exc. III mode disappears when probe polarization aligns perpendicular to b axis. The findings underscore the stacking-order driven optical properties and carrier dynamics of ReS2 , mediate many seemingly contradictory results in the literature, and open up an opportunity to engineer electronic devices with new functionalities by manipulating the stacking order.

33 citations

Journal ArticleDOI
TL;DR: Using first-principles density functional theory and semiclassical Boltzmann transport theory, the authors reported high thermoelectric performance of a silicon-based chalcogenide Si2Te3.
Abstract: Achieving large thermoelectric figure of merit in a low-cost material, having an appreciable degree of compatibility with the modern technology is required to convert waste heat into electrical energy efficiently. Using first-principles density functional theory and semiclassical Boltzmann transport theory, we report high thermoelectric performance of a silicon-based chalcogenide Si2Te3. Previously unknown ground state structure of Si2Te3 was obtained by finding out the 8 most energetically favorable sites for Si in a unit cell of 12 Te and 8 Si atoms. Out of total C(28,8) combinations of structures, the search was narrowed down to 15 by using Wyckoff positions of space group P31c. The minimum energy configuration having layered structure exhibits combination of desirable electronic and transport properties for an efficient thermoelectric material, including confinement of heavy and light bands near the band edges, large number of charge carrier pockets and low conductivity effective mass for n-type carr...

31 citations


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Journal Article
TL;DR: A trustful prediction of new promising materials, identification of anomalies, and scientific advancement are doubtful when the scientific connection between the descriptor and the actuating mechanisms is unclear.
Abstract: Statistical learning of materials properties or functions so far starts with a largely silent, nonchallenged step: the choice of the set of descriptive parameters (termed descriptor). However, when the scientific connection between the descriptor and the actuating mechanisms is unclear, the causality of the learned descriptor-property relation is uncertain. Thus, a trustful prediction of new promising materials, identification of anomalies, and scientific advancement are doubtful. We analyze this issue and define requirements for a suitable descriptor. For a classic example, the energy difference of zinc blende or wurtzite and rocksalt semiconductors, we demonstrate how a meaningful descriptor can be found systematically.

455 citations

01 Jan 2004
TL;DR: In this paper, the effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips, and a conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.
Abstract: Light emitting diodes, LEDs, historically have been used for indicators and produced low amounts of heat. The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards general illumination. The increased electrical currents used to drive the LEDs have focused more attention on the thermal paths in the developments of LED power packaging. The luminous efficiency of LEDs is soon expected to reach over 80 lumens/W, this is approximately 6 times the efficiency of a conventional incandescent tungsten bulb. Thermal management for the solid-state lighting applications is a key design parameter for both package and system level. Package and system level thermal management is discussed in separate sections. Effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips. The higher thermal conductivity of the SiC chip provided about 2 times better thermal performance than the latter, while the under-filled Sapphire chip package can only catch the SiC chip performance. Later, system level thermal management was studied based on established numerical models for a conceptual solid-state lighting system. A conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.

242 citations

Journal ArticleDOI
TL;DR: In this paper, the authors study C2N/WS2 van der Waals heterostructure as a possible photocatalyst for water splitting and find that band edges of the heterostructures satisfy both water oxidation and reduction energy levels, ensuring the occurrence of these two reactions.

207 citations

Journal Article
TL;DR: Using easily available properties of the MXene, namely, boiling and melting points, atomic radii, phases, bond lengths, etc., as input features, models were developed using kernel ridge (KRR), support vector, Gaussian process (GPR), and bootstrap aggregating regression algorithms.
Abstract: MXenes are two-dimensional (2D) transition metal carbides and nitrides, and are invariably metallic in pristine form. While spontaneous passivation of their reactive bare surfaces lends unprecedented functionalities, consequently a many-folds increase in number of possible functionalized MXene makes their characterization difficult. Here, we study the electronic properties of this vast class of materials by accurately estimating the band gaps using statistical learning. Using easily available properties of the MXene, namely, boiling and melting points, atomic radii, phases, bond lengths, etc., as input features, models were developed using kernel ridge (KRR), support vector (SVR), Gaussian process (GPR), and bootstrap aggregating regression algorithms. Among these, the GPR model predicts the band gap with lowest root-mean-squared error (rmse) of 0.14 eV, within seconds. Most importantly, these models do not involve the Perdew–Burke–Ernzerhof (PBE) band gap as a feature. Our results demonstrate that machin...

150 citations

Journal Article
TL;DR: In this paper, a Weyl point, widely examined in 3D Weyl semimetals and superfluids, can be used to develop a pair of non-degenerate gapless spheres.
Abstract: We demonstrate that a Weyl point, widely examined in 3D Weyl semimetals and superfluids, can develop a pair of non-degenerate gapless spheres. Such a {\em bouquet of two spheres} is characterized by {\em three distinct} topological invariants of manifolds with full energy gaps, i.e., the Chern number of a 0D point inside one developed sphere, the winding number of a 1D loop around the original Weyl point, and the Chern number of a 2D surface enclosing the whole bouquet. We show that such structured Weyl points can be realized in the Fulde-Ferrell superfluid quasiparticle spectrum of a 3D degenerate Fermi gas subject to spin-orbit couplings and Zeeman fields.

100 citations