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1,954 results on '"Dravid, Vinayak P."'

51. Elucidating the Reaction Pathway in the Ammonolysis of MoO3 via In Situ Powder X-ray Diffraction and Transmission Electron Microscopy

Author

Zhang, Chi, primary, Goldfine, Elise A., additional, He, Kun, additional, Wenderott, Jill K., additional, Pandey, Shobhit A., additional, dos Reis, Roberto, additional, Shen, Jiahong, additional, Wolverton, Chris, additional, Bedzyk, Michael J., additional, Poeppelmeier, Kenneth R., additional, Dravid, Vinayak P., additional, and Haile, Sossina M., additional

Published
2024
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52. Ultrathin silicon nitride microchip for in situ/operando microscopy with high spatial resolution and spectral visibility

Author

Koo, Kunmo, primary, Li, Zhiwei, additional, Liu, Yukun, additional, Ribet, Stephanie M., additional, Fu, Xianbiao, additional, Jia, Ying, additional, Chen, Xinqi, additional, Shekhawat, Gajendra, additional, Smeets, Paul J. M., additional, dos Reis, Roberto, additional, Park, Jungjae, additional, Yuk, Jong Min, additional, Hu, Xiaobing, additional, and Dravid, Vinayak P., additional

Published
2024
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53. Off‐Centering of Ge Atoms in GeBi2Te4 and Impact on Thermoelectric Performance

Author

Dong, Jinfeng, primary, Hu, Lei, additional, Liu, Jue, additional, Liu, Yukun, additional, Jiang, Yilin, additional, Yu, Zhiling, additional, Tan, Xian Yi, additional, Suwardi, Ady, additional, Zheng, Qiang, additional, Li, Qian, additional, Li, Jing‐Feng, additional, Dravid, Vinayak P., additional, Yan, Qingyu, additional, and Kanatzidis, Mercouri G., additional

Published
2024
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60. Off‐Centering of Ge Atoms in GeBi2Te4 and Impact on Thermoelectric Performance.

Author

Dong, Jinfeng, Hu, Lei, Liu, Jue, Liu, Yukun, Jiang, Yilin, Yu, Zhiling, Tan, Xian Yi, Suwardi, Ady, Zheng, Qiang, Li, Qian, Li, Jing‐Feng, Dravid, Vinayak P., Yan, Qingyu, and Kanatzidis, Mercouri G.

Subjects
SYNCHROTRON radiation, DISTRIBUTION (Probability theory), THERMOELECTRIC materials, ATOMS, PHONON scattering, TRANSMISSION electron microscopy
Abstract

The crystal structure and transport properties of GeBi2Te4 are investigated as a layered compound with potential applications as thermoelectric materials. A disordered arrangement of Ge and Bi atoms in a septuple‐layer structure is discovered through synchrotron radiation X‐ray diffraction and transmission electron microscopy. Neutron pair distribution function analysis revealed the presence of discordant Ge atoms with an off‐centering distance of 0.12 Å at 300 K. The thermal conductivity of GeBi2Te4 is very low due to the strong phonon scattering. This is a result of the three Einstein local oscillators coupled with the disordered arrangement of atoms. This study also explores further the structural characteristics of these materials and their associated phonon scattering processes. The effect of Sb substitution for Ge on the electrical transport properties of the sample is profound, resulting in a change from p‐type to n‐type conduction. An enhanced thermoelectric figure of merit (ZT) of 0.45 at 523 K in the in‐plane direction is obtained. This research provides valuable insights into the crystal structure and transport properties of GeBi2Te4, showcasing its promising role as a thermoelectric material with potential for near‐room‐temperature applications. [ABSTRACT FROM AUTHOR]

Published
2024
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66. A three-dimensional quantum dot network stabilizes perovskite solids via hydrostatic strain

Author

Liu, Yuan, primary, Zhu, Tong, additional, Grater, Luke, additional, Chen, Hao, additional, dos Reis, Roberto, additional, Maxwell, Aidan, additional, Cheng, Matthew, additional, Dong, Yitong, additional, Teale, Sam, additional, Leontowich, Adam F.G., additional, Kim, Chang-Yong, additional, Chan, Phoebe Tsz-shan, additional, Wang, Mingcong, additional, Paritmongkol, Watcharaphol, additional, Gao, Yajun, additional, Park, So Min, additional, Xu, Jian, additional, Khan, Jafar Iqbal, additional, Laquai, Frédéric, additional, Walker, Gilbert C., additional, Dravid, Vinayak P., additional, Chen, Bin, additional, and Sargent, Edward H., additional

Published
2023
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67. Influence of Stoichiometry on the Optical and Electrical Properties of Chemical Vapor Deposition Derived MoS$_{2}$

Author

Kim, In Soo, Sangwan, Vinod K., Jariwala, Deep, Wood, Joshua D., Park, Spencer, Chen, Kan-Sheng, Shi, Fengyuan, Ruiz-Zepeda, Francisco, Ponce, Arturo, Jose-Yacaman, Miguel, Dravid, Vinayak P., Marks, Tobin J., Hersam, Mark C., and Lauhon, Lincoln J.

Subjects
Condensed Matter - Materials Science
Abstract

Ultrathin transition metal dichalcogenides (TMDCs) of Mo and W show great potential for digital electronics and optoelectronic applications. Whereas early studies were limited to mechanically exfoliated flakes, the large-area synthesis of 2D TMDCs has now been realized by chemical vapor deposition (CVD) based on a sulfurization reaction. Since then, the optoelectronic properties of CVD grown monolayer MoS$_{2}$ have been heavily investigated, but the influence of stoichiometry on the electrical and optical properties has been largely overlooked. Here we systematically vary the stoichiometry of monolayer MoS$_{2}$ during CVD via controlled sulfurization and investigate the associated changes in photoluminescence and electrical properties. X-ray photoelectron spectroscopy is employed to measure relative variations in stoichiometry and the persistence of MoO$_{x}$ species. As MoS$_{2-{\delta}}$ is reduced (increasing {\delta}), the field-effect mobility of monolayer transistors increases while the photoluminescence yield becomes non-uniform. Devices fabricated from monolayers with the lowest sulfur content have negligible hysteresis and a threshold voltage of ~0 V. We conclude that the electrical and optical properties of monolayer MoS$_{2}$ crystals can be tuned via stoichiometry engineering to meet the requirements of various applications.

Published
2014
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74. Band-Like Transport in High Mobility Unencapsulated Single-Layer MoS2 Transistors

Author

Jariwala, Deep, Sangwan, Vinod K., Late, Dattatray J., Johns, James E., Dravid, Vinayak P., Marks, Tobin J., Lauhon, Lincoln J., and Hersam, Mark C.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Ultra-thin MoS2 has recently emerged as a promising two-dimensional semiconductor for electronic and optoelectronic applications. Here, we report high mobility (>60 cm2/Vs at room temperature) field-effect transistors that employ unencapsulated single-layer MoS2 on oxidized Si wafers with a low level of extrinsic contamination. While charge transport in the sub-threshold regime is consistent with a variable range hopping model, monotonically decreasing field-effect mobility with increasing temperature suggests band-like transport in the linear regime. At temperatures below 100 K, temperature-independent mobility is limited by Coulomb scattering, whereas, at temperatures above 100 K, phonon-limited mobility decreases as a power law with increasing temperature.

Published
2013
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79. Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi4NbO8Cl–Bi2GdO4Cl Intergrowths

Author

Christudas Beena, Nayana, Magnard, Nicolas P. L., Puggioni, Danilo, dos Reis, Roberto, Chatterjee, Kaustav, Zhan, Xun, Dravid, Vinayak P., Rondinelli, James M., Jensen, Kirsten M. Ø., and Skrabalak, Sara E.

Abstract

Mixed metal oxyhalides are an exciting class of photocatalysts, capable of the sustainable generation of fuels and remediation of pollutants with solar energy. Bismuth oxyhalides of the types Bi4MO8X (M = Nb and Ta; X = Cl and Br) and Bi2AO4X (A = most lanthanides; X = Cl, Br, and I) have an electronic structure that imparts photostability, as their valence band maxima (VBM) are composed of O 2p orbitals rather than X np orbitals that typify many other bismuth oxyhalides. Here, flux-based synthesis of intergrowth Bi4NbO8Cl–Bi2GdO4Cl is reported, testing the hypothesis that both intergrowth stoichiometry and M identity serve as levers toward tunable optoelectronic properties. X-ray scattering and atomically resolved electron microscopy verify intergrowth formation. Facile manipulation of the Bi4NbO8Cl-to-Bi2GdO4Cl ratio is achieved with the specific ratio influencing both the crystal and electronic structures of the intergrowths. This compositional flexibility and crystal structure engineering can be leveraged for photocatalytic applications, with comparisons to the previously reported Bi4TaO8Cl–Bi2GdO4Cl intergrowth revealing how subtle structural and compositional features can impact photocatalytic materials.

Published
2024
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