Asha Gupta
University of Texas at Austin
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Publication
Featured researches published by Asha Gupta.
ACS Applied Materials & Interfaces | 2013
Yong-Mao Lin; Paul R. Abel; Asha Gupta; John B. Goodenough; Adam Heller; C. Buddie Mullins
Sn0.9Cu0.1 nanoparticles were synthesized via a surfactant-assisted wet chemistry method, which were then investigated as an anode material for ambient temperature rechargeable sodium ion batteries. The Sn0.9Cu0.1 nanoparticle-based electrodes exhibited a stable capacity of greater than 420 mA h g(-1) at 0.2 C rate, retaining 97% of their maximum observed capacity after 100 cycles of sodium insertion/deinsertion. Their performance is considerably superior to electrodes made with either Sn nanoparticles or Sn microparticles.
Advanced Materials | 2015
Asha Gupta; William D. Chemelewski; C. Buddie Mullins; John B. Goodenough
LiNi0.8 Al0.2 O2 with a higher Ni(3+) /Li(+) ordering, synthesized by the solution-combustion method, gives oxygen-evolution-reaction (OER) activity in alkaline solution that is comparable to that of IrO2 . This confirms that the octahedral-site Ni(IV) /Ni(III) couple in an oxide is an active redox center for the OER with -redox energy pinned at the top of the O-2p bands.
Inorganic Chemistry | 2015
Asha Gupta; Preetam Singh; Hugo Celio; C. Buddie Mullins; John B. Goodenough
Stabilization of Ta-Ta bonding in an oxide across a shared octahedral-site edge of a Ta2 dimer is not known. Investigation of Li insertion into the trirutile structure of MTa2O6 with M = Mg, Cr, Fe, Co, and Ni indicates that Ta-Ta bonding across the shared octahedral-site edge of the dimer can be stabilized by a reversible electrochemical reduction of Ta(V) to Ta(IV) for M = Cr, Fe, Co, and Ni but not for M = Mg. Chemical reduction of MTa2O6 by n-butyl lithium only reduced NiTa2O6 to any significant extent. With M = Fe, Co, or Ni, electrochemical formation of the Ta-Ta bonds is accompanied by a partial reduction of the Fe(II), Co(II), or Ni(II) to Fe(0), Co(0), or Ni(0). For M = Cr, two Li per formula unit can be inserted reversibly with no displacement of Cr(0). For M = Mg, no Mg(II) are displaced by Li insertion, but a solid-electrolyte interphase (SEI) layer is formed on the oxide with no evidence of Ta-Ta bonding. Stabilization of Ta-Ta bonding across a shared octahedral-site edge in a dimer appears to require significant hybridization of the Ta(V) 5d(0) and M 4s(0) states.
Journal of Advanced Ceramics | 2014
V. Jayaram; Asha Gupta; K. P. J. Reddy
Strong shock wave interactions with ceramic material ceria (CeO2) in presence of O2 and N2 gases were investigated using free piston driven shock tube (FPST). FPST is used to heat the test gas to very high temperature of about 6800–7700 K (estimated) at pressure of about 6.8–7.2 MPa for short duration (2–4 ms) behind the reflected shock wave. Ceria is subjected to super heating and cooling at the rate of about 106 K/s. Characterization of CeO2 sample was done before and after exposure to shock heated test gases (O2 and N2). The surface composition, crystal structure, electronic structure and surface morphology of CeO2 ceramic were examined using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Results obtained from the experimental investigations show that CeO2 can withstand high pressure accompanied by thermal shock without changing its crystal structure. Reducible CeO2 releases lattice oxygen making it possible to shift between reduced and oxidized states upon the interaction with shock heated gas. Due to such reaction mechanism, CeO2 ceramic undergoes nitrogen doping with decrease in lattice parameter. Investigations reveal that CeO2 retains its crystal structure during strong shock interaction, even at elevated pressure.
Chemistry of Materials | 2010
Asha Gupta; Umesh V. Waghmare; M. S. Hegde
Journal of Physical Chemistry C | 2013
Paul R. Abel; Yong Mao Lin; Tania De Souza; Chia Yun Chou; Asha Gupta; John B. Goodenough; Gyeong S. Hwang; Adam Heller; C. Buddie Mullins
Journal of Physical Chemistry C | 2009
Tinku Baidya; Asha Gupta; Paraag A. Deshpandey; Giridhar Madras; M. S. Hegde
Chemistry of Materials | 2009
Asha Gupta; Anil Kumar; Umesh V. Waghmare; M. S. Hegde
Journal of Power Sources | 2012
Asha Gupta; Ramaswamy Murugan; M. Parans Paranthaman; Zhonghe Bi; Craig A. Bridges; Masahiro Nakanishi; Alexei P. Sokolov; Kee Sung Han; Edward W. Hagaman; Hui Xie; C. Buddie Mullins; John B. Goodenough
Chemistry of Materials | 2009
Asha Gupta; M. S. Hegde; K. R. Priolkar; Umesh V. Waghmare; P. R. Sarode; S. Emura
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Jawaharlal Nehru Centre for Advanced Scientific Research
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