Search

Your search keyword '"Iyakutti, K."' showing total 529 results
Start Over Author "Iyakutti, K."
529 results on '"Iyakutti, K."'

105. Pressure-induced structural phase transition in transition metal carbides TMC (TM = Ru, Rh, Pd, Os, Ir, Pt): a DFT study.

Author

Manikandan, M., Rajeswarapalanichamy, R., and Iyakutti, K.

Subjects
DENSITY functional theory, TRANSITION metal carbides, ELECTRONIC structure, PHASE transitions, CRYSTAL structure
Abstract

First-principles calculations based on density functional theory was performed to analyse the structural stability of transition metal carbides TMC (TM = Ru, Rh, Pd, Os, Ir, Pt). It is observed that zinc-blende phase is the most stable one for these carbides. Pressure-induced structural phase transition from zinc blende to NiAs phase is predicted at the pressures of 248.5 GPa, 127 GPa and 142 GPa for OsC, IrC and PtC, respectively. The electronic structure reveals that RuC exhibits a semiconducting behaviour with an energy gap of 0.7056 eV. The high bulk modulus values of these carbides indicate that these metal carbides are super hard materials. The high B/G value predicts that the carbides are ductile in their most stable phase. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

106. Electronic and Optical Properties of Cubic Perovskites CsPbCl3−yIy(y= 0, 1, 2, 3)

Author

Padmavathy, R., Amudhavalli, A., Rajeswarapalanichamy, R., and Iyakutti, K.

Abstract

Lead-based halide perovskites are attractive substrates for solar cells because of their excellent power conversion efficiency and low cost. The ground-state properties, electronic structure, as well as optical and phonon properties of lead-based halide perovskites (CsPbCl3−yIy(y= 0, 1, 2, 3) are investigated by first-principles calculations based on density functional theory. Their electronic structure indicates that CsPbCl3−yIy(y= 0, 1, 2, 3) compounds exhibit semiconducting behaviour at normal pressure. The energy gap of CsPbCl3can be tuned by substituting iodine atoms for chlorine atoms. The energy gap values are found to be 3.06, 2.681, 2.330, and 2.030 eV using HSE06 calculations for CsPbCl3, CsPbCl2I, CsPbClI2, and CsPbI3, respectively. Also, it is found that the energy gap values of these materials decrease with increase in pressure and that a semiconductor-to-metallic phase transition is observed at high pressure. The optical properties of these Pb-based compounds are analysed. The dynamical stability of these perovskites is analysed by their phonon dispersion curves.

Published
2019
Full Text
View/download PDF

119. Structural stability, electronic structure and mechanical properties of alkali gallium hydrides AGaH4 (A = Li, Na).

Author

Santhosh, M., Rajeswarapalamchamy, R., Manikandan, M., Murugan, A., Amudhavalli, A., and Iyakutti, K.

Subjects
STRUCTURAL stability, ELECTRONIC structure, MECHANICAL properties of metals, GALLIUM hydride, CRYSTAL structure
Abstract

Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of alkali gallium hydrides AGaH4 (A = Li, Na) for three different crystal structures, namely tetragonal (P421/C). tetragonal (P42/nmc) and monoclmic (P21,c). Among the considered structures, tetragonal (P421C) phase is found to be the most stable phase for these hydrides at normal pressure. A pressure induced structural phase transition from tetragonal (P421C) to tetragonal (P42/nmc) is observed. The electronic structure reveals that these hydrides are insulators. The calculated elastic constants indicate that these ternary imides are mechanically stable at normal pressure. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

140. Effect of surface doping on the band structure of graphene: a DFT study.

Author

Iyakutti, K., Kumar, E., Lakshmi, I., Thapa, Ranjit, Rajeswarapalanichamy, R., Surya, V., and Kawazoe, Y.

Subjects
ELECTRONIC band structure, ELECTRIC properties of graphene, DIRAC function, DENSITY functional theory, BAND gaps
Abstract

Various techniques, like doping, vacancy creation, strain engineering are tried to open a gap in the bandstructure of graphene and in some cases the gap has opened up. However, when the gap opens up the Dirac cones disappear. Without Dirac cones, graphene loses all its novelty. So opening a gap in graphene, retaining Dirac cones has become a challenging task. We, through first principles study using Density Functional theory, have done band gap tuning investigations. We have succeeded in opening the band gap, retaining the Dirac cones. Surface doping (adsorption) of various elements are tried and finally surface doping of sulfur is found to induce band gap opening in graphene. The Dirac cones are retained and the graphene is now a semiconductor with fast moving massless Dirac Fermions. We are reporting this type of calculations for the first time. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results