Putting DFT to the trial: First principles pressure dependent analysis on optical properties of cubic perovskite SrZrO3

Rajpoot

Int J of Quantum Chemistry

et al. 2019

Theoretical investigation of different physical parameters of Cr4AlB6 have been done within the framework of density functional theory. Cr4AlB6 is a no band gap material. Its Cr‐3d states contributes the most at the Fermi level. Thermal properties are investigated using quasi‐harmonic Debye model as implemented in Gibbs code for different values of pressure and temperature. Study of transport property suggests that its electrical conductivity increases nonlinearly with increase in temperature but the relative change in its value is very low whereas its thermal conductivity increases linearly with the increase in temperature and relative increase in thermal conductivity is very high. The behavior of Cr4AlB6 is anisotropic and property is ceramic. It has potential applications in making ceramic capacitors. Its reflectivity is high in low energy region. It suggests that material can be used as coating material for far‐infrared radiation. Study of the transport property suggests that because of very high value of thermal conductivity, it can be used for heat sink applications.

ε_{1}^{xx} ((), 0), ε_{1}^{yy} ((), 0),

and

ε_{1}^{zz} ((), 0)

, respectively, about 62.3, 67.8, and 39.9 show that Cr 4 AlB 6 is an efficient dielectric material and an eligible candidate in manufacture of fixed capacitance ceramic capacitors…”

Section: Resultsmentioning

confidence: 93%

Ab‐initio study of electronic, optical, thermal, and transport properties of Cr₄AlB₆

Rajpoot

Int J of Quantum Chemistry

et al. 2019

“…PZO belongs to a family of perovskite compounds [35][36][37]. A cubic PZO structure ABO 3 type has the space group 221_P m3m with the Wyckoff positions: Pb [38] and dielectric attributes [39].…”

Section: Resultsmentioning

confidence: 99%

Under Pressure DFT Investigations on Optical and Electronic Properties of PbZrO₃

et al. 2018

Self Cite

In this article, density functional theory has been used to investigate the structural and optoelectronic properties of PbZrO3 (PZO) under pressure from 0 to 350 GPa. In order to achieve ground state structural stability, generalized gradient approximations has been utilized. By studying electronic properties, indirect band-gap nature of PZO appears to change at 15 GPa to direct band-gap. Optical analysis include under pressure responses of real and imaginary parts of dielectric function, optical conductivity, optical absorption coefficient, energy loss function, refractive index, reflectivity and extinction coefficient. Most of the results have been found to be consistent with literature. Study reveals that static dielectric constant and band-gap are in accordance with the Penn model which validates our computed results. Moreover, static dielectric constant and static refractive index directly increases with pressure. Material preserves its positive value of refractive index at all pressures and therefore, it is not a negative index metamaterial. Plasma frequency increases directly with pressure that destabilize the under study material. Our results could be very useful for developing novel optoelectronic devices based on PZO suitable to work under extreme conditions.

Journal of Applied Physics

“…The electronic diploe transition matrix element W ij (k), which represents the transition rate from state j/ i i to state j/ j i, is given by W ij ðkÞ ¼ h/ j ðkÞjê Á pj/ i ðkÞi, withê and p are the polarization vector and the momentum operator, respectively. The absorption coefficient is then extracted using the Kramers-Kronig relation 51,52 which is based on the causality, linear response theory, and the boundedness of physical observables…”

Section: Structures and Approachmentioning

confidence: 99%

“…Given the real and imaginary parts of the complex dielectric function, the extinction coefficient and thus the optical absorption coefficient can be evaluated. 52…”

Section: Structures and Approachmentioning

confidence: 99%

The effect of oxide shell thickness on the structural, electronic, and optical properties of Si-SiO2 core-shell nano-crystals: A (time dependent)density functional theory study

Nazemi

Pourfath

Soleimani

et al. 2016

Due to their tunable properties, silicon nano-crystals (NC) are currently being investigated. Quantum confinement can generally be employed for size-dependent band-gap tuning at dimensions smaller than the Bohr radius (∼5 nm for silicon). At the nano-meter scale, however, increased surface-to-volume ratio makes the surface effects dominant. Specifically, in Si-SiO2 core-shell semiconductor NCs the interfacial transition layer causes peculiar electronic and optical properties, because of the co-existence of intermediate oxidation states of silicon (Sin+, n = 0–4). Due to the presence of the many factors involved, a comprehensive understanding of the optical properties of these NCs has not yet been achieved. In this work, Si-SiO2 NCs with a diameter of 1.1 nm and covered by amorphous oxide shells with thicknesses between 2.5 and 4.75 Å are comprehensively studied, employing density functional theory calculations. It is shown that with increased oxide shell thickness, the low-energy part of the optical transition spectrum of the NC is red shifted and attenuated. Moreover, the absorption coefficient is increased in the high-energy part of the spectrum which corresponds to SiO2 transitions. Structural examinations indicate a larger compressive stress on the central silicon cluster with a thicker oxide shell. Examination of the local density of states reveals the migration of frontier molecular orbitals from the oxide shell into the silicon core with the increase of silica shell thickness. The optical and electrical properties are explained through the analysis of the density of states and the spatial distribution of silicon sub-oxide species.