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Photoelectrocatalytic Carbon Dioxide Reduction to Value-Added Products
Published in Anirban Das, Gyandshwar Kumar Rao, Kasinath Ojha, Photoelectrochemical Generation of Fuels, 2023
Paras Kalra, Cini M. Suresh, Rashid, Pravin P. Ingole
CO2 is a very stable, non-polar, linear-shaped molecule with two C=O bonds where carbon is in its highest oxidation state which makes it thermodynamically very stable. CO2 molecules also have a stable linear and centrosymmetric (O=C=O) structure [14]. The activation of CO2 to value-added products requires high energy and extreme reaction conditions in order to overcome this high potential barrier.
Gap Solitons in Photorefractive Optical Lattices
Published in Arpan Deyasi, Pampa Debnath, Asit K. Datta, Siddhartha Bhattacharyya, Photonics, Plasmonics and Information Optics, 2021
A centrosymmetric crystal is one which possesses inversion symmetry or an inversion centre as a symmetry element. The first discovery of stable optical spatial solitons in PR materials was in noncentrosymmetric crystals like SBN. The mediating nonlinearity was because of the linear electro-optic effect or the Pockels’ effect. The Pockels’ effect mandates the change in refractive index is proportional to the electric field. Optical spatial solitons in centrosymmetric PR crystals were later predicted by Segev et al.[13]. Centrosymmetric PR crystals exhibit quadratic electro-optic effect or the dc Kerr effect in which the refractive index changes as the square of field, i.e.Δn α E2. The gap solitons in such centrosymmetricPR materials have been studied in [12] and we shall follow the same approach to introduce the topic to the reader.
Topological Analysis of Local Structure in Atomic Systems
Published in Jeffrey P. Simmons, Lawrence F. Drummy, Charles A. Bouman, Marc De Graef, Statistical Methods for Materials Science, 2019
Emanuel A. Lazar, David J. Srolovitz
More sophisticated aphysical approaches consider not only the number of neighbors of an atom, but also the manner in which those neighbors are arranged. In an ideal triangular lattice, for example, every atom is surrounded by six equally-spaced neighbors; adjacent pairs of neighbors make identical angles α = π/3; see Figure 15.2. Centroysymmetry analysis [483] and bond-angle analysis [4] are but two examples of widely-used methods that measure deviation from this ideal structure. Centrosymmetry measures the extent to which neighbors of an atom can be matched in equally-spaced but oppositely-directed pairs, so that their displacement vectors cancel. Bond-angle analysis measures the extent to which angles between “bonds” from a central atom to neighboring atoms remain close to an idealized value, π/3 in the example of Figure 15.2.
Semi-analytical solution for mixed supported and multilayered two-dimensional thermo-elastic quasicrystal plates with interfacial imperfections
Published in Journal of Thermal Stresses, 2023
Xin Feng, Liangliang Zhang, Han Zhang, Yang Gao
According to the conventions in crystallography, all the elastic properties and thermal expansion properties possess intrinsic centrosymmetry [39]. Thus, the constitutive equations with nonlocal and thermal effects for 2D decagonal QCs with point groups 10 mm, 1022, 2 m, and 10/mmm can be expressed as follows [12] where C11, C12, C13, C33, C44 are the elastic constants with the relationship 2C66 = C11 – C12 in the phonon field; K1, K2, K4, and R1 represent the phason elastic constants, and phonon–phason coupling elastic constants, respectively; β1 and β3 are the thermal constants; T represents the variation of the temperature.
Chiral and non-centrosymmetric effects on the nonlinear wave propagation characteristics of architectured cellular materials
Published in Waves in Random and Complex Media, 2022
N. Karathanasopoulos, J.-F. Ganghoffer
Up to now, the analysis of nonlinear wave propagation effects arising from the very structural pattern of the periodic material has been restrained in the study of achiral and centrosymmetric lattices. Contrary to achiral architectures, chiral structures exhibit an inherent lack of symmetry with respect to their mirror image [39], while non-centrosymmetric architectures lack a center of symmetry, so that any point within their unit-cell is not invariant with respect to coordinate inversions [40]. Chirality has been shown to play an important role in the wave propagation characteristics of the effective medium, so that hexachiral lattices exhibit utterly different linear dispersion characteristics compared to the ones obtained for triangular lattices, despite of their common hexagonal symmetry and macroscopic isotropy [9,15,41]. What is more, the effects of a non-centrosymmetric inner material configuration on the nonlinear wave propagation attributes of periodic lattice structures have not been up to now analyzed, even though it is well established that non-centrosymmetric material architectures can be found in numerous natural and artificial mechanical components, from nanotubes to bones [42]. Their wave propagation attributes are influenced by non-centrosymmetry already in the linear analysis regime [43,44].
Thickness-twist waves in the nanoplates with flexoelectricity
Published in Mechanics of Advanced Materials and Structures, 2021
Jun Zhu, Shaowei Chen, Yudan Chen, Jiaxi Chen, Puying Hu, Helong Wu, Yunying Zhou
In the traditional crystallographic considerations, the property of non-centrosymmetry is the necessary condition for a crystal to exhibit piezoelectricity. However, a nonuniform strain (strain gradient) could locally break the inversion symmetry of a crystal, therefore, potentially induce the polarization even in nonpiezoelectric dielectrics. Such coupling of strain gradient with polarization called flexoelectric effect, demonstrating strong size-dependence usually cannot be ignored when the nanoscale dielectric is involved. The phenomena, e. g. the deviation of the measured film capacitance from the classical theory [1], weak piezoelectricity of carbon nanotubes [2], and the size effect of piezoelectric properties of boron nitride nanotubes [3], can be reasonably explained by the flexoelectric effect [4–6].