Origin of the large phonon band-gap in SrTiO3 and the vibrational signatures of ferroelectricity in ATiO3 perovskite: First principles lattice dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3 - Condensed MatReportar como inadecuado




Origin of the large phonon band-gap in SrTiO3 and the vibrational signatures of ferroelectricity in ATiO3 perovskite: First principles lattice dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3 - Condensed Mat - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We report first principles density functional perturbation theorycalculations and inelastic neutron scattering measurements of the phonondensity of states, dispersion relations and electromechanical response ofPbTiO3, BaTiO3 and SrTiO3. The phonon density-of-states of the quantumparaelectric SrTiO3 is found to be fundamentally distinct from that offerroelectric PbTiO3 and BaTiO3 with a large 70-90 meV phonon band-gap. Thephonon dispersion and electromechanical response of PbTiO3 reveal giantanisotropies. The interplay of covalent bonding and ferroelectricity, stronglymodulates the electromechanical response and give rise to spectacularsignatures in the phonon spectra. The computed charge densities have been usedto study the bonding in these perovskites. Distinct bonding characteristics inthe ferroelectric and paraelectric phases give rise to spectacular vibrationalsignatures. While a large phonon band-gap in ATiO3 perovskites seems acharacteristic of quantum paraelectrics, anisotropy of the phonon spectracorrelates well with ferroelectric strength. These correlations between thephonon spectra and ferroelectricity, can guide future efforts at customdesigning still more effective piezoelectrics for applications. These resultssuggest that vibrational spectroscopy can help design novel materials.



Autor: Narayani Choudhury Bhabha Atomic Research Centre, E. J. Walter College of William and Mary, A. I. Kolesnikov Argonne National Lab

Fuente: https://arxiv.org/







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