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Persistent URL http://purl.org/net/epubs/work/50390244
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Record Id 50390244
Title Sodium Diffusion and Dynamics in Na2Ti3O7: Neutron Scattering and Ab-initio Simulations
Abstract We have performed quasielastic and inelastic neutron scattering (QENS and INS) measurements from 300 K to 1173 K to investigate the Na-diffusion and underlying host dynamics in Na2Ti3O7. The QENS data show that the Na atoms undergo localized jumps up to 1173 K. The ab-initio molecular dynamics (AIMD) simulations supplement the measurements and show 1-d long-ranged diffusion along the a-axis above 1500 K. The simulations indicate that the occupancy of the interstitial site is critical for long-range diffusion. The nudged-elastic-band (NEB) calculation confirmed that the activation energy barrier is lowest for diffusion along the a-axis. In the experimental phonon spectra the peaks at 10 and 14 meV are dominated by Na dynamics that disappear on warming, suggesting low-energy phonons significantly contribute to large Na vibrational amplitude at elevated temperatures that enhances the Na hopping probability. We have also calculated the mode Gr\"uneisen parameters of the phonons and thereby calculated the volume thermal expansion coefficient, which is found to be in excellent agreement with available experimental data.
Keywords RB1910264 , RB1868015
Funding Information
Related Research Object(s): 10.5286/ISIS.E.RB1910264 , 10.5286/ISIS.E.RB1868015 , 51330885
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Language English (EN)
Type Details URI(s) Local file(s) Year
Preprint Mater Adv 2021. https://arxiv.org/abs/2107.09905 2021