Structural and dynamical phase transitions of 
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 from first-principles calculations

Amisi, Safari; Lambin, Philippe; Ghosez, Philippe

doi:10.1103/physrevmaterials.7.024408

Cited by 4 publications

(1 citation statement)

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“…On the other hand, for NaNbO 3 whose t is 0.97 (where now t < 1), NbO 6 octahedral tilting (inter-octahedral distortion) dominates over the ferroelectric instability (due to Nb-site off-centering) and undergoes the antiferrodistortive (AFD) phase transition. This is due to the dominant soft modes at the other high-symmetry points in the first Brillouin zone, resulting in more complex and diverse phase transition pathways 4,12,13 .…”

Section: Introductionmentioning

confidence: 99%

Exploring anharmonic lattice dynamics and dielectric relations in niobate perovskites from first-principles self-consistent phonon calculations

Kim,

Hwang,

et al. 2023

npj Comput Mater

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Group I niobates (KNbO3 and NaNbO3) are promising lead-free alternatives for high-performance energy storage applications. Despite their potential, their complex phase transitions arising from temperature-dependent phonon softening and anharmonic effects on dielectric properties remain poorly explored. In this study, we employ density-functional theory (DFT) and self-consistent phonon (SCP) calculations to investigate finite-temperature phonons in cubic niobate perovskites. To include explicit anharmonic vibrational effects, SCP frequencies are shifted by the bubble self-energy correction within the quasiparticle (QP) approximation, providing precise descriptions of phonon softening in these strongly anharmonic solids. We further calculate the static dielectric constant of KNbO3 and NaNbO3 as a function of temperature using the Lyddane-Sachs-Teller (LST) relation and QP-corrected phonon dispersions. Our theoretical results align with experimental data, offering reliable temperature-dependent phonon dispersions while considering anharmonic self-energies and thermal expansion effects, enhancing our understanding of the complex relations between lattice vibrations and phase transitions in these anharmonic oxides.

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Section: Introductionmentioning

confidence: 99%