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

作　　者：Kwangrae Kim Woohyun Hwang Seung-Hyun Victor Oh Aloysius Soon 

机构地区：[1]Department of Materials Science&Engineering,Yonsei University,Seoul 03722,Republic of Korea

出　　处：《npj Computational Materials》2023年第1期757-766,共10页计算材料学（英文）

基　　金：We gratefully acknowledge support by grant from National Research Foundation of Korea under the Material Convergence Innovation Technology Development Program(2020M3D1A2102913);Computational resources have been kindly provided by the KISTI Supercomputing Center(KSC-2022-CRE-0038);the Australian National Computational Infrastructure(NCI)。

摘　　要：Group I niobates(KNbO_(3) and NaNbO_(3))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 KNbO_(3) and NaNbO_(3) 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.

关 键 词：harmonic PHONON DIELECTRIC 

分 类 号：O62[理学—有机化学]