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人工晶体学报 ›› 2025, Vol. 54 ›› Issue (9): 1584-1592.DOI: 10.16553/j.cnki.issn1000-985x.2025.0068

• 研究论文 • 上一篇    下一篇

KNbO3高压下相变行为的第一性原理研究

冷昊宁(), 孙霄霄(), 穆柏旭, 宁丽娜   

  1. 牡丹江师范学院物理与电子工程学院,牡丹江 157012
  • 收稿日期:2025-04-02 出版日期:2025-09-20 发布日期:2025-09-23
  • 通信作者: 孙霄霄
  • 作者简介:冷昊宁(1999—),男,黑龙江省人,硕士研究生。E-mail:lenghaoning1999@163.com
  • 基金资助:
    牡丹江师范学院科学技术研究一般项目(YB2021002);牡丹江师范学院横向课题(2202224008)

First-Principles Study on the Phase Transition Behavior of KNbO3 under High Pressure

LENG Haoning(), SUN Xiaoxiao(), MU Baixu, NING Lina   

  1. School of Physics and Electronic Engineering,Mudanjiang Normal University,Mudanjiang 157012,China
  • Received:2025-04-02 Online:2025-09-20 Published:2025-09-23
  • Contact: SUN Xiaoxiao

摘要: 为了深入掌握钙钛矿氧化物KNbO3在高压条件下的相变行为,并为铁电材料在极端条件下的工程应用提供关键参数,本文采用基于密度泛函理论的第一性原理方法,在绝对零度(0 K)条件下,对KNbO3高压下的结构相变、弹性性质及电子性质进行系统研究。计算结果表明,在零压下,KNbO3的最稳定结构为正交Amm2结构,材料表现为延展性,且为中心力固体。在0~50 GPa压力范围内,KNbO3经历了两次相变:7.7 GPa时,由正交Amm2结构转变为四方P4mm结构;10.1 GPa时,由四方P4mm结构转变为三方R3mR结构。两次相变均伴随着体积变化,为一级相变。弹性分析显示,KNbO3在相变过程中经历了从延展性到脆性的转变,并且具有弹性各向异性特征。能带结构分析表明,零压下Amm2结构的带隙为2.125 eV,为间接带隙半导体。随着压力的增加,带隙先减小后增大。本研究不仅丰富了对KNbO3相变行为的理解,还为设计和应用新型KNbO3材料提供了理论支持。

关键词: KNbO3; 第一性原理; 密度泛函理论; 结构相变; 弹性性质; 电子性质

Abstract: To gain a comprehensive understanding of the phase transition behavior of perovskite oxide KNbO3 under high pressure conditions, and provide crucial parameters for the engineering applications of ferroelectric materials under extreme conditions, a first-principles method based on density functional theory was employed in this study. The structural phase transitions, elastic properties, and electronic properties of KNbO3 under high pressure were systematically investigated at absolute zero (0 K). The results indicate that the most stable structure of KNbO3 is the orthorhombic Amm2 structure at zero pressure. The material exhibits ductility and is characterized as a central-force solid. Within the pressure range from 0 GPa to 50 GPa, KNbO3 undergoes two phase transitions: from the Amm2 structure to the tetragonal P4mm structure under 7.7 GPa, and from the P4mm structure to the trigonal R3mR structure under 10.1 GPa. Both phase transitions are accompanied by volume changes and are classified as first-order phase transitions. Elastic analysis reveals that KNbO3 transitions from ductility to brittleness during the phase transitions and exhibits significant elastic anisotropy. Band structure analysis shows that the band gap of the Amm2 structure under zero pressure is 2.125 eV, indicating an indirect band gap semiconductor. As pressure increases, the band gap initially decreases and then increases. This study not only enriches the understanding of the phase transition behavior of KNbO3, but also provides theoretical support for the design and application of new KNbO3 materials.

Key words: KNbO3; first-principle; density functional theory; structural phase transition; elastic property; electronic property

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