| Cite this article as: Chu Xin-Jian,Lei Bo-Cheng,Liu Chen-Xi,Liu Ji-Bo. First-principles study of the ferroelectric properties of (K0.5Na0.5)Nb1-xTaxO3 [J]. J. At. Mol. Phys.(原子与分子物理学报), 2025, 42: 046003 (in Chinese) |
| First-principles study of the ferroelectric properties of (K0.5Na0.5)Nb1-xTaxO3 |
| Hits 147 Download times 19 Received:October 08, 2023 Revised:October 27, 2023 |
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| DOI
10.19855/j.1000-0364.2025.046003 |
| Key Words
first principles, perovskite results, KNN, ferroelectricity, |
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| Abstract
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| With the large-scale use of lead-based ceramics, causing serious environmental and health problems, in order to be able to find alternative materials for lead-based ceramics, people have begun to explore lead-free ceramic materials. (K0.5Na0.5)NbO3 materials have become representative of lead-free ceramic materials due to their excellent ferroelectric properties, but the temperature sensitivity of KNN ceramics makes its application range extremely limited. Based on this consideration, based on the first principles method of density functional theory, this paper explores the ferroelectric properties of nine systems (K0.5Na0.5)Nb1-xTaxO3 (x=0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1) nine systems. The results show that with the increase of Ta concentration, the lattice constant changes, so it is speculated that the orthogonal-monoclinic phase transition of KNN material occurs with the increase of Ta concentration; the incorporation of Ta can reduce the sintering difficulty of KNN material, and with the increase of Ta concentration, the formation difficulty gradually decreases; in the doping system, the Ta-4f orbital and Na-3p, K-4p and O-2s orbital electrons are hybridized, so that the state density peak of the conduction band bottom Nb-4d and Na-3p electrons moves towards the high-energy region. The gap width shows an increasing trend; When analyzing the ferroelectric mechanism of KNN material, it was found that the iron polarization type of KNN is ion displacement polarization, and does not have polarization ability in the [001] direction. Analysis of the polarization intensity of each system after doping, it is found that with the increase of Ta concentration, the polarization intensity gradually decreases, but the polarization has an upward trend when doping at low concentration, which may be caused by the presence of orthogonal and monoclinic MPBs in low concentration, from which it can be judged that low concentration doping is conducive to improving the ferroelectric properties of KNN materials. |
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