Niu Junyu, Li Chong, Xi Zengzhe
Shaanxi Key Laboratory of Photoelectric Functional Materials and Devices, School of Materials and Chemical Engineering, Xi'an Technological University Xi'an 710021 Shaanxi China
Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 P. R. China.
RSC Adv. 2024 Dec 2;14(51):38245-38252. doi: 10.1039/d4ra06270a. eCollection 2024 Nov 25.
The phase diagram of Pb(Zr Ti )O (PZT) is quite clear; however, the existence and intrinsic piezoelectricity of low-symmetry structures near the MPB (morphotropic phase boundary) remain subjects of considerable uncertainty. The impact of the MPB on the piezoelectric properties of PZT was investigated first principles study. Different PZT structures were established by virtual crystal approximation (VCA). The density functional theory (DFT) with plane-wave basis set method was utilized to calculate the energy, elastic, and piezoelectric properties. The presence of the monoclinic phase in MPB was confirmed near ∼ 0.53. This phase exhibited distinct piezoelectric properties. Although the coefficients and were lower, the maximum value of reached -198.33 pm V. By exhaustively exploring all possible structures at the MPB, we demonstrate that the intrinsic piezoelectricity of monoclinic structures is not the main contributor to the MPB effect. Further study shows that this is related to the hybridization between the O2p orbital and the d orbital of the central atom. Finally, analysis of the energy barrier along the polarization rotation paths implies a flattening of free energy in the monoclinic phase, suggesting a high intrinsic piezoelectric coefficient. The intrinsic piezoelectric properties of the monoclinic phase may bring new ideas to the study of the MPB effect.
锆钛酸铅（PZT）的相图相当清晰；然而，准同型相界（MPB）附近低对称结构的存在及其固有压电性仍然存在很大的不确定性。通过第一性原理研究，探讨了MPB对PZT压电性能的影响。采用虚拟晶体近似（VCA）建立了不同的PZT结构。利用平面波基组方法的密度泛函理论（DFT）计算能量、弹性和压电性能。在约0.53附近证实了MPB中存在单斜相。该相表现出独特的压电性能。虽然系数d31和d33较低，但d15的最大值达到-198.33 pm/V。通过详尽探索MPB处的所有可能结构，我们证明单斜结构的固有压电性不是MPB效应的主要贡献因素。进一步研究表明，这与O2p轨道和中心原子的d轨道之间的杂化有关。最后，对沿极化旋转路径的能垒分析表明单斜相中的自由能趋于平缓，这表明其固有压电系数较高。单斜相的固有压电性能可能为MPB效应的研究带来新的思路。
