摘要
铁电薄膜由于其优异物理性能,而被广泛应用于微电子、光电子、微机电领域。在铁电薄膜理论研究方面,热力学理论可以有效地预测铁电薄膜的相结构、极化特性和机电性能等,且已在(001)取向铁电薄膜的研究中取得了较好的应用,而对于(111)取向铁电薄膜的研究报道非常少。因此,本文通过对序参量坐标转换的方法,构建了(111)取向薄膜的热力学势能函数及其机电性能计算方法。基于此,研究了(111)取向0.7PMN-0.3PT铁电薄膜的相结构及其机电性能。研究结果表明,(111)取向0.7PMN-0.3PT铁电薄膜的相结构主要存在沿晶轴方向三个极化可互换的对称相:顺电相PE、菱方相R和单斜相M_(A)(或M_(B))。在应变和外电场的调控下,(111)取向0.7PMN-0.3PT薄膜展现出优良的机电性能,在R和M_(A)相变点处,介电常数ε_(11)、ε_(22)、ε_(33)和面外压电系数d_(33)取得了极大值。在外电场E 3分别为0、50 kV/cm、100 kV/cm和200 kV/cm时,面外介电常数ε_(33)的峰值分别为4382、2646、2102和1600,面外压电系数d_(33)的峰值分别为303.8 pm/V、241.9 pm/V、219.7 pm/V和195.1 pm/V。应变和外电场能够较好地调控薄膜的机电耦合性能,可为优异机电耦合性能的器件制备提供参考。
Due to its excellent physical properties,ferroelectric thin films are widely used in the fields of microelectronics,optoelectronics,and microelectromechanics.In terms of theoretical research on ferroelectric thin films,the phenomenological theory of thermodynamics can effectively predict the phase structure,polarization characteristics and electromechanical properties of ferroelectric thin films,and has been well applied in the research of(001)-oriented ferroelectric thin films.However,there are very few research reports on(111)-oriented ferroelectric thin films.Therefore,the thermodynamic potential energy function and the calculation method of electromechanical properties of the(111)-oriented thin film by transforming order parameters of the system was constructed in this paper.Based on constructed theory,the phase structure and electromechanical properties of(111)-oriented 0.7PMN-0.3PT ferroelectric thin film were studied.The results reveal that the phase structures of the(111)-oriented 0.7PMN-0.3PT ferroelectric thin film mainly have three symmetrical phases with interchangeable polarizations along the crystal axis,they are paraelectric phase PE,rhombohedral phase R and monoclinic phase M_(A)(or M_(B)).By the controling of misfit strain and external electric field,the(111)-oriented 0.7PMN-0.3PT thin film exhibits excellent electromechanical properties.At the boundary of the R-M_(A) phase transformation,the dielectric constantsε_(11),ε_(22),ε_(33) and the out-of-plane piezoelectric coefficient d_(33) have achieved a maximum value.With the external electric field E 3=0,50 kV/cm,100 kV/cm and 200 kV/cm,the peak values of the out-of-plane dielectric constantε_(33) are 4382,2646,2102 and 1600,respectively,and the peak values of the out-of-plane piezoelectric coefficient d_(33) are 303.8 pm/V,241.9 pm/V,219.7 pm/V and 195.1 pm/V.The misfit strain and external electric field can better control the electromechanical coupling performance of the film,which provide a reference for the preparation of devices with exce
作者
李强
张培芝
吕锦彬
章庆勇
刘莉
叶洋
LI Qiang;ZHANG Peizhi;LYU Jinbin;ZHANG Qingyong;LIU Li;YE Yang(Xinjiang Second Medical College,Karamay 834000,China)
出处
《人工晶体学报》
CAS
北大核心
2022年第1期112-119,共8页
Journal of Synthetic Crystals
基金
2020年新疆维吾尔自治区大学生创新创业训练计划(S202013560009)。
关键词
铌镁钛酸铅
铁电薄膜
(111)取向
相结构
热力学理论
压电系数
介电常数
lead magnesium niobium titanate
ferroelectric thin film
(111)-orientation
phase structure
thermodynamic theory
piezoelectric coefficient
dielectric constant
