Joseph Aruna, Raj R S Arun, Haridev K A, Maity Tuhin, Joy Lija K
Centre for Advanced Functional Materials (CAFM), Department of Physics, Bishop Moore College, Mavelikara, Alappuzha, Kerala 690110, India.
School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India.
Nanotechnology. 2024 Aug 28;35(46). doi: 10.1088/1361-6528/ad6e8c.
Pristine and Dy substituted MnFeOMnFeDyO(= 0.00, 0.02, 0.04, 0.06, 0.08 & 0.10) were successfully synthesized by sol-gel method to investigate the dielectric properties of the system. MnFeOexhibits a high dielectric permittivity of order 10which is further augmented by 60% through Dy substitution. This is owing to the rise in interfacial polarization resulting from localized states, dipolar polarization arising from the multiple valence states of Fe and Mn ions, atomic polarization due to structural distortion induced by strain, and electronic polarization stemming from the concentration of free charge carriers. The enhancement of induced strain, mixed valence ratio of Fe/Feand Mn/Mn, localized states, and free charge carrier concentration are confirmed from the XRD, XPS, and optical studies, respectively. The dielectric relaxation mechanism of MnFeDyOfollows a modified Havriliak-Negami relaxation model with conductivity contribution. Complex impedance analyses further validate the contribution of grain-grain boundary mechanisms to the dielectric properties confirmed through Nyquist plots. A comprehensive analysis of conductivity reveals the significant impact of Dy substitution on the electrical conductivity of MnFeO. This influence is strongly related to the variations in the concentration of free charge carriers within the MnFeDyOsystem. The understanding of the underlying physics governing the dielectric properties of Dy-substituted MnFeOnot only enhances the fundamental knowledge of material behavior but also opens new avenues for the design and optimization of advanced electronic and communication devices.
通过溶胶 - 凝胶法成功合成了纯净的以及Dy取代的MnFeO（MnFeDyO，其中Dy = 0.00、0.02、0.04、0.06、0.08和0.10），以研究该体系的介电性能。MnFeO表现出高达10量级的高介电常数，通过Dy取代进一步提高了60%。这归因于由局域态引起的界面极化增加、Fe和Mn离子的多价态引起的偶极极化、应变诱导的结构畸变导致的原子极化以及自由电荷载流子浓度引起的电子极化。分别从XRD、XPS和光学研究中证实了诱导应变、Fe/Fe和Mn/Mn的混合价态比、局域态以及自由电荷载流子浓度的增强。MnFeDyO的介电弛豫机制遵循具有电导率贡献的修正Havriliak - Negami弛豫模型。复阻抗分析进一步验证了通过奈奎斯特图确认的晶粒 - 晶界机制对介电性能的贡献。对电导率的综合分析揭示了Dy取代对MnFeO电导率的显著影响。这种影响与MnFeDyO体系中自由电荷载流子浓度的变化密切相关。对Dy取代的MnFeO介电性能背后物理机制的理解不仅增强了对材料行为的基础知识，还为先进电子和通信设备的设计与优化开辟了新途径。
