Tang Rujun, Jiang Chen, Qian Wenhu, Jian Jie, Zhang Xin, Wang Haiyan, Yang Hao
Jiangsu Key Laboratory of Thin Films, College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, P. R. China.
Testing and Analysis Center, Soochow University, Suzhou 215006, P. R. China.
Sci Rep. 2015 Aug 28;5:13645. doi: 10.1038/srep13645.
The dielectric properties of Z-type hexaferrite Sr3Co2Fe24O41 (SCFO) have been investigated as a function of temperature from 153 to 503 K between 1 and 2 GHz. The dielectric responses of SCFO are found to be frequency dependent and thermally activated. The relaxation-type dielectric behavior is observed to be dominating in the low frequency region and resonance-type dielectric behavior is found to be dominating above 10(8) Hz. This frequency dependence of dielectric behavior is explained by the damped harmonic oscillator model with temperature dependent coefficients. The imaginary part of impedance (Z″) and modulus (M″) spectra show that there is a distribution of relaxation times. The scaling behaviors of Z″ and M″ spectra further suggest that the distribution of relaxation times is temperature independent at low frequencies. The dielectric loss spectra at different temperatures have not shown a scaling behavior above 10(8) Hz. A comparison between the Z″ and the M″ spectra indicates that the short-range charges motion dominates at low temperatures and the long-range charges motion dominates at high temperatures. The above results indicate that the dielectric dispersion mechanism in SCFO is temperature independent at low frequencies and temperature dependent at high frequencies due to the domination of resonance behavior.
研究了Z型六方铁氧体Sr3Co2Fe24O41（SCFO）在153至503 K温度范围内、1至2 GHz频率下的介电性能。发现SCFO的介电响应与频率有关且具有热激活特性。观察到在低频区域弛豫型介电行为占主导，而在高于10(8) Hz时共振型介电行为占主导。这种介电行为的频率依赖性通过具有温度相关系数的阻尼谐振子模型来解释。阻抗（Z″）和模量（M″）谱的虚部表明存在弛豫时间分布。Z″和M″谱的标度行为进一步表明，在低频时弛豫时间分布与温度无关。在高于10(8) Hz时，不同温度下的介电损耗谱未表现出标度行为。Z″和M″谱的比较表明，低温下短程电荷运动占主导，高温下长程电荷运动占主导。上述结果表明，由于共振行为占主导，SCFO中的介电色散机制在低频时与温度无关，在高频时与温度有关。
