论文标题
LACO $ _ {0.7} $ nb $ _ {0.3} $ o $ $ _3 $的高温介电和阻抗光谱研究
High temperature dielectric and impedance spectroscopy study of LaCo$_{0.7}$Nb$_{0.3}$O$_3$
论文作者
论文摘要
我们报告了高温介电和{\ it ac}的阻抗光谱研究NB取代的LACO $ _ {0.7} $ nb $ _ {0.3} $ _3 $ _3 $ polycrystalline样品。在400〜K处观察到最大介电恒定值$ \ $ \ $ 1400，其中峰值在较高的温度和频率下显示趋势下降。与温度的介电损失（TAN $δ$）行为反映了类似的变化，这表明材料中电荷载体的热激活。高温阻抗光谱数据的分析通过将Nyquist图拟合到等效电路来显示晶粒和晶界的贡献。从对阻抗和模量光谱的分析，可以辨别重叠晶粒，晶界和电极接口的影响。放松时间随温度的升高而减少，激活能量从0.44〜EV变为400〜K的0.56〜EV，这是由于热激活参与电荷载体的传导。发现给定频率的电导率随温度增加而增加，这再次显示了半导体行为。而在较低温度下的电导率随频率的增加而增加。同样，电导率在高温下几乎随频率饱和。
We report the high temperature dielectric and {\it ac} impedance spectroscopy investigation of Nb substituted LaCo$_{0.7}$Nb$_{0.3}$O$_3$ polycrystalline sample. The maximum dielectric constant value was observed $\approx$1400 at around 400~K where the peak value shows a decreasing trend at higher temperatures and frequency. Similar variation was reflected in the dielectric loss (tan$δ$) behavior with temperature, which shows the thermal activation of the charge carriers in the material. The analysis of high temperature impedance spectroscopy data shows the grain and grain boundary contributions by fitting the Nyquist plots to the equivalent circuit. From the analysis of the impedance and modulus spectra, it was possible to discern between the effects of overlapping grains, grain boundaries, and electrode interfaces. The relaxation time decreases with an increase in the temperature and the activation energy changes from 0.44~eV to 0.56~eV at around 400~K, which is due to involvement of thermal activation in the conduction of charge carriers. The conductivity is found to be increased with temperature for a given frequency, which again shows the semiconducting behavior. Whereas the conductivity increases with increase in frequency at lower temperatures. Also, the conductivity almost saturates with frequency at high temperatures.
