Improved electrical and dielectric properties of La-doped Co ferrite
Improved electrical and dielectric properties of La-doped Co ferrite
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DOI：
10.1557/jmr.2010.37
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发表时间：
2011-02
影响因子：
2.7
通讯作者：
K. Bharathi;C. Ramana
中科院分区：
文献类型：
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作者：
K. Bharathi;C. Ramana
本文报道了La部分取代Fe后，Co铁氧体（CoO·Fe_2O_3）的介电常数和电阻率的提高。La掺杂Co铁氧体CoO·Fe_（1.925）La_（0.075）O_3的结构特征为立方反尖晶石相和少量的LaFeO_3附加相。得到的晶格参数为8.401 μ m（±0.001 μ m），高于Co铁氧体的晶格参数（8.387 μ m，±0.001 μ m）。CoO·Fe_（1.925）La_（0.075）O_3的介电常数和电阻率均高于纯Co铁氧体。CoO.Fe_1.925La_0.075O_3在100 Hz ~ 1 MHz频率范围内的介电常数色散符合修正的德拜函数，其中多个离子对弛豫有贡献。随温度变化的电阻率曲线表现出两个不同的区域，指示两种不同类型的导电机制。数据分析表明，小极化子和可变范围的跳跃机制是在220至300 K和160至220 K的温度范围内，分别操作。
We report on the enhanced dielectric constant and electrical resistivity of the Co-ferrite (CoO.Fe_2O_3) by partially substituting Fe with La. Structural characteristics of La-doped Co ferrite namely CoO.Fe_1.925La_0.075O_3 indicate the cubic inverse spinel phase with a small amount of LaFeO_3 additional phase. The lattice parameter obtained is 8.401 Å (±0.001 Å), which is higher than that reported for Co ferrite (8.387 Å, ±0.001 Å). The dielectric constant and electrical resistivity of CoO.Fe_1.925La_0.075O_3 are higher compared with pure Co ferrite. The dielectric constant dispersion of CoO.Fe_1.925La_0.075O_3 in the frequency range of 100 Hz to 1 MHz fits to the modified Debye’s function with more than one ion contributing to the relaxation. Temperature-dependent electrical resistivity curves exhibit two distinct regions indicative of two different types of conduction mechanisms. Analysis of the data indicates that the small polaron and variable-range hopping mechanisms are operative in the 220 to 300 K and 160 to 220 K temperature regions, respectively.