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Impedance and Electric Modulus Spectroscopy of Polycrystalline La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– Cathode Ceramic for Intermediate Temperature SOFCs
Indian Journal of Pure & Applied Physics ( IF 0.6 ) Pub Date : 2021-08-23
Sunder Singh, Manindra Kumar, Anil Kumar, Deepash Shekhar Saini

In the present research work, La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– cathode ceramic powder is synthesized through cost-effective flash pyrolysis process and followed by conventional sintering for IT-SOFCs. The Rietveld refinement program is used to determine the crystal structure, unit cell parameters and bond length. The XRD result indicates existence of a pure single phase of rhombohedral structure with R3􀴤 C space group symmetry detected from the sample sintered at 700 ℃. FESEM micrographs of fracture surface of sample sintered at 700 ℃ showed a high porosity and nano grain sizes (50-100 nm). Combined impedance and electric modulus spectroscopic are used to investigate the relaxation phenomena in La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– ceramic over a broad range of temperature and frequency. A single relaxation peak is observed in the imaginary part of impedance and electric modulus spectra, which could be due to the contribution of grain boundary of La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– ceramic. The imaginary part of modulus (𝑀") spectra is studied with help of non-exponential decay function or Kohlrausch–Williams–Watts (KWW) parameter (β). In the combined plot of the imaginary part of impedance (𝑍") and electric modulus (𝑀") spectra at 210 ℃, only a single peak of 𝑍"and 𝑀" is observed at the same frequency which specifies that the conduction process is a long-range motion of the charge carriers. The frequencydependent conductivity is followed by the Jonscher’s double power law in the temperature range 30-210 ℃.

中文翻译:

用于中温 SOFC 的多晶 La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– 阴极陶瓷的阻抗和电模量谱

在目前的研究工作中,La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– 阴极陶瓷粉末是通过具有成本效益的快速热解工艺合成的,然后是 IT-SOFC 的常规烧结。Rietveld 精修程序用于确定晶体结构、晶胞参数和键长。XRD 结果表明,在 700 ℃ 烧结的样品中检测到具有 R3􀴤 C 空间群对称性的纯单相菱面体结构。700 ℃烧结样品断口的FESEM显微照片显示出高孔隙率和纳米晶粒尺寸(50-100 nm)。组合阻抗和电模量光谱用于研究 La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– 陶瓷在很宽的温度和频率范围内的弛豫现象。在阻抗和电模量谱的虚部中观察到单个弛豫峰,这可能是由于 La0.5Sr0.5Bi0.2Co0.4Fe0.4O3– 陶瓷晶界的贡献。在非指数衰减函数或 Kohlrausch–Williams–Watts (KWW) 参数 (β) 的帮助下研究模量 (𝑀") 谱的虚部。在阻抗虚部 (𝑍") 和电的虚部的组合图中模量 (𝑀") 谱在 210 ℃ 时,仅观察到 𝑍" 和 𝑀" 的单峰在相同频率下,这表明传导过程是电荷载流子的长程运动。频率相关的电导率之后是Jonscher 的双幂定律在 30-210 ℃ 的温度范围内。5Bi0.2Co0.4Fe0.4O3–陶瓷。在非指数衰减函数或 Kohlrausch–Williams–Watts (KWW) 参数 (β) 的帮助下研究模量 (𝑀") 谱的虚部。在阻抗虚部 (𝑍") 和电的虚部的组合图中模量 (𝑀") 谱在 210 ℃ 时,仅观察到 𝑍" 和 𝑀" 的单峰在相同频率下,这表明传导过程是电荷载流子的长程运动。频率相关的电导率之后是Jonscher 的双幂定律在 30-210 ℃ 的温度范围内。5Bi0.2Co0.4Fe0.4O3–陶瓷。在非指数衰减函数或 Kohlrausch–Williams–Watts (KWW) 参数 (β) 的帮助下研究模量 (𝑀") 谱的虚部。在阻抗虚部 (𝑍") 和电的虚部的组合图中模量 (𝑀") 谱在 210 ℃ 时,仅观察到 𝑍" 和 𝑀" 的单峰在相同频率下,这表明传导过程是电荷载流子的长程运动。频率相关的电导率之后是Jonscher 的双幂定律在 30-210 ℃ 的温度范围内。
更新日期:2021-08-23
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