|Titov, YA |
1Taras Shevchenko National University of Kyiv
2Ivan Franko State University of Zhytomyr
|Dopov. Nac. akad. nauk Ukr. 2020, 6:37-45|
|Section: Materials Science|
The electrophysical properties of ceramic samples of new compounds Sr2LaBIIIBIVO7 (BIII = Sc, In, BIV = Ti, Sn) with two-slab structure were investigated by the method of impedance spectroscopy. The dependences of the complex impedance Z*(ν) of these compounds on the frequency of the probing sinusoidal electric signal and temperature were analyzed. The analysis of results indicates the considerable contribution of the ionic electroconductivity in Sr2LaBIIIBIVO7 ceramic samples. To simulate the impedance spectrum, we used the method of equivalent circuits, represented by radio engineering elements, which allows one to see, in the pure form, the properties of microcrystalline grains of ceramics, that is, the investigated material, without the influence of intergranular and electrode effects. The temperature dependence of the direct current electroconductivity, the frequency dependences of electroconductivity, imaginary components of impedance, and electrical module in the temperature range from 300 K to 800 K were investigated. It was found that the activation energy of the direct current electroconductivity for all Sr2LaBIIIBIVO7 ceramic samples was over the range 0.285 eV to 0.301 eV, and the conductivity values themselves differed by two orders of values. The frequency dependence of the electroconductivity is described by a universal power law with allowing a correlation between direct and reverse ion jumps. A definite contribution to the ionic component of the electroconductivity can be made by the lanthanum and strontium cations localized at the boundaries of perovskite-like blocks. One of the reasons for the higher electroconductivity values for indium-containing compounds can be the greater deformation of the In(Sn,Ti)O6 octahedra than that of the Sc(Sn,Ti)O6 octahedra.
|Keywords: activation energy., An+1BnO3n+1 compounds, ceramics, electroconductivity, impedance, slab perovskite-like structure|
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