| Autor: |
Liedienov, N. A., Pashchenko, A. V., Pashchenko, V. P., Prokopenko, V. K., Tatarchuk, D. D., Revenko, Yu. F., Turchenko, V. A., Burchovetskii, V. V., Sycheva, V. Ya., Sil'cheva, A. G., Didenko, Yu. V., Levchenko, G. G. |
| Předmět: |
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| Zdroj: |
Low Temperature Physics; Sep2017, Vol. 43 Issue 9, p1076-1085, 10p, 1 Black and White Photograph, 2 Charts, 8 Graphs |
| Abstrakt: |
The structure, its defects, nanostructural clustering and functional properties of the La0.7Ca0.3-xKxMn1+xO3-δ ceramic with x=0-0.3 have been investigated by x-ray diffraction, thermogravimetric, SEM, resistance, magnetic, magnetoresistance and dielectric spectroscopy methods. We establish that the lattice parameter of the cubic structure increases when the Ca2+ ions are substituted with ions of K+. We show that the real perovskite structure contains different valence states of manganese MnA2+,MnB3+ and MnB4+ in A- and B-positions, as well as vacancy type point defects, in the form of anionic V(a) and cationic V(c) vacancies. The increase in the content of the superstoichiometric manganese is connected to the nanostructured clustering process. We find that K+ and superstoichiometric manganese cause the increase in relative permittivity ε′ and dielectric loss tangent angle tg δ. The experimental phase diagram of the magnetic state has been constructed and allows determining the composition of the magnetoresistant La0.7Ca0.3-xKxMn1+xO3-δ ceramics with set magnetotransport properties. The optimal La0.7Ca0.3-xKxMn1+xO3-δ composition showing the highest magnetoresistance effect at room temperature has been determined by comparing the functional properties of lanthanum-calcium, lanthanum-strontium and lanthanum-calcium-potassium manganites. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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