Enhancement of negative capacitance effect in (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion beam sputtering in argon and oxygen atmosphere
АуториKoltunowicz, T. N.
Fedotova, J. A.
Fedotov, A. K.
Kasiuk, J. V.
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The paper presents frequency f and temperature T-p dependences of phase shift angle Theta, admittance sigma and capacitance C-p for the as-deposited and annealed (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion-beam sputtering of a compound target in a mixed argon-oxygen gas atmosphere in vacuum chamber. The studied films presented metallic FeCoZr cores covered with FeCo-based oxide shells embedded into oxygen-free dielectric matrix (fluorite). It was found for the metallic phase content within the range of 52.2 at.% LT = x LT = 84.3 at.% in low-f region that Theta values were negative, while in the high-f region we observed the Theta LT 0 degrees. It was obtained that the f-dependences of capacitance module displayed minimum at the corresponding frequency when the Theta(f) crossed its zero line Theta = 0 degrees. It was also observed that the sigma(T-p) dependence displayed the occurrence of two minima that were related to the values of Theta(1) = 90 degrees (the first ...minimum) and of Theta(2)= -90 degrees (the second one). Some possible reasons of such behavior of (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films are discussed. (C) 2013 Elsevier B.V. All rights reserved.
Кључне речи:Electronic transport / Hopping conductance / Nanocomposites / Percolation
Извор:Journal of Alloys and Compounds, 2014, 615, S361-S365
- Iuventus Plus program of Polish Ministry of Science and Higher Education [IP2012 026572], Visby Program of Swedish Institute, State Sub-Programme Crystalline and molecular systems of Belarus
- International Symposium on Metastable, Amorphous and Nanostructured Materials (ISMANAM), Jun 30-Jul 05, 2013, Torino, Italy
ISSN: 0925-8388 (print); 1873-4669 (electronic)