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Teplofizika vysokikh temperatur, 2013, Volume 51, Issue 1, Pages 61–66
(Mi tvt56)
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This article is cited in 3 scientific papers (total in 3 papers)
Thermophysical Properties of Materials
Heat capacity and electrophysical properties of $\mathrm{GdMeFe_2O_5}$($\mathrm{Me}$–$\mathrm{Li}$, $\mathrm{Na}$, $\mathrm{K}$, $\mathrm{Cs}$)-type ferrites
Sh. B. Kasenovaa, Zh. I. Sagintaevaa, B. K. Kasenova, S. Zh. Davrenbekova, S. M. Sergazinab, E. K. Zhumadilovc a AO Fitokhimia International Research-Industrial Holding, Gazalieva ul. 4, Karaganda, Republic of Kazakhstan
b Sh. Ualikhanov Kokshetaus State University, Abay ul. 76, Kokshetau, 020000, Republic of Kazakhstan
c Karaganda State Technical University, pr. Mira 56, Karaganda, 100009, Republic of Kazakhstan
Abstract:
The heat capacity of $\mathrm{GdMeFe_2O_5}$($\mathrm{Me}$–$\mathrm{Li}$, $\mathrm{Na}$, $\mathrm{K}$, $\mathrm{Cs}$) is investigated within the temperature range of $298.15$–$673$ K by a calorimetric method. $\lambda$-points are revealed in the $C_p^\circ(T)$ curves at $448$ K and $598$ K in $\mathrm{GdLiFe_2O_5}$, at $473$ K and $573$ K in $\mathrm{GdNaFe_2O_5}$, at $448$ K and $598$ K in $\mathrm{GdKFe_2O_5}$, and at $448$ in $\mathrm{GdCsFe_2O_5}$ related to a phase transition of the second kind. The temperature dependencies are calculated for the thermodynamic functions $C_p^\circ(T)$, $H^\circ(T)-H^\circ(298.15)$, $S^\circ(T)$, and $\Phi^{**}(T)$. The electrophysical characteristics of the synthesized ferrites are studied within the temperature range of $303$–$493$ K: Effects similar to those found in the $C_p^\circ(T)$ curves are also revealed in the $\log\varepsilon(T)$ and $\log R(T)$ curves. The compositions are shown to exhibit a semiconductor-type electrical conductivity. At the $T_{\text{cond}}$ points of the ferrites, the semiconductor-type conductivity changes the metal type one and both the capacities and permittivities vary sharply, and that may be related to a ferroelectric phase transition (the Curie and the Neel points). These effects provide a certain possibility to clarify the nature of the $\lambda$-points in the $C_p^\circ(T)$ curves.
Received: 12.10.2010
Citation:
Sh. B. Kasenova, Zh. I. Sagintaeva, B. K. Kasenov, S. Zh. Davrenbekov, S. M. Sergazina, E. K. Zhumadilov, “Heat capacity and electrophysical properties of $\mathrm{GdMeFe_2O_5}$($\mathrm{Me}$–$\mathrm{Li}$, $\mathrm{Na}$, $\mathrm{K}$, $\mathrm{Cs}$)-type ferrites”, TVT, 51:1 (2013), 61–66; High Temperature, 51:1 (2013), 54–59
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https://www.mathnet.ru/eng/tvt56 https://www.mathnet.ru/eng/tvt/v51/i1/p61
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Abstract page: | 182 | Full-text PDF : | 49 | References: | 44 |
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