Yazar "Ari, Mehmet" seçeneğine göre listele

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    Öğe
    Electrical properties of triple-doped bismuth oxide electrolyte for solid oxide fuel cells
    (Taylor & Francis Ltd, 2016) Gonen, Yunus Emre; Ermis, Ismail; Ari, Mehmet
    In this study, the quaternary solid solutions of (Bi2O3)((0.8-x))(Tb4O7)(0.1)(Ho2O3)(0.1)(Dy2O3)(x) (x = 0.05, 0.10, 0.15, 0.20) as an electrolyte were synthesized for solid oxide fuel cells by the technique of solid-state synthesis. The products were characterized by X-ray powder diffraction, differential thermal analysis/thermal gravimetry and the four-point probe technique (4PPT). The total electrical conductivity is measured on the temperature and the doped concentration by 4PPT. All samples have been obtained as the delta-phase. According to the measurements of the 4PPT, the electrical conductivities of the samples increase with the temperature but decrease with the amount of doping rate. The value of the highest conductivity (sigma) is found as 1.02 x 10(-1) S cm(-1) for the system of (Bi2O3)(0.75)(Tb4O7)(0.1)(Ho2O3)(0.1)(Dy2O3)(0.05) at 850 degrees C. The thermal gravimetry (TG) curve shows that there is no mass loss of sample during the measurement. The analyses of differential thermal reveal that there are neither endothermic peaks nor exothermic peaks during the heating and cooling cycles (ranging from 30 to 1000 degrees C).
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    Öğe
    Phase stability and electric conductivity of Eu2O3-Tb4O7 co-doped Bi2O3 electrolyte
    (Pergamon-Elsevier Science Ltd, 2015) Ermis, Ismail; Ari, Mehmet; Acer, Semra Durmus; Dagdemir, Yilmaz
    In this study, eight different samples of Tb4O7 and Eu2O3 co-doped Bi2O3 were prepared by solid-state synthesis techniques. (Bi2O3)(1-x-y)(Tb4O7)(x)(Eu2O3)(y) (x = 5,10; y = 5, 10, 15, 20 mol %) ternary systems were investigated by using X-ray powder diffraction (XRD), differential thermal analysis/thermal gravimetry (DTA/TG), and four-point probe techniques (4PPT). Effect of concentration of doping elements on the temperature and electrical conductivity was investigated. All samples were evaluated by calculating activation energies and average crystal sizes. XRD measurements show that five samples have a single phase (phase) structure. According to electrical conductivity measurements, the conductivity increases with increasing temperature but decreases with increasing amount of Eu2O3. The highest ionic conductivity was measured as 7.28 x 10(-1) (ohm.cm)(-1) for the (Bi2O3)(0.90)(Tb4O7)(0.05) (Eu2O3)(0.05) sample at 850 degrees C and the lowest activation energy was measured as 0.64 eV for (Bi2O3)(0.90)(Tb4O7)(0.05) (Eu2O3)(0.05). Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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    Öğe
    Synthesis of (Bi2O3)0.9-x(Tb4O7)0.1(Sm2O3)x electrolyte for IT-SOFCs
    (Taylor & Francis Inc, 2018) Ermis, Ismail; Sertkol, Murat; Corumlu, Vahit; Dagdemir, Yilmaz; Ari, Mehmet
    In this study (Bi2O3)(0.9-x)(Tb4O7)(0.1)(Sm2O3)(x) ternary solid solutions were synthesized by solid-state synthesis techniques. The products were characterized by means of X-ray powder diffraction, differential thermal analysis/thermal gravimetry, and the four-point probe technique (4PPT). Total electrical conductivity (sigma T) depending on the temperature and doping concentration has been measured by 4PPT. Activation energy of the four samples are calculated by Arrhenius relation. Activation energies of the samples increases with the concentration of dopant Sm2O3. Bi2O3-based ceramic system doped with Sm2O3 and Tb4O7 showed an oxide ionic-type electrical conductivity which is increased with the increasing amount of Sm2O3. The highest conductivity value is found as 3.48x10(-1) S cm(-1) for the (Bi2O3)(0.85)(Tb4O7)(0.1)(Sm2O3)(0.05) ternary system at 850 degrees C.
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    Öğe
    The phase stability and conductivity of Ho2O3-Gd2O3 co-doped electrolyte for solid oxide fuel cell
    (Springer, 2016) Corumlu, Vahit; Ermis, Ismail; Acer, Semra D.; Cifci, Tugba; Dagdemir, Yilmaz; Ari, Mehmet
    In this study, Bi2O3 ternary system sample materials were synthesized by using solid state reaction method. Two oxides, Ho2O3 and Gd2O3, were used to stabilize the delta (cubic) Bi2O3 phase used as an electrolyte of solid oxide fuel cell applications. The characteristics and electrical properties of these electrolyte samples for solid oxide fuel cells were evaluated by X-ray diffraction (XRD), scanning electron microscope and the four-point probe technique. According to XRD measurements, delta-phase (x = 0.05-0.1, y = 0.05, 0.1, 0.15, 0.2) samples were obtained with a stable structure. The results of the electrical measurements of the (Bi2O3)(1-x-y)(Ho2O3)(x) (Gd2O3) y ternary system show that the electrical conductivity increase with decreasing amount of Gd2O3 molar ratio at a fixed molar ratio of Ho2O3. The value of highest conductivity was found as 2.53 x 10(-1) S cm(-1) for the (Bi2O3)(1-x-y)(Ho2O3)(x)(Gd2O32O3)(y) ternary system (x = 0.05 mol% and y = 0.05 mol%) at 973 K. It was found that activation energy at low temperature varied from 1.10 to 1.29 eV and the activation energy at high temperature varied from 0.61 to 0.70 eV.