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    Electrical and Dielectric Characterization of Bi-La Ion-Substituted Barium Hexaferrites
    (Springer, 2017) Auwal, I.; Ünal, B.; Baykal, Abdulhadi; Kurtan, U.; Yıldız, Aylin
    BaLa (x) Bi (x) Fe12-2xO19 (0.0 ae x ae 0.5) hexaferrites were produced by solid-state synthesis route, and the effect of Bi3+ and La3+ substitutions on electrical and dielectric properties of barium hexaferrite material were investigated. It is noticed that ac conductivity of barium (BaM) increases slightly with ionic substitutions of both La3+ and Bi3+ and then decreases. Ac conductivity is increased with increasing frequency at lower temperatures then remains constant for higher temperatures. This type of conductivity attitude could be originated from the indication of both electronics and polaron hopping mechanisms. The dielectric properties of BaLa (x) Bi (x) Fe12-2xO19 (0.0 ae x ae 0.5) hexaferrites represent a very interesting tunability as functions of frequency, temperature, and Bi3+ and La3+ ions.
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    Electrical and Dielectric Properties of Y3+-Substituted Barium Hexaferrites
    (Springer, 2017) Auwal, I. A.; Ünal, B.; Baykal, Abdulhadi; Kurtan, U.; Amir, M. D.; Yıldız, Aylin; Sertkol, M.
    In this study, Y3+ ion-substituted M-type barium hexaferrites (BaM; BaFe12O19) were fabricated via facile ceramic route. As-prepared powders were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, and impedance spectroscopy. XRD (Rietveld) analyses confirmed the presence of a single characterization of all samples (except x = 0.0 and 0.1 samples). The crystallite sizes of products are found in the range of 47.2-63.2 nm. Spectral analysis (FT-IR) also presented the formation of spinel structure for all products. The ac conductivity of the substituted samples was found to initially decrease slightly with increase in Y3+ compared with unsubstituted, and then variation tendency changes at the medium substitution ranges are observed with a different attitude against temperature. In the end, the lower conductivity for high substitutions is recorded and increases as functions of frequency while it also increases with the elevation of temperature. It was observed that ac conductivities of products increased by increasing frequency which indicate that observed ac conductivity is due to both electronic and polaron hopping mechanism.
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    Synthesis of magnetically recyclable MnFe2O4@SiO2@Ag nanocatalyst: Its high catalytic performances for azo dyes and nitro compounds reduction
    (Elsevier, 2016) Kurtan, U.; Amir, M. D.; Yıldız, Aylin; Baykal, Abdulhadi
    In this study, magnetically recycable MnFe2O4@SiO2@Ag nanocatalyst (MnFe2O4@SiO2@Ag MRCs) has been synthesized through co-precipition and chemical reduction method. XRD analysis confirmed the synthesis of single phase nanoproduct with crystallite size of 10 nm. VSM measurements showed the superparamagnetic property of the product. Catalytic studies showed that MnFe2O4@SiO2@Ag MRC could catalyze the reduction of the various azo compounds like methyl orange (MO), methylene blue (MB), eosin Y (EY), and rhodamine B (RhB) and also aromatic nitro compounds such as 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) and 2-nitroaniline (2-NA). Moreover, the magnetic nanocatalyst showed an excellent reusability properties that remained unchanged after several cycles. Therefore, MnFe2O4@SiO2@Ag is the potential candidate for the application of organic pollutants for wastewater treatment. (C) 2016 Elsevier B.V. All rights reserved.