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    Öğe
    Investigation of the crystal/magnetic structure, magnetic and optical properties of SrYxNbxFe12-2xO19 (x <= 0.05) hexaferrites
    (Iop Publishing Ltd, 2020) Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan; Nawaz, Muhammad; Alahmari, Firas S.; Manikandan, Ayyar; Baykal, Abdulhadi
    Series of Sr hexaferrites (HFs) co-substituted with Nb3+ and Y3+ ions (SrYxNbxFe12-2xO19 (x <= 0.05) were prepared via sol-gel combustion method. In addition to their optical, low temperature, magnetic properties and hyperfine interactions were investigated in detail. X-ray diffraction (XRD) patterns were considered proving both the formation and pureness of products. Mossbauer analysis indicated that the hyperfine field on iron nuclei at all sites decrease with substitution of Y3+-Nb3+ ions into Sr-hexaferrite as a result of changing the magnetic Fe3+ (5 mu(B)) ions by nonmagnetic Y3+ and Nb3+ ions. This leads to decreasing of the magnetic super exchange interaction between the ions. Measurements of AC susceptibility and ZFC-FC magnetizations implemented in a range from room temperature (RT) down to around 2 K. The analysis of M-FC-M-ZFC data proves the ferrimagnetic performance of different prepared HFs in the whole range of 2-325 K and a super-spin glass-like behavior was identified at minimal temperatures. The investigation of AC susceptibility revealed a weakening in the magnetic exchange interactions with the rise in the Nb3+ and Y3+ ions ratios.
  • [ X ]
    Öğe
    Synthesis and characterization of electrospun NiCoCdNdFeO4 nanofibers
    (Elsevier B.V., 2020) Alahmari, Firas S.; Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan; Shirsath, Sagar E.; Akhter, Shameem; Baykal, Abdulhadi
    We report here the production of novel Ni0.5Co0.5?xCdxNd0.02Fe1.78O4 nanofibers (NFs) (0.00 ? x ? 0.25) via electrospinning method with using polyvinylpyrrolidone (PVP) as a polymer agent. The investigation of the partial substitution effect of Co by Cd ions in Co0.5Ni0.5Fe1.78Nd0.02O4 NFs on their morphological, structural and magnetic properties was performed. The XRD confirmed the successful formation of Ni0.5Co0.5?xCdxNd0.02Fe1.78O4 (0.00 ? x ? 0.25) NFs with cubic structure. The hyperfine parameters were determined from the analysis of Mössbauer results. The hyperfine magnetic field of both sites was not much affected by the substitution. Mössbauer analysis indicated that the Cd2+ ions strongly occupy A site and the Fe3+ions emigrated from A site to B site, and hence the content of Co2+ions diminished at B site. Room temperature (RT; T = 300K) and 10 K magnetization curves were investigated via vibrating sample magnetometer (VSM). All prepared samples displayed ferrimagnetic behavior at both measured temperatures. The saturation magnetization (Ms) enhances from x = 0.00 to 0.05 and thereafter reduces with the further increase in Cd2+ ion contents. All the Cd-substituted samples displayed higher Ms values than that of the non-substituted sample. The improvement in Ms values with Cd substitution is largely ascribed to the surface spins effects and cations distribution on Td and Oh sites. Magnetic moments, remanence (Mr) and coercivity (Hc) were determined and investigated.