Abstract
The nanoparticles of spinel ferrites having composition Ni0.2Ca0.8Fe2O4 were synthesized by an advanced sol-gel method and subsequently coated with intrinsically conducting polypyrrole (PPy) by chemical oxidative polymerization of the corresponding monomer (pyrrole) using ammonium peroxodisulphate as oxidant. The X-ray diffraction and TEM measurements were obtained to understand the crystalline structure, size and morphology of evolution of the samples. The dc electrical investigation revealed that at room temperature the surface conductivity increased from 2.8×10−5 S cm−1 to 1.5×10−3 S cm−1 on polymerization. Mössbauer investigations revealed that the polymerization causes migration of Fe3+ ions from A to B site, resulting to the enhancement of the observed hyperfine field. In agreement with this, the dc magnetization measurements performed on VSM revealed an enhancement in saturation magnetization in the M–H curves on polymerization. The value of blocking temperature (T B) is found to have credibly increased from 110 K to 130 K, which confirms the increase in crystallite size after polymerization.
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Because of scientific errors, Prasad, A.S., Dolia, S.N., Dhawan, M.S., Kumar, S., Reddy, V.R.: Synthesis, Structural and Magnetic Properties of Polypyrrole Coated Ni0.2Ca0.8Fe2O4 Nanocomposite. Journal of Superconductivity and Novel Magnetism 25, 1921–1927 (2012). doi: 10.1007/s10948-012-1513-5 has been retracted at the request of the authors. The paper was previously corrected with an Erratum: Prasad, A.S., Dolia, S.N., Dhawan, M.S., Kumar, S., Reddy, V.R.: Erratum to: Synthesis, Structural and Magnetic Properties of Polypyrrole Coated Ni0.2Ca0.8Fe2O4 Nanocomposite. Journal of Superconductivity and Novel Magnetism 26, 2985 (2013). doi: 10.1007/s10948-013-2314-1.
An erratum to this article is available at http://dx.doi.org/10.1007/s10948-015-2952-6.
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Prasad, A.S., Dolia, S.N., Dhawan, M.S. et al. RETRACTED ARTICLE: Synthesis, Structural and Magnetic Properties of Polypyrrole Coated Ni0.2Ca0.8Fe2O4 Nanocomposite. J Supercond Nov Magn 25, 1921–1927 (2012). https://doi.org/10.1007/s10948-012-1513-5
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DOI: https://doi.org/10.1007/s10948-012-1513-5