RETRACTED ARTICLE: Synthesis, Structural and Magnetic Properties of Polypyrrole Coated Ni0.2Ca0.8Fe2O4 Nanocomposite

Autor: S. Kumar, M. S. Dhawan, V. R. Reddy, S. N. Dolia, Arun S. Prasad
Rok vydání: 2012
Předmět:
Zdroj: Journal of Superconductivity and Novel Magnetism. 25:1921-1927
ISSN: 1557-1947
1557-1939
DOI: 10.1007/s10948-012-1513-5
Popis: 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. Mossbauer 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 (TB) is found to have credibly increased from 110 K to 130 K, which confirms the increase in crystallite size after polymerization.
Databáze: OpenAIRE
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