We report on the
realization of particle size, morphology, and
chemical composition controlled cobalt ferrite nanoparticles (CFO
NPs) with tunable magnetic properties for application in electronic
and electromagnetic devices. The effect of oleic acid concentration
(0.0–0.1 M) on the structural, physical, chemical, electronic,
and magnetic properties of solvothermally synthesized CFO NPs is investigated
in detail by using the oleic acid (OA) based chemical method for synthesis.
Crystalline, cubic, and chemically homogeneous CFO NPs (5–15
nm) can be obtained by controlling the OA concentration. Spectroscopic
analyses revealed that the OA molecules form covalent bonds with CFO
NPs. The particle-size control was achieved by bridging bidentate
interactions between the OA molecules and CFO NPs. Detailed magnetic
measurements revealed that the OA concentration helps to effectively
control the magnetic behavior of particle-size-controlled CFO NPs.
The interfacing between OA molecules and CFO surface atoms leads to
modified magnetism which is the key to understand the underlying mechanisms
and utilize magnetic nanoparticles in practical applications. The
anisotropy constant variation directly with nanoparticle size indicates
that the magnetocrystalline component governs the magnetic anisotropy
in OA coated CFO. Removal of OA (after thermal treatment) induces
enhanced magnetic anisotropy and exchange bias as consequence of surface
component. The results and analyses suggest that the molecular coating
of nanoparticles offers the most important and critical step to design
novel nanostructured magnetic materials for current and emerging electronic
device technologies.
Nickel chalcogenide (S and Se) based nanostructures intrigued scientists for some time as materials for energy conversion and storage systems. Interest in these materials is due to their good electrochemical stability, eco‐friendly nature, and low cost. The present review compiles recent progress in the area of nickel‐(S and Se)‐based materials by providing a comprehensive summary of their structural and chemical features and performance. Improving properties of the materials, such as electrical conductivity and surface characteristics (surface area and morphology), through strategies like nano‐structuring and hybridization, are systematically discussed. The interaction of the materials with electrolytes, other electro‐active materials, and inactive components are analyzed to understand their effects on the performance of energy conversion and storage devices. Finally, outstanding challenges and possible solutions are briefly presented with some perspectives toward the future development of these materials for energy‐oriented devices with high performance.
Abstract:The structural, transport and magnetic properties of MgB 2 superconductor heavily blended with Mg is studied. The samples are synthesized with a new approach in both,
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