Structural and Magnetic Response in Bimetallic Core/Shell Magnetic Nanoparticles.
Bimagnetic monodisperse CoFe₂O₄/Fe₃O₄ core/shell nanoparticles have been prepared by solution evaporation route. To demonstrate preferential coating of iron oxide onto the surface of ferrite nanoparticles X-ray diffraction (XRD), High resolution transmission electron microscope (HR-TEM) and Raman spectroscopy have been performed. XRD analysis using Rietveld refinement technique confirms single phase nanoparticles with average seed size of about 18 nm and thickness of shell is 3 nm, which corroborates with transmission electron microscopy (TEM) analysis. Low temperature magnetic hysteresis loops showed interesting behavior. We have observed large coercivity 15.8 kOe atT= 5 K, whereas maximum saturation magnetization (125 emu/g) is attained atT= 100 K for CoFe₂O₄/Fe₃O₄ core/shell nanoparticles. Saturation magnetization decreases due to structural distortions at the surface of shell below 100 K. Zero field cooled (ZFC) and Field cooled (FC) plots show that synthesized nanoparticles are ferromagnetic till room temperature and it has been noticed that core/shell sample possess high blocking temperature than Cobalt Ferrite. Results indicate that presence of iron oxide shell significantly increases magnetic parameters as compared to the simple cobalt ferrite.
Centre for High Energy Physics, University of the Punjab, Lahore 54000, Pakistan. adeela16@gmail.com.
Adeela
A
Nairan
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. usman_cssp@yahoo.com.|Centre for Excellence in Solid State Physics, University of the Punjab, Lahore 54000, Pakistan. usman_cssp@yahoo.com.
Usman
U
Khan
Centre for High Energy Physics, University of the Punjab, Lahore 54000, Pakistan. muniqbal@yahoo.com.
Munawar
M
Iqbal
Nanomaterials Research Group, Physics Division PINSTECH, Nilore, Islamabad 45650, Pakistan. maaz@impacs.ac.cn.
Maaz
M
Khan
Department of Physics, Forman Christian College, Lahore 54000, Pakistan. khaliduet@gmail.com.
Khalid
K
Javed
Centre for Excellence in Solid State Physics, University of the Punjab, Lahore 54000, Pakistan. saira_cssp@yahoo.com.
Saira
S
Riaz
Centre for Excellence in Solid State Physics, University of the Punjab, Lahore 54000, Pakistan. shahzad_naseem@yahoo.com.
Shahzad
S
Naseem
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. xfhan@iphy.ac.cn.
Xiufeng
X
Han
FC/ZFC; Rietveld refinement; core/shell nanoparticles; surface effects