Objective:
The influence of Manganese (Mn2+) and Cobalt (Co2+) ions doping on the optical
and magnetic properties of ZnO nanoparticles was studied.
Methods:
Nanoparticle samples of type ZnO, Zn0.97Mn0.03O, Zn0.96Mn0.03Co0.01O, Zn0.95Mn0.03
Co0.02O, Zn0.93Mn0.03Co0.04O, and Zn0.91Mn0.03Co0.06O were synthesized using the wet chemical coprecipitation
method.
Results:
X-ray powder diffraction (XRD) patterns revealed that the prepared samples exhibited a
single phase of hexagonal wurtzite structure without any existence of secondary phases. Transmission
electron microscope (TEM) images clarified that Co doping at high concentrations has the ability
to alter the morphologies of the samples from spherical shaped nanoparticles (NPS) to nanorods
(NRs) shaped particles. The different vibrational modes of the prepared samples were analyzed
through Fourier transform infrared (FTIR) measurements. The optical characteristics and structural
defects of the samples were studied through Photoluminescence (PL) spectroscopy. PL results clarified
that Mn2+ and Co2+ doping quenched the recombination of electron-hole pairs and enhanced the
number of point defects relative to the undoped ZnO sample. Magnetic measurements were carried
out at room temperature using a vibrating sample magnetometer (VSM). (Mn, Co) co-doped ZnO
samples exhibited a ferromagnetic behavior coupled with paramagnetic and weak diamagnetic contributions.
Conclusion:
Mn2+ and Co2+ doping enhanced the room temperature Ferromagnetic (RTFM) behavior
of ZnO. In addition, the signature for antiferromagnetic ordering between the Co ions was revealed.
Moreover, a strong correlation between the magnetic and optical behavior of the (Mn, Co) co-doped
ZnO was analyzed.