Abstract
xMoO2-(1-x)α-Fe2O3 nanoparticle system with molarities x = 0.1, 0.3, 0.5 and 0.7 was successfully synthesized by mechanochemical activation of MoO2 and α-Fe2O3 mixtures for 0 - 12 hours of ball milling time. X-ray powder diffraction (XRD), Mössbauer spectroscopy and magnetic measurements were used to study the phase evolution of the molybdenum dioxide-hematite nanoparticle system under the mechanochemical activation process. Rietveld refinement of the XRD patterns yielded the values of the crystallite size and lattice parameters as function of milling times and indicated the presence of Mo-substituted hematite and Fe-doped molybdenum dioxide at long milling times. The Mössbauer studies yielded the magnetic hyperfine fields and the relative abundance of a quadrupole-split doublet as function of the milling time for all molar concentrations involved. Recoilless fraction was determined using our dual absorber method and was found to decrease with increasing ball milling time. Magnetic measurements recorded at 5 and 300 K in an applied magnetic field of 50,000 Oe showed the magnetic properties in the antiferromagnetic and canted ferromagnetic states. The Morin transformation was evidenced by zero-field cooling-field cooling (ZFC-FC) measurements in a magnetic field of 200 Oe.
Highlights
Due to its potential applications in energy-related materials, catalysis and electrochemistry, molybdenum dioxide (MoO2) is currently the subject of intense investigations
Rietveld refinement of the X-ray powder diffraction (XRD) patterns yielded the values of the crystallite size and lattice parameters as function of milling times and indicated the presence of Mo-substituted hematite and Fe-doped molybdenum dioxide at long milling times
Titanium-doped molybdenum dioxide system was obtained to study the kinetics of hydrogen reduction [8]
Summary
Due to its potential applications in energy-related materials, catalysis and electrochemistry, molybdenum dioxide (MoO2) is currently the subject of intense investigations. MoO2 nanoparticles were found to serve as high capacity intercalation anode for long-cycle lithium ion battery [2]. A facile hydrothermal method was proposed in [4] for the synthesis of MoO2 nanoparticles for high-performance supercapacitor electrodes and photocatalysts. The synthesis and electrochemical properties of MoO2/reduced graphene oxide hybrid for efficient anode of lithium ion battery were reported [5]. Titanium-doped molybdenum dioxide system was obtained to study the kinetics of hydrogen reduction [8]. All these investigations point towards obtaining mixed systems of MoO2 nanoparticles and another system, which would be able to tailor its functional properties
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