Study of the hydrogenation and re-heating of Co-doped ZnO and In2O3 Nano composites

Abstract

Nanocomposite samples of zinc oxide (ZnO) and indium oxide (In2O3) doped with Co (at 1.5% molar concentration) are synthesized through conventional solid-state reaction technique. These samples are taken in a quartz tube and placed in reduction furnace for post-annealing in the presence of hydrogen for ~ 10 h at around 550 °C. The X-ray diffraction (XRD) study confirms the formation of hexagonal wurtzite structure for ZnO, Zn0.985CO0.015O and Zn0.985CO0.015O:H samples whereas cubic bixbyite structure for In2O3, (In0.985CO0.015)2O3 and (In0.985CO0.015)2O3:H samples. The magnetization data investigations depict that both undoped ZnO and In2O3 have small negative susceptibilities and exhibit diamagnetic behavior at room temperature. The doping of Co ions induces paramagnetic property in both the samples. Interestingly, the hydrogenated samples Zn0.985CO0.015O:H and (In0.985CO0.015)2O3:H exhibited a perceptible ferromagnetic behavior at 300 K whereas it overturns significantly after long air sintering. An effort has been made to fit the experiential M-H data of hydrogenated samples to the Bound Magnetic Polaron (BMP) model. MATLAB-based simulations have been performed to validate the homogeneity in particle distribution of the samples evinced through SEM micrographs. A multivariate assessment viz. hierarchical cluster analysis is also executed to corroborate and strengthen the experimental findings of magnetic properties.