Effect of magnetic field on phase morphology transformation of MnO₂ nanostructures in a hydrothermal process

Abstract

MnO2 nanostructures with various phases and morphologies were successfully synthesized by a magnetic‐field‐assisted hydrothermal approach. By applying a pulsed magnetic field to the reaction system, the phase and morphology transformation progress, i.e. urchin‐like α‐ and γ‐MnO2 nanostructures converting to β‐MnO2 nanowires was interfered comparing with those reacted without magnetic field. The effect of pulsed magnetic field on the growth of MnO2 was investigated by tracking the evolution of phase and morphology of the samples at different reaction stages by using X‐ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. It is found that the pulsed magnetic field obviously affects the nucleation and growth of MnO2 nanostructures and therefore influences the phase and morphology transformation of MnO2. The transformation mechanism for the MnO2 nanostructures in hydrothermal treatment is the well‐known “Ostwald ripening process”. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Magnetic-assisted preparation and performance control of Fe3O4/PVDF gradient magnetic composites

“…Hu et al 16 believed that magnetic fields can enhance the diffusion of Mo ions and promote the oriented growth of MoS 2 , thereby improving its conductivity and lithium storage performance. Zhu et al 17 applied a magnetic field during the hydrothermal preparation process of MnO 2 nanostructures and studied its influence on phase and morphology transitions. Hippo et al 18 obtained highly oriented silicon arrays with a diameter of 100 nm and an aspect ratio of 160 using magnetic field-assisted anodization.…”