Annealing-induced enhancement of ferromagnetism in SnO2-core/Cu-shell coaxial nanowires

Abstract

In this study, we have coated tin oxide (SnO2) nanowires with a Cu shell layer via the sputtering method and subsequently investigated the effects of thermal annealing. The annealing-induced changes in morphologies, microstructures, and compositions of the resulting core-shell nanowires were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and energydispersive X-ray spectroscopy (EDX). The Cu shell layers were agglomerated to form clusters, which were mainly comprised of the Cu2O phase. For the first time, a hysteresis loop indicating weak ferromagnetism was observed from the pure SnO2 nanowires. Both the coercivity and the retentivity in the hysteresis loop were slightly increased by Cu-sputtering, indicating a very slight enhancement of ferromagnetism. Also, the ferromagnetic behavior was significantly enhanced by thermal annealing. We discuss the possible mechanisms of annealing-induced enhancement of ferromagnetism in the SiO 2 /Cu core-shell nanowires, which include the generation of Cu 2 O phase, Cu-doping into the SnO 2 lattice, and the generation of oxygen vacancies in SnO 2 core nanowires.

Selective Improvement of NO2 Gas Sensing Behavior in SnO2 Nanowires by Ion-Beam Irradiation

“…The experimental procedure used for fabricating pristine SnO 2 nanowires in the present work has been described previously . Sn powder (purity: 99.9%), which was placed in a ceramic boat, was used as a source material.…”

“…The experimental procedure used for fabricating pristine SnO 2 nanowires in the present work has been described previously. 25 Sn powder (purity: 99.9%), which was placed in a ceramic boat, was used as a source material. A gold (Au)-coated Si plate was used as a substrate for the growth of nanowires (∼3 nm-thick Au layer).…”