Defect‐Related Emissions and Magnetization Properties of ZnO Nanorods

Abstract

A clear correlation between defect‐related emissions and the magnetization of ZnO nanorods synthesized by a one‐step aqueous chemical method is demonstrated. The relative contribution of the emission bands arising from various types of defects is determined and found to be linked with the size of the nanorods and annealing conditions. When the size of the nanorods and the annealing temperature are increased, the magnetization of pure ZnO nanorods decreases with the reduction of a defect‐related band originating from singly charged oxygen vacancies ($V_{\rm o}^ +$). With a sufficient increase of annealing temperature (at 900 °C), the nanorods show diamagnetic behavior. Combining with the electron paramagnetic resonance results, a direct link between the magnetization and the relative occupancy of the singly charged oxygen vacancies present on the surface of ZnO nanorods is established.

Size Dependence of Defect-Induced Room Temperature Ferromagnetism in Undoped ZnO Nanoparticles

“…Second, the observed RTFM exhibits near linear size dependence because most of V O + exist near the surface, and its relative occupancy can be modulated linearly by the surface-to-volume ratio. These results are consistent with the view recognized by several pervious studies ,, that the surface and size are very important for defect-induced RTFM in pure metal oxides. And they can further explain why this d 0 RTFM is often found only in low-dimensional nanostructures or thin film with high surface-to-volume ratio.…”

Lithium-Doped Zinc Oxide Nanowires–Polymer Composite for High Performance Flexible Piezoelectric Nanogenerator

“…It can be obviously observed that relative intensity of yellow emission gradually increases as Li doping concentration increases. The results presented here are consistent with the study reported previously. − Next, the NGs were fabricated using grown Li-doped ZnO NWs with different Li concentrations and were subsequently poled under high electric field to align piezoelectric domain of the NWs. Figure d shows the representative piezoelectric output voltages of the NGs, measured after poling under different electric fields from 0 to 105 kV cm –1 at 65 °C for 20 h: the NWs used here were synthesized in the solution with a ratio of LiNO 3 :Zn(NO 3 ) 2 = 50:50 mM.…”

High UV and Sunlight Photocatalytic Performance of Porous ZnO Nanostructures Synthesized by a Facile and Fast Microwave Hydrothermal Method

“…Regarding the yellow emission observed around 596 nm, it has been reported that it may originate from the transition from the CB or Zn i to the O i defect level, which has been placed at around 2.28 eV below the CB [ 81 , 86 , 88 , 102 , 103 , 104 ], which is in good agreement with the yellow–orange PL in this work. It has been suggested that annealing at high temperatures in an oxygen-rich environment increases the intensity of this emission [ 86 , 103 ], which may explain the higher intensity of this PL band for the porous ZnO nanostructures calcinated at 700 °C in air.…”