Abstract
RETRACTED PAPER: The fabrication of nanospinel zinc chromite (ZnCr2O4) crystals by the means of thermal treatment method from an aqueous solution containing metal nitrates, polyvinyl pyrrolidone (PVP), and deionized water was described in this study. The samples were calcined at various temperatures ranging from 773 to 973 K for the decomposition of the organic compounds and crystallization of the nanocrystals. PVP was used as capping agent to control the agglomeration of the particles. The characterization studies of the fabricated samples were carried out by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), energy dispersed X-ray spectroscopy (EDX) and electron spin resonance spectroscopy (ESR). The corresponding peaks of Zn, Cr and O were observed in the EDX spectrum of the sample which confirms the formation of ZnCr2O4. The XRD patterns also confirmed the formation of the single faced nanocrystallines of spinel ZnCr2O4 with a face-centered cubic structure. The average particle size of the synthesized crystals was also determined from the XRD patterns using the Scherers formula which shows that the crystallite sizes increases with increase in calcination temperature and was in good agreement with the TEM images which shows cubical ZnCr2O4 nanocrystals with uniform morphology and particle size distributions. The ESR spectra confirmed the existence of unpaired electron in the fabricated samples and the increase in g-factor and decreases in resonant magnetic field (Hr) were observed as the calcination temperature increases.
Highlights
E ranging from 773 to 973 K for the decomposition of the organic compounds and crystallization of the nanocrystals
The average particle size of the synthesized crystals was determined from the X-ray diffraction (XRD) patterns using the Scherer’s formula which shows that the crystallite sizes increases with increase in calcination temperature and was in good agreement
Because of these drawbacks of the previous methods, we have introduced the thermal treatment method for synthesizing spinel zinc chromite
Summary
Spinels are important class of mixed-metal oxides and has the general chemical formula A2+B23+O42- where A and B are cations occupying tetrahedral and octahedral sites, respectively. Breakthrough due to the complicated procedures such as longer reaction times, high reaction temperatures, toxic reagents and potentially harmful by-products involved in most of these synthesis methods, it has been difficult to employ these methods on large scale production [9] Because of these drawbacks of the previous methods, we have introduced the thermal treatment method for synthesizing spinel zinc chromite. We investigated the influence of calcination temperature on the structural and magnetic properties of spinel ZnCr2O4 synthesized by the thermal treatment method. T Fig. 3 (a) and (b) shows the TEM images and crystal size distribution of ZnCr2O4 nanocrystallines calcined at temperatures of 773 and 973 K respectively. The thermal treatment method is very effective, because no loss of element was observed in the fabrication process
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