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G. Mahmoudzadeh 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.4
The dispersed nanocrystallite particles of ZnFe2O4 have been synthesized by sol-gel auto-combustion with the aid of ultrasonic irradiation methods using different fuel additives of glycine, urea and thiourea. The ratios of fuel- to- nitrates were maintained variously at 1.2 : 1, 2 : 1, and 3 : 1. The results revealed that, the difference in the phase composition formed are mainly attributed to the combustion process. In turn, different fuel additives exert a direct influence in the combustion reaction on the formation of a homogeneous gel, the formation of a good complex with metal cations and release chemical energy; as well as, showed that, the crystallite size of Zn ferrite powders is affected by the compositional ratios of fuel–to-nitrates. High fuel/ oxidant ratios increase the particle size and may enhance dopant segregation. The studies on the composition of phases, crystallite sizes, and morphology of the powder ferrite formed were investigated by X-Ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results demonstrated that, the average crystal sizes distribution obtained were in the range 11-38 nm for all compositions.
S. S. Madani,G. Mahmoudzadeh,S. Abedini Khorrami 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.2
Cobalt ferrite (CoFe2O4) powders with nanocrystalline sizes were produced by a combination of sol-gel auto-combustion and ultrasonic irradiation methods employing a mixture of urea, thiourea and glycine as the fuel with the corresponding metal nitrates. The pH in the starting solution affects the combustion process, and then determines the particle size of the assynthesized powder. The influence of the pH value on the gel auto-combustion and the phase composition of the synthesized powders have been studied with the help of scanning electron microscopy (SEM) observations, Fourier transform infra red (FTIR) spectroscopy and X-Ray diffraction (XRD) techniques. The synthesized powders had a particle size distribution in the range of 23-43 nm.
S. Abedini Khorrami,G. Mahmoudzadeh,S. S. Madani,F. Gharib 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5
ZnFe2O4 nanocrystallites were synthesized successfully by a combination of sol-gel auto combustion and ultrasonic irradiation techniques. The influence of the calcination temperature on the particle sizes was investigated. The particles have been calcined at temperatures varying from 400 to 900 oC. The studies were carried out using XRD and SEM techniques. The gradual increase in the crystallite size with the calcination temperature indicates the formation of bigger particles by the calcination.