Elsevier

Materials Letters

Volume 60, Issue 3, February 2006, Pages 371-374
Materials Letters

FTIR study of Ni, Cu and Zn substituted nano-particles of MgFe2O4

https://doi.org/10.1016/j.matlet.2005.08.053Get rights and content

Abstract

Nano-particles of polycrystalline M0.5Mg0.5Fe2O4 are prepared using sol-gel method with M = Ni, Cu and Zn. They are obtained as dried gel after the successful chemical reaction of their respective metal nitrate solutions in the midst of citric acid as catalyst. Synthesis of materials is confirmed using XRD from the report of single phase polycrystalline ferrite material. Their corresponding reflection planes are also determined. Lattice constant and particle size are determined for these materials. Cu and Zn mixed ferrites have more values of lattice constant as they are bigger ions than Ni. Particle size is observed to decrease by substitution of Cu to Zn. The estimation of cation distribution is done.

The dried powder of these nano-ferrites is subjected to VSM measurements and FTIR characterization. The magnetic moment values are determined and the theoretical calculation of them is done for proposed cation distribution. FTIR frequency data for the respective sites are analyzed. The higher frequency band (v1) and lower frequency band (v2) are assigned to the tetrahedral and octahedral complexes. The values of force constant (KA, KB) have been calculated from IR band frequency data. The difference in the trends of bond length and force constant in comparison to frequency and moment data are able to elucidate the role of crystal field effect.

Introduction

Nano-Ferrites of M0.5Mg0.5Fe2O4 (M = Ni,Cu,Zn) have technological importance as they can play a role in the miniaturization process of several microwave components [1], [2], [3]. It has been known in literature [4], [5], [6] that the substitution of Magnesium in the bulk ferrites enabled a substantial modification of electrical and magnetic properties. Nano-ferrites with Magnesium substitution, synthesized using sol-gel method, are studied in the present work. The Sol-gel method of preparing nanoferrite has many significant advantages such as good stoichiometric control and for the production of ultra fine particle with narrow size distribution in relatively short processing time at lower temperature [7], [8], [9], [10]. Consequently the difference in nature of cation and its distribution in spinel as well as ionic states of the metal ions in A- and B-sites when studied using X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Infrared spectra (FTIR) would provide a meaningful correlation of their structure and effective changes in the environs of ions.

Section snippets

Synthesis

A set of ferrites M0.5Mg0.5Fe2O4 (M = Ni, Cu, Zn) is synthesized using sol-gel (auto-combustion) method. The required amount of metal nitrates and citric acid are taken so as to have a molar ratio of 1 : 1 and dissolved in 100 ml of deionized water. A required amount of ammonia is added into the solution in order to adjust the pH value to about 7 since base catalysts are employed in order to speed up the reaction. Sol so formed is poured in a silica crucible and heated at 135 °C under constant

XRD study

XRD patterns of sol-gel route-wise synthesized materials are shown in Fig. 1. The existence of a peak around the diffraction angle (2θ) equal to 35° corresponding to (311) plane confirms the formation of spinel ferrites. A careful analysis of XRD patterns helps to determine their respective planes and face centered cubic structure of these ferrites. Well resolved peaks in XRD pattern clearly indicate the single phase and polycrystalline nature of the samples. The values of lattice constant are

Conclusion

A close scrutiny of the vibration band frequencies of end member ferrites namely Ni ferrite (660 and 587 cm 1), Fe3O4 (640 and 590 cm 1), Zn ferrite (660 and 550 cm−1) and Cu ferrite (620 and 565 cm 1) [20] and Mg ferrite (565 and 406 cm 1) [21] with the data in Table 3 shows the shift in the position of the bands. Legitimately it is caused by the change of the environment of ions in the tetrahedral and octahedral sites viz., Table 1 shows the difference in constitution of ions in the

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