Far-infrared spectra for copper-zinc mixed ferrites

Infrared spectra of Zn2+ ions substituted Cu ferrites with the general formula Cu1-xZnxFe2O4 (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1) have been analyzed in the frequency range 200-1000 cm-1. These mixed ferrites were prepared by the standard double sintering ceramic method. Two prominent bands were observed, high-frequency band ν1 around 550 cm-1 and low-frequency band ν2 around 395 cm-1 and assigned to tetrahedral and octahedral sites for spinel lattice, respectively. On introducing zinc ions IR spectra indicate new shoulders or splitting on tetrahedral absorption bands around 600 and 700 cm-1. A small absorption band ν3 was observed around 310 cm-1. This indicates the migration of some Zn2+ ions to octahedral site. Another small weak absorption band was also observed around 265 cm-1; its intensity increased with Zn content. Force constant was calculated for both tetrahedral and octahedral sites. Threshold frequency νth for the electronic transition was determined and found to increase with an increase in Zn ions. The half bandwidth for each site was calculated and the ratio seemed to increase with an increase in zinc content. The cation distribution for these ferrites was estimated in the light of IR spectra.