Spectroscopic Study of Al 3+ -Substituted Strontium Hexaferrite

Abstract

The substituted Y type hexaferrites Sr 2 Zn 2 Al í µí±¥ Fe 12−í µí±¥ O 22 (where í µí±¥ = 2, 4, 6, 10) are prepared by standard ceramic technique. The infrared absorption spectra of the prepared compounds are studied in the range 400 cm −1 to 4600 cm −1 . These spectra are used to locate the vibrational ranges due to substituted cations with the nearest oxygen layers and also to understand the band positions attributed to the lattice sites. The absorption regions found around 460 cm −1 and 600 cm −1 are the common features of all spinel ferrites. Both X-ray and IR spectroscopic studies in these ferrites do not detect the presence of Fe 2+ . Also with increase in aluminium substitution, the higher frequency bands start disappearing. This may be due to reduced vibrations of trivalent cations Fe–O bonds at both octahedral and tetrahedral sites which in turn affect Fe 3+ –O 2− –Fe 3+ superexchange interactions present in the structure.