<title>Infrared absorption and dielectric properties of Li-Cu ferrite</title>

Abstract

The mixed ferrites Lio5.5CuFe2.5o5 (where x 0 to 1) were prepared by the ceramic method. Infrared (IR) absorption and dielectric properties were used to investigate this ferrite. The JR spectra in the range from 200 to 1000 cm' were reported. Mainly, two bands were observed.The band at around 575 cm' ( v) and the band at around 385 cm' ( v) were assigned to the tetrahedral and octahedral complexes, respectively. A small band at about 325 cm' (v3) indicated the presence of octahedral divelant metal-oxygen in complexes. This band decreases with the increase of copper concentration and completely disappears at sample ofx 0.3. The threshold frequency for the electronic transition was determined. It was found that the threshold frequency for electronic transition seems to be decreasing with increasing Cu2 content.The ac conductivity and dielectric properties (dielectric constant ', dielectric loss e" and loss tangent tan ö) were measured at room temperature as a function of frequencies from 102 to 106 Hz. A hopping model was applied in order to discuss the obtained results. The frequency exponential factor s, was estimated and compared with available data.