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The infrared absorption and dielectric properties of manganese substituted lithium ferrite at room temperature

S.A.Mazen, N.I.Abu-Elsaad

Polycrystalline ferrites with general formula Li0.5-0.5xMnxFe2.5-0.5xO4 (where x=0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) have been prepared by the ceramicmethod. The IR spectra have been reported in the range from 200 to 1000 cm-1. The two primary bands corresponding to tetrahedral õA and octahedral õB were observed around 575 cm-1 and 370 cm-1, respectively. Elastic properties of these mixed ferrites have been estimated as a function of composition. The values of YoungÂ’s modulus (E), rigidity modulus (G), bulk modulus (B), Debye temperature (èD) and mean sound velocity (Vm) have been calculated from transverse (Vt) and longitudinal (Vl) wave velocities. The variation of elastic moduli with composition has been interpreted in terms of binding forces between the atoms of spinel lattice. The a.c. conductivity ó ~ and dielectric properties (dielectric constant Ý and dielectric loss å” with loss tangent tan ä) were measured at room temperature as a function of frequencies from102 to 106 Hz. The electrical conductionmechanismwas explained in terms of the electron hoppingmodel. The frequency exponential factor (s) was estimated and it was found to vary between 0.4 and 0.8.