Positron Annihilation And Electrical Conductivity Studies Of Cu Substitution Effect In Li[sub 0.5-0.5x]Cu[sub x]Fe[sub 2.5-0.5x]O[sub 4] Spinel Ferrite

Abstract

Positron annihilation lifetime (PAL), and electrical conductivity studies were carried out on a series of polycrystalline spinel ferrite with composition Li0.5‐0.5xCuxFe2.5‐0.5xO4 where (x = 0.2, 0.4, 0.6, 0.8, 1). The radii of the tetrahedral A‐sites (rA) and the octahedral B‐sites (rB) were studied as a function of composition. The infrared spectra have been analyzed in the frequency range 200–1000 cm−1 and two bands were observed. The bands around 589 cm−1 (υA) and 400 cm−1 (υB) were assigned to the tetrahedral and octahedral complexes, respectively. The compositional dependence of the dc electrical conductivity σdc showed a maximum at x = 0.4 then decreases with increasing Cu2+ ions content. For lifetime measurements, a conventional fast –fast coincidence system was used. The variations in positron lifetime parameters with Cu2+ ions substitution are attributed to positron trapping in A‐ and B‐ sites.