Structural, electrical and dielectric properties of yttrium substituted nickel ferrites

The influence of Y3+ substitution on the structural, electrical and dielectric properties of Ni-Y ferrites was studied in the ferrite series NiY2xFe2-2xO4 where x = 0-0 12 in steps of 0.02. This series was prepared by conventional double sintering ceramic method XRD analysis reveals single phase samples up to x = 0 06. At x >= 0 08, a secondary phase of iron yttrium oxide (YFeO3) appears along with the spinel phase The incorporation of Y3+ for Fe3+ ions results in a slight increase of lattice constant due to larger ionic radius of the Substituted ions. It was inferred that the substitution of yttrium limits the grain growth. The physical densities are about 90% of their X-ray densities FTIR spectra obtained at room temperature in the wave number range 370-1100 cm(-1) show splitting of the two fundamental absorption bands, thereby confirming the completion of solid state reaction. The increase in dc resistivity has been found with the increase in Y3+ contents. Dielectric constant (epsilon') and loss tangent (tan delta) were measured at room temperature in the frequency range from 10 Hz to 10 MHz A significant reduction in the values of dielectric constant and dielectric loss tangent has been observed with the increase of Y3+ ions. The high dc resistivity and low dielectric losses are the desired characteristics of Ni-Y ferrites used to prepare microwave devices. (C) 2009 Elsevier B V. All rights reserved