Mossbauer studies and enhanced electrical properties of R (R=Sm, Gd and Dy) doped Ni ferrite

Abstract

Structural, Mossbauer studies and improved electrical characteristics of Sm, Gd and Dy doped Ni ferrite materials in comparison to that of pure NiFe2O4 are reported. Pure NiFe2O4 crystallizes in inverse spinet phase without any impurity phase. NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds crystallize in the cubic inverse spinel phase with a very small amount. of REeO(3) as additional phase. The back scattered electron imaging analysis indicates the primary and secondary phase formation in NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds. The room temperature DC resistivity values of NiFe2O4, NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 compounds are found to be 17 x 10(7) Omega cm, 162 x 10(7) Omega cm, 171 x 10(7) Omega cm and 305 x 10(7) Omega cm respectively. The AC resistivity values (at 1 KHz) of NiFe2O4, NiFe1.925Sm0.075O4, NiFe1.925Gd0.075O4 and NiFe1.925Dy0.075O4 materials are 10 x 10(5) Omega cm, 77 x 10(5) Omega cm, 147 x 10(5) Omega cm and 251 x 10(7) Omega cm, respectively. Temperature dependent electrical resistivity curves reveal two different types of conduction mechanisms. The hyperfine parameters viz., the hyperfine magnetic field, the isomer shift and the quadrupole splitting confirms the substitutions of R3+ ions at B site and their effects on superexchange interactions and structural distortion. The enhanced electrical resistivity of rare earth doped Ni ferrite suggest that tuning properties for desired high frequency applications can be achieved by controlling the doping element and their amount.