Monita Bhat

Electrical and Magnetic Properties of Some Rare Earth Orthoferrites (RFeO3 where R = Y, Ho, Er) Systems

The electrical and magnetic characteristics of some rare earth orthoferrites (RFeO3, where R = Y, Ho & Er) have been discussed. These two characteristics suggest that such system can be categorized under multiferroic with different Curie and Neel temperature. The electrical characteristics shows relaxation phenomenon with Curie temperature varies with change in frequency. The Curie temperature is in the range of 340–480°C, whereas Neel temperature is about 370°C.

Irradiation Effects on Dielectric Behaviour of M—Type Hexaferrites

Pure Strontium hexaferrite grown by flux method were used in present investigation. Dielectric analysis was carried out using fully automated HP4192A impedance analyzer. The samples were irradiated using Lithium beam of energy 50 MeV with fluence rate 1 × 1013 ions/cm2 at NSC, New Delhi. Dielectric studies of both irradiated and unirradiated samples have been carried out and the effect of irradiation is studied. The variation of dielectric constant ϵ′ for unirradiated and irradiated SrFe12O19 were studied as a function of frequency of a.c. field in the frequency range 1 KHz to 10 MHz from room temperature to 200°C. Dielectric constant is found to decrease with frequency, however, ϵ′ increases with temperature for both virgin as well as irradiated crystals. The crystals show increase in dielectric constant after irradiation. The variation of tanδ with frequency shows cusps for all samples. The variation has been explained on the basis of Maxwell-Wagner Interfacial polarization.