Effect of 200 MeV Ag ion irradiation on magnetic and dielectric properties of nanocrystalline Zn–Cr ferrite.

Nanocrystalline samples of ZnCr0.4Fe1.6O4ferrite were synthesized by the advanced sol–gel method to investigate the effect of 200 MeV Ag+15ion irradiation on the cation distribution, magnetic and dielectric properties. Rietveld profile refinement of the X-ray diffraction (XRD) patterns confirms the single-phase cubic spinel structure of the specimens. The irradiated sample retains the cubic spinel structure with a slight increase in the lattice parameters and the average crystallite size. Temperature- and field-dependent dc magnetization studies show an appreciable enhancement in the saturation magnetization and blocking temperature of the irradiated samples, which could be attributed to the slight increase in the particle size due to the heat evolved during irradiation. Subsequently, the rearrangement of cations in the lattice structure and the ion-induced modifications on the surface states of the nanoparticles could be accountable. The room temperature dielectric constant and the loss tangent in the frequency range 75 kHz–10 MHz revealed the normal frequency dispersion. The increase in ϵrand tan δ on irradiation could be attributed to the slight crystal growth and hence the availability of the sufficient number of Fe2+and/or Zn3+ions particularly at the octahedral site on the grain boundaries, showing a fair agreement with the magnetization results. [ABSTRACT FROM AUTHOR]