Abstract:
\(\text{Ni}_{0.65}\text{Cd}_{0.35}\text{Fe}_{2-x}\text{Al}_x\text{O}_4\) (0 ≤ x ≤ 0.060 with step 0.015) disc and toroid shaped bulk specimen has been fabricated from the sol-gel synthesized nanocrystalline powders and illustrated how influence of Al substitution in its structural, optical, dielectric, electric and magnetic properties. Structural characterization has been analyzed using X-ray diffraction (XRD) and Fourier Transform Infrared Spectra (FTIR) data. Theoretical analysis has been carried out using the Rietveld refinement method from the experimentally obtained XRD data. Crystallite size has been computed (39-36) nm, (43-36) nm, (64-46) nm, (44-38) nm applying Scherer's formula, modified Scherer's formula, Williamson-Hall method and Size-strain plot method respectively. Surface morphology as well as microstructure have been analyzed using Scanning Electron Microscope (SEM). From FTIR spectra, like force constant, stiffness constant, elastic moduli, wave velocities and Debye temperature have been estimated. Intrinsic magnetic hysteresis parameters at room temperature and temperature dependent magnetization have been measured using the Physical Properties Measurement System (PPMS). Law of Approach to saturation applied for theoretical analysis as well as magnetic entropy changes for relative cooling power estimated which is an important for magnetic caloric refrigeration application. Using optical properties measurement, Kramers Kroning (K-K) relation is employed to compute the refractive index (n) and the extinction coefficient (K). Initial permeability spectra have been obtained from 20 to 10MHz by an impedance analyzer in order to understand the high frequency application. Dielectric, permittivity, dielectric loss tangent and AC conductivity have been measured using impedance analyzer data. Complex impedance and modulus spectra have been calculated from impedance data as well as theoretical analysis of the grain and grain boundary parameters Rg, Rgb, Cg, Cgb using Z-sim software.
