Structural and electromagnetic behavior evaluation of Nd-doped lithium–cobalt nanocrystals for recording media applications

Nano-crystalline Li 0.5 Co 0.5 Nd x Fe 2− x O 4 ( x = 0.0, 0.035, 0.070, 0.105, 0.140, 0.175) ferrites have been synthesized via micro-emulsion technique. Thermal analysis, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), magnetometer analysis and a.c. electrical studies are employed to observe the impact of Nd 3+ doping in Li 0.5 Co 0.5 Fe 2 O 4 on crystallite size, spectral bands, dielectric and magnetic parameters. Thermal analysis depicts the weight loss with various temperatures and it illustrates that there is no further weight loss above 950 °C. XRD analysis establishes the formation of single phase cubic spinel structure. Although for x = 0.0 and thereafter for x ⩾ 0.035 a peak of second phase (NdFeO 3 ) occurs. The XRD data analysis revealed that the Nd substituted Li 0.5 Co 0.5 Fe 2 O 4 ferrites revealed crystallite size 52.02–106 nm ranges. The lattice parameter and crystallite size show a nonlinear behavior. The FTIR data between 400 and 1000 cm −1 defined the intrinsic cation vibrations of the characteristic spinel structure. The dielectric parameters are investigated in the range of 1 MHz–3 GHz frequency. A damping effect in the dielectric parameters is observed by Nd 3+ incorporation and also by increasing the frequency. Magnetic measurements at room temperature exhibit an appreciable increase in the saturation magnetization and coercivity with the substitution of Nd 3+ cations. Coercivity is in range of soft ferrite. The dominating effects of doping on dielectric properties propose that these nano-ferrites are useful in the fabrication of high frequency devices, whereas increase in magnetization and coercivity propose the use for high density recoding media.