Controllable synthesis of La3+ doped Zn0.5Co0.25Cu0.25Fe2-xLaxO4 (x=0.0, 0.0125, 0.025, 0.0375, 0.05) nano-ferrites by sol-gel auto-combustion route

Zn0.5Co0.25Cu0.25Fe2-xLaxO4(x = 0.0, 0.0125, 0.025, 0.0375, 0.05) ferrite powders with uniform distribution of ions and close-packed configuration were prepared via solgel auto-combustion route. XRD spectra showed the formation of spinel-phase cubic crystalline structure. SEM results revealed that the irregularity in size and shape of particles increases, and particle distribution uniformity decreases with La3+ concentration. Moreover, each curve of the UV-vis spectra revealed two optical energy band gaps. More importantly, DC resistivity (rho) and the activation energy (Delta E) have minimum values at x = 0.0375. The dielectric loss was explained according to Maxwell-Wager space charge polarization. The P-E loop showed the ferroelectric nature of the synthesized samples. Moreover, VSM results revealed that the as-prepared samples possessed maximum saturation magnetization (Ms = 56.77 +/- 0.0283) and 8-12 GHz operating microwave frequency (omega(m)) range at x = 0.0375. All these results show the potential of Zn0.5CO0.25Cu0.25Fe1.9625La0.0375O4 ferrite powders for X-band microwave applications.