Tailoring structural, photoluminescence, and dielectric properties of cobalt ferrite via La3+ doping for high-performance ceramic applications

Abstract

In this study, a sol–gel auto-combustion technique was adopted to synthesize La³⁺-substituted CoFe₂O₄ (x = 0.00, 0.05, and 0.10) nanoparticles for use in electronic device applications by modifying the dielectric loss control of CFO nanoparticles. The PL spectra revealed a decrease in charge recombination at a doping content of x = 0.10 and an increase in charge recombination at a doping content of x = 0.20. The doping of x = 0.10 increases the particle size and crystallinity, which supports the decrease in dielectric loss by minimizing defect states, grain boundary density, and unwanted polarization mechanisms. When the doping concentration further increases to x = 0.20, the dielectric loss increases. A doping of x = 0.05 achieves the lowest tan δ (0.74), while x = 0.10 shows higher losses (1.5); the real part of the dielectric constant fluctuates between 48k and 170k and the imaginary part fluctuates between 118k and 313k. The higher ac conductivity of 0.126 was recorded for x = 0.05 La³⁺ doping composition at 1MHz, with significantly lower values of 0.017 for x = 0.00, and 0.013 μS cm⁻¹ for x = 0.10. The obtained dielectric loss values suggest that the CFO nanoparticles with a lower lanthanum doping concentration (x = 0.10) presented in this study offer potential opportunities for use in electronic devices.