Synergy effects between Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles and CuO-Bi2O3 mixtures in low-temperature sintered LiZnTi ferrites with enhanced gyromagnetic and microwave dielectric properties

Promoting grain growth and optimizing microstructure are valid strategies for enhancing gyromagnetic and microwave dielectric properties of low-temperature sintered ferrite materials. Here, a modified low-temperature sintering technique was attempted for the synthesis of LiZnTi ferrites that have compact microstructure and improved performances. Trace amounts of CuO-Bi 2 O 3 mixtures (0.50 wt%) were adopted as sintering additives to promote grain growth and to reduce the sintering temperature. Meanwhile, Li 0.42 Zn 0.27 Ti 0.11 Fe 2.2 O 4 nanoparticles (∼21.9 nm) were synthesized using a sol-gel auto-combustion method and were used to optimize the microstructure and to restrain abnormal grain growth . XRD Rietveld refinement and SEM images revealed that uniform and dense LiZnTi ferrites with single-phase spinel structure were obtained. Results demonstrated that co-doping of Li 0.42 Zn 0.27 Ti 0.11 Fe 2.2 O 4 nanoparticles and CuO-Bi 2 O 3 mixtures allows low-temperature sintering (900 °C) to be achieved and also promotes grain growth and densification. In particular, LiZnTi ferrites that were modified with 5.00 wt% Li 0.42 Zn 0.27 Ti 0.11 Fe 2.2 O 4 nanoparticles and 0.50 wt% CuO-Bi 2 O 3 sintering additives exhibited narrow ferromagnetic resonance linewidth (Δ H , ∼145 Oe) and low dielectric loss tangent (tan δ ε , ∼2.45 × 10 −4 ) at ∼9.50 GHz, high saturation flux density ( B s , ∼364 mT), and high squareness ratio ( B r / B s , ∼0.89). Such a modified sintering technique at a low sintering temperature, as reported in this work, provides a reference for other advanced ferrites.