Investigation of grain boundary diffusion and grain growth of lithium zinc ferrites with low activation energy

Abstract

Activation energy and diffusion kinetics are important factors for grain growth and densification. Here, Bi2O3 was introduced into Li0.43Zn0.27Ti0.13Fe2.17O4 ferrite ceramics via a presintered process to lower the reaction activation energy and to achieve low temperature sintering. Interestingly, Bi3+ ions entered the lattice and substituted for Fe3+ in the B‐site (i.e., a pure LiZn spinel ferrite). Also, SEM image results show that Bi2O3‐substituted LiZn ferrite ceramics have low critical temperature for grain growth (920°C), which is very advantageous for LTCC technology. This indicates that Bi2O3 is an excellent dopant for ceramics. Furthermore, to promote normal grain growth of the ceramics at low temperatures, different volumes of V2O5 additive were added at the final sintering stage. Results indicate that an optimal volume of V2O5 additive promotes grain growth (with no abnormal grains) and enhances magnetic performances of the ceramics at low sintering temperature. Finally, adding the optimal volume of V2O5 additive resulted in a homogeneous and compact LiZnTiBi ferrite ceramic with larger grains (average size of ~8 μm), high 4πMs (~4100 gauss), and low ΔH (~190 Oe) obtained (at 900°C). Moreover, the doping method reported in this study also provides a reference for other low temperature sintered ceramics.

Influence of Li<sub>2</sub>CO<sub>3</sub> and ZnO Nanoparticle on Microstructure and Magnetic Properties of Low-Temperature Sintering LiZnTiBi Ferrites for High-Frequency Applications

“…LiZn ferrite is a good and optional material for high-frequency microwave devices because of its high Curie temperature (T c ), high remanence ratio (B r /B s ) and large saturation magnetization (4πM s ) [12]. However, high sintering temperature of the LiZn ferrite don't meet requirement of low temperature co-fired ceramic (LTCC) technology.…”