Study on structure, magnetic and dielectric properties of li-Zn ferrite with low ferromagnetic resonance line-width and high saturation magnetization synthesized at low temperature by LTCC

Abstract

Spinel structure Li0·43Zn0·27Ti0.13BixFe2.17-xO4 (x = 0 or 0.003) ceramic with high saturation magnetization (Ms) and low ferromagnetic resonance line-width (nH)was successfully prepared by low temperature co-fired ceramic (LTCC) technology adoping Bi2O3 as active agent and B2O3 as sintering agent. Crystalline structure analysis was performed by XRD, and results show that Bi3+ entering the lattice replaces Fe3+ at B site on octahedral or tetrahedral crystal structure, resulting in lattice expansion and overall left shift of diffraction peaks. Based on SEM, the principle of Bi2O3 and B2O3 promoting sintering is analyzed, and the mechanism of this process is illustrated by a diagrammatic model. The reason of high Ms and low nH is revealed by VSM, which is attributed to the decrease of activation energy and the effect of sintering agent on grain boundary diffusion and grain growth. Dielectric properties were investigated, and it is found that the dielectric constant (ε´) is affected by grain size, defect, grain boundary, doping and usage frequency, etc., and the reason and law of the influence are explored by space charge polarization theory. Finally, by adding the optimal amount of Bi2O3 (x = 0.003) and B2O3 (y = 0.6), a LiZnTi ferrite with a low ferromagnetic resonance line-width (nH as low as 181.6 Oe) and a high saturation magnetization (Ms up to 353.1 kA/m) was successfully prepared at a low temperature (915 °C) by LTCC.