Modulation of magnetic and dielectric properties of La-substituted barium ferrite based on BBSZ for microwave device applications

The low temperature co-fired ferrite (LTCF) technology is critical for improving microwave device performance and enabling miniaturization and integration of electronic systems. In present work, La-doped Ba
1
.
5
Sr
1.5
Co
2-x
La
x
Fe
23
O
41
(x = 0.00 to 0.75 with a step of 0.15) ferrite was prepared by a solid-phase reaction method at low temperatures with the addition of 1.5%wt BBSZ (H
3
BO
3
-Bi
2
O
3
-SiO
2
-ZnO) as flux. The XRD results show that the second phase, W-type phase, is always present in the samples and becomes more pronounced in the samples as the amount of La doping increases. The relative densities of all samples are above 92%, and SEM reveals that the samples have a well-densified structure. Particularly, at
$x$
= 0.3, the saturation magnetization increases from 56.15 emu/g to 58.78 emu/g, and the permeability μ’ of the sample shows a 38% increase at 200MHz. For dielectric properties, the dielectric constant є’ of the samples remains stable within the frequency range of 10 to 500 MHz, with a maximum value of 21.18, and the dielectric loss maintains a low value. Consequently, these La-doped barium ferrites demonstrate considerable promise for extensive use across electronic devices.