Enhanced ferromagnetic properties of low temperature sintering LiZnTi ferrites with Li2O–B2O3–SiO2–CaO–Al2O3 glass addition

Li2O-B2O3-SiO2-CaO-Al2O3 and Bi2O3 co-doped gyromagnetic Li0.43Zn0.27Ti0.13Fe2.17O4 ferrite ceramics for LTCC Technology

“…As integral microwave components, phase shifters have been demonstrated miniaturization using LTCC ferrite tapes [1][2][3][4][5]. One member of gyromagnetic materials, LiZnTi ferrites have been investigated and applied in phase shifters due to their high Curie temperature, excellent temperature stability, high remanence square ratio, wide range of saturation magnetization, and low cost [6][7][8][9][10][11][12][13][14]. However, these ferrites prepared by traditional methods need to be sintered above 1100°C to achieve high densification and uniform grain size distribution.…”

“…Since this is much higher than the melting point of silver (961°C), it is necessary to decrease the sintering temperature of LiZnTi ferrites to ∼950°C in order to cofire with silver electrodes and apply in LTCC phase shifters. To meet the demand of sinterability in LTCC technology, several approaches have been proposed so far, and it is believed that adding low-melting oxides or glass flux is an effective and feasible way [8,[13][14][15][16][17][18][19].…”

“…In order to lower the firing temperature of LiZnTi ferrites below 950°C, low-melting glass and Bi substitution have been investigated to achieve this goal [8,[13][14][15]. However, abnormal grain growth (AGG) occurs in lowtemperature liquid-phase sintered Li-based ferrites or other ceramics while their porosity generally remains above 2%, which would deteriorate their performances such as magnetic loss for microwave ferrite ceramics [8,[13][14][15][19][20][21][22]. In our prior work, NiZn ferrite nanoparticles were adopted to introduce into LiZnTi ferrites to suppress AGG of the microsize grains; nevertheless, the porosity was still larger than 2% [12].…”

Effect of ZnO–B2O3–SiO2 glass additive on magnetic properties of low-sintering Li0.43Zn0.27Ti0.13Fe2.17O4 ferrites

“…The value of DH is around 640 Oe without ZBS glass added. This can be explained by the following formula [9,19]:…”

“…Lithium ferrites as one kind of potential microwave materials have been widely studied in recent years, due to their low loss and superior magnetic performance [5][6][7]. It was reported that the substituted lithium ferrites (LiZnTi ferrites) have higher saturation induction (Bs), lower coercive force (Hc) and higher remanence square ratio (Br/Bs) than pure lithium ferrites, which could be applied in phase shifters [8][9][10][11]. However, the conventional LiZnTi ferrites couldn't meet the essential demands of LTCC technology due to their relatively high sintering temperature.…”