Effects of V2O5-Al2O3 sintering aid on properties of lowtemperature sintered Li-Zn microwave ferrites br

With the progress of modern wireless communication technology, microwave communication devices aredeveloping toward miniaturization and integration, and low-temperature co-firing ceramic/ferrite technology isthe key to meet the above demands. In this paper, V2O5-Al2O3 (VA) sintering aid is used to realize low-temperature sintering (below melting point of silver that is 950 degrees C) of Li-Zn microwave ferrite, which is suitablefor radar phase shifter. In this work, firstly, Li-Zn ferrite pre-firing material is prepared by mechanochemicalball-milling method, and then VA composite is selected as sintering aid to prepare Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4ferrite at low temperatures. The effects of adding amount of VA sintering aid and sintering temperature oncrystal structure, microstructure and magnetic properties (saturation induction, coercivity, linewidth offerromagnetic resonance, etc.) of the materials are also studied. The VA sintering aid can reduce the sinteringtemperature and maintain the spinel crystal structure of Li-Zn microwave ferrite, the diffraction peaks of V2O5and Al2O3 involved in the sintering process are observed from none of the samples sintered at differenttemperatures, because the additive amount of VA sintering aid is very low compared with that of Li-Zn ferrite,so no corresponding impurity peaks are detected. The introduction of VA sintering aid can promote the graingrowth, with the average grain size increasing from 0.92 mu m to 9.74 mu m. In the sintering process of Li-Zn ferrite,V2O5 in VA sintering aid will melt first to form liquid phase due to its low melting point, which promotes thegrowth of grains. At the same time, Al2O3 with higher melting point can inhibit the grain growth and make thegrain uniform. It is worth noting that when excessive VA sintering aid is added, the grain size of ferrite willdecrease instead, because too much VA sintering aid will form a large number of liquid phases around thegrains, thus splitting the grains and hindering the further growth of the Li-Zn grains. Under the condition ofoptimal VA sintering aid addition (0.18%, weight percentage), the saturation induction of the sample increasesfrom 144 mT to 281 mT; the rectangular ratio increases from 0.57 to 0.78; the coercivity decreases from 705 A/mto 208 A/m; the linewidth of ferromagnetic resonance decreases from 648 Oe to 247 Oe. In summary, VAsintering aid can effectively improve the properties of Li-Zn microwave ferrite, which has a positive significancein developing low- temperature co-firing ceramic/ferrite technology