锆硅掺杂M型钡铁氧体毫米波吸收性能研究

Millimeter Wave Absorbing Properties of Zr^(4+)-Si^(4+)Co-doped M-type Barium Ferrite

目的进一步提升钡铁氧体吸收剂在Ka波段(26.5~40 GHz)的吸波性能,并降低烧结温度,提高基于固相法制备Si^(4+)掺杂和Zr^(4+)-Si^(4+)共掺的钡铁氧体吸收剂的效率。方法通过分析Si^(4+)单掺时的微观形貌和相成分变化,选择合适的Si^(4+)掺杂量,制备Zr^(4+)-Si^(4+)共掺钡铁氧体Ba Fe11.8-yZrySi0.2O19。探究Zr^(4+)掺杂量和烧结温度对其产物成分、微观形貌和电磁性能等的影响。结果通过Si^(4+)掺杂可以有效降低烧结温度,促进固相反应。当掺杂量超过一定量时会产生杂相,最佳掺杂量x=0.2。经Zr^(4+)-Si^(4+)共掺杂后,Zr^(4+)掺杂量和烧结温度对材料介电常数的影响较小,介电实部和虚部分别稳定在8.5、2.5左右。当Zr^(4+)掺杂量从y=0.2增至y=0.4时,自然共振频率从35 GHz降至28 GHz左右,温度的影响较小。结论通过Zr^(4+)-Si^(4+)共同掺杂能够在较低的烧结温度下提高掺杂元素的固溶量,有效地将共振峰调节到Ka波段,提高了材料的磁损耗能力。最终在1150℃下烧结制备吸收剂BaFe11.4Zr0.4Si0.2O19,以粉胶比3∶1填充到基体后,在厚度为0.82 mm时,Ka全频段可达到-15 d B以下,最低反射率在39 GHz时达到-29 d B。

The work aims to synthesize Si^(4+)doped and Zr^(4+)-Si^(4+)co-doped barium ferrite absorbents through the solid-state method to improve the absorption performance of barium ferrite absorbers in the Ka-band(26.5-40 GHz),reduce the sintering temperature and improve the preparation efficiency.By analyzing the microstructure and phase composition of the absorbents when only Si^(4+)was doped,an appropriate amount of Si^(4+)was selected.Subsequently,BaFe11.8−yZrySi0.2O19 was prepared through doping of barium ferrite with Zr^(4+)and Si^(4+),and the effects of the Zr^(4+)doping amount and sintering temperature on product composition,microstructure,and electromagnetic performance were investigated.The study revealed that Si^(4+)doping effectively reduced the sintering temperature and promoted solid-phase reaction,but excessive doping lead to the formation of secondary phases;therefore,the optimal doping amount of Si^(4+)was x=0.2.After co-doping with Zr^(4+)and Si^(4+),both the grain size and dielectric constant exhibited minor changed with increasing temperature,and the real and imaginary parts of the dielectric were approximately 8.5 and 2.5,respectively.The natural resonance frequency decreased from 35 GHz to 28 GHz as the Zr^(4+)doping amount increased from y=0.2 to y=0.4,and this change was less affected by temperature.Consequently,Zr^(4+)-Si^(4+)co-doping can increase the solid solubility of the doping elements at a lower sintering temperature,enabling the effective adjustment of the resonance peak to the Ka band,thereby improving the magnetic loss of the material.Finally,the absorbent BaFe11.4Zr0.4Si0.2O19 sintered at 1150℃ was filled into the matrix with a mass ratio of 3∶1.When the coating thickness was 0.82 mm,the absorbing materials exhibited a minimum reflection loss(RL)of−29 dB at 39 GHz and below−15 dB across the Ka band.