W型铁氧体Ba(MnCu)_xCo_(2-2x)Fe_(16)O_(27)的微波吸收性能

Microwave Absorbing Properties of W-type Ferrite Ba(MnCu)_xCo_(2-2x)Fe_(16)O_(27)

采用溶胶-凝胶法制备了（MnCu）组合掺杂W型钡钴铁氧体Ba（MnCu）xCo2-2xFe16O27（x=0．1、0．2、0．3、0．4、0．5）样品。用XRD和SEM对样品的晶体结构、表面形貌、粒径进行了表征，用微波矢量网络分析仪测试了该样品在2～18GHz微波频率范围的电磁参数，根据测量数据计算电磁损耗角正切及得出微波反射率与频率的关系，探讨了该材料的微波吸收性能与电磁损耗机理。研究结果表明，Ba（MnCu）xCo2-2xFe16O27晶粉呈微米级六角片状形貌，煅烧温度1235℃以上的晶体结构为W型，是一种宽频带强损耗微波吸收材料。当x=0．3时，厚度为2．3mm的样品在频率为10GHz处的吸收峰为24dB，10dB以上频带宽度达8．8GHz。样品的微波吸收主要来自畴壁共振、磁化弛豫和自然共振引起的磁损耗，介电损耗较弱。

The samples of （MnCu）-doped W-type barium ferrite Ba（MnCu）xCo2-2xFe16O27 （x= 0. 1, 0. 2, 0. 3, 0. 4, 0. 5）were prepared by sol-gel process. The structure, surface morphology and particle size of them were characterized by XRD and SEM. Their electromagnetic parameters were measured by microwave vector network analyzer in the frequency range from 2GHz to 18GHz. The relationships between microwave reflectivity and frequency, between loss tangent and frequency were calculated according to measurements. The microwave absorbing properties and electromagnetic loss mechanism of the material were studied. The results show that for Ba（MnCu）xCo2-2xFe16O27, the crystal powder morphology is micro-hexagonal flake shape and W-type hexaferrite crystal structure is formed at above 1235℃ in air and it is such an excellent microwave absorption material with wide band and high loss that the absorption peak is 24dB at 10GHz frequency and the absorption bandwidth above 10dB is 8. 8GHz when its thickness is 2. 3 mm and x= 0. 3. The microwave absorption is resulted in magnetic loss mainly caused by domain wall resonance, magnetization relaxation and natural resonance but dielectric loss weakly.