Camouglage Division, Defence Laboratory, Ratanada Palace, Jodhpur-342011, India.
Department of Physics &Center for Solar Energy, Indian Institute of Technology Jodhpur, Old Residency Road, Jodhpur-342011, India.
Sci Rep. 2017 Mar 15;7:44457. doi: 10.1038/srep44457.
The gel to carbonate precipitate route has been used for the synthesis of NiZnFeO (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδ) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. NiZnFeO- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded NiZnFeO/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (f) and destructive interference at λ/4 matched thickness near ~10 GHz (f) in these composite systems. These studies suggest the potential of tuning the twin frequencies in NiZnFeO/NBR composite samples for possible microwave absorption applications.
凝胶碳酸沉淀法已用于合成 NiZnFeO（x=0、0.25、0.5 和 0.75）块状反尖晶石铁氧体粉末样品。最佳锌（50%）取代显示出最大的饱和磁矩，并导致整个 2-10GHz 频率范围内最大的磁损耗正切（tanδ）>−1.2，在 6GHz 时达到最佳值-1.75。NiZnFeO-丙烯腈丁二烯橡胶（NBR）复合材料样品按不同的铁氧体负载分数（wt%）在橡胶中进行制备，用于微波吸收评估。80wt%负载的 NiZnFeO/NBR 复合材料（FMAR80）样品在 5GHz 和 10GHz 处显示出两个反射损耗（RL）峰。有趣的是，在 3.25mm 厚度时，在 10GHz 处的单个峰值可以通过将厚度增加到 4.6mm 增加到 5GHz 来减小。在 FMAR80 复合材料样品中出现这种双匹配频率的起因是在这些复合材料系统中，约 5GHz（f）处的自旋共振弛豫和在10GHz（f）处的 λ/4 匹配厚度处的相消干涉。这些研究表明，有可能在 NiZnFeO/NBR 复合材料样品中调整双频，以实现可能的微波吸收应用。
