Ameer Shahid, Gul Iftikhar Hussain
School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad, Pakistan.
PLoS One. 2016 Jun 7;11(6):e0153544. doi: 10.1371/journal.pone.0153544. eCollection 2016.
The magnetic nanoparticle composite NiFe2O4 has traditionally been studied for high-frequency microwave absorption with marginal performance towards low-frequency radar bands (particularly L and S bands). Here, NiFe2O4 nanoparticles and nanohybrids using large-diameter graphene oxide (GO) sheets are prepared via solvothermal synthesis for low-frequency wide bandwidth shielding (L and S radar bands). The synthesized materials were characterized using XRD, SEM, FTIR and microwave magneto dielectric spectroscopy. The dimension of these solvothermally synthesized pristine particles and hybrids lies within 30-58 nm. Microwave magneto-dielectric spectroscopy was performed in the low-frequency region in the 1 MHz-3 GHz spectrum. The as-synthesized pristine nanoparticles and hybrids were found to be highly absorbing for microwaves throughout the L and S radar bands (< -10 dB from 1 MHz to 3 GHz). This excellent microwave absorbing property induced by graphene sheet coupling shows application of these materials with absorption bandwidth which is tailored such that these could be used for low frequency. Previously, these were used for high frequency absorptions (typically > 4 GHz) with limited selective bandwidth.
磁性纳米颗粒复合材料NiFe2O4传统上一直被用于高频微波吸收研究，但在低频雷达波段（特别是L波段和S波段）性能欠佳。在此，通过溶剂热合成法制备了NiFe2O4纳米颗粒以及使用大直径氧化石墨烯（GO）片材的纳米杂化物，用于低频宽带屏蔽（L波段和S波段雷达）。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）和微波磁介电光谱对合成材料进行了表征。这些通过溶剂热合成的原始颗粒和杂化物的尺寸在30 - 58纳米范围内。在1兆赫兹至3吉赫兹频谱的低频区域进行了微波磁介电光谱分析。结果发现，所合成的原始纳米颗粒和杂化物在整个L波段和S波段雷达频段（1兆赫兹至3吉赫兹范围内< -10分贝）对微波具有高吸收性。由石墨烯片耦合诱导的这种优异的微波吸收性能表明，这些材料具有可定制的吸收带宽，可用于低频。此前，这些材料用于高频吸收（通常> 4吉赫兹），选择性带宽有限。
