Dar M Abdullah, Majid Kowsar, Hanief Najar Mohd, Kotnala R K, Shah Jyoti, Dhawan S K, Farukh M
Department of Chemistry, National Institute of Technology Srinagar, Hazaratbal, Srinagar-190006, India.
Phys Chem Chem Phys. 2017 Apr 19;19(16):10629-10643. doi: 10.1039/c7cp00414a.
This work reports the exploitation of nanocrystalline NiZnFeCeO ferrite for potential application by designing quasi-spherical shaped polythiophene (PTH) composites via in situ emulsion polymerization. The structural, electronic, dielectric, magnetic, and electromagnetic interference (EMI) shielding properties of PTH/NiZnFeCeO composites were investigated. Our results suggest that these properties could be optimized by modulating the concentration of x (composition) in the polymer matrix. Higher values of ε' and ε'' were obtained on composite formation, and could be due to the heterogeneity developed in the material. An enhancement in the value of saturation magnetization (123 emu g for x = 0.04) and Curie temperature was obtained with Ce concentration, which is useful for high density recording purposes. A low value of saturation magnetization was obtained for the PTH/NiZnFeCeO composite (36 emu g for x = 0.04). This could be attributed to the non-magnetic nature of the polymer. A total shielding effectiveness (SE = SE + SE) up to 34 dB (≈99.9% attenuation) was recorded for PTH/NiZnFeCeO composites (x = 0.04) in a frequency range of 8.2-12.4 GHz (X-band), which surpasses the shielding criteria of SE > 30 dB for commercial purposes. Such a material with high SE identifies its potential for making electromagnetic shields. The effect of Ce substitution on the microstructure, dielectric, impedance and magnetic properties of PTH/NiZnFeCeO ferrite composites was also investigated. X-ray diffraction analysis confirmed cubic spinel phase formation, and the broad reflection peaks indicated the formation of smaller sized particles. The smaller energy band gap (2.53 eV) of the composite indicated that this material could be used for photocatalysis in the visible region. Dielectric and impedance measurements were carried out in a frequency range of 8.2-12.4 GHz. Dielectric properties were improved considerably by the substitution of Ce ions in PTH/NiZnFeCeO composites. Impedance spectroscopy was used to study the effect of grain and grain boundaries on the electrical properties of PTH/NiZnFeCeO composites. Cole-Cole plots showed the formation of single semi-circles for all samples in the measured frequency range. This showed that the composite material was composed of good conducting grains and poorly conducting grain boundaries.
这项工作报道了通过原位乳液聚合设计准球形聚噻吩（PTH）复合材料来开发纳米晶NiZnFeCeO铁氧体的潜在应用。研究了PTH/NiZnFeCeO复合材料的结构、电子、介电、磁性和电磁干扰（EMI）屏蔽性能。我们的结果表明，这些性能可以通过调节聚合物基体中x（组成）的浓度来优化。复合材料形成时获得了较高的ε'和ε''值，这可能是由于材料中形成的不均匀性。随着Ce浓度的增加，饱和磁化强度值（x = 0.04时为123 emu g）和居里温度得到提高，这对于高密度记录用途是有用的。PTH/NiZnFeCeO复合材料（x = 0.04）的饱和磁化强度值较低（36 emu g）。这可能归因于聚合物的非磁性性质。在8.2 - 12.4 GHz（X波段）频率范围内，PTH/NiZnFeCeO复合材料（x = 0.04）的总屏蔽效能（SE = SE + SE）高达34 dB（≈99.9%衰减），超过了商业用途SE > 30 dB的屏蔽标准。这种具有高SE的材料表明其具有制造电磁屏蔽的潜力。还研究了Ce替代对PTH/NiZnFeCeO铁氧体复合材料的微观结构、介电、阻抗和磁性的影响。X射线衍射分析证实形成了立方尖晶石相，宽反射峰表明形成了较小尺寸的颗粒。复合材料较小的能带隙（2.53 eV）表明该材料可用于可见光区域的光催化。在8.2 - 12.4 GHz频率范围内进行了介电和阻抗测量。通过在PTH/NiZnFeCeO复合材料中替代Ce离子，介电性能有了显著改善。阻抗谱用于研究晶粒和晶界对PTH/NiZnFeCeO复合材料电学性能的影响。Cole-Cole图显示在测量频率范围内所有样品都形成了单个半圆。这表明复合材料由良好导电的晶粒和导电较差的晶界组成。
