Abstract A series of nickel substituted copper ferrite nanocrystals (NixCu1-xFe2O4, x = 0 , 0.1 , 0.3 , 0.5 , 0.7 ) were synthesized by co-precipitation technique. The prepared powders were calcined twice at 900 °C (pre-calcination) and 1100 °C (post-calcination) respectively. The structural, morphological and magnetic properties were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transformed infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM), respectively. XRD analysis shows that all the samples have a single-phase cubic spinel structure. The crystallite size was calculated by using Debye-Scherrer’s formula. It was observed that the crystallite size decreases with the increasing nickel (Ni) content and increases after post-calcination. The saturation magnetization increased with the increasing Ni content, whereas the coercivity decreased. The saturation magnetization further increased after post-calcination. The parameters such as dielectric constant, dielectric loss and ac conductivity were also studied in the frequency range from 1 to 12 GHz. The complex dielectric permittivity of NixCu1-xFe2O4 nanocrystals was decreased with the increasing Ni contents and as well as after post calcination. Furthermore, the dielectric loss tangent and ac conductivity also decreases with the increasing Ni contents and as well as after post calcination.

中文翻译：

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纳米晶尖晶石 NixCu1-xFe2O4 的结构、磁性和介电性能

摘要 采用共沉淀法合成了一系列镍取代铜铁氧体纳米晶(NixCu1-xFe2O4, x = 0 , 0.1 , 0.3 , 0.5 , 0.7 )。将制备的粉末分别在 900°C（预煅烧）和 1100°C（煅烧后）下煅烧两次。分别通过X射线衍射（XRD）、场发射扫描电子显微镜（FE-SEM）、傅里叶变换红外光谱（FT-IR）和振动样品磁强计（VSM）对结构、形态和磁性进行了表征。XRD分析表明，所有样品均具有单相立方尖晶石结构。通过使用德拜-谢勒公式计算微晶尺寸。观察到晶粒尺寸随着镍 (Ni) 含量的增加而减小，并在煅烧后增加。随着Ni含量的增加，饱和磁化强度增加，而矫顽力降低。后煅烧后饱和磁化强度进一步增加。还研究了 1 至 12 GHz 频率范围内的介电常数、介电损耗和交流电导率等参数。NixCu1-xFe2O4 纳米晶的复介电常数随着 Ni 含量的增加以及后煅烧后的增加而降低。此外，介电损耗角正切和交流电导率也随着 Ni 含量的增加以及后煅烧而降低。还研究了 1 至 12 GHz 频率范围内的介电损耗和交流电导率。NixCu1-xFe2O4 纳米晶的复介电常数随着 Ni 含量的增加以及后煅烧后的增加而降低。此外，介电损耗角正切和交流电导率也随着 Ni 含量的增加以及后煅烧而降低。还研究了 1 至 12 GHz 频率范围内的介电损耗和交流电导率。NixCu1-xFe2O4 纳米晶的复介电常数随着 Ni 含量的增加以及后煅烧后的增加而降低。此外，介电损耗角正切和交流电导率也随着 Ni 含量的增加以及后煅烧而降低。