Abstract The effect of Ho3+ substitution on the structural, magnetic and transport properties of a series of CoFe2-xHoxO4 (referred to CFHO) ferrites, (where, x = 0.00–0.20 in steps of 0.05) were studied. All the samples investigated were synthesized by the standard solid state reaction technique. X-ray diffraction (XRD) patterns confirmed the formation of single phase cubic spinel structure in all the compositions. The increases in the values of lattice parameter with the increase in Ho3+ concentrations suggested the expansion of unit cells. Bulk density was found to be decreased, and porosity increased for CFHO with composition x = 0.05 due to some structural distortion. Field emission scanning electron microscopy (FESEM) images showed that Ho3+ had a significant effect on the grain growth of the samples. The substitution of Ho3+ strongly influenced the magnetic characteristics which were confirmed from the magnetization measurements examined by vibrating sample magnetometer (VSM). Curie temperature (Tc) was found to be decreased linearly with the increase of Ho content ascribed to the weakening of A-B exchange interaction. The initial permeability was found to be independent of frequency up to a high frequency region for all the studied composites. All the samples showed very low loss factor at high frequency region and remained almost constant. AC electrical resistivity was found to be decreased with the composition up to 0.15 and then increased for x = 0.20. Frequency dependent dielectric constant measurements showed that Ho3+ substitution improved the dielectric constant values of the CFHO ferrites.

中文翻译：

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钬取代对 CoFe 2-x Ho x O 4 铁氧体结构、磁性和传输性能的影响

摘要 研究了 Ho3+ 取代对一系列 CoFe2-xHoxO4（称为 CFHO）铁氧体（其中，x = 0.00–0.20，步长为 0.05）的结构、磁性和传输特性的影响。所研究的所有样品均通过标准固态反应技术合成。X 射线衍射 (XRD) 图案证实在所有组合物中形成单相立方尖晶石结构。随着Ho3+浓度的增加，晶格参数值的增加表明晶胞的扩展。发现体积密度降低，并且由于某些结构变形，对于组成 x = 0.05 的 CFHO，孔隙率增加。场发射扫描电子显微镜 (FESEM) 图像显示 Ho3+ 对样品的晶粒生长有显着影响。Ho3+ 的取代强烈影响了磁特性，这从通过振动样品磁强计 (VSM) 检查的磁化测量中得到证实。发现居里温度 (Tc) 随着 Ho 含量的增加而线性降低，这归因于 AB 交换相互作用的减弱。对于所有研究的复合材料，发现初始磁导率与频率无关，直到高频区域。所有样品在高频区域都表现出非常低的损耗因子，并且几乎保持不变。发现 AC 电阻率随组成降低至 0.15，然后在 x = 0.20 时增加。频率相关的介电常数测量表明，Ho3+ 取代提高了 CFHO 铁氧体的介电常数值。