Othmani J, Dhahri Ah, Hcini S, Bouazizi M L, Khirouni K, Dhahri E, Costa Benilde F O
Laboratoire de Physique Appliquée, Faculté des Sciences, Université de Sfax Tunisia.
University of Coimbra, CFisUC, Physics Department Rua Larga P-3004-516 Coimbra Portugal
RSC Adv. 2025 Sep 4;15(38):31853-31864. doi: 10.1039/d5ra04995d. eCollection 2025 Aug 29.
Nanoscale materials are attracting a great deal of attention due to their exceptional properties, making them indispensable for many advanced applications. Among these materials, spinel ferrites stand out for their potential applications in electronic, optoelectronic, energy storage and other devices. This is why the development of a synthesis process combined with rigorous optimization of annealing conditions is provided to be an essential approach to control nanoparticle formation and fine-tuning their structural, morphological and functional characteristics. A new approach is proposed to tailor the multifunctional properties of cobalt-manganese ferrites by synthesizing a non-stoichiometric composition. The compound CoMnFeO, containing an excess of Fe in the B sites, was obtained by the coprecipitation method combined with controlled annealing treatments. This strategy allows for the synergistic adjustment of structural, morphological, optical, and dielectric properties, and establishes a direct link between microstructural evolution and improved device performance. X-ray diffraction analysis confirmed the formation of a single-phase cubic spinel phase. The average crystallite size increased from 28 nm to 31 nm with higher annealing temperatures, indicating improved crystallinity. Morphological analysis by scanning electron microscopy revealed a significant grain growth and a reduction in irregular grain boundaries, which can minimize charge carrier scattering (beneficial for high-frequency capacitor and microwave device applications). UV-visible-near infrared spectroscopy showed a decrease in the optical band gap from 3.13 eV to 2.45 eV with increasing temperature, indicating a change in electronic structure. This variation suggests that the material can be integrated into devices such as transistors, modulators or optical switches. Finally, dielectric measurements revealed a high dielectric constant with low losses, underlining the potential of this material for applications in high-performance components.
纳米级材料因其卓越的性能而备受关注，使其在许多先进应用中不可或缺。在这些材料中，尖晶石铁氧体因其在电子、光电子、能量存储和其他器件中的潜在应用而脱颖而出。这就是为什么开发一种结合严格退火条件优化的合成工艺被认为是控制纳米颗粒形成并微调其结构、形态和功能特性的关键方法。本文提出了一种通过合成非化学计量组成来定制钴锰铁氧体多功能特性的新方法。通过共沉淀法结合可控退火处理，制备了在B位含有过量Fe的化合物CoMnFeO。该策略能够协同调整结构、形态、光学和介电性能，并建立微观结构演变与器件性能改善之间的直接联系。X射线衍射分析证实形成了单相立方尖晶石相。随着退火温度升高，平均晶粒尺寸从28 nm增加到31 nm，表明结晶度提高。扫描电子显微镜的形态分析显示晶粒显著生长，不规则晶界减少，这可以最小化电荷载流子散射（有利于高频电容器和微波器件应用）。紫外-可见-近红外光谱表明，随着温度升高，光学带隙从3.13 eV降低到2.45 eV，表明电子结构发生了变化。这种变化表明该材料可集成到晶体管、调制器或光开关等器件中。最后，介电测量显示出高介电常数和低损耗，突出了该材料在高性能组件中的应用潜力。
