Abstract Nickel-cobalt ferrite spinels are ferrimagnetic ceramic materials that possess a great potential for application in highdensity magnetic media, recording, color imaging, ferrofluids, and high-frequency devices. A change of their structure from micro- to nano- improves their properties drastically, therefore many methods have been investigated to fabricate nanopowder of these spinels. Gel combustion method is one of them. In this research, Ni0 5Co0 5Fe2O4 nanoparticles were fabricated via gel combustion method using metallic nitrates as an oxidant and citric acid, glycine and urea as fuels and the effects of fuel type on the reaction behavior, structure and morphology of Ni0 5Co0 5Fe2O4 nanoparticles were investigated. The reaction behavior was studied by thermal analysis method (TGA-DTA), crystallite size of powders was characterized by X-ray diffraction (XRD) and their morphology was studied by FE-SEM. The results revealed that the reaction was initiated in urea, glycine and citric at 219 °C, 197 °C, 212 °C, respectively. Samples fabricated from glycine and citric acid had a pure spinel structure but the others fabricated with urea fuel had iron oxide impurity. The crystallite size of nickel cobalt ferrite nanoparticles was in the range of 58 nm to 64 nm and the nanoparticles were agglomerated.

中文翻译：

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燃料类型对Ni0.5Co0.5Fe2O4纳米颗粒燃烧反应行为、相结构和形貌的影响

摘要 镍钴铁氧体尖晶石是一种亚铁磁性陶瓷材料，在高密度磁介质、记录、彩色成像、铁磁流体和高频器件方面具有巨大的应用潜力。它们的结构从微米到纳米的变化极大地改善了它们的性能，因此已经研究了许多方法来制造这些尖晶石的纳米粉末。凝胶燃烧法就是其中之一。本研究以金属硝酸盐为氧化剂，柠檬酸、甘氨酸和尿素为燃料，采用凝胶燃烧法制备了Ni0 5Co0 5Fe2O4纳米颗粒，研究了燃料类型对Ni0 5Co0 5Fe2O4纳米颗粒反应行为、结构和形貌的影响。 . 通过热分析法（TGA-DTA）研究反应行为，通过 X 射线衍射 (XRD) 表征粉末的微晶尺寸，并通过 FE-SEM 研究它们的形貌。结果表明，反应在尿素、甘氨酸和柠檬酸中分别在 219 °C、197 °C、212 °C 下引发。由甘氨酸和柠檬酸制成的样品具有纯尖晶石结构，但其他由尿素燃料制成的样品含有氧化铁杂质。镍钴铁氧体纳米颗粒的微晶尺寸在 58 nm 至 64 nm 的范围内，并且纳米颗粒团聚。