Abstract Cobalt ferrite nanoparticles were exposed to mechanochemical activation, with and without equimolar amounts of graphene nanoparticles, for time periods ranging from 0 to 12 hours. Their structural and magnetic properties were detailed from Mӧssbauer spectroscopy and magnetic measurements. The Mӧssbauer spectrum corresponding to the unmilled cobalt ferrite powder was analyzed using 2 sextets, corresponding to the tetrahedral and octahedral sites of ferrites. The rest of the spectra was deconvoluted using an additional quadrupole-split doublet, with an abundance close to 30% and was assigned to superparamagnetic particles. Moreover, the spectra corresponding to milling with graphene at the longest times needed a third sextet, which could be assigned to iron carbide. The degree of inversion was determined from the Mӧssbauer spectra and found to decrease with milling time, both for the set with and that without graphene. The canting angle was derived and studied as function of the ball milling time for both sets of samples. Hysteresis loops were recorded at 5 K in an applied magnetic field of 5 T and was found to exhibit a wasp-waist shape. Magnetization was plotted as function of temperature in the range 5-300 K with an applied magnetic field of 200 Oe using zero-field-cooling-field-cooling (ZFC-FC) measurements. These made it possible to determine the blocking temperature of the samples. Our data exhibit new characteristics of the cobalt ferrite nanopowders milled with and without graphene nanoparticles.

中文翻译：

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石墨烯对铁氧体钴纳米粒子机械化学活化的影响

摘要 钴铁氧体纳米粒子暴露于机械化学活化，有或没有等摩尔量的石墨烯纳米粒子，时间范围为 0 到 12 小时。它们的结构和磁性特性从 Mӧssbauer 光谱和磁性测量中得到了详细说明。使用对应于铁氧体的四面体和八面体位点的 2 个六重体分析对应于未研磨钴铁氧体粉末的 Mӧssbauer 光谱。其余的光谱使用额外的四极分裂双峰进行解卷积，丰度接近 30%，并分配给超顺磁性粒子。此外，与石墨烯在最长时间内研磨相对应的光谱需要第三个六重奏，这可以分配给碳化铁。反转度由 Mӧssbauer 光谱确定，发现随着研磨时间的增加而降低，对于有和没有石墨烯的组。倾斜角被推导出和研究作为两组样品的球磨时间的函数。磁滞回线在 5 K 和 5 T 的外加磁场中记录，并被发现呈现黄蜂腰形状。使用零场冷却场冷却 (ZFC-FC) 测量，将磁化绘制为 5-300 K 范围内温度的函数，外加磁场为 200 Oe。这使得确定样品的封闭温度成为可能。我们的数据展示了用和不用石墨烯纳米颗粒研磨的钴铁氧体纳米粉末的新特性。倾斜角被推导出和研究作为两组样品的球磨时间的函数。磁滞回线在 5 K 和 5 T 的外加磁场中记录，并被发现呈现黄蜂腰形状。使用零场冷却场冷却 (ZFC-FC) 测量，将磁化绘制为 5-300 K 范围内温度的函数，外加磁场为 200 Oe。这使得确定样品的封闭温度成为可能。我们的数据展示了用和不用石墨烯纳米颗粒研磨的钴铁氧体纳米粉末的新特性。倾斜角被推导出和研究作为两组样品的球磨时间的函数。磁滞回线在 5 K 和 5 T 的外加磁场中记录，并被发现呈现黄蜂腰形状。使用零场冷却场冷却 (ZFC-FC) 测量，将磁化绘制为 5-300 K 范围内温度的函数，外加磁场为 200 Oe。这使得确定样品的封闭温度成为可能。我们的数据展示了用和不用石墨烯纳米颗粒研磨的钴铁氧体纳米粉末的新特性。使用零场冷却场冷却 (ZFC-FC) 测量，将磁化绘制为 5-300 K 范围内温度的函数，外加磁场为 200 Oe。这使得确定样品的封闭温度成为可能。我们的数据展示了用和不用石墨烯纳米颗粒研磨的钴铁氧体纳米粉末的新特性。使用零场冷却场冷却 (ZFC-FC) 测量，将磁化绘制为 5-300 K 范围内温度的函数，外加磁场为 200 Oe。这使得确定样品的封闭温度成为可能。我们的数据展示了用和不用石墨烯纳米颗粒研磨的钴铁氧体纳米粉末的新特性。