While Co ferrite nanoparticles (NPs) have been widely considered for potential applications in magnetic storage, photocatalysts, and hyperthermia, significantly less attention has been paid to explore their detailed magnetic characteristics as a function of the Co content. Herein, a hydrothermal method was successfully used for the preparation of CoxFe3−xO4 (0.5 ≤ x ≤ 2) NPs, employing stable ferric and cobalt salts with PVP surfactant as a capping agent. Hysteresis loop measurements showed maximum coercivity (Hc) and saturation magnetization (Ms) of 982 Oe and 46 emu/g for Co0.5Fe2.5O4 and CoFe2O4 compounds, respectively. Detailed magnetic characteristics of the resulting NPs with different morphologies ranging from nanocubes to dense nanospheres were comprehensively investigated by first-order reversal curve analysis. It was found that CoxFe3−xO4 (0.5 ≤ x < 1) NPs with both spinel and hematite phases comprise noticeable hard and soft phases, whereas superparamagnetic phase starts to dominate magnetic behavior of CoxFe3−xO4 (1 ≤ x ≤ 2) NPs with reduced grain size and pure spinel phase.

中文翻译：

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在 PVP 表面活性剂存在下合成的钴铁氧体 (CoxFe3−xO4) 纳米粒子的详细磁特性

虽然 Co 铁氧体纳米粒子 (NPs) 已被广泛考虑在磁存储、光催化剂和热疗中的潜在应用，但很少有人关注探索它们作为 Co 含量函数的详细磁特性。在此，水热法成功地用于制备 CoxFe3-xO4 (0.5 ≤ x ≤ 2) NPs，采用稳定的铁盐和钴盐，PVP 表面活性剂作为封端剂。磁滞回线测量显示 Co0.5Fe2.5O4 和 CoFe2O4 化合物的最大矫顽力 (Hc) 和饱和磁化强度 (Ms) 分别为 982 Oe 和 46 emu/g。通过一阶反转曲线分析，对所得具有从纳米立方体到致密纳米球的不同形态的纳米颗粒的详细磁特性进行了全面研究。