Abstract Here we present the magnetization and electron spin resonance (ESR) measurements of α-Li3V2(PO4)3/C composite, which can be potentially used as a cathode material in a lithium ion battery. Magnetization measurements of α-Li3V2(PO4)3/C indicate that the investigated sample is in paramagnetic state and exhibits Curie-Weiss like behavior above T = 50K. The negative value of the Curie-Weiss temperature θCW = −22 K suggests the presence of the antiferromagnetic interactions between magnetic spins of V3+ ions (3 d2, S = 1). At the same time, the presence of the magnetic phase transition was not observed in the investigated temperature range from 2 K up to room temperature. The nonlinear behavior of the field dependence of the magnetization was observed only at T = 2 K suggesting the possible magnetic ordering below this temperature. ESR measurements were performed both for as-prepared α-Li3V2(PO4)3/C composite and for α-Li3V2(PO4)3/C sample after Li deintercalation and intercalation processes. The complete reduction of vanadium ions to the initial valence state V3+ after the first charge/discharge cycle was determined indicating the reversible intercalation of all lithium ions to the structure during the first delithiation/lithiation cycle in the investigated α-Li3V2(PO4)3/C composite.

中文翻译：

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α-Li3V2(PO4)3/C 复合材料中的磁性和钒氧化态：磁化和 ESR 测量

摘要 在这里，我们介绍了 α-Li3V2(PO4)3/C 复合材料的磁化和电子自旋共振 (ESR) 测量，该复合材料有可能用作锂离子电池的正极材料。α-Li3V2(PO4)3/C 的磁化测量表明所研究的样品处于顺磁性状态，并在 T = 50K 以上表现出类似居里-魏斯的行为。Curie-Weiss 温度 θCW = -22 K 的负值表明 V3+ 离子（3 d2，S = 1）的磁自旋之间存在反铁磁相互作用。同时，在从 2 K 到室温的研究温度范围内未观察到磁性相变的存在。仅在 T = 2 K 时观察到磁化场依赖性的非线性行为，这表明低于该温度的可能的磁序。对制备的 α-Li3V2(PO4)3/C 复合材料和锂脱嵌和嵌入过程后的 α-Li3V2(PO4)3/C 样品进行 ESR 测量。在第一次充电/放电循环后，钒离子完全还原到初始价态 V3+ 表明所有锂离子在所研究的 α-Li3V2(PO4)3/ 的第一次脱锂/锂化循环期间可逆嵌入到结构中C复合。