Abstract The location of redox couples in transition metal compounds is among the key factors that determine their applicability. AM2(PO4)3 NASICONs (A = Na, Li; M = Ti, Zr, Hf, Ge, Sn, Fe, …) form an intriguing group that feature fast ion diffusion and tunable reduction/oxidation potentials and can therefore find numerous applications. The present study focuses on the LiTi2(PO4)3 member of this family and the possibility of controlling its transport and redox properties. It highlights the close relationship between the modification of the crystal and band structures via substitutions in the Ti sublattice or intercalation with lithium and its redox behaviour as well as transport properties. The correlation between ionic conductivity and the position of the Ti4+/Ti3+ redox potential is discussed. UV-VIS reflectance spectra revealed a significant impact of the type of dopant as well as the level of intercalation on the position of the fundamental absorption edge, indicating the possibility of modifying the electronic structure. In the case of some of the examined dopants (Nb, Sn, In), more complex interaction was observed, since they introduce their own redox activity, and thus enable the material's behaviour to be modified even further.

中文翻译：

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控制 LiTi 2 (PO 4 ) 3 快速锂离子导体中的氧化还原行为和离子电导率

摘要 过渡金属化合物中氧化还原对的位置是决定其适用性的关键因素之一。AM2(PO4)3 NASICONs（A = Na、Li；M = Ti、Zr、Hf、Ge、Sn、Fe ……）形成了一个有趣的基团，具有快速离子扩散和可调还原/氧化电位，因此可以找到许多应用. 本研究的重点是该家族的 LiTi2(PO4)3 成员以及控制其传输和氧化还原特性的可能性。它强调了通过 Ti 亚晶格中的取代或嵌入锂来改变晶体和能带结构之间的密切关系，以及它的氧化还原行为和传输特性。讨论了离子电导率与 Ti4+/Ti3+ 氧化还原电位位置之间的相关性。UV-VIS 反射光谱揭示了掺杂剂类型以及嵌入水平对基本吸收边位置的显着影响，表明可能修改电子结构。在一些被检测的掺杂剂（Nb、Sn、In）的情况下，观察到更复杂的相互作用，因为它们引入了自己的氧化还原活性，从而能够进一步改变材料的行为。