A new iron phosphate Li_0.75Mn_1.50Fe_1.75(PO₄)₃ has been prepared by the flux method and its structure was characterized from single crystal X-ray diffraction data. It crystallizes as an alluaudite type structure, characterized by the A(2)A(2)’A(1)A(1)’A(1)”M(1)M(2)₂(PO₄)₃ general formula with a = 12.002(9) Å, b = 12.509(9) Å, c = 6.404(7) Å, β = 115.07(7)° in the monoclinic C2/c space group. The 3D framework consists of infinite chains of edge-sharing M(2)₂O₁₀ dimers and M(1)O₆ octahedra connected by phosphate tetrahedra leading to two sets of hexagonal tunnels. The Li⁺ and Mn²⁺ ions partially occupy one of them, the other tunnel being empty. The Mössbauer spectroscopy confirmed the occurrence of only Fe³⁺ ions in octahedral environment. Electrochemical cycling tests in Li cells were performed using Li_0.75Mn^II_1.50Fe^III_1.75(PO₄)₃ powder as electrode material. Only a small amount of Li⁺ ions can be reversibility deintercalated/intercalated corresponding to a capacity as low as 30 mAh/g with a 3.2 V average voltage. Moreover, a strong polarization due to low electronic and ionic conductivities is observed. The presence of Mn²⁺ ions in the same tunnel as Li⁺ probably hinders a good Li⁺ ionic diffusion.

通过助熔剂法制备了一种新的磷酸铁Li _0.75 Mn _1.50 Fe _1.75（PO ₄）_3，并根据单晶X射线衍射数据对其结构进行了表征。它结晶为一种钙铝榴石型结构，其特征在于A（2）A（2）'A（1）A（1）'A（1）” M（1）M（2）₂（PO ₄）₃通式 在单斜C 2 / c空间群中，a = 12.002（9）Å，b = 12.509（9）Å，c = 6.404（7）Å，β = 115.07（7）° 。3D框架由边缘共享M（2）₂的无限链组成O ₁₀二聚体和M（1）O ₆八面体通过磷酸盐四面体连接，从而形成两组六角形通道。Li ⁺和Mn ²⁺离子部分占据其中一个，另一条隧道为空。Mössbauer光谱证实八面体环境中仅存在Fe ³⁺离子。使用Li _0.75 Mn ^II _1.50 Fe ^III _1.75（PO ₄）₃粉末作为电极材料在Li电池中进行电化学循环测试。只有少量的Li ⁺离子可反嵌/嵌入的离子对应于平均电压为3.2 V时低至30 mAh / g的容量。此外，观察到由于低的电子和离子电导率而引起的强极化。在与Li ⁺相同的隧道中存在Mn ²⁺离子可能会阻碍良好的Li ⁺离子扩散。