Abstract Lithium tantalate solid solution, Li3+5xTa1−xO4 was prepared by conventional solid-state reaction at 925 °C for 48 h. The XRD analysis confirmed that these materials crystallized in a monoclinic symmetry, space group C2/C and Z = 8, which was similar to the reported International Crystal Database (ICDD), No. 98-006-7675. The host structure, β-Li3TaO4 had a rock-salt structure with a cationic order of Li+:Ta5+ = 3:1 over the octahedral sites. A rather narrow subsolidus solution range, i.e. Li3+5xTa1−xO4 (0 ⩽ x ⩽ 0.059) was determined and the formation mechanism was proposed as a replacement of Ta5+ by excessive Li+, i.e. Ta5+ ↔ 5Li+. Both Scherrer and Williamson-Hall (W-H) methods indicated the average crystallite sizes in the range of 31 nm to 51 nm. Two secondary phases, Li4TaO4:5 and LiTaO3 were observed at x = 0.070 and x = −0:013, respectively. These materials were moderate lithium ionic conductors with the highest conductivity of ~2.5 × 10−3 Ω −1 ˙ cm−1 at x = 0, at 0 °C and 850 °C; the activation energies were found in the range of 0.63 eV to 0.68 eV.

中文翻译：

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岩盐结构Li3+5xTa1−xO4电瓷的亚固溶体和离子电导率

摘要 钽酸锂固溶体Li3+5xTa1−xO4 采用常规固相反应在925 ℃、48 h 的条件下制备。XRD 分析证实，这些材料以单斜对称、空间群 C2/C 和 Z = 8 结晶，这与报道的国际晶体数据库 (ICDD) 第 98-006-7675 号相似。主体结构 β-Li3TaO4 具有岩盐结构，其八面体位点上的阳离子顺序为 Li+:Ta5+ = 3:1。确定了一个相当窄的亚固溶范围，即 Li3+5xTa1−xO4 (0 ⩽ x ⩽ 0.059)，并提出形成机制为用过量的 Li+ 替代 Ta5+，即 Ta5+ ↔ 5Li+。Scherrer 和 Williamson-Hall (WH) 方法均表明平均微晶尺寸在 31 nm 至 51 nm 范围内。在 x = 0.070 和 x = -0:013 处观察到两个第二相 Li4TaO4:5 和 LiTaO3，分别。这些材料是中等的锂离子导体，在 x = 0、0 °C 和 850 °C 时具有 ~2.5 × 10−3 Ω -1 ˙ cm−1 的最高电导率；发现活化能在 0.63 eV 到 0.68 eV 的范围内。