Based on the bond valence (BV) energy landscape method, we have revealed the potential to conduct La³⁺ in the cuspidine-type compound La₄Ga₂O₉ (space group P2₁/c) along the a-axis direction and demonstrated the conduction species to be La³⁺ with the transference number of 0.992. The bulk conductivity (σ_bulk) of the random grain-oriented polycrystal steadily increased from 1.05 × 10^–7 to 1.11 × 10^–4 S cm^–1 with increasing temperature from 623 to 1073 K, with the activation energy of 0.94 eV. In the temperature range 623–973 K, the σ_bulkvalues were superior to those of La_1/3Zr₂(PO₄)₃, a NASICON-type La³⁺ conductor, at the same temperature. At 873 K, La₄Ga₂O₉ exhibited approximately 22 times higher σ_bulkvalue than La_1/3Zr₂(PO₄)₃. The crystal structure of this compound allows for three-dimensional conduction of La³⁺, which is in contrast to the unidirectional conduction in La₄Ga₂O₉. In other cuspidine-type compounds of RE₄³⁺Ga₂O₉ (RE = Pr, Nd, and Sm) and RE₄³⁺Al₂O₉ (RE = Y, Nd, Eu, Tb, and Lu), the distributions of bond valence energy also showed the potential to conduct RE³⁺ in the a-axis directions.

中文翻译：

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Cuspidine 型化合物 La4Ga2O9 中 La3+ 的传导

基于键价(BV)能谱法，我们揭示了尖峰型化合物La ₄ Ga ₂ O ₉ (空间群P 2 ₁ / c )中La ^3+沿a轴方向传导的潜力，证明传导物种为 La ³⁺，迁移数为 0.992。随着温度从623 K升高到1073 K，随机晶粒取向多晶的体电导率(σbulk _)从1.05× ^10-7稳定增加到1.11 ×10-4Scm ^{- 1}，活化能为0.94eV。在623-973 K温度范围内，σ_体积值优于相同温度下的NASICON型La ^3+导体La _1/3 Zr ₂ (PO ₄ ) ₃ 。在873K时，La ₄ Ga ₂ O ₉表现出比La _1/3 Zr ₂ (PO ₄ ) ₃高约22倍的σ_体积值。该化合物的晶体结构允许La ³⁺进行三维传导，这与La ₄ Ga ₂ O ₉中的单向传导相反。在RE ₄ ³⁺ Ga ₂ O ₉ ( RE = Pr、Nd 和 Sm) 和RE ₄ ³⁺ Al ₂ O ₉ ( RE = Y、Nd、Eu、Tb 和 Lu)的其他尖峰型化合物中，键价能的分布也显示出在a轴方向上传导RE ³⁺的潜力。