ION CONDUCTOR, ION-CONDUCTIVE SINTERED BODY, PRECURSOR SOLUTION, PRECURSOR POWDER AND METHOD FOR PRODUCING THEM

To provide an ion conductor comprising oxides based on the β-Li3PO4 type crystal structure, featuring improved lithium ion conductivity.SOLUTION: An ion conductor comprises, in its main phase, a crystal phase of the β-Li3PO4 type crystal structure, which comprises Li, Si, and P in the crystal lattice, with the Si/(Si+P) atomic ratio of 0.05 or more and 0.40 or less. The ion conductor is obtained by firing, at e.g., 150-550°C, a precursor derived from a colloidal solution that is prepared by mixing a water-soluble lithium compound with the Li, Si, and P composition ratio adjusted within a predetermined range, silicon alkoxide, and a water-soluble phosphorus compound in an aqueous solvent.SELECTED DRAWING: Figure 1 【課題】β－Ｌｉ３ＰＯ４型の結晶構造を基本とする酸化物において、リチウムイオン伝導性を改善したイオン伝導体を提供する。【解決手段】Ｌｉ、Ｓｉ、Ｐを結晶格子中に含むβ－Ｌｉ３ＰＯ４型構造の結晶相を主相に持ち、Ｓｉ／（Ｓｉ＋Ｐ）原子比が０.０５以上０.４０以下である、イオン伝導体。このイオン伝導体は、水系溶媒中で、Ｌｉ、Ｓｉ、Ｐ組成比が所定範囲に調整された水溶性リチウム化合物、ケイ素アルコキシド、および水溶性リン化合物を混合して得られるコロイド溶液に由来する前駆体を、例えば１５０～５５０℃で焼成することによって得ることができる。【選択図】図１