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Multi-valent Cation Conductors and their Application for Electrochemical Use

多价阳离子导体及其电化学应用

基本信息

批准号：
62550566
负责人：
ESAKA Takao
金额：
$ 1.28万
依托单位：
Tottori University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

项目摘要

The results of this study are summarized in the followings, (1) YPO_4 shows a zircon-type crystal structure, which is a stereochemically rough one. Although this compound includes no divalent cation, if calcium is doped as a phosphate, the crystal can contain the interstitial calcium ion, which plays an important role for the calcium ion conduction. The conductivity is 5x10^<-3>Scm^<-1> at 800ﾟC. In the case of magnesium, the similar result is obtained. But the magnesium ion conductivity is not so high as the calcium ion conductivity. In the solid solutions based on vanadate and arsenate, di-valeut ion conduction is not observed, although they have almost the same crystal structure.(2) Calcium sulfate, having a strained NaCl-type structure, shows calcium ion conduction, if another compound is doped intending formation of interstitial calcium ion. The Conductivity of the sample including 5 m/o excess calcium is 3x10^<-3>Scm^<-1> at 1000ﾟC. We can also introduce calcium ion vacancy to the host crystal by doping of Al_2(SO_4)_2. In that case, the similar conduction behavior is observed, but the conductivity itself is relatively lower.(3) If we substitute divalent cations for alkali ions of the conventional alkali ion conductors we can obtain cation conductor only in the special case such as ramsdellite-based system. However, these are unstable and apt to decompose into two phases at lower temperature ranges.(4) The ionic conductors found on this study are possible to employ electrochemically as electrolytes, considering emf response on construction of cell and formation of calcium compound on electrolysis.

本研究的结果概括如下：(1)YPO_4呈现锆石型晶体结构，是一种立体化学粗糙的晶体结构。尽管该化合物不含二价阳离子，但如果以磷酸盐形式掺杂钙，则晶体可以含有间隙钙离子，这对于钙离子传导起着重要作用。 800℃时电导率为5x10^<-3>Scm^<-1>。在镁的情况下，得到了类似的结果。但镁离子电导率不如钙离子电导率高。在基于钒酸盐和砷酸盐的固溶体中，尽管它们具有几乎相同的晶体结构，但没有观察到二价离子传导。(2)硫酸钙具有应变的氯化钠型结构，如果掺杂另一种化合物以形成间隙钙离子，则显示出钙离子传导。含有 5 m/o 过量钙的样品的电导率在 1000°C 时为 3x10^<-3>Scm^<-1>。我们还可以通过掺杂Al_2(SO_4)_2向主晶体引入钙离子空位。在这种情况下，观察到类似的导电行为，但电导率本身相对较低。(3)如果用二价阳离子代替传统碱离子导体的碱离子，我们只能在特殊情况下获得阳离子导体，例如基于斜方锰矿的体系。然而，它们不稳定，在较低温度范围内容易分解成两相。(4)考虑到电池结构的电动势响应和电解时钙化合物的形成，本研究发现的离子导体可以用作电化学电解质。