Development of Neutron Radiography Technique to Visuslize Lithium Ions in Solod Electrolytes

(1)在京都大学反应堆的NR装置上安装了一个使用红外光束的电加热器，用于高温下固体电解质中Li^+运动的原位测量。利用模拟样品（陶瓷材料与水润湿）对加热器的性能及其对设备的影响进行了实验评估。(2)用中子照相法研究了高温型离子导体Li_ Ti_O_4中锂离子的迁移<1.33><1.67>。在直流电流通过特殊制备的具有不同同位素比（^6Li/^7Li）的氧化物进行电解后，获得了一组NR图像，这证实了氧化物中的锂离子导电性。图像分析表明，Li_ Ti_ O_4中锂离子的迁移数几乎等于1.0，并且锂离子<1.33><1.67>的迁移几乎是可逆的，这与外加电场的极性有关。(3)用冷中子照相法研究了替代白钨矿型氧化物Ca_Li_WO_4中锂离子的导电<0.95><0.10>性。锂离子分布曲线是从一组具有不同^6Li/^7Li比的电解氧化物的中子射线照相图像中获得的。结果表明，该氧化物的锂离子迁移数为0.99，这与电化学测量的结果一致。此外，在Ca_ Li_ WO_4中，只有一半的锂离子<0.95><0.10>可以随电荷转移而移动，而另一半则停留在钙位上。因此，可以认为锂离子传导将是由于50%的间隙锂离子。(4)实验证明，冷中子照相与成像板的结合可以有效地提高氧化物中Li^+的测量精度。

(1) An electric heater using IR beam was installed in the NR facility of Kyoto University Reactor for in-situ measurements of Li^+ movement in solid electrolytes under high temperature. The performance of the heater and its influence to the facility were experimentally evaluated using some simulated samples(ceramic materials wet with water).(2) Neutron radiography was used to study the transfer of lithium ions in the high temperature-type ionic conductor, Li_<1.33>Ti_<1.67>O_4. After dc current was passed for electrolysis through specially prepared xides with different isotope ratios(^6Li/^7Li), a set of NR images was obtained, which confirmed the lithium ion conduction in the oxides. Analysis of the imagesclarified that the lithium ion transport number of the oxide is almost equal to 1.0 and that lithium ions in the Li_<1.33>Ti_<1.67>O_4 were transferred almost reversibly according to the polarity of the electric field applied.(3) Cold neutron radiography was applied to study the lithium ion conduction in the substituted scheelite-type oxide of Ca_<0.95>Li_<0.10>WO_4. The lithium ion distribution profile were obtained from a set of neutron radiography images of the electrolyzed oxides having different ^6Li/^7Li ratios. They showed that the lithium ion transport number of the oxide is 0.99, which coincided with the result of electrochemical measurements. Furthermore, they denoted that only a half of all lithium ions in Ca_<0.95>Li_<0.10>WO_4 can move with charge transfer, but another half stays at the calcium sites. Therefore, it can be considered that the lithium ion conduction would be due to the 50% of the interstitial lithium ions.(4) It was confirmed that the combination of cold neutron radiography and an imaging plate was effective to improve the accuracy of the technique to measure Li^+ in the oxides.