Nr Measurements to Study The Reversible Transfer of Lithium Ion in Lithium Titanium Oxide
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ctrolysis at 900*C, where the baked gold on smpNLi was used as the anode and the gold on smp7Li as the cathode. Thereafter, the polarity of electrolyzing field was changed to intent lithium ions, transferred once toward the cathode, to go anode(Au) back to their initial positions. This reverse electrolysis was carried out at 20 to 25 mA cmf . ga-vanostat smp"Li In order to check the change of sample surfaces Li after electrolysis, X-ray diffraction with nickelfiltered CuKa radiation was employed. In order obtain exact profiles of lithium coulometer contents in Li 3Ti 704 as numeric values, rectangular samples (e x 9 mm, 16 mm length) ctatooisctu we-re separately prepared. Dc current (j = 24 mA 2 cm ) was passed through the gold paste baked on both opposite planes of the samples for electrolysis at 900*C. In this case, the electrolysis with reverse polarity was also carried out. The Fig.1 Schematic illustration of electrolysis. standard samples were prepared, which have defined contents (0, 20, 40, 60, 80 and 100%) of NLi in the same sized depth of samples. The 10 %" and "100 %"samples correspond to TiO 2 and Li , 33Ti 04, respectively. In order to convert the film gray levels into numeric data, an image scanner (H Scanjet 3c) connected to a computer was employed In the case to see the lithium ion insertion into TiO2, a cylindrical sample of TiO 2 with 9 mm diameter by 3 mm length was prepared. This was attached to SmpNLi, placed in the furnace and electrolyzed at 37 mA cm" at 900-C, where TiO2was a catholyte and the smpNLi an anolyte. Radioeraphic proedure
After the electrolysis, the samples were taken out from the furnace and fixed on the surface of a vacuum film cassette (12.5gm Gd + Kodak SR for industrial use). Then they were irradiated for defined minutes in the thermal neutron radiography (TNR) facility of Research Reactor Institute, Kyoto University. periods were changed occasionally on the conditionsarnples of the Reactor, especially Irradiated heavy water tank for attenuation of neutrons; depending 16 minutes for cjlindricai and 45 minutes for rectangular sample. The NR images of the samples (i.e. smp Li) containing Li should be observed as much more whitish parts on negative films than those of the samples
including no 'Li. RESULTS AND DISCUSSION Lithium ion transfer in Li,.33-i, . 7
Figure, 2 shows a N4• image of Li, nTi, •O4 samples. The smp Li contains no Li and the smp Li cntains a few percent of 'Li. The magnitude of interaction between neutron and each lithium isotope is so different that the presence of lithium in each sample7can be distinguished as difý ce of the brightness; smp Li looks blackish and smp Li whitish on the radiogram (negative film), which means that the former is transparent and the latter is opaque to neutron. Here, we can also see the difference of brightness between the sample center and side, which is based on the sample thickness because of usage of cylindrical samples. The NR images of electrolyzed samples are presented in Fig. 3. The whitish region moved from smpNLi toward
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