| AVS 64th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Thursday Sessions |
| Session EM-ThP |
| Session: | Electronic Materials and Photonics Poster Session |
| Presenter: | Yoshikazu Kaji, Kogakuin University, Japan |
| Authors: | Y. Kaji, Kogakuin University, Japan N. Yoshida, Kogakuin University, Japan T. Okura, Kogakuin University, Japan |
| Correspondent: | Click to Email |
Our group has developed Na+-superionic conductive Narpsio (typically represented as a general formula of Na3RPySi3-yO9, R=rare earth) glass-ceramics, as analogues of Na5RSi4O12 (N5)-type Na+-superionic conductors, and it was revealed that these showed excellent ionic conductivity up to ~10-1 S/cm, which is comparable to those of the conventional ceramic Na+-conductor such as b- and b²-aluminas and NASICONs. Recently we achieved two important replacements, that is, R with Fe, and carrier Na+ with H+. The replacement of R with cheap and rich Fe is important in terms of cost and amounts of resources. The carrier ion exchange of Na+ with H+ will spread its applications, such as a fuel cell.
In this study, Na4.9FeP0.1Si3.9O12 glass-ceramics of N5 phase was prepared at first, and then, exchange of carrier Na+ ion with H+ was tried in several conditions.
Na4.9FeP0.1Si3.9O12 glass-ceramics of N5 phase was prepared by melt-quenching and glass-crystallization method. Ion exchange experiment was carried out as follows; while monitoring with pH meter, prepared glass-ceramics was immersed into HCl aq. with/without NaCl at room temperature.The obtained samples were characterized by X-ray diffraction analyses (XRD), thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC).
XRD measurement indicated that glass-ceramic Na4.9FeP0.1Si3.9O12 of N5 phase was successfully prepared. After ion exchange without addition of NaCl, unknown phase was appeared in XRD pattern, and this change could not be suppressed by changing concentration of HCl aq. A possible explanation against this change is due to dissolution of bonding Na+ in addition to carrier Na+. After ion exchange with addition of NaCl, unknown phase was disappeared, although slight decrease in crystallinity was observed.
Glass-ceramic Na4.9FeP0.1Si3.9O12 of N5 phase was successfully prepared and replaced carrier Na+ ion with H+ without significant changes in crystallinity under the conditions of ion exchange with addition of NaCl. Detail of experiments and thermodynamic data will be discussed in the presentation.