Formation of amorphous LiCl aggregate regions within Li+-ion conducting glasses of (LiCl)x(LiPO3)1-x evidenced by 7Li MAS NMR

Li+-ion conducting glasses of (LiCl)x(LiPO3)1-x with high LiCl compositions up to x = 0.45 were prepared successfully by using a twin-roller quenching method. 7Li magic angle spinning (MAS) NMR spectra of the glasses showed a broad signal, and a linear dependence of the chemical shift on LiCl composition, x, was observed. The chemical shift estimated by extrapolating the linear relation to the LiCl composition limit of x = 1 was very different from that of crystalline LiCl, and was concluded to correspond to that of amorphous LiCl. A linear relation to the LiCl composition was also observed for the linewidth of the signal, and quite a sharp signal was expected for amorphous LiCl from the relation. The glasses with relatively high LiCl compositions of x ≥ 0.40 exhibited a sharp signal besides the broad one in the spectra, and the chemical shift of the sharp signal corresponded well with that estimated for amorphous LiCl. This result clearly shows the formation of 'amorphous LiCl aggregate regions' in the (LiCl)x(LiPO3)1-x glasses with increase of the LiCl composition, and the sharp signal was reasonably attributed to the Li+ ions included in the amorphous LiCl aggregate regions