1. 1) D. Leroy, J. Lucat, M. Poulain, and D. Ravine, Mater. Res. Bull., 13, 1125 (1978).
2. 3) Y. Kawamoto, J. Fujisawa, and Y. Umetani, Solid State Ionics, 24, 253 (1994).
3. 4) J. P. Miranday, C. Jacoboni, and R. Pape, J. Non-Cryst. Solids, 43, 393 (1981).
4. 5) N. Aurint, J. Guery, A. M. Mercier, C. Jacoboni, and R. Pape, Mater. Res. Bull., 20, 309 (1978).