The extent of Mg insertion into α-phase samples was found to be less than that for Li and Na under comparable conditions. Room-temperature electrochemical measurements revealed the existence of 2 monophase regions, in MgxU3O8, when x was between 0.2 and 0.27; or was greater than 0.4. These regions shifted to higher x-values when the discharge temperature was increased to 100C. Ionic conductivity (table 136), chemical (table 137) and self-diffusion (table 138) coefficients were deduced by using a current-pulse method. The resultant diffusivity values were up to 3 orders of magnitude lower than those for Li in this oxide.
R.E.Dueber, J.M.Fleetwood, P.G.Dickens: Solid State Ionics, 1992, 50[3-4], 329-37
Table 136
Room-Temperature Partial Ionic Conductivity of Mg in MgxU3O8
x | s (S/cm) |
0.02 | 1.4 x 10-9 |
0.12 | 2.6 x 10-9 |
0.16 | 4.8 x 10-9 |
0.20 | 1.1 x 10-8 |
0.24 | 2.3 x 10-8 |
0.27 | 1.4 x 10-8 |
0.30 | 2.7 x 10-8 |
0.33 | 2.1 x 10-8 |
0.36 | 2.2 x 10-8 |
0.39 | 1.3 x 10-8 |
0.42 | 8.2 x 10-8 |
0.45 | 1.1 x 10-8 |
Table 137
Room-Temperature Chemical Diffusivity of Mg in MgxU3O8
x | D (cm2/s) |
0.02 | 8.1 x 10-13 |
0.12 | 3.1 x 10-13 |
0.16 | 7.6 x 10-13 |
0.20 | 4.9 x 10-12 |
0.24 | 1.3 x 10-11 |
0.27 | 2.0 x 10-12 |
0.30 | 5.6 x 10-12 |
0.33 | 5.2 x 10-12 |
0.36 | 6.6 x 10-12 |
0.39 | 2.5 x 10-12 |
0.42 | 1.1 x 10-10 |
0.45 | 3.0 x 10-12 |
Table 138
Room-Temperature Self-Diffusion of Mg in MgxU3O8
x | D (cm2/s) |
0.02 | 4.7 x 10-13 |
0.12 | 1.4 x 10-13 |
0.16 | 2.0 x 10-13 |
0.20 | 3.7 x 10-13 |
0.24 | 6.4 x 10-13 |
0.27 | 3.4 x 10-13 |
0.30 | 5.9 x 10-13 |
0.33 | 4.3 x 10-13 |
0.36 | 4.1 x 10-13 |
0.39 | 2.2 x 10-13 |
0.42 | 1.3 x 10-12 |
0.45 | 1.6 x 10-13 |