The conductivity of face-centered cubic systems which were doped with Cd2+, K+, and Na+, was studied. In solid solutions with 67mol% Ag2HgI4, that were doped with Cd2+, a phase transition occurred at a lower temperature than in the parent compounds, and the system exhibited a higher conductivity. This increase was explained in terms of the vacancies that were produced. The K+-doped Ag2HgI4 exhibited a higher conductivity before the phase transition (table 216), and this was attributed to lattice-loosening. A decrease in conductivity was observed at temperatures above 140C, and this was attributed to anion framework collapse. The Na+-doped Ag2HgI4 exhibited a high conductivity in the high-temperature phase, because of the small size of the Na+ ions.
S.M.Nair, A.I.Yahya, A.Ahmad: Journal of Solid State Chemistry, 1996, 122[2], 349-52
Table 216
Activation Energy for Ionic Conductivity
in Doped Ag2HgI4-Cu2HgI4 Compositions
Cu2HgI4 (mol%) | Dopant (mol%) | Transition (C) | Condition | Q (kJ/mol) |
0 | 0 | 52 | pre-transition | 27 |
0 | 0 | 52 | post-transition | 63 |
100 | 0 | 70 | pre-transition | 25 |
100 | 0 | 70 | post-transition | 91 |
67 | 0 | 59 | pre-transition | 27 |
67 | 0 | 59 | post-transition | 59 |
50 | 0 | 55 | pre-transition | 31 |
50 | 0 | 55 | post-transition | 65 |
33 | 0 | 33 | pre-transition | 65 |
33 | 0 | 33 | post-transition | 51 |
33 | 6 | 54 | pre-transition | 153 |
33 | 6 | 54 | post-transition | 57 |
0 | 7 | 60 | pre-transition | 22 |
0 | 7 | 60 | post-transition | 25 |
0 | 15 | 65 | pre-transition | 172 |
0 | 15 | 65 | post-transition | 31 |