| Abstract: | Chemical stability of binary Coulomb compounds is studied through extensive calculation of their Madelung energies. A remarkable finding is that the compounds with disordered ionic arrangements in a certain range of the composition are stable against chemical separation beyond the charge ratio around 6; clearly the entropic effect due to finite temperature promotes the mixing of ions of different species. For the ordered AB3‐type compounds, there exists a crystalline structure which is more chemically bounded than that of Dyson (1971). Relative stability o the ordered and disordered compounds is also discussed. |
