Calculated Heats of Dilute Solid Solution among the Alkali Halides Other Than Cesium Salts

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Abstract
Limiting high-temperature heats (energies) of dilute solid solution are calculated for all 96 cases of one NaCl-type alkali halide (except Cs salts) dissolving in another having a common ion. The direct-summation shell treatment used is based on a slightly modified Born—Mayer potential function and on the polarization energy up to terms square in the ion polarizabilities. Preliminary general expansion of the energy in positive powers (up to cubic) of the lattice-relaxation (ion-displacement) parameters of the first eight shells (98 neighbors) facilitated application to specific cases. In the linear solution for the minimum-potential lattice relaxation, one or two iterations for the first two shells sufficed. The convergence of the energy expansions and the sensitivity of the calculated energies to arbitrary variations in the semiempirical parameters were extensively investigated. Comparison is made with calorimetric heats of solution in 16 cases, the agreement (averaging ±10%) lying within the experimental and computative errors.