Calculations of the lattice energy of fluoride solid solutions with fluorite structure

It was found that the equation E-cr = AZ(+)Zn(-)n/r(0) (A is a constant; Z( +) and Z(-) are the valences of the cation and anion, respectively; n is th e number of ions in the formula unit; r(0) is the shortest distance between the cation and anion, and E-cr is the lattice energy) proposed by Kapustin sky is applicable to MF crystals (M = Li, Na, K, Rb, Cs, Ag) with NaCl-type structure and to MF2 crystals (M = Ca, Sr, Ba, Cd, Ph) with fluorite-type structure. The values of E-cr for fluorite-type solid solutions of trifluor ides of rare earth metals in fluorides of alkaline-earth metals, cadmium, a nd lead(II) were estimated.