We show that a layer rigidity model which includes the effects of elastic deformations of the host layers can account for the composition dependence of the c-axis lattice expansion of a variety of layered intercalation compounds. Rigidity parameters deduced from this model for each of the three classes of layered solids are reflective of structurally derived rigidity as are the healing lengths computed on the basis of discrete and continuum analyses. The layer rigidity model provides the first quantitative explanation for the 1D non–Vegard’s-law behavior of a 2D solid solution.

• Received 8 February 1989

DOI:https://doi.org/10.1103/PhysRevLett.62.3066