Phonon stabilized polytypism in PbI2: in situ Raman spectroscopy and transferable core-shell model calculations

Publisher Website
Google Scholar
Abstract
Frequency shifts observed by in situ Raman spectroscopy of the reversible phase transition between the 2H and 12R polytype of PbI2 suggest that softening of phonons in the 12R polytype may stabilize this phase relative to the 2H phase at high temperatures. A core-shell model using short-range pair potentials and long-range electrostatic interactions for PbI2 was used for static lattice and lattice dynamics calculations. The potential parameters, which are fully transferable to other polytypes, were derived empirically for the 2H polytype and then transferred to the 12R polytype. The experimentally observed absence of dielectric anomalies is reproduced by static lattice energy calculations. The phonon contributions to the free energies of the polytypes were calculated for both polytypes, showing that the stabilization of the 12R relative to the 2H polytype is due to the phonon contribution to the free energy.

This publication has 12 references indexed in Scilit: