Fig. 2: Hypothetical mechanism of lone-pairs driven structural transformation in the (p-type) lead telluride single crystal.
From: Structural complexity and the metal-to-semiconductor transition in lead telluride
(a) pristine atomic arrangement in NaCl-type PbTe; (b) disordered lone-pairs in the pristine structure; (c) lone-pair ordering allowing layers shifts in the (001) plane due lone-pair repulsive interaction; (d) atomic arrangement with layers shifted by (0.25 0 0) reducing the repulsion between the lone-pairs; (e, f) the resulting atomic arrangement (cf. Fig. 1). The stoichiometry and composition in all panels is 1:1. Orange spheres–lead, green–tellurium, gray spheres symbolize lone pairs at the orange Pb atoms. The larger size of the gray spheres is used to emphasize the enhanced volume need of the lone pairs.
