Fig. 3: Evolution of the direction of local polar vectors.

a Composition-dependent stereographs of the directions polar vectors extracted from the refined atomic configuration. The colors display the density distribution. The lower right corner indicates the average direction of polar vectors from 45PT to 20PT. b Orientation order parameter S = 1.5 < cos2θ > −0.5, showing the extent of direction deviation of the polar vectors from the three representative directions, as indicates by the inset. Specifically, the value of 1 indicates perfect polar ordering, and the value of 0 denotes a complete polar disordering. It provides a quantitative description of the extent of randomness along the corresponding direction.