Impurity-induced resistivity of ferroelastic domain walls in doped lead phosphate

The topology and the trace of ferroelastic domains, namely W walls, of Ca-doped lead orthophosphate (Pb1-x, Ca-x)(3) (PO4)(2) with a Ca content of 2.7% mol were studied on the monoclinic cleavage plane (100) using contact mode atomic force microscopy. Furthermore, conducting atomic force microscopy was applied using a bias voltage across the cantilever and the sample inducing a tunnelling current. As a reference a pure lead phosphate crystal was used, Only the Ca-doped lead phosphate crystals showed a considerable difference in conductivity between walls and the bulk. The conductivity in the bulk was found to be approximately 7% higher than in the domain walls. The experimental results show that ferroelastic domain walls of atomistic width can work as barriers to dielectric transport.