Characterization of domain structures from diffraction profiles in tetragonal ferroelastic ceramics

The underlying domain structures of ferroelastic ceramics have a large influence on their macroscopic electromechanical properties. The profile shape functions of certain pseudo-cubic peaks in diffraction patterns collected from these materials can provide a great deal of information about such domain structures. Using both constant-wavelength neutron and high-energy synchrotron x-ray diffraction, profile shape functions of the pseudo-cubic 002 reflection are evaluated in a soft, tetragonal PZT ceramic. Errors in the integrated intensity ratio, important for measuring the degree of domain boundary movement in these materials, are subject to further scrutiny. It is shown that an asymmetric Pearson VII type distribution, integrated numerically between reasonable limits, gives the most accurate value of relative domain populations in these materials. It is also shown that the diffuse scattering caused by ferroelastic domain walls may be used to estimate the amount of material that is affected by microstrains originating at these walls.