Revealing the average cation distribution in Sr5xBa5-5xNb10O30

Sr5xBa5-5xNb10O30 (SBN) is a ferroelectric material crystallizing in an unfilled tetragonal tungsten bronze (TTB, general formula (A1)2(A2)4C4(B1)2(B2)8O30) structure, with three species (Sr, Ba and a vacancy) distributed over the A1 and A2 sites, resulting in inherent disorder. The cation distribution directly affects the ferroelectric and dielectric properties of SBN, and can even be used to tune the material properties. Thus, it is important to characterize and quantify the cation disorder. However, with this configuration of cations (two sites and three species), the occupancies of all species on both sites are impossible to retrieve from a single X-ray diffraction experiment. We intend to perform high-resolution resonant scattering on SBN with selected compositions (x = 0.25, 0.33, 0.50, 0.61) at different temperatures (T = RT, 300, 800, 950 °C) to overcome the limitation of conventional powder diffraction, and accurately quantify the cation disorder in SBN.