Atomic resolution of dielectric with low temperature coefficient

Ba_(6-3x)Nd_(8+2x)Ti₍₁₈₎O₍₅₄₎ (BNTl14) is a high permittivity dielectric with low temperature coefficient (T_cf). Low coefficient of change of dielectric permittivity with temperature (T_cf) is an unusual materials property. The research is aimed at discovering how atomic structure relates to temperature coefficient. Sub-Ångström scanning transmission electron microscopy (STEM) is used to measure mixed occupancy of Nd and Ba in atomic columns. It was expected that phase separation would occur to accommodate mixing of dissimilar ions. However no evidence of phase separation was found. There is a good image match between experiment and high angle annular dark field (HAADF) simulation. Vacancies and excess Ba ions appear to be randomly arranged on the available sites which would result in distortion of TiO₆ octahedra. The low T_cf may arise from TiO₆ distortion.