Title :
Atomic resolution of dielectric with low temperature coefficient
Author :
Barry, John C. ; Aoki, Toyohiro
Author_Institution :
Sci. & Eng. Fac., Queensland Univ. of Technol., Brisbane, QLD, Australia
Abstract :
Ba(6-3x)Nd(8+2x)Ti(18)O(54) (BNTl14) is a high permittivity dielectric with low temperature coefficient (Tcf). Low coefficient of change of dielectric permittivity with temperature (Tcf) 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 Tcf may arise from TiO6 distortion.
Keywords :
barium compounds; low-temperature techniques; mixing; nanostructured materials; neodymium compounds; permittivity; scanning-transmission electron microscopy; vacancies (crystal); (Ba(6-3x)Nd(8+2x)Ti(18)O(54)); HAADF; STEM; atomic resolution; atomic structure; dielectric properties; dissimilar ions; high angle annular dark field simulation; high dielectric permittivity; low-temperature coefficient; materials property; mixed occupancy; mixing; nanometer phase separation; scanning transmission electron microscopy; vacancies; Atomic measurements; Barium; Educational institutions; Ions; Permittivity; Standards; Temperature; Dielectrics; HAADF; Perovskites; atomic resolution; dielectric devices; microwave communication;
Conference_Titel :
Nanoscience and Nanotechnology (ICONN), 2014 International Conference on
Conference_Location :
Adelaide, SA
DOI :
10.1109/ICONN.2014.6965248
