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HL: Fachverband Halbleiterphysik

HL 10: Photovoltaics: Kesterites and less widely used materials (with DF)

HL 10.6: Talk

Monday, March 16, 2015, 12:30–12:45, ER 164

Modelling of octahedral tilts in NBT by first-principles — •Kai-Christian Meyer, Melanie Gröting, and Karsten Albe — TU Darmstadt, Jovanka-Bontschits-Str 2, 64287 Darmstadt

In this work we deal with the structural configuration of Sodium Bismuth Titanate (NBT) on a atomistic level by first-principles studies and we link our results to the experimentally observed dielectric properties. NBT is a lead-free relaxor ferroelectric with interesting physical properties around the temperature range from 100-200 °C, where it shows a broad frequency dependent peak in the dielectric constant. Around 200°C the tetragonal and rhombohedral (and octahedral) phase are simultaneously present. We believe that a connection between polar nanoregions (PNR) and planar octahedral defects in a rhombohedral matrix exist. We show among other things that certain chemical orders enhance the probability for PNRs to occur.