We have prepared polycrystalline samples of the trimer Ir oxide BaIrO3 with face-shared Ir3O12 trimers, and have investigated the origin of the phase transition at 182 K by measuring resistivity, thermopower, magnetization and synchrotron x-ray diffraction. We propose a possible electronic model and transition mechanism, starting from a localized electron picture on the basis of the Rietveld refinement. Within this model, BaIrO3 can be basically regarded as a Mott insulator, when the Ir3O12 trimer is identified to one pseudo-atom or one lattice site. The transition can be viewed as a transition from the Mott insulator phase to a kind of charge ordered insulator phase.
Cite
@article{arxiv.1603.03525,
title = {Novel Charge Ordering in the Trimer Iridium Oxide BaIrO3},
author = {Ichiro Terasaki and Shun Ito and Taichi Igarashi and Shinichiro Asai and Hiroki Taniguchi and Ryuji Okazaki and Yukio Yasui and Kensuke Kobayashi and Reiji Kumai and Hironori Nakao and Youichi Murakami},
journal= {arXiv preprint arXiv:1603.03525},
year = {2016}
}