Solution-grown single crystals of Fe2OBO3 were characterized by specific heat, Mossbauer spectroscopy, and x-ray diffraction. A peak in the specific heat at 340 K indicates the onset of charge order. Evidence for a doubling of the unit cell at low temperature is presented. Combining structural refinement of diffraction data and Mossbauer spectra, domains with diagonal charge order are established. Bond-valence-sum analysis indicates integer valence states of the Fe ions in the charge ordered phase, suggesting Fe2OBO3 is the clearest example of ionic charge order so far.
@article{arxiv.0707.2743,
title = {Charge Order Superstructure with Integer Iron Valence in Fe2OBO3},
author = {M. Angst and P. Khalifah and R. P. Hermann and H. J. Xiang and M. -H. Whangbo and V. Varadarajan and J. W. Brill and B. C. Sales and D. Mandrus},
journal= {arXiv preprint arXiv:0707.2743},
year = {2007}
}
Comments
4 pages, 5 figures. Fig. 3 is available in higher resolution from the authors. PRL in print