Selective Crystal Growth and Structural, Optical, and Electronic Studies of Mn3Ta2O8
datasetposted on 06.07.2015, 00:00 by Karl Rickert, Eric A. Pozzi, Rabi Khanal, Masatoshi Onoue, Giancarlo Trimarchi, Julia E. Medvedeva, Mark C. Hersam, Richard P. Van Duyne, Kenneth R. Poeppelmeier
Mn3Ta2O8, a stable targeted material with an unusual and complex cation topology in the complicated Mn–Ta–O phase space, has been grown as a ≈3-cm-long single crystal via the optical floating-zone technique. Single-crystal absorbance studies determine the band gap as 1.89 eV, which agrees with the value obtained from density functional theory electronic-band-structure calculations. The valence band consists of the hybridized Mn d–O p states, whereas the bottom of the conduction band is formed by the Ta d states. Furthermore, out of the three crystallographically distinct Mn atoms that are four-, seven-, or eight-coordinate, only the former two contribute their states near the top of the valence band and hence govern the electronic transitions across the band gap.