Disappearance of Localized Valence Band Maximum of Ternary Tin Oxide with Pyrochlore Structure, Sn2Nb2O7

• DOI: 10.1021/acs.jpcc.6b12572
• Publication Date: 2017-04-13T03:53:19Z
• Authors: Yoshihiro Aiura; Kenichi Ozawa; Izumi Hase; Kyoko Bando; Hiroto Haga; Hirofumi Kawanaka; Akane Samizo; Naoto Kikuchi; Kazuhiko Mase
• Keywords: Tetragonal crystal system

The electronic structure of ternary tin oxide with pyrochlore structure, Sn2Nb2O7, which has the contribution Sn 5s orbitals in valence band, is examined by synchrotron-radiation-excited photoelectron spectroscopy and X-ray absorption together ab initio calculations. empirical spectra are qualitatively consistent calculated density states exception a striking discrepancy around band maximum (VBM). calculation suggests presence sharp peak VBM, mainly due to dispersionless bands that derived from hybridization O 2p close atom. However, show no such characteristic spectral feature. From theoretical prediction about orbital origin localized VBM experimental estimation elemental composition chemical analysis, it seems reasonable conclude caused off-stoichiometric effect point defects as oxygen vacancies Sn2+, Sn2+ vacancies, Sn4+-on-Nb5+ substitutional defects. Oxides not considered be suitable for practical p-type semiconductors. Therefore, disappearance theoretically predicted possibility improve mobility hole carriers, closely related our success development semiconductor Sn2Nb2O7.