Combined 135/137Ba Solid-State NMR at an Ultrahigh Magnetic Field and Computational Study of β-Barium Borate
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- 作者：Andre Sutrisno ; Cheng Lu ; R. H. Lipson ; Yining Huang
- 刊名：Journal of Physical Chemistry C
- 出版年：2009
- 出版时间：December 17, 2009
- 年：2009
- 卷：113
- 期：50
- 页码：21196-21201
- 全文大小：237K
- 年卷期：v.113,no.50(December 17, 2009)
- ISSN：1932-7455
文摘
β-Barium Borate (β-BBO or β-BaB2O4) is an important nonlinear optical material with many practical applications. In this work, we have directly probed the local Ba environment in β-BBO by acquiring static 135Ba and 137Ba solid-state NMR spectra at an ultrahigh magnetic field of 21.1 T. The observed spectra are completely dominated by the second-order quadrupolar interaction. The measured quadrupolar coupling constants are 14.9 and 22.8 MHz for 135Ba and 137Ba, respectively. A computational study of the electric field gradient tensor at Ba2+ was also performed using both plane-wave pseudopotentials (CASTEP) and ab initio (Gaussian 03) methods. Combining the experimental and theoretical results allows one to shed some light on the controversy regarding the true space group of β-BBO. We conclude that the space group R3c represents the true structure of β-BBO rather than does the space group R3. This work demonstrates that a combination of 135/137Ba NMR and theoretical calculations is a useful tool for characterization of Ba-containing materials with unknown or poorly described structures.