Nuclear quadrupole coupling parameters and structural nature of the nonlinear optical material Li2B4O7 by NMR

- Two types of boron atoms.
- Quadrupole parameter.
- Principal axis of EFG tensor.

The structural nature underlying the nonlinear optical (NLO) properties of Li2B4O7 is characterized by nuclear magnetic resonance (NMR). The rotation patterns of 11B NMR were measured. We observed sixteen different spectra which were divided into two groups, corresponding to two types of boron atoms, 4-coordinated B(1) and 3-coordinated B(2), which have different boron-oxygen rings and lie at chemically inequivalent sites. From these results, the quadrupole parameter and the principal axis of the electric field gradient (EFG) tensor were determined for the two borons.