NQR Studies of Borate Glasses*

P. J. Bray

Department of Physics, Box 1843, Brown University, Providence, Rhode Island, 02912 USA

Abstract—Nuclear quadrupole resonance (NQR) techniques and spectrometers are being used to study the
structure of borate glasses. They can detect and resolve ¹¹B and ¹⁰B responses that in NMR spectra are com-
pletely hidden or distorted and partially obscured by other resonances. The accuracy of measurement of the qua-
drupolar parameters (the coupling constant and asymmetry parameter) is greatly increased over NMR-derived
values. This increases the ability to identify the structural groupings in the borate glasses. The spectra and data
are given for 3-coordinated borons in crystalline and vitreous boron oxide B₂O₃, crystalline calcium metaborate
CaO B₂O₃, and a glass of molar composition 0.15Na₂O B₂O₃. Two 3-coordinated boron sites are detected by
NQR in vitreous B₂O₃; only one had been detected earlier by NMR. Thermal history effects are evident in the
NQR spectra for vitreous B₂O₃ prepared using different procedures. The NQR responses from tetrahedral (i.e.,
4-coordinated) borons in several borates have been detected in initial studies.

Pleiades Publishing home page | journal home page | top

If you have any problems with this server, contact webmaster.