NMR AND NQR STUDIES OF BORATE GLASSES

Nuclear magnetic resonance (NMR) has been used for some 40 years to st udy atomic arrangements, chemical bonding, and structural groupings in berate glasses and crystalline compounds, and nuclear quadrupole reso nance (NQR) has more recently increased the resolution and accuracy of the measurements. Examples are presented of the use of first-order an d second-order quadrupolar effects in B-11 NMR spectra to obtain struc tural information, and B-11 and B-10 NQR spectra to obtain the quadrup olar parameters Q(cc) (the coupling constant) and eta (the asymmetry p arameter) with accuracies of 5 or 6 significant figures, and 3 figures , respectively. Q(cc) and eta are extremely sensitive to changes in at omic rearrangements and chemical bonds, so they are excellent monitors and provide identification of bonding configurations and structural g roupings in berates: Examples are also presented in which combinations of NMR and NQR data are used to extract the desired information. NQR detection of resonances at frequencies as low as 276 kHz is discussed.