Solid state B-11, Al-27 and P-31 nuclear magnetic resonance spectrosco
py has been used to study the microstructure of 16 Al2O3-B2O3-P2O5 gla
sses whose constitutents may all act as glass formers. To obtain the f
undamental parameters for the quadrupolar Al-27 nuclei satellite trans
ition spectroscopy has been applied. As a result, boron occurs always
four-coordinated, while aluminium atoms are distinguished by three wel
l defined environments assigned to four-, five- and six-coordination;
the proportion of four-coordinated Al species decreases with increasin
g P2O5 content, that of five- and six-coordinated species increases. P
hosphorus is tetrahedrally coordinated, its chemical shift varies syst
ematically as a function of the bonding behavior in the second coordin
ation sphere. The experimental findings can be described by a random n
etwork model for the whole glass-forming region, which includes a cont
inuous transition from a silica-like structure of AlPO4 and BPO4 for [
P2O5]/([B2O3] + [Al2O3(4)]) ratios of about 1, to a more loosened stru
cture containing AlO4, AlO5 as well as Al(PO3)(3) elements, if there i
s excess oxygen and this ratio becomes larger.