The preparation conditions and properties of three new calcium, magnesium,
and lithium boronitrides Ca6BN5, Mg6BN5, and Li3Mg3B2N5 were considered. Th
e compounds were obtained by caking metal nitrides with boron nitride under
atmospheric and high pressures. All these compounds are typical boronitrid
e powders and, similarly to the known boronitride Mg3BN3, seem to contain a
n N3- anion in their structure.