  The synthesis, morphology and magnetization measurements of GaN nanoceramics
obtained under high pressure are reported. In particular the effect of grain
size on magnetic properties of GaN nanopowders and nanoceramics was
investigated. It was found that for the GaN nanoceramic characterized by the
stronger deformation of nanocrystalline grains the diamagnetic signal changes
with external magnetic field similarly to the Meissner effect in
superconductors.
