The microstructural features of MgB2 at ambient and high pressures were investigated by means of in situ synchrotron radiation X-ray diffraction and transmission electron microscopy. The X-ray diffraction measurements indicated that nanocrystalline MgB2 formed in the range of 26.3 to 30.2GPa. Transmission electron microscopic investigations revealed complex structure domains with evident lattice distortion in the relevant samples.

Formation of Nanocrystalline MgB2 Under High Pressure. L.Sun, J.Li, T.Kikegawa, L.Cao, Z.Zhan, Q.Wu, X.Wu, W.Wang: Journal of Physics - Condensed Matter, 2002, 14, 13905-9