From the results of Fourier Transform infrared (FTIR) spectra and X-ra
y Diffraction (XRD), we found that there exists size effect on the str
ucture and infrared behavior in nanocrystalline MgO. When the grain si
ze decreases, the crystal lattice dilates anisotropically, and the red
shift of stretching vibrational mode coexists with the blue shift of
the bending vibrational mode. We give a preliminary interpretation to
the above abnormal phenomena. (C) 1998 Acta Metallurgica Inc.