STRUCTURE IMPERFECTION OF GAMMA-AL2O3

The X-ray diffraction pattern of gamma-Al2O3 is found to be broadened with every diffraction line being different. This is attributed to the difference of regularity of oxygen ions and aluminium ions. In order to study the structural information shown by this selected broadening, the peak separation processing for the gamma-Al2O3 X-ray diffraction pattern has been carried out. It is found that the lattice distortion of gamma-Al2O3 can be neglected and the gamma-Al2O3 crystallite size i s approximately isotropic. Therefore it might be deduced that the sele ctive widening of the diffraction line does not come mainly from the a nisotropy of the crystallite shape. According to our result that the d iffraction line width with low index (220) is wider than that with hig h index (440) the selective widening of the diffraction line might com e mainly from the structure defect. This implies the possibility of th e existence of the stacking fault in the gamma-Al2O3 structure and it might be concluded that the diffraction line widening of the gamma-Al2 O3 caused by the stacking fault leads to the crystalline structure imp erfection.