It is affirmed that the absorption edge below 4. 0 eV is attributable to indirect transition,the significant discussion of three straight-line parts of spectral line are obtained by studing the curve of LiNbO3. The energy gap E, is 3. 38eV.

• 通过对晶体a~(1/2)-hv曲线的研究；肯定了40.；eV以下吸收边的间接跃迁性质；并讨论了三段直线的意义。 确定了禁带宽度E_f的值为3