Abstract: The curve shape of the X-ray diffraction line is derived by considering the difference of absorption between different crystal plans. The exact expression for the curve is obtained, which is different from that of the interference function calculated from the grating diffraction used to describing crystalline diffraction. Our result is varified by compare the theoretic expression with experiment data. As a result, the deviation between them is less. It is therefore verified that the absorption of the X-ray is a main factor for affecting the shape of the diffraction line.

Key words: X-ray diffraction, absorption, interference