The Effect of Size of X-Ray Source on the Measurement of Lattice Parameter

Abstract

To obtain the accurate lattice parameter of material by using Debye-Scherrer camera, it is necessary to consider the various effective factors which can cause errors (systematic error) in the measurement of Bragg angle θ, and to find out how these errors in θ vary with the angle itself. In practice, the effect of thickness of the specimen on the measurements of θ is very important in finding the accurate lattice parameter. Nishiyama proposed a method for eliminating this effect on the assumption that an X-ray source is large enough to the radius of the specimen. His assumption, however, becomes incorrect when the radius of the specimen is not negligible compared with that of the X-ray source.The purpose of this study is to consider the error in the value of θ due to the size of the X-ray source, and to compare the results obtained by the proposed method with those obtained otherwise. It can be concluded from these experiments that the size of the X-ray source is an important factor to obtain the accurate lattice parameter of the material under study.