Defocusing for the Schulz Technique of Determining Preferred Orientation

During measurement of preferred crystallographic orientation with the Schulz x-ray diffraction technique, several factors can cause defocusing. Earlier investigations showed that tilt of the specimen in Φ, the angle between the normal to the sample surface and the normal to the diffracting plane, is the most severe limitation for the Schulz reflection technique. The present study shows that this defocusing effect is strongly dependent on the size of the Bragg diffraction angle θ: The greater the Bragg angle, the smaller the decrease in intensity for a given tilt angle of Φ. On the other hand, the absorption coefficient μ of the sample has no influence on the decrease in intensity with increasing tilt in Φ, and its effect is negligibly small for most metals. Correction factors for the loss of intensity can be derived and have a general analytic form, but different coefficients are required for each goniometer setting.