The amorphous character and particle size distributions of powders produced with the Micronizing Mill for quantitative x‐ray powder diffractometry

The rapid rise in the popularity of the McCrone Micronizing Mill for sample preparation in routine quantitative analytical x‐ray powder diffractometry (XRPD) has led to the present examination of material obtained with the device and a comparison with material produced by the widely used Tema Mill. Specimens of α‐quartz, prepared for a range of milling times under wet‐ and dry‐grinding conditions, were assessed according to their particle size distributions and XRPD integrated intensities. Particle size distributions were measured using a sedimentation technique. Changes in XRPD integrated intensity with milling treatment have been used to derive amorphous content indices representing the change in estimated intensity attributed to milling. The results show that the McCrone Mill can produce XRPD specimens of α‐quartz for assay work which adequately satisfy particle size criteria. Powders obtained by wet‐milling with the McCrone device are more acceptable for XRPD work than those prepared by dry‐milling, and both are clearly superior to powders produced with the Tema Mill under the dry‐grinding conditions considered in this study.