Use of an Air Brush to Spray Dry Samples for X-Ray Powder Diffraction

ABSTRACT: The construction and operation of a spray drier is described where the spray is produced using an air brush, essentially a miniature spray gun. The spray-dried products consist of spheres 5060 mm in diameter and typical product recoveries are 80%, a marked improvement over simple two-nozzle systems. The spray-dried samples are easy to load into XRD powder holders and present a smooth surface and relatively constant bulk density to the X-ray beam. Problems of preferred orientation are effectively eliminated and the resulting X-ray powder patterns are completely reproducible by different operators. The importance of sample preparation for X-ray powder diffraction cannot be overemphasized (Brindley, 1984; Bish & Reynolds, 1989). One of the characteristics most commonly desired is a completely random arrangement of the individual particles in a powder sample. All types of X-ray powder diffraction, ranging from structure to quantitative analysis, rely on the preparation o