1. INTRODUCTIONCrystallization is an essential technique in pharmaceutical manufacturing since most active pharmaceutical ingredients (APIs) are available in solid form1. It plays an important role in marketing, manufacturing and interaction with excipients in the crystalline state2. The physical properties of active pharmaceutical ingredients such as crystalline shape, morphology and particle size distribution will strongly influence the solubility and bioavailability of a solid dosage form (Table 1) 3. The crystallization process, especially crystallization from solution, is used as a separation and purification technique and in the production of solid pharmaceutical forms3,4. Knowledge of the crystal structure allows the crystal engineer to know and manipulate the chemistry of the crystal in order to optimize the performance of the exact characteristics. 3. Furthermore, the chemical and physical properties of a material are dictated by the crystallization process. Crystal properties such as: particle size, shape, surface characteristics, purity and defect structure, as well as thermodynamic and mechanical properties3 will be affected by even small changes in crystallization conditions5.1.1 CrystalA crystal is defined as a solid form that contains a high degree of internal three-dimensional order of the component atoms, molecules and ions2. The crystalline structure of atoms and molecules has a unique arrangement, which leads to the regular repetition of interatomic distances within the material4. The shape of a crystal is a reflection of its internal structure on an atomic scale. The faces of a crystal are labeled with respect to the axes of the crystal. Each face has a series of three integers (h, k, l), known as Mill...... middle of paper ......ed to provide sufficient data to determine the unit cell and crystal system30- 35. Once the optimal data collection is automatically calculated by the control system, a complete series of images is recorded, which will provide the entire data set required for structure determination35.4.2 X-ray powder diffractionPowder diffraction is used for the identification of unknown materials. For a powder, the flecks seen in single-crystal patterns are smeared into rings of dust. In powder X-ray diffraction it is not necessary to move the sample in the powder diffractometer, because for each plane of the Bragg crystal, some crystallites will statistically be oriented correctly34. All necessary information requiring identification of a phase through comparison with a database of patterns from known materials is provided when a single radial scan is shown35.