Phosphates are ionic compounds that contain PO or related anions. They can be highly complex, featuring many crystallographically distinct anions, giving rise to a large unit cell with low symmetry and a complex associated diffraction pattern. The A-lab paper reports As mentioned previously, one must be careful in refining such complex structures because the abundance of reflections and atomic positions may lead to meaningless fits that have too many parameters. As such, a pure sample, high quality PXRD data, and other identification methods are imperative to assert the synthesis of a new phase, if the structure is highly complex and of low symmetry. Errors one (poor fit) and three (no evidence of cation order) are very common in the analysis of the phosphates.