The PO13 crystal structure of ROY

Abstract

A novel polymorph of ROY was found by thermal methods. The crystal structure was solved by matching calculated powder X-ray diffraction patterns from a previously published crystal structure prediction to the experimental data. The structure was further refined by the Rietveld method. The new polymorph is pumpkin-orange in color and was therefore designated as PO13. At room temperature PO13 is less stable than form Y. After 5 years, a sample of 99% pure form PO13 converted to a mixture of 45% PO13/55% form Y.