Research into a new method for separating palladium from rhodium, based on radiochemical principles, necessitated a re-investigation of the Gmelins Handbuch data indicating that Rh has allotropes. Two independent and different methods were used, which both yielded the same results; i.e. that no allotropy can be found. Non-ambient
temperature X-ray diffraction (HT-XRD) did not show any difference in the diffractograms due to phase transformation of Rh-metal at elevated temperatures. Differential thermal analysis (DTA) confirmed the HT-XRD result in the temperature range of 1000–1400 C. In conclusion, the absence of allotropy of the metal rhodium was proven.