High-pressure structural systematics of lanthanides compressed in a neon pressure medium: the case of Pr and Dy.*

Lanthanides have been the focus of many studies over the years, however the majority of these have been performed under nonhydrostatic conditions. One reason given for this has been the potential reaction with the pressure medium. In this talk I will present new results from compression studies on Pr and Dy which were compressed in a soft Ne pressure medium. No reaction between these lanthanides and Ne was observed up to ~185 GPa. I will discuss the effects of nonhydrostatic stress on these soft lanthanides and show how the structural systematics can differ between quasi-hydrostatic and nonhydrostatic compression of these materials. I will discuss the effects of nonhydrostatic compression on the dFCC and collapsed phases of Dy. While in Pr the previously reported primitive orthorhombic structure reported to be stable above ~147 GPa was not observed when compressed in Ne. New experimental and theoretical results show a potential new phase in Dy beyond the collapsed phase.