Roy, Callum R.Storm, C. V.Munro, K.McMahon, M. I.2025-01-202025-01-202024-11-13Roy CR, Storm VC, Munro K, McMahon MI. (2024) High pressure structure of lanthanum - Poster. DSDS24, Cranfield Defence and Security Doctoral Symposia 2024, 13-14 November 2024, STEAM Museum, Swindon, UKhttps://dspace.lib.cranfield.ac.uk/handle/1826/23414https://doi.org/10.57996/cran.ceres-2719The behaviour of the lanthanum (La) metal at high pressure is of great interest because it provides insight into the behaviour of f electrons in high density metals, and also because high-pressure lanthanum hydrides have some of the highest superconducting temperatures known. Understanding the high-pressure phases of La is then vital in identifying the hydrogen content of these super-hydrides. However, the structure of La above 70 GPa is uncertain and a number of different, but related, structural forms have been reported in the literature. We have collected new, high-quality diffraction data to 230 GPa (2.3 Mbars) using the sub-micron diameter x-ray beam now available at the PETRA-III synchrotron. Analysis of this new data using Rietveld and Le Bail analysis reveals that La transforms to a body-centred tetragonal structure above ~80 GPa, a structure long-known in neighbouring element Ce, and confirming a previous unpublished experimental result from our group and a recent computational prediction.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/High pressurelanthanidesphase transitionsx-ray diffractionPoster