The high-pressure, high-temperature phase diagram of cerium. (15th May 2020)

• Record Type: Journal Article
• Authors: Munro, K A; Daisenberger, D; MacLeod, S G; McGuire, S; Loa, I; Popescu, C; Botella, P; Errandonea, D; McMahon, M I
• Is Part Of: Journal of physics. Volume 32:Number 33(2020)
• Publication Date: 2020-05-15
• Subjects: high pressure -- phase diagram -- cerium; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/ab7f02
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: We present an experimental study of the high-pressure, high-temperature behaviour of cerium up to ∼22 GPa and 820 K using angle-dispersive x-ray diffraction and external resistive heating. Studies above 820 K were prevented by chemical reactions between the samples and the diamond anvils of the pressure cells. We unambiguously measure the stability region of the orthorhombic oC 4 phase and find it reaches its apex at 7.1 GPa and 650 K. We locate the α- cF 4– oC 4– tI 2 triple point at 6.1 GPa and 640 K, 1 GPa below the location of the apex of the oC 4 phase, and 1–2 GPa lower than previously reported. We find the α- cF 4 → tI 2 phase boundary to have a positive gradient of 280 K (GPa) −1, less steep than the 670 K (GPa) −1 reported previously, and find the oC 4 → tI 2 phase boundary to lie at higher temperatures than previously found. We also find variations as large as 2–3 GPa in the transition pressures at which the oC 4 → tI 2 transition takes place at a given temperature, the reasons for which remain unclear. Finally, we find no evidence that the α- cF 4 → tI 2 is not second order at all temperatures up to 820 K.