Experimental and theoretical confirmation of an orthorhombic phase transition in niobium at high pressure and temperature

Errandonea, D; Burakovsky, L; Preston, DL; MacLeod, SG; Santamaría-Perez, D; Chen, S; Cynn, H; Simak, SI; McMahon, MI; Proctor, JE; Mezouar, M

Abstract

Compared to other body-centered cubic (bcc) transition metals, Nb has been the subject of fewer compression studies and there are still aspects of its phase diagram which are unclear. Here, we report a combined theoretical and experimental study of Nb under high pressure and temperature. We present the results of static laser-heated diamond anvil cell experiments up to 120 GPa using synchrotron-based fast x-ray diffraction combined with ab initio quantum molecular dynamics simulations. The melting curve of Nb is determined and evidence for a solid-solid phase transformation in Nb with increasing temperature is found. The high-temperature phase of Nb is orthorhombic Pnma. The bcc-Pnma transition is clearly seen in the experimental data on the Nb principal Hugoniot. The bcc-Pnma coexistence observed in our experiments is explained. Agreement between the measured and calculated melting curves is very good except at 40–60 GPa where three experimental points lie below the theoretical melting curve by 250 K (or 7%); a possible explanation is given.

Citation

Errandonea, D., Burakovsky, L., Preston, D., MacLeod, S., Santamaría-Perez, D., Chen, S., …Mezouar, M. (2020). Experimental and theoretical confirmation of an orthorhombic phase transition in niobium at high pressure and temperature. communications materials, 1, 60. https://doi.org/10.1038/s43246-020-00058-2

• Journal Article Type: Article
• Acceptance Date: Jul 14, 2020
• Online Publication Date: Aug 13, 2020
• Publication Date: Aug 13, 2020
• Deposit Date: Sep 14, 2020
• Publicly Available Date: Sep 14, 2020
• Journal: Communications Materials
• Publisher: Nature Research
• Volume: 1
• Pages: 60
• DOI: https://doi.org/10.1038/s43246-020-00058-2
• Publisher URL: https://doi.org/10.1038/s43246-020-00058-2
• Related Public URLs: https://www.nature.com/commsmat/
• Additional Information: Funders : Spanish Ministerio de Ciencia, Innovación y Universidades;Generalitat Valenciana; Grant Number: MAT2016-75586-C4-1-P, PGC2018-097520-A-100, and RED2018-102612-T; Grant Number: Prometeo/2018/123 EFIMAT