A15 Nb3Si: a ‘high’ T c superconductor synthesized at a pressure of one megabar and metastable at ambient conditions
| Autor: | Jinhyuk Lim, Richard G. Hennig, Bart Olinger, James Hamlin, Yundi Quan, Jungsoo Kim, Peter Hirschfeld, G. R. Stewart, Ajinkya Hire |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
High-temperature superconductivity Condensed Matter - Superconductivity Enthalpy Analytical chemistry FOS: Physical sciences 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Diamond anvil cell law.invention Superconductivity (cond-mat.supr-con) Tetragonal crystal system Pressure measurement law Electrical resistivity and conductivity Phase (matter) 0103 physical sciences General Materials Science 010306 general physics 0210 nano-technology Ambient pressure |
| Zdroj: | Journal of Physics: Condensed Matter. 33:285705 |
| ISSN: | 1361-648X 0953-8984 |
| Popis: | A15 Nb$_3$Si is, until now, the only high temperature superconductor produced at high pressure (~110 GPa) that has been successfully brought back to room pressure conditions in a metastable condition. Based on the current great interest in trying to create metastable-at-room-pressure high temperature superconductors produced at high pressure, we have restudied explosively compressed A15 Nb$_3$Si and its production from tetragonal Nb$_3$Si. First, diamond anvil cell pressure measurements up to 88 GPa were performed on explosively compressed A15 Nb$_3$Si material to trace Tc as a function of pressure. Tc is suppressed to ~ 5.2 K at 88 GPa. Then, using these Tc (P) data for A15 Nb$_3$Si, pressures up to 92 GPa were applied at room temperature (which increased to 120 GPa at 5 K) on tetragonal Nb$_3$Si. Measurements of the resistivity gave no indication of any A15 structure production, i.e., no indications of the superconductivity characteristic of A15 Nb$_3$Si. This is in contrast to the explosive compression (up to P~110 GPa) of tetragonal Nb$_3$Si, which produced 50-70% A15 material, Tc = 18 K at ambient pressure, in a 1981 Los Alamos National Laboratory experiment. Our theoretical calculations show that A15 Nb$_3$Si has an enthalpy vs the tetragonal structure that is 0.07 eV/atom smaller at 100 GPa, implying that the accompanying high temperature (1000 deg C) caused by explosive compression is necessary to successfully drive the reaction kinetics of the tetragonal -> A15 Nb$_3$Si structural transformation. Annealing experiments on the A15 explosively compressed material reaching time scales of 39 years are consistent with this viewpoint. 6 figures |
| Databáze: | OpenAIRE |
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