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Synchrotron‐radiation study of phase transitions in phosphorus at high pressures and temperatures
Author(s) -
Kikegawa T.,
Iwasaki H.,
Fujimura T.,
Endo S.,
Akahama Y.,
Akai T.,
Shimomura O.,
Yagi T.,
Akimoto S.,
Shirotani I.
Publication year - 1987
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889887086394
Subject(s) - trigonal crystal system , synchrotron radiation , phase transition , orthorhombic crystal system , diffraction , synchrotron , transition temperature , hexagonal crystal system , chemistry , phase (matter) , materials science , analytical chemistry (journal) , crystallography , thermodynamics , condensed matter physics , crystal structure , optics , physics , superconductivity , organic chemistry , chromatography
Results are reported of an investigation using synchrotron radiation into the effects of temperatures up to 1173 K on pressure‐induced phase transitions in phosphorus. A cubic type multi‐anvil press was employed and a diffraction pattern in an energy‐dispersive mode was taken for a period of time, typically 200 s, without suffering from a deterioration of the sample material. The pressure of the first transition, orthorhombic–rhombohedral (As‐type), decreases with increasing temperature at a rate of 2.3 MPa K −1 and the As‐type structure is stable at a pressure as low as 2.6 GPa at a temperature of 1073 K. The volume discontinuity at the transition, ΔV , is 10% at room temperature and remains almost unchanged with increasing temperature. The axial ratio c / a , when the rhombohedral structure is referred to the hexagonal system, changes mostly with pressure but only slightly with temperature, approaching √6 = 2.45 on going to the second transition, rhombohedral–simple cubic. The pressure of this transition, in contrast to the first one, is independent of temperature but ΔV at this transition, 3.7%, continuously decreases with increasing temperature.