A new high-pressure and high-temperature polymorph of FeS

摘要: A new polymorph of FeS has been observed at pressures above 30 GPa 1,300 K by in situ synchrotron X-ray diffraction measurements a laser-heated diamond anvil cell. It is stable up to, least, 170 K. The phase (here called VI) an orthorhombic unit cell with lattice parameters = 4.8322 (17) A, b 3.0321 (6) and c 5.0209 (8) 85 300 Its topological framework based on the NiAs-type structure as case for other reported polymorphs (FeS I-V). VI is, however, more distorted (contracted) along [010] direction original For example, c/b axial ratio ∼1.66 K, which considerably smaller than that II (∼1.72) hexagonal V (=√3 ≈ 1.73). boundary between IV expected to be located around transition accompanied gradual continuous changes volume ratios may second order. At room temperature, becomes over III 36 GPa. therefore, suggested III–VI and/or IV–VI negative pressure dependence.