Pressure-induced effects on the structure of the FeSe superconductor

• Published in: Solid state communications 2009-05, Vol.149 (17), p.707-710
• Main Authors: Millican, Jasmine N., Phelan, Daniel, Thomas, Evan L., Leão, Juscelino B., Carpenter, Elisabeth
• Format: Article
• Language: English
• Subjects: A. Superconductors; C. Crystal structure and symmetry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; D. Phase transitions; E. Neutron scattering; Exact sciences and technology; Metals, alloys and compounds (a15, 001c15, laves phases, chevrel phases, borocarbides, etc.); Physics; Structure of solids and liquids; crystallography; Superconducting materials (excluding high-tc compounds); Superconductivity
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2009.02.011

A polycrystalline sample of FeSe, which adopts the tetragonal PbO-type structure ( P 4/ nmm) at room temperature, has been prepared using solid state reaction. We have investigated pressure-induced structural changes in tetragonal FeSe at varying hydrostatic pressures up to 0.6 GPa in the orthorhombic ( T=50 K) and tetragonal ( T=190 K) phases using high resolution neutron powder diffraction. We report that the structure is quite compressible with a Bulk modulus ≈31 GPa to 33 GPa and that the pressure response is anisotropic with a larger compressibility along the c -axis. Key bond angles of the SeFe 4 pyramids and FeSe 4 tetrahedra are also determined as a function of pressure.