title: Compression of silver sulfide: X-ray diffraction measurements and total-energy calculations.
abstract: Angle-dispersive X-ray diffraction measurements have been performed in acanthite, Ag(2)S, up to 18 GPa in order to investigate its high-pressure structural behavior. They have been complemented by ab initio electronic structure calculations. From our experimental data, we have determined that two different high-pressure phase transitions take place at 5 and 10.5 GPa. The first pressure-induced transition is from the initial anti-PbCl(2)-like monoclinic structure (space group P2(1)/n) to an orthorhombic Ag(2)Se-type structure (space group P2(1)2(1)2(1)). The compressibility of the lattice parameters and the equation of state of both phases have been determined. A second phase transition to a P2(1)/n phase has been found, which is a slight modification of the low-pressure structure (Co(2)Si-related structure). The initial monoclinic phase was fully recovered after decompression. Density functional and, in particular, GGA+U calculations present an overall good agreement with the experimental results in terms of the high-pressure sequence, cell parameters, and their evolution with pressure.
authors.affiliation: Departamento de Quı́mica Fı́sica I, Universidad Complutense de Madrid, 28040 Madrid, Spain. dsantamaria@quim.ucm.es
authors.forename: David
authors.initials: D
authors.lastname: Santamaría-Pérez
authors.forename: Miriam
authors.initials: M
authors.lastname: Marqués
authors.forename: Raquel
authors.initials: R
authors.lastname: Chuliá-Jordán
authors.forename: José M
authors.initials: JM
authors.lastname: Menendez
authors.forename: Oscar
authors.initials: O
authors.lastname: Gomis
authors.forename: Javier
authors.initials: J
authors.lastname: Ruiz-Fuertes
authors.forename: Juan A
authors.initials: JA
authors.lastname: Sans
authors.forename: Daniel
authors.initials: D
authors.lastname: Errandonea
authors.forename: José M
authors.initials: JM
authors.lastname: Recio