title: High-Pressure Crystal Structure, Lattice Vibrations, and Band Structure of BiSbO4.
abstract: The high-pressure crystal structure, lattice-vibrations, and electronic band structure of BiSbO4 were studied by ab initio simulations. We also performed Raman spectroscopy, infrared spectroscopy, and diffuse-reflectance measurements, as well as synchrotron powder X-ray diffraction. High-pressure X-ray diffraction measurements show that the crystal structure of BiSbO4 remains stable up to at least 70 GPa, unlike other known MTO4-type ternary oxides. These experiments also give information on the pressure dependence of the unit-cell parameters. Calculations properly describe the crystal structure of BiSbO4 and the changes induced by pressure on it. They also predict a possible high-pressure phase. A room-temperature pressure-volume equation of state is determined, and the effect of pressure on the coordination polyhedron of Bi and Sb is discussed. Raman- and infrared-active phonons were measured and calculated. In particular, calculations provide assignments for all the vibrational modes as well as their pressure dependence. In addition, the band structure and electronic density of states under pressure were also calculated. The calculations combined with the optical measurements allow us to conclude that BiSbO4 is an indirect-gap semiconductor, with an electronic band gap of 2.9(1) eV. Finally, the isothermal compressibility tensor for BiSbO4 is given at 1.8 GPa. The experimental (theoretical) data revealed that the direction of maximum compressibility is in the (0 1 0) plane at ∼33° (38°) to the c-axis and 47° (42°) to the a-axis. The reliability of the reported results is supported by the consistency between experiments and calculations.
authors.affiliation: Departamento de Física Aplicada-ICMUV and Edificio de Investigación, MALTA Consolider Team, Universidad de Valencia , C. Dr. Moliner 50, 46100 Burjassot, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Errandonea
authors.affiliation: Departamento de Física and Instituto de Materiales y Nanotecnología, MALTA Consolider Team, Universidad de La Laguna , 38206 La Laguna, Tenerife Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Muñoz
authors.affiliation: Departamento de Física and Instituto de Materiales y Nanotecnología, MALTA Consolider Team, Universidad de La Laguna , 38206 La Laguna, Tenerife Spain.
authors.forename: Placida
authors.initials: P
authors.lastname: Rodríguez-Hernández
authors.affiliation: Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica, MALTA Consolider Team, Universitat Politècnica de València , Camí de Vera s/n, 46022 València, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Gomis
authors.affiliation: Chemistry Division, Bhabha Atomic Research Centre , Mumbai 400 085, India.
authors.forename: S Nagabhusan
authors.initials: SN
authors.lastname: Achary
authors.affiliation: CELLS-ALBA Synchrotron Light Facility , Cerdanyola 08290, Spain.
authors.forename: Catalin
authors.initials: C
authors.lastname: Popescu
authors.affiliation: Chemistry Division, Bhabha Atomic Research Centre , Mumbai 400 085, India.
authors.forename: Sadeque J
authors.initials: SJ
authors.lastname: Patwe
authors.affiliation: Chemistry Division, Bhabha Atomic Research Centre , Mumbai 400 085, India.
authors.forename: Avesh K
authors.initials: AK
authors.lastname: Tyagi