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Phase behavior of Ag2CrO4 under compression: structural, vibrational, and optical properties

DOI: 10.1021/jp401524s DOI Help

Authors: David Santamaría-Pérez (University of Valencia) , Enrico Bandiello (University of Valencia) , Daniel Errandonea (Universidad de Valencia) , Javier Ruiz-Fuertes (Universidad de Valencia) , Oscar Gomis (Universidad Politécnica de Valencia) , Juan Angel Sans (Universidad Politécnica de Valencia) , Francisco Javier Manjón (Universidad Politécnica de Valencia) , Plácida Rodríguez-Hernández (Universidad de La Laguna) , Alfonso Muñoz (Universidad de La Laguna)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C , VOL 117 (23) , PAGES 12239 - 12248

State: Published (Approved)
Published: June 2013

Abstract: We have performed an experimental study of the crystal structure, lattice dynamics, and optical properties of silver chromate (Ag2CrO4) at ambient temperature and high pressures. In particular, the crystal structure, Raman-active phonons, and electronic band gap have been accurately determined. When the initial orthorhombic Pnma Ag2CrO4 structure (phase I) is compressed up to 4.5 GPa, a previously undetected phase (phase II) has been observed with a 0.95% volume collapse. The structure of phase II can be indexed to a similar orthorhombic cell as phase I, and the transition can be considered to be an isostructural transition. This collapse is mainly due to the drastic contraction of the a axis (1.3%). A second phase transition to phase III occurs at 13 GPa to a structure not yet determined. First-principles calculations have been unable to reproduce the isostructural phase transition, but they propose the stabilization of a spinel-type structure at 11 GPa. This phase is not detected in experiments probably because of the presence of kinetic barriers. Experiments and calculations therefore seem to indicate that a new structural and electronic description is required to model the properties of silver chromate.

Subject Areas: Materials, Chemistry

Instruments: I15-Extreme Conditions

Other Facilities: ALBA Synchrotron Light Sources

Added On: 30/06/2014 11:16

Discipline Tags:

Physical Chemistry Chemistry Materials Science

Technical Tags:

Diffraction High-Pressure X-ray Diffraction (HP-XRD)