Phase Behavior of Ag2CrO4 under Compression: Structural, Vibrational, and Optical Properties

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• 作者：David Santamar铆a-P茅rez ; Enrico Bandiello ; Daniel Errandonea ; Javier Ruiz-Fuertes ; Oscar Gomis ; Juan Angel Sans ; Francisco Javier Manj贸n ; Pl谩cida Rodr铆guez-Hern谩ndez ; Alfonso Mu帽oz
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：June 13, 2013
• 年：2013
• 卷：117
• 期：23
• 页码：12239-12248
• 全文大小：497K
• 年卷期：v.117,no.23(June 13, 2013)
• ISSN：1932-7455

文摘

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.