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Towards a metallic quasi‐d 9 system without copper: AgO at high pressure
Author(s) -
Włodarska Izabela,
Derzsi Mariana,
Grochala Wojciech
Publication year - 2015
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201510200
Subject(s) - condensed matter physics , fermi level , band gap , dumbbell , copper , semiconductor , valence (chemistry) , phonon , instability , metal , valence band , chemistry , materials science , crystallography , physics , electron , quantum mechanics , metallurgy , medicine , optoelectronics , organic chemistry , physical therapy
AgO is a prototypical mixed‐valence compound, with markedly different coordination environment of dumbbell Ag(1+) and low‐spin square‐planar Ag(3+) which render it a narrow band gap semiconductor. The hybrid HSE06 functional reproduces fairly well the band gap of its P 2 1 / c form at ambient conditions (Δ E exp = 1.0–1.1 eV, Δ E theor = 0.94 eV) and suggest progressive band gap decrease with external pressure with metallization at 50 GPa via band overlap. Dynamic (phonon) instability appears at the onset of metallization leading to a structural phase transition to a more stable but still metallic P 1 ̄form. The density of electronic states at the Fermi level of the P 1 ̄polymorph is small and a pseudo‐gap at the Fermi level is preserved.Illustration of the predicted P 2 1 / c → P 1 ̄transformation.(© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)