Single crystal X-ray diffraction study of a mixed-valence gold compound, Cs2AuIAuIIICl6 under high pressures up to 18GPa: Pressure-induced phase transition coupled with gold valence transition

Electronic Structure of Novel Superconductor AuSb6Te

“…Mixed-valence compound CsAuCl 3 forms the ideal cubic perovskite structure with the pressure above 12.5GPa [12]. In this compound Au takes 2+ valence in the high-pressure phase, as experimentally clarified in the Mössbauer spectroscopy [12]. Our results show that the number of the Au 5d electrons in AuSb 6 Te is similar to those of CsAuCl 3 and AuSe.…”

“…and the hybridization with the anion orbitals. Mixed-valence compound CsAuCl 3 forms the ideal cubic perovskite structure with the pressure above 12.5GPa [12]. In this compound Au takes 2+ valence in the high-pressure phase, as experimentally clarified in the Mössbauer spectroscopy [12].…”

Pressure-induced symmetry breaking in tetragonal CsAuI3

“…The associated MV-SV transition is consistent with the observation from Raman spectroscopy 7 , and charge density analysis from synchrotron powder XRD 21 . In the case of CsAuI 3 , the structural transition observed at ~5.9 GPa that breaks the tetragonal symmetry has not been observed in the chloride and bromide 4,5,6,9,15,21 support the notion of an incomplete valence transition at ~5.9 GPa. However, one must note that the measurement was conducted at 4K, at which temperature the first order transition can be very sluggish.…”

Ultrafast pump-probe measurements of short small-polaron lifetimes in the mixed-valence perovskite Cs2Au2I6Trigo1, Chen2, Jiang3 et al. 2012Phys. Rev. B230160View full textAdd to dashboardCite

“…As the pressure increases above ∼ 5.5 GPa, increased overlap between the molecular orbitals of the gold iodide complexes is thought to drive the system into the single Au valence. The suppression of the Au 1+ − Au 3+ charge order relaxes the octahedral distortion [6,10], and results in the softening and broadening of the phonon mode as seen in Fig. 2 (b).…”

“…The Cs 2 Au 2 X 6 family, with X = Cl, Br or I, is a mixed-valence perovskite that shows a pressure induced phase transition at 11, 9 and 5.5 GPa as the size of the halogen atom increases from Cl, to Br to I, respectively [6,9,10]. In the low pressure phase, the gold ion appears in a MV state with alternating Au 1+ and Au 3+ sites and the surrounding halogen ions form a distorted octahedron as depicted in Fig.…”