title: Pressure-induced intersite Bi-M (M=Ru, Ir) valence transitions in hexagonal perovskites.
abstract: Pressure-induced charge transfer from Bi to Ir/Ru is observed in the hexagonal perovskites Ba(3+n)BiM(2+n)O(9+3n) (n=0,1; M=Ir,Ru). These compounds show first-order, circa 1% volume contractions at room temperature above 5 GPa, which are due to the large reduction in the effective ionic radius of Bi when the 6s shell is emptied on oxidation, compared to the relatively negligible effect of reduction on the radii of Ir or Ru. They are the first such transitions involving 4d and 5d compounds, and they double the total number of cases known. Ab initio calculations suggest that magnetic interactions through very short (ca. 2.6 Å) M-M bonds contribute to the finely balanced nature of their electronic states.
authors.affiliation: School of Chemistry, The University of Sydney, Sydney 2006 (Australia).
authors.forename: Zixin
authors.initials: Z
authors.lastname: Huang
authors.forename: Josie E
authors.initials: JE
authors.lastname: Auckett
authors.forename: Peter E R
authors.initials: PE
authors.lastname: Blanchard
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Kennedy
authors.forename: Wojciech
authors.initials: W
authors.lastname: Miiller
authors.forename: Qingdi
authors.initials: Q
authors.lastname: Zhou
authors.forename: Maxim
authors.initials: M
authors.lastname: Avdeev
authors.forename: Mark R
authors.initials: MR
authors.lastname: Johnson
authors.forename: Mohamed
authors.initials: M
authors.lastname: Zbiri
authors.forename: Gaston
authors.initials: G
authors.lastname: Garbarino
authors.forename: William G
authors.initials: WG
authors.lastname: Marshall
authors.forename: Qinfen
authors.initials: Q
authors.lastname: Gu
authors.forename: Chris D
authors.initials: CD
authors.lastname: Ling
keywords: ab initio calculations; charge transfer; high-pressure chemistry; perovskite phases; phase transitions