Effect of IrO2 Spatial Distribution on the Stability and Charge Distribution of Ti1- xIrxO2 Alloys

Marco A. Villena, Blanka Magyari-Köpe, Yoshio Nishi, Paul C. McIntyre, Mario Lanza

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Rutile structure IrO2 and the related alloy Ti1-xIrxO2 are studied by ab initio simulations. Iridium oxide attracts interest due its exotic metal-insulator transition which may have important applications. In addition, its alloy with TiO2 exhibits reasonable optical transparency, a large work function, high electronic conductivity, corrosion resistance, and excellent properties as a water oxidation catalyst; however, the stability of the alloy with respect to phase separation is not well understood. To study the structure and properties of this metal oxide alloy, a new tool called SCIR (structure classification by image recognition) is developed, allowing the analysis of large sets of local arrangements of iridium oxide and titanium oxide in Ti1-xIrxO2 alloys by image recognition techniques. This study demonstrates that applying hydrostatic pressure to bulk IrO2 can modify its local charge distribution, increasing the electronic charge density between Ir and O ions as the pressure increases. Further, it is found that a local aggregation of iridium oxide in Ti1-xIrxO2 in which four Ir-O octahedra columns are connected to form a "pipe" structure parallel to the c-axis of the crystal structure is the most stable arrangement, suggesting a modest propensity for phase separation in this alloy system. This local IrO2 aggregation increases the electronic conductivity of the alloy by creating conductive channels for charge transport.
Original languageEnglish (US)
JournalChemistry of Materials
DOIs
StatePublished - Jan 1 2019
Externally publishedYes

ASJC Scopus subject areas

  • Materials Chemistry
  • Chemical Engineering(all)
  • Chemistry(all)

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