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Updated: Dec 31, 2025
05:41
Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods
Published on: February 11, 2016
10.0K
Phase Relations Between Iridium and the Sesquioxides in Air
Summary
Iridium (Ir) and iridium dioxide (IrO2) react with rare earth oxides in air, forming pyrochlore compounds that dissociate at high temperatures. These reactions provide insights into the stability of iridium-oxide systems with various rare earth elements.
Area of Science:
- Materials Science
- Inorganic Chemistry
- Solid-State Chemistry
Background:
- Understanding the high-temperature reactions of transition metals with oxides is crucial for developing advanced materials.
- Iridium and its oxides exhibit unique properties relevant to catalysis and high-temperature applications.
- Rare earth oxides are known for their diverse structural and chemical characteristics.
Purpose of the Study:
- To investigate the reaction products and phase behavior between iridium (Ir) and iridium dioxide (IrO2) with various rare earth oxides (Ln2O3) and other metal oxides in an air environment.
- To characterize the structural properties and thermal stability of the formed compounds.
- To elucidate the reaction pathways and phase diagrams of selected systems, particularly the Nd2O3-IrO2 system.
Main Methods:
- X-ray diffraction (XRD) analysis was employed to identify reaction products and determine crystal structures.
- High-temperature experiments were conducted in an air environment to study phase transitions and dissociation temperatures.
- Detailed analysis of the pseudo-binary Nd2O3-IrO2 system was performed as a representative case.
Main Results:
- Iridium oxidizes to IrO2 in air at low temperatures, dissociating at 1020 °C.
- Two new compounds were identified in the Nd2O3-IrO2 system: Nd2O3·2IrO2 (cubic pyrochlore, dissociates at 1190 °C) and 3Nd2O3·2IrO2 (dissociates at 1300 °C).
- B- and C-type rare earth oxides formed cubic pyrochlore compounds with IrO2, which dissociated upon heating. No reaction was observed between IrO2 and In2O3, Sc2O3, or Al2O3.
Conclusions:
- The study successfully characterized the reactions between Ir/IrO2 and various oxides, revealing the formation of pyrochlore structures with rare earth oxides.
- The thermal stability of these pyrochlore compounds is limited, with dissociation occurring at elevated temperatures.
- The findings contribute to the understanding of phase equilibria in Ir-containing oxide systems and their potential applications.
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