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Structure and Properties of Ir-Containing Oxides with Large Spin-Orbit Coupling: Ba2In(2-x)Ir(x)O(5+δ)
Joshua Flynn1, Jun Li1, Arthur W Sleight1
1Department of Chemistry, Oregon State University , Corvallis, Oregon 97331, United States.
Inorganic Chemistry
|March 4, 2016
Summary
This study synthesizes and characterizes Ba2In(2-x)Ir(x)O5+δ solid solutions. Researchers observed structural transitions and stabilized iridium(VI) oxide, revealing semiconducting properties and dual charge carriers.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Inorganic Chemistry
Background:
- Barium indates and iridates are explored for their potential electronic and magnetic properties.
- Understanding the phase behavior and oxidation states of transition metals in complex oxides is crucial for materials design.
Purpose of the Study:
- To synthesize and characterize the solid solution series Ba2In(2-x)Ir(x)O5+δ.
- To investigate the structural, magnetic, and charge-transport properties as a function of iridium content.
- To explore the stabilization of higher oxidation states of iridium.
Main Methods:
- Solid-state synthesis methods were employed to create the Ba2In(2-x)Ir(x)O5+δ series.
- Neutron diffraction and X-ray diffraction were used for structural analysis.
- Magnetization measurements and electrical resistivity studies were conducted to probe magnetic and transport properties.
Main Results:
- Three structural transitions (orthorhombic, tetragonal, cubic, monoclinic) were observed with increasing Ir content.
- Neutron diffraction confirmed cubic and monoclinic structures for specific compositions, differing from prior X-ray data.
- Curie-Weiss behavior indicated a mixture of Ir(V) and Ir(VI), with Ir(VI) stabilized under ambient conditions for the first time.
- All compounds exhibited semiconducting behavior with decreasing resistivity as Ir content increased.
- A sign reversal in the Seebeck coefficient indicated both electron and hole charge transport.
Conclusions:
- The Ba2In(2-x)Ir(x)O5+δ system exhibits rich structural chemistry and tunable electronic properties.
- The stabilization of Ir(VI) in this oxide system opens new avenues for materials research.
- The observed semiconducting behavior and dual charge transport suggest potential applications in thermoelectric devices.
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