The innovation engine for new materials

Fransisco Contreras


University of Chile


Chemical Engineering


Phillip Barton

Faculty Sponsor(s): 

Professor Ram Seshadri

Faculty Sponsor's Department: 


Project Title: 

Preparation and magnetic characterization of complex iriduim oxides

Project Description: 

The magnetism of compounds containing 5d transition metals is less well explored and understood in comparison to 3d. Significant differences occur in with higher atomic number Z, including enhanced crystal field splitting Δ, spin-orbit coupling λ, and relativistic effects. Here, we investigate two complex Ir oxides, Y2Ir2O7 and Bi2Ir2O7, which crystallize in the pyrochlore structure. They were prepared through solid-state reactions with the metal oxides as the starting reagents. Reaction was conducted through several heating steps at 1,000°C for 48 hours each time. X-ray diffraction was conducted to investigate phase purity and structural parameters were determined through Rietveld. A phase pure sample of Bi2Ir2O7 was obtained, but samples of Y2Ir2O7 contained small amounts of impurity phases including Y2O3 and others. A flux of Bi2O3 was added for the Y2Ir2O7 preparation to increase diffusion and help enable phase formation, but the products were not measurably improved. Magnetic characterization of Bi2Ir2O7 is consistent with weak paramagnetism expected for a metal with high Z. Further experiments include synchrotron X-ray diffraction for detailed structure determination, heat capacity to look for heavy fermion effects, and electrical transport measurements to confirm metallic conductivity.