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Abstract:
A novel CaCu3Cu2Ir2O12-delta polycrystalline sample was synthesized at 8
GPa and 1373 K. Rietveld structural analysis shows that this compound
crystallizes in an AA(3)'B4O12-type A-site ordered perovskite structure
with space group Im-3. X-ray absorption spectra reveal a +2-charge state
for both the square-planar and octahedral coordinated Cu ions, and the
valence state of Ir is found to be about +5. Although the A-site Ca and
the A'-site Cu2+ are 1:3 ordered at fixed atomic positions, the
distribution of B-site Cu2+ and Ir5+ is disorderly. As a result, no
long-range magnetic ordering is observed at temperatures down to 2 K.
Electrical transport and heat capacity measurements demonstrate
itinerant electronic behavior. The crystal structure is stable with
pressure up to 35.7 GPa at room temperature.
