The crystal chemistry and magnetic properties of two hexagonal nickel(IV)-containing perovskites, Ba4Ni1.94Ir2.06O12 and BaNiO3, are reported. The 12R perovskite, Ba4Ni1.94Ir2.06O12, possesses an unexpected coexistence of nickel(II) and nickel(IV). This quadruple… Click to show full abstract
The crystal chemistry and magnetic properties of two hexagonal nickel(IV)-containing perovskites, Ba4Ni1.94Ir2.06O12 and BaNiO3, are reported. The 12R perovskite, Ba4Ni1.94Ir2.06O12, possesses an unexpected coexistence of nickel(II) and nickel(IV). This quadruple perovskite structure contains Ir2NiO12 mixed-metal-cation units in which direct metal-metal bonding between nickel(IV) and iridium(V) is inferred. X-ray absorption near-edge spectroscopy and X-ray photoelectron spectroscopy measurements were conducted to confirm the simultaneous presence of nickel(II) and nickel(IV).
               
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