La2Ni2O6: A New Double T'-type Nickelate with Infinite Ni1=/2=O2 Layers
New mixed-valent, Ni{sup 1+}/Ni{sup 2+}, metastable nickelate, La{sub 3}Ni{sub 2}O{sub 6}, was synthesized by low-temperature reduction of La{sub 3}Ni{sub 2}O{sub 7} with CaH{sub 2}. The crystal structure of La{sub 3}Ni{sub 2}O{sub 6} (space group: I4/mmm, a = 3.9686(1) Angstroms and c = 19.3154(6) Angstroms) was determined from powder neutron diffraction data by Rietveld analysis. The structure can be described as an intergrowth of LaO{sub 2} fluorite and double infinite layer (LaNiO{sub 2}){sub 2} blocks and represents the n = 2 homologue of the T'-type series La{sub n+1}Ni{sub n}O{sub 2n+2}. Such double T'-type structural arrangement has never been observed before. The 3d{sup 9}/3d{sup 8} electronic configuration of Ni{sup 1+}/Ni{sup 2+} and the presence of NiO{sub 2} infinite layers resemble electronic and structural features of the superconducting cuprates. X-ray absorption spectroscopy supports the 1+/2+ oxidation state and planar coordination of Ni in agreement with the structure determination.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 914212
- Report Number(s):
- BNL-78780-2007-JA; JACSAT; TRN: US0801605
- Journal Information:
- J. Am. Chem. Soc., Vol. 128; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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