Nd2CuO4 was fluorinated using XeF2 as a soft fluorinating agent at temperatures ranging from 200 degreesC to 500 degreesC, The structure of the fluorinated samples was studied using a combination of X-ray powder diffraction, electron diffraction, and high-resolution electron microscopy. Samples annealed in the temperature range of 300 degreesC to 400 degreesC reveal the formation of a new monoclinic phase (a approximate to 12.96 Angstrom, b approximate to 5.5 Angstrom, c approximate to 5.8 Angstrom, and beta approximate to 92 degrees; space group C2/c), The structural model was deduced from electron microscopy investigations, It involves an ordered occupation of anion sites between two adjacent Nd layers by anions and anion vacancies and the partial migration of anions from these tetrahedrally coordinated fluorite-type positions to octahedral interstices forming apical vertexes of Cu(O, F)(6) octahedra, No superconductivity was observed for this new monoclinic phase, The relationships between the structures of fluorinated T, T ', and T* phases are discussed. (C) 2001 Academic Press. [References: 13]
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