A re-investigation of the crystal structure of La2NiO4:Non stoichiometry and “LaO” layers
1988; Elsevier BV; Volume: 66; Issue: 12 Linguagem: Inglês
10.1016/0038-1098(88)90044-0
ISSN1879-2766
AutoresJ. Choisnet, Jean‐Marc Bassat, Henry Pillière, P. Odier, M. Leblanc,
Tópico(s)Electronic and Structural Properties of Oxides
ResumoThe crystal structure of La2NiO4(a = 3.869(1)Å), (c = 12.664(3)Å), Z = 2,I4/mmm) has been re-investigated on single crystal by using a four circle diffractometer. The structure was solved from 143 independent reflections to R = 0.044, Rw = 0.043. The lanthanum deficiency of the compound was taken into account during the refinements. Calculations provide direct evidence that, at the scale experimented by the X-ray determination, the structure can tolerate significant non-stoichiometry. Both holes and oxygen vacancies compensate the lanthanum vacancies: the oxygen vacancies are probably localized on axial oxygens (O1). The possible non-stoichiometry of "LaO" layers and its relation with anisotropy of thermal parameters is discussed for a better understanding of the high Tc superconductivity occuring in the iso-structural Ba-La-Cu-O.
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