Additional Oxygen Ordering in "La2NiO4.25" (La8Ni4O17)
1993; Elsevier BV; Volume: 106; Issue: 2 Linguagem: Inglês
10.1006/jssc.1993.1292
ISSN1095-726X
AutoresAlain Demourgues, François Weill, B. Darriet, Alain Wattiaux, Jean‐Claude Grenier, P. Gravereau, Michel Pouchard,
Tópico(s)Thermal Expansion and Ionic Conductivity
ResumoA new material with the composition La2NiO4.25 exhibiting a large additional oxygen amount with respect to the K2NiF4-type structure has been prepared using an electrochemical process. A monoclinic unit cell (C-centered) has been determined by TEM. This monoclinic unit cell is four times bigger than the average orthorhombic unit cell and the refined parameters are a = 13.832 Å, b = 10.930 Å, c = 10.912 Å, β = 113.31°. The structure has been determined from neutron powder-diffraction data at 300 and 9 K. The space group is C2. In this space group the site of the additional oxygen atoms is fully occupied. The composition La2NiO4.25 corresponds to a define compound: La8Ni4O17.
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