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Preparation, Crystal Structure, and Reducibility of K2NiF4Type Oxides Eu2−xSrxNiO4+δ

✍ Scribed by Lou Hui; Chen Ping; Ge Yuping; Lu Yueqing; Lü Guanglie; Xü Yuanzhe; Ma Futai

Publisher
Elsevier Science
Year
1998
Tongue
English
Weight
320 KB
Volume
141
Category
Article
ISSN
0022-4596

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✦ Synopsis

K 2 NiF 4 type compounds Eu 2؊x Sr x NiO 4؉ (0.54x41.2) have been prepared by a citric acid complex decomposition method. Rietveld refinement of the powder X-ray diffraction data showed that there was a crystal system transformation from orthorhombic Fmmm to tetragonal I4/mmm at around x ‫؍‬ 0.6-0.7. The Sr substitution caused a drastic shift of the O II ions along the c-axis from Eu(Sr) toward Ni while scarcely affecting the NiO 4 network in the basal plane. The Jahn-Teller distortion of the NiO 6 octahedron decreased while the percentage of Ni 3؉ increased with increasing x. The variation of the higher peak temperature on the TPR profiles with x are opposite to the variation of the cell parameters c.

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