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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 22, Number 3
BKCSDE 22(3)
March 20, 2001 

Raman Spectra of the Solid-Solution between Rb2La2Ti3O10 and RbCa2Nb3O10
Hee Jin Kim, Song-Ho Byeon, Hoseop Yun
Layered structure, Oxides, Raman spectra, Site preference.
A site preference of niobium atom in Rb2-xLa2Ti3-xNbxO10 (0.0 ≤ x ≤1.0) and RbLa2-xCaxTi2-xNb1+xO10 (0.0 ≤ x ≤2.0), which are the solid-solutions between Rb2La2Ti3O10 and RbCa2Nb3O10, has been investigated by Raman spectroscopy. The Raman spectra of Rb2-xLa2Ti3-xNbxO10 (0.0 ≤ x ≤1.0) gave an evidence that niobium atoms substituted for titanium atoms preferably occupy the highly distorted outer octahedral sites rather than the central ones in triple-octahedral perovskite layers. In contrast, the Raman spectra of RbLa2-xCaxTi2-xNb1+xO10 (0.0 ≤ x ≤2.0) showed no clear information for the cationic arrangement in perovskite slabs. This difference indicated that a site preference of niobium atoms is observed only when the linear Rb-O-Ti linkage can be replaced by much stronger terminal Nb-O bond with double bond character. From comparison with the Raman spectroscopic behavior of CsLa2-xA’xTi2-xNb1+xO10 (A’ = Ca and Ba; 0.0 ≤x ≤2.0), it is also proposed that a local difference in arrangement of interlayer atoms causes a significantly different solid acidity and photocatalytic activity of the layered perovskite oxides, despite their crystallographically similar structures.
298 - 302
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