Raman Spectra of the Solid-Solution between $Rb_2La_2Ti_3O_10$ and $RbCa_2Nb_3O_10

• Published in: Bulletin of the Korean Chemical Society Vol. 22; no. 3; pp. 298 - 302
• Main Authors: 김희진, 변송호, 윤호섭, Kim, Hui Jin, Byeon, Song Ho, Yun, Ho Seop
• Format: Journal Article
• Language: Korean
• Published: 2001
• Subjects: Raman spectra; Site preference; Oxides; Layered structure
• ISSN: 0253-2964; 1229-5949

A site preference of niobium atom in Rb2-xLa2Ti3-xNbxO10 (0.0 $\leq$ x $\leq1.0)$ and RbLa2-xCaxTi2-xNb1+xO10 (0.0 $\leq$ x $\leq2.0)$, which are the solid-solutions between Rb2La2Ti3O10 and RbCa2Nb3O10, has been investigated by Raman spectroscopy. The Raman spectra of Rb2-xLa2Ti3-xNbxO10 (0.0 $\leq$ x $\leq1.0)$ 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 $\leq$ x $\leq2.0)$ 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 $\leqx\leq2.0)$, 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.