Structure and ionic conductivity of NaLnTiO{sub 4}: Comparison with those of Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = La, Nd, Sm, and Gd)
- Kyung Hee Univ. (Korea, Democratic People`s Republic of)
- Tokyo Institute of Technology, Yokohama (Japan)
The crystal structures of NaLnTiO{sub 4} (Ln = La, Nd, Sm, and Gd) were determined by Rietveld refinements on their powder X-ray diffraction patterns. They had K{sub 2}NiF{sub 4}-type related superstructure (space group P4/nmm (D{sub 4h}{sup 7})) in which NaO and LnO double layers are 1:1 ordered perpendicular to the c axis. Although the c parameter decreases form Ln-La to Nd, Sm, and Gd, the Na-O distance along the c axis was not proportional to the variation of the unit cell parameter. A strong corrugation parameter was observed, which would be induced by the poor charge compensation between NaO and LnO layers. Due to such a corrugation, the a parameter did not show decreasing tendency despite the fact that the constituting lanthanide ion becomes smaller. Ionic conductivity of NaLnTiO{sub 4} lower than that of Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = La, Nd, Sm, and Gd) also resulted from the corrugation of LnO layer with coordination number 9 accompanied by contraction of the NaO layer.
- OSTI ID:
- 223740
- Journal Information:
- Journal of Solid State Chemistry, Vol. 121, Issue 2; Other Information: PBD: 1 Feb 1996
- Country of Publication:
- United States
- Language:
- English
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