Structures and magnetic properties of new fluorite-related quaternary rare earth oxides LnY{sub 2}TaO{sub 7} and LaLn{sub 2}RuO{sub 7} (Ln=rare earths)

Journal Article · Fri Jan 15 00:00:00 EST 2016 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2015.10.012· OSTI ID:22573990

Hinatsu, Yukio; Doi, Yoshihiro

New fluorite-related quaternary rare earth oxides LnY{sub 2}TaO{sub 7} (Ln=La–Dy) and LaLn{sub 2}RuO{sub 7} (Ln=Eu–Tb) have been prepared. They crystallize in an orthorhombic superstructure of cubic fluorite with space groups C222{sub 1} and Cmcm, respectively. The results of the Rietveld analysis for LnY{sub 2}TaO{sub 7} (Ln=La–Dy) indicate that there exists no structural ordering of the Ln and Y ions at the eight-coordinate 4b site and the seven-coordinate 8c site, but the larger Ln ions occupy the eight-coordinate 4b site rather than the seven-coordinate 8c site, with increasing the Ln ionic radius. On the other hand, the results of the Rietveld analysis for the X-ray diffraction profiles of LaTb{sub 2}RuO{sub 7} showed that La and Tb atoms are almost situated at the eight-coordinated site (4a site) and seven-coordinated site (8g site), respectively, i.e., cation ordering occurs on the 4a and 8g sites. All compounds LnY{sub 2}TaO{sub 7} (Ln=La–Dy) are paramagnetic down to 1.8 K. On the other hand, LaTb{sub 2}RuO{sub 7} shows an antiferromagnetic transition at 17 K. In addition, another magnetic anomaly has been found at 10 K. Analysis of the magnetic specific heat for LaTb{sub 2}RuO{sub 7} indicates that the magnetic transitions at 10 and 17 K are due to the magnetic ordering of Tb{sup 3+} and Ru{sup 5+} ions, respectively. - Graphical abstract: Two magnetic anomalies have been observed in the temperature dependence of ∂(χT)/∂T for LaTb{sub 2}RuO{sub 7}. It is discussed that the anomalies at 10 and 17 K are due to the magnetic ordering of Tb{sup 3+} and Ru{sup 5+} ions, respectively. - Highlights: • New fluorite-related quaternary rare earth oxides Ln′Ln″{sub 2}MO{sub 7} have been prepared. • All compounds LnY{sub 2}TaO{sub 7} (Ln=La–Dy) are paramagnetic down to 1.8 K. • LaTb{sub 2}RuO{sub 7} shows two magnetic anomalies at 10 and 17 K.

• OSTI ID: 22573990
• Journal Information: Journal of Solid State Chemistry, Vol. 233; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANTIFERROMAGNETISM
CATIONS
FLUORITE
MAGNETIC PROPERTIES
MAGNETIC SPECIFIC HEAT
MAGNETIZATION
ORTHORHOMBIC LATTICES
OXIDES
PARAMAGNETISM
RUTHENIUM
RUTHENIUM IONS
SPACE GROUPS
TEMPERATURE DEPENDENCE
TERBIUM
TERBIUM IONS
X RADIATION
X-RAY DIFFRACTION
YTTRIUM IONS