Electron-doping through La{sup III}-for-Sr{sup II} substitution in (Sr{sub 1-} {sub x} La {sub x} ){sub 2}FeTaO{sub 6}: Effects on the valences and ordering of the B-site cations, Fe and Ta

Journal Article · Sun Jan 15 00:00:00 EST 2006 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2005.10.004· OSTI ID:20784838

Rautama, E -L ^[1]; Chan, T S ^[2]; Liu, R S ^[2]; Chen, J M ^[3]; Yamauchi, H ^[1]; Karppinen, M ^[1]

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1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)
2. Department of Chemistry and Center for Nano Storage Research, National Taiwan University, Taipei, (China)
3. National Synchrotron Radiation Research Center, Hsinchu, (China)

We have employed aliovalent A-site cation substitution, La{sup III}-for-Sr{sup II}, to dope the Sr(Fe{sub 0.5}Ta{sub 0.5})O{sub 3} perovskite oxide with electrons. Essentially single-phase samples of (Sr{sub 1-} {sub x} La {sub x} )(Fe{sub 0.5}Ta{sub 0.5})O{sub 3} were successfully synthesized up to x{approx}0.3 in a vacuum furnace at 1400 deg. C. The samples were found to crystallize (rather than with orthorhombic symmetry) in monoclinic space group P2{sub 1}/n that accounts for the partial ordering of the B-site cations, Fe and Ta. With increasing La-substitution level, x, the degree of Fe/Ta order was found to increase such that the La-richest compositions are best described by the B-site ordered double-perovskite formula (Sr,La){sub 2}FeTaO{sub 6}. From Fe L {sub 3} and Ta L {sub 3} XANES spectra it was revealed that upon electron doping the two B-site cations, Fe{sup III} and Ta{sup V}, are both prone to reduction. Magnetic susceptibility measurements showed spin-glass type behaviour for all the samples with a transition temperature slightly increasing with increasing x. -- Graphical abstract: Valence states of Fe and Ta are controlled in the partially ordered perovskite oxide (Sr,La){sub 2}FeTaO{sub 6}, through aliovalent La{sup III}-for-Sr{sup II} substitu0010ti.

• OSTI ID: 20784838
• Journal Information: Journal of Solid State Chemistry, Vol. 179, Issue 1; Other Information: DOI: 10.1016/j.jssc.2005.10.004; PII: S0022-4596(05)00464-0; Copyright (c) 2005 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
ABSORPTION SPECTROSCOPY
CATIONS
IRON COMPOUNDS
LANTHANUM COMPOUNDS
MAGNETIC SUSCEPTIBILITY
MONOCLINIC LATTICES
ORTHORHOMBIC LATTICES
OXIDES
PEROVSKITE
SPACE GROUPS
SPIN GLASS STATE
STRONTIUM COMPOUNDS
TANTALUM COMPOUNDS
TRANSITION TEMPERATURE
VALENCE
X-RAY SPECTROSCOPY