Ln{sub 2}Sr{sub 2}PtO{sub 7+{delta}} (Ln=La, Pr, and Nd): Three new Pt-containing [A{sub 2}{sup '}O{sub 1+{delta}}] [A{sub n}B{sub n-1}O{sub 3n}]-type hexagonal perovskites

Journal Article · Sat Dec 15 00:00:00 EST 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.10.005· OSTI ID:21043767

Erztoument, Chasanoglou ^[1]; Marozau, Ivan ^[2]

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1. Lehrstuhl fuer Festkoerperchemie, Institut fuer Physik, Universitaet Augsburg, Universitaetsstrasse 1, D-86159 Augsburg (Germany)
2. Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

Polycrystalline samples of Ln{sub 2}Sr{sub 2}PtO{sub 7+{delta}} (Ln=La, Pr, Nd) were prepared by conventional solid state synthesis. The three compounds are new examples for n=2 members of the [A{sub 2}{sup '}O{sub 1+{delta}}][A{sub n}B{sub n-1}O{sub 3n}] family of hexagonal perovskites containing platinum as the B-type cation. XRD Rietveld refinements show the platinates to crystallize in space group R3-bar and, in the case of Pr and Nd, revealed a complete ordering of Ln/Sr on the two distinct A-type positions, while for La a partial disorder was observed. By XANES investigations at the Pt-L{sub III} threshold the oxidation state +4 for platinum was found. Thermogravimetry revealed a small oxygen excess for Ln=La and Pr ({delta}=0.13 and 0.07), pointing to the presence of peroxide ions as already observed for isostructural Ru- and Ir-based compounds. UV-Vis measurements were done for the yellow lanthanum and the green neodymium compound. They revealed two optical band gaps of 2.52 and 3.05 eV, respectively. Magnetic measurements showed La{sub 2}Sr{sub 2}PtO{sub 7+{delta}} to be diamagnetic as expected for Pt{sup 4+} with low-spin (t{sub 2g}{sup 6}) configuration. For Ln=Pr and Nd the observed strong paramagnetism can be explained solely by the magnetic moments of the rare earths. - Graphical abstract: Hexagonal perovskites of the [A{sub 2}{sup '}O{sub 1+{delta}}][A{sub n}B{sub n-1}O{sub 3n}] family have so far only been known for the transition metals Mn, Nb, Ru, and Ir. In this paper, three new n=2 examples containing platinum as B-type cation are presented. The structure and physical properties of the three title compounds were investigated by XRD Rietveld refinements, thermogravimetry, X-ray absorption spectroscopy, magnetic measurements and optical spectroscopy.

• OSTI ID: 21043767
• Journal Information: Journal of Solid State Chemistry, Vol. 180, Issue 12; Other Information: DOI: 10.1016/j.jssc.2007.10.005; PII: S0022-4596(07)00415-X; Copyright (c) 2007 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
EV RANGE 01-10
LANTHANUM COMPOUNDS
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
NEODYMIUM COMPOUNDS
OXIDES
OXYGEN
PARAMAGNETISM
PEROVSKITES
PEROXIDES
PLATINUM COMPOUNDS
PLATINUM IONS
POLYCRYSTALS
PRASEODYMIUM COMPOUNDS
SPACE GROUPS
STRONTIUM COMPOUNDS
SYNTHESIS
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY