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Title: 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

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: Hexagonalmore » 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.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Lehrstuhl fuer Festkoerperchemie, Institut fuer Physik, Universitaet Augsburg, Universitaetsstrasse 1, D-86159 Augsburg (Germany), E-mail: stefan.ebbinghaus@physik.uni-augsburg.de
  2. Lehrstuhl fuer Festkoerperchemie, Institut fuer Physik, Universitaet Augsburg, Universitaetsstrasse 1, D-86159 Augsburg (Germany)
  3. Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)
Publication Date:
OSTI Identifier:
21043767
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal 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)
Country of Publication:
United States
Language:
English
Subject:
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