Ultramarine colored: Solid-phase elution of Pt into perovskite oxides
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Ultramarine colored: Solid-phase elution of Pt into perovskite oxides Katsuhiro Nomuraa) Research Institute for Ubiquitous Energy Devices,National Institute of Advanced Industrial Science and Technology (AIST), Midorigaoka, Ikeda, Osaka 563-8577, Japan
Masakazu Daté Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Onogawa, Tsukuba, Ibaraki 305-8569, Japan
Hiroyuki Kageyama Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST), Midorigaoka, Ikeda, Osaka 563-8577, Japan
Susumu Tsubota Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Onogawa, Tsukuba, Ibaraki 305-8569, Japan (Received 4 May 2007; accepted 28 June 2007)
We have found a new route for preparing Pt containing perovskites. Ba containing perovskite powder, (La0.7Sr0.2Ba0.1)ScO3–␦ (LSBS), reacted with Pt foil at 1898 K in air, and formed ultramarine colored Pt containing perovskite, (La0.7Sr0.2Ba0.1)(Sc,Pt)O3–␦, without changing the GdFeO3-type structure. The chemical compositions of the samples before and after firing, measured with inductively coupled plasma (ICP) optical emission spectrometry, were La: Sr: Ba: Sc ⳱ 0.70(1): 0.206(4): 0.101(2): 0.98(2) and La: Sr: Ba: Sc: Pt ⳱ 0.70(1): 0.197(4): 0.085(2): 0.95(2): 0.0062(2), respectively. The reaction proceeded not only at the interface between perovskite powder and Pt foil, but also over whole powder surface. We name this new preparation method the “solid-phase elution (SE) method”, because the process involves elution of Pt ions from the Pt foil to the LSBS perovskite lattice. It is expected that we can control the amount of Pt introduced into perovskites by using the SE method after optimizing the reaction time and temperature.
In the last few decades, perovskite-type and perovskite-related oxides have been intensively investigated for use as electrode materials, electrolyte materials, high Tc super-conductors, oxidation catalysts, etc.1 Of these, some electrode materials and oxidation catalysts contain Pt in their crystal structures and show higher catalytic activities.2–6 In general, Pt containing oxides can be divided into two groups, i.e., those containing partially oxidized Ptn+ (n < 4) ions with a square planer coordination PtO4 and those containing fully oxidized Pt4+ ions with an octahedral coordination PtO6.7 Pt containing perovskites belong to the latter group. So far, Pt containing perovskite-type and perovskite-related oxides have been prepared by the following routes: (i) a flux method a)
Address all correspondence to this author. e-mail: nomura-k@aist.go.jp DOI: 10.1557/JMR.2007.0340 J. Mater. Res., Vol. 22, No. 10, Oct 2007
using the flux of raw material in a Pt crucible, e.g., (La0.7Pb0.3)MnO3 single crystal containing 0–5200 ppm of Pt from lead borate flux,3,4 Ba3Pt2O7 single crystal from BaCl2 flux containing a trace amount of Ba(OH)2,8 (ii) a sol
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