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Title

Optical and structural properties of a Eu(II)-doped silico-aluminate with channel structure and partial site occupation

Authors
Rief, A.
Published in Zeitschrift für Naturforschung. B. 2007, vol. 62b, no. 12, p. 1535-1542
Abstract A new barium silico-aluminate phase with the stoichiometry Ba13.35(1)Al30.7Si5.3O70 has been found and characterized. The compound crystallizes in the space group P63/m (No. 176) with a = 15.1683(17), c = 8.8708(6) ˚ A, V = 1767.5(4) ˚A3, Z = 1, Rw = 0.026, 32 refined parameters. A 3- dimensional matrix of Al/SiO4 tetrahedra with Ba(II) ions located in channels along the c axis builds up the structure. One of these channels is partially filled with Ba(II) ions (CN 6+3) in Wyckoff position 2a, leaving ~ 1/3 of the positions empty. The second and third type of Ba(II) ions occupy channels orientated along the c axis with CN 4+2+2 and 4+3+1, respectively. The structure shows a rare clustered arrangement of six tetrahedra filled exclusively by Al(III) and therefore is an exception to Loewenstein's rule. The other tetrahedral positions show an Al to Si ratio of ~ 4 : 1. The Al/Si–O bond lengths in the tetrahedral Al/Si positions drawn vs. site occupation show linear behavior similar to the prediction by Vegard's rule for solid solutions. After doping with Eu(II) the compound shows bright orange-yellow luminescence with an unusual large shift of the Eu(II) emission band.
Keywords DisorderStructure refinementSilico-aluminateLuminescence
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Structures
Research group Groupe Hagemann
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RIEF, A., KUBEL, Frank, HAGEMANN, Hans-Rudolf. Optical and structural properties of a Eu(II)-doped silico-aluminate with channel structure and partial site occupation. In: Zeitschrift für Naturforschung. B, 2007, vol. 62b, n° 12, p. 1535-1542. https://archive-ouverte.unige.ch/unige:3579

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Deposited on : 2009-10-02

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