Preparation and optical properties of trivalent europium doped into cordierite using the sol-gel process

Resumo

The photoluminescence properties of the Eu3+ ion doped into α-cordierite were studied based on the excitation and emission spectra and lifetime measurements. These samples were prepared by the sol-gel method and calcined by heating the xerogel at different temperatures: 873, 1133, 1223 and 1473K. X-ray diffraction patterns were used to characterize the luminescent material. The 5D0→7F0 transition of the samples exhibits only one broad peak arising from the inhomogeneous linewidth of the amorphous phase, except for the ceramic material obtained at 1473K that presents two peaks. Also, in the latter case the luminescence decay lifetime exhibits a bi-exponential fit when excited at 280nm, corroborating that the Eu3+ ion exists in two sites of symmetry. The experimental intensity parameter Ω2 (10.0×10-20cm2) indicates a moderately polarizable chemical environment around the Eu3+ ion. The emission spectra of the Mg2Al4Si5O18:Eu3+ samples calcined at 873, 1133 and 1223K also presented inhomogeneous profiles for the 5D0→7FJ transitions suggesting disorder of the material. On the other hand, the sample calcined at 1473K shows narrow bands indicating the crystalline form. The emission quantum efficiency (η) of the α-cordierite system is also discussed. © 2003 Elsevier Science (USA). All rights reserved.

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