The new rare earth-based germanate compound Ca2Gd2Ge2O9 (orthorhombic (Pnma) crystal structure), has been characterized and investigated for the first time, using synchrotron powder X-ray diffraction. From Rietveld refinement calculations on the collected powder pattern we observe an inhomogeneous distribution of the two available cationic sites by Gd3+ and Ca2+ ions. In particular, the former prefers the occupation (67.5%) of the site with 8-fold coordination. In addition, we observed a not negligible degree of distortion of the Ge2O76- unit Finally, luminescence spectra and decay curves of Eu3+ doped Ca2Gd2Ge2O9 were measured and analysed taking into account the structural features of the host. The results reveal that this material shows strong red luminescence upon excitation in the region where blue LEDs emit (470 nm)

Structural study of Ca2Gd2Ge2O9 and optical spectroscopy of the Eu3+ dopant ion

PICCINELLI, FABIO;PEDRONI, Marco;SPEGHINI, Adolfo;BETTINELLI, Marco Giovanni
2014-01-01

Abstract

The new rare earth-based germanate compound Ca2Gd2Ge2O9 (orthorhombic (Pnma) crystal structure), has been characterized and investigated for the first time, using synchrotron powder X-ray diffraction. From Rietveld refinement calculations on the collected powder pattern we observe an inhomogeneous distribution of the two available cationic sites by Gd3+ and Ca2+ ions. In particular, the former prefers the occupation (67.5%) of the site with 8-fold coordination. In addition, we observed a not negligible degree of distortion of the Ge2O76- unit Finally, luminescence spectra and decay curves of Eu3+ doped Ca2Gd2Ge2O9 were measured and analysed taking into account the structural features of the host. The results reveal that this material shows strong red luminescence upon excitation in the region where blue LEDs emit (470 nm)
2014
Rietveld refinement; Crystal structure; X-ray diffraction
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/728161
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