It is well-known that when an RE2Si2O7 matrix is doped with active lanthanide ions, it displays promising luminescent responses for optical applications. The crystalline structure adopted by the silicate matrix as well as the distribution of the dopants among the available RE crystallographic sites have important effects on the luminescent yields of these compounds. The present study is aimed at analyzing the structural behavior as well as the luminescent properties of Ho3+-substituted La 2Si2O7. Several compositions across the La 2Si2O7-Ho2Si2O 7 system were synthesized using the sol-gel method followed by calcination at 1600 C. The resulting powders were analyzed by means of X-ray and neutron diffraction to determine the phase stabilities across the system. The results indicated a solid solubility region of G-(La,Ho)2Si 2O7 which extends to the La0.6Ho 1.4Si2O7 composition. Compositions richer in Ho3+ show a two-phase domain (G+δ), while δ-(La,Ho) 2Si2O7 is the stable phase for Ho3+ contents higher than 90% (La0.2Ho1.8Si2O 7). Anomalous diffraction data interestingly indicated that the La3+ for Ho3+ substitution mechanism in the G-(La,Ho) 2Si2O7 polymorph is not homogeneous, but a preferential occupation of Ho3+ for the RE2 site is observed. The Ho3+-doped G-La2Si2O7 phosphors exhibited a strong green luminescence after excitation at 446 nm. Lifetime measurements indicated that the optimum phosphor was that with a Ho3+ content of 10%. © 2013 American Chemical Society.

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