Fluorescence properties of Sm2+ ions in silicate glasses

The fluorescence properties of Sm2+ ions incorporated in silicate glasses were investigated using steady-state and laser-induced line narrowing techniques. Sm2+ ions were incorporated in the glass matrix by heating the Sm3+ ion-containing glasses in H-2 gas. The reaction of Sm3+ into Sm2+ was accelerated with increasing temperature. The fluorescence intensity of the Sm2+ ions increased with heating to 800 degrees C. Further heating above 900 degrees C precipitated mullite crystals. Accordingly, the fluorescence intensity of the Sm2+ ions abruptly decreased and the fluorescence of Sm3+ ions again appeared. Sm2+ ions are preferentially coordinated with Al-O polyhedrons. The crystallization of mullite induces the decrease in Al2O3 content in the remaining glassy phase, resulting in the redox equilibrium producing the high valence samarium ion. Three Stark splitting fluorescence peaks of the D-5(0) --> F-7(1) transition were analyzed to determine the parameters of the crystal field surrounding the Sm2+ ion. The decrease in the number of Al-O bonds surrounding Sm2+ causes the Sm2+ ions' coordination number to decrease with the short distance of the Sm-O bonds. (C) 1996 American Institute of Physics.