Er3+ doped glasses are important for basic as well as applied science. Since the spectroscopic properties of Er3+ in the glasses are environment dependent, it is desirable to probe the local structure around Er3+ to understand the effect of different surroundings on such properties. In this work, we report results on EXAFS investigations about changes in local structure of Er3+ in two different systems: tellurite bulk glasses with different relative Zinc/Lead content and silica hafnia glass ceramics waveguides having different thermal history. Er-doped tellurite glasses (TZPE) [(70TeO2-(30-x)ZnO-xPbO)0.99-(Er2O3)0.01] with x=5, 10, 15, 20 were produced by melt quenching. SiO2-HfO2 glassy thin films were prepared following the sol-gel (SG) route and successive thermal treatments. Hafnia nanocrystals were grown inside Er-doped waveguides produced in two different ways: in the standard one, the glassy film 80SiO2-20HfO2 was heated at 900 °C for 30 min or at 1000 °C for 30 min and 24 hr; in an alternative way, HfO2 nanocrystals were mixed in the starting sol-gel composition and successively heat treated at 900 °C for 30 min, 24 hr and 48 hr. EXAFS measurements were performed at the BM08-Gilda Beamline of ESRF (Grenoble, F) in fluorescence detection configuration. In tellurite glasses, independently from Zn/Pb content, the structural information for the first shell of oxygen atoms around Er3+ give a constant distance of 2.34 Å, while coordination number (N) and Debye Waller factor (DW) were found to be ~6.5 and ~0.015 Å2 respectively, slightly increasing for x >= 10. Next nearest shells are difficult to quantify, due to high static disorder, indicating the absence of preferential bonds. In the silica-hafnia waveguides, the first shell coordination number of Erbium is reduced to about 5, but the most important difference is the presence of temperature dependent next nearest shell contributions, due to the progressive ordering of the HfO2 nanocrystals where Erbium ions are located. The paper will present in details the evolution of Er environment in different waveguides as a function of thermal history.
"Investigation of Er3+ coordination in zinc-lead tellurite bulk glasses and in silica hafnia glass ceramics waveguides"
F Rocca
2012
Abstract
Er3+ doped glasses are important for basic as well as applied science. Since the spectroscopic properties of Er3+ in the glasses are environment dependent, it is desirable to probe the local structure around Er3+ to understand the effect of different surroundings on such properties. In this work, we report results on EXAFS investigations about changes in local structure of Er3+ in two different systems: tellurite bulk glasses with different relative Zinc/Lead content and silica hafnia glass ceramics waveguides having different thermal history. Er-doped tellurite glasses (TZPE) [(70TeO2-(30-x)ZnO-xPbO)0.99-(Er2O3)0.01] with x=5, 10, 15, 20 were produced by melt quenching. SiO2-HfO2 glassy thin films were prepared following the sol-gel (SG) route and successive thermal treatments. Hafnia nanocrystals were grown inside Er-doped waveguides produced in two different ways: in the standard one, the glassy film 80SiO2-20HfO2 was heated at 900 °C for 30 min or at 1000 °C for 30 min and 24 hr; in an alternative way, HfO2 nanocrystals were mixed in the starting sol-gel composition and successively heat treated at 900 °C for 30 min, 24 hr and 48 hr. EXAFS measurements were performed at the BM08-Gilda Beamline of ESRF (Grenoble, F) in fluorescence detection configuration. In tellurite glasses, independently from Zn/Pb content, the structural information for the first shell of oxygen atoms around Er3+ give a constant distance of 2.34 Å, while coordination number (N) and Debye Waller factor (DW) were found to be ~6.5 and ~0.015 Å2 respectively, slightly increasing for x >= 10. Next nearest shells are difficult to quantify, due to high static disorder, indicating the absence of preferential bonds. In the silica-hafnia waveguides, the first shell coordination number of Erbium is reduced to about 5, but the most important difference is the presence of temperature dependent next nearest shell contributions, due to the progressive ordering of the HfO2 nanocrystals where Erbium ions are located. The paper will present in details the evolution of Er environment in different waveguides as a function of thermal history.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
