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Detailed Program
Paper Number : GL-O06
Time Frame : 13:55~14:07
Presentation Date : Thurse day, 27, November
Session Name : Glass & Optp-Electonic Materials
Session Chair 1# : Woon Jin Chung
Session Chair 2# : Hirokazu Masai
Kinetics of PbS Quantum Dots Precipitation on Nd3+-O Clusters
J. Heo
Pohang University of Science and Technology
Quantum dots (QDs) have received attention in the past years due to their unique optical and electronic properties depending on their size. Therefore, precise control on the size of QDs is important for the applications. It was reported that PbS QDs size can be controlled by the changing Er3+ , Tm3+ and La3+ ion content in glasses [1-2]. However, it has been difficult to understand the on the role of rare-earth ions during the crystallization.
Glasses containing different amount of Nd3+ ions were prepared by conventional melt-quenching methods and PbS QDs were precipitated following various pre-determined heat treatment. Diameters of QDs were calculated from positions of the absorption bands and were plotted as a function of time at different temperature. It suggested that nucleation and growth of QDs were slower than that during the classical crystallization process. (Fig. 1.) EELS analysis showed that Nd3+ ions were preferentially concentrated inside the PbS QDs compared to glass matrix after heat-treatment. EXAFS result indicates that Nd3+ ions are surrounded by oxygen ions instead of sulfur even after heat-treatment.



[Fig. 1.] Growth kinetics of PbS QDs in Nd3+-free and 0.4 mol% Nd3+ ions containing glasses. Glass was heat-treated at 500oC for 1-36h.
References:

[1] S. M. Shim, C. Liu, Y. K. Kwon, J. Heo, J. Am. Ceram. Soc., 93 (2010) 3092-3094
[2] M. A. Kim, Y. K. Kwon, C. Liu, J. Heo, J. Non-Cryst. Solids, 383 (2014) 173-175


Acknowledgements :