SAXS and UV-Vis combined to Quick-XAFS monitoring of ZnO nanoparticles formation and growth

Nenhuma Miniatura disponível

Data

2011-01-01

Autores

Caetano, Bruno Leonardo [UNESP]
Santilli, Celso Valentim [UNESP]
Pulcinelli, Sandra Helena [UNESP]
Briois, Valerie

Título da Revista

ISSN da Revista

Título de Volume

Editor

Taylor & Francis Ltd

Resumo

Time-resolved X-ray absorption-fine structure (Quick-XAFS) and UV-Vis absorption spectroscopies were combined for monitoring simultaneously the time evolution of Zn-based species and ZnO quantum dot (Qdot) formation and growth during the sol-gel synthesis from zinc oxy-acetate precursor solution. The time evolution of the nanostructural features of colloidal suspension was independently monitored in situ by small angle X-ray scattering (SAXS). In both cases, the monitoring was initialized just after the addition of NaOH solution (B = [OH]/[Zn] = 0.5) to the precursor solution at 40 degrees C. Combined time-resolved Quick-XAFS and UV-Vis data showed that the formation of ZnO colloids from the zinc oxy-acetate consumption achieves a quasi-steady-state chemical equilibrium in less than 200s. Afterwards, the comparison of the ZnO Qdots size and Guinier gyration radius evidences a limited aggregation process coupled to the Qdots growth. The analysis of the experimental results demonstrates that the nanocrystal coalescence and Ostwald ripening control the kinetics of the Qdot growth.

Descrição

Palavras-chave

time-resolved X-ray absorption, UV-Visible absorption, SAXS, quantum dots formation, ZnO, sol-gel

Como citar

Phase Transitions. Abingdon: Taylor & Francis Ltd, v. 84, n. 8, p. 714-725, 2011.