Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Chemical Vapor Synthesis and Characterization of Aluminum Nitride Nanoparticles as Precursors for Phosphors
The aim of this work is to develop a process able to synthesize high quality aluminum nitride nanoparticles suitable for use as precursors in the production of phosphors. This is achieved by combining theoretical and experimental approaches to synthesis optimization, thorough characterization of the synthesized nanoparticles as well as phosphor synthesis and characterization. Triethylaluminum (TEAl) and ammonia are reacted in the gas phase inside a chemical vapor synthesis (CVS) reactor. The numerical simulations performed using the reaction-coagulation-sintering model (cvssin) suggest that unagglomerated AlN particles with diameters below 10 nm can be synthesized at temperatures above 1500 °C and pressures below 50 mbar. The experimental results agree very well with these simulations, except at low temperatures where the particle growth may be dominated by surface growth not included in the model. Phase-pure wurtzite AlN nanocrystals are obtained at all tested process parameters. Importantly, experiments confirm the possibility of synthesizing particles below 10 nm and no hard agglomerates by the CVS method. A Monte Carlo type algorithm (cvssinmc) is used to discover new process parameters for the synthesis of nanoparticles with specified characteristics. The result is a dual-zone temperature profile meant to separate coagulation and coalescence processes in order to produce nanoparticles with no hard agglomeration. The synthesized AlN nanoparticles are structurally characterized by a combination of X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and X-ray absorption spectroscopy (XANES and EXAFS). While the data indicate partially disordered systems, combined analysis reveals that the observed disorder is a direct consequence of the nanoparticles’ small size, i.e. the large surface to volume ratios. The nanoparticles produced by the CVS process are highly crystalline with particle surface playing a dominant role in determining the amount of disorder present in the nanoparticles below 6 nm. Small ...
Chemical Vapor Synthesis and Characterization of Aluminum Nitride Nanoparticles as Precursors for Phosphors
The aim of this work is to develop a process able to synthesize high quality aluminum nitride nanoparticles suitable for use as precursors in the production of phosphors. This is achieved by combining theoretical and experimental approaches to synthesis optimization, thorough characterization of the synthesized nanoparticles as well as phosphor synthesis and characterization. Triethylaluminum (TEAl) and ammonia are reacted in the gas phase inside a chemical vapor synthesis (CVS) reactor. The numerical simulations performed using the reaction-coagulation-sintering model (cvssin) suggest that unagglomerated AlN particles with diameters below 10 nm can be synthesized at temperatures above 1500 °C and pressures below 50 mbar. The experimental results agree very well with these simulations, except at low temperatures where the particle growth may be dominated by surface growth not included in the model. Phase-pure wurtzite AlN nanocrystals are obtained at all tested process parameters. Importantly, experiments confirm the possibility of synthesizing particles below 10 nm and no hard agglomerates by the CVS method. A Monte Carlo type algorithm (cvssinmc) is used to discover new process parameters for the synthesis of nanoparticles with specified characteristics. The result is a dual-zone temperature profile meant to separate coagulation and coalescence processes in order to produce nanoparticles with no hard agglomeration. The synthesized AlN nanoparticles are structurally characterized by a combination of X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and X-ray absorption spectroscopy (XANES and EXAFS). While the data indicate partially disordered systems, combined analysis reveals that the observed disorder is a direct consequence of the nanoparticles’ small size, i.e. the large surface to volume ratios. The nanoparticles produced by the CVS process are highly crystalline with particle surface playing a dominant role in determining the amount of disorder present in the nanoparticles below 6 nm. Small ...
Chemical Vapor Synthesis and Characterization of Aluminum Nitride Nanoparticles as Precursors for Phosphors
Ognjanović, Stevan (Autor:in) / Winterer, Markus
03.12.2019
Hochschulschrift
Elektronische Ressource
Englisch
Properties of Nanosize Aluminum Nitride Powders Synthesized by Chemical Vapor Synthesis
| British Library Online Contents | 2010
Synthesis and characterization of nano-scale aluminum nitride produced from vapor phase
| British Library Online Contents | 2001
Aluminum titanium nitride films grown with multiple precursors
| British Library Online Contents | 1999
| British Library Online Contents | 2001
Porous silicon nitride ceramic phosphors
| British Library Online Contents | 2005