3,126 research outputs found
Ken Friedenreich Interview
No full textThis interview is an oral history conducted by Linfield College student Camille Weber with Ken Friedenreich. The interview took place at the Jereld R. Nicholson Library at Linfield College on October 16, 2015.
Ken Friedenreich is an author who has written about Oregon wine and its history. The interview includes how he got interested in wine, what it\u27s like to write about wine for a living, the effects that prohibition had on Oregon, and advice for people new to wine
Kinetic Analysis of the Redox Reaction in an Aqueous Vanadium-Oxalate System
No full textThe redox reaction between dioxovanadium(V) and oxalate is proposed as a suitable system to analyze the kinetics of a two-step reaction mechanism using UV-vis spectroscopy. First, the spectra of dioxovanadium(V) and its reduced counterpart oxovanadium(IV) are compared and explained using the crystal field theory. The change in absorbance can be used to determine the reaction order and rate equation by the method of initial rates. Next, the students are introduced to the Guggenheim time-lag method to calculate the apparent rate constant. By performing the experiment at different temperatures, ranging from 20 to 50 degrees C, an Arrhenius plot can be constructed to obtain the activation energy for this redox reaction
Solution synthesis of Al doped ZnO transparent electrodes: mission impossible or need for more insight?
No full textTransparent conducting oxides (TCO) are gaining increasing importance, not only in solar panels, but also in various new thin film based technologies. The herewith increasing demand of TCO’s is associated with immense scientific and economic challenges: First, reliable synthesis routes have to be developed that allow mass production at justifyable cost. Solution based deposition is in this respect an appealing alternative to standard physical deposition methods, as they often require (high) vacuum conditions. Second, the vastly increasing demands for TCO materials motivate the search for cost-effective alternatives to Indium doped Tin Oxide (ITO). (Doped) zinc oxide (ZnO) is among such promising alternatives. Although the proposed routes and materials have important advantages, some crucial challenges jeopardize their success in e.g. energy applications.
We investigate and compare various approaches to synthesize Aluminium doped ZnO. A first route is based on precursor solutions comprising the dissolution of molecular precursors followed by solution deposition on a substrate. A thermal treatment is then needed to transform the molecular precursor into the desired (crystalline) oxide. A second route starts with the preparation of TCO nanoparticles, which are consecutively dispersed in a liquid before deposition and thermal treatment. We address experimental strategies towards optimizing the molecular precursor routes in terms of less toxic solvents and lower temperature thermal treatments [1]. For the nanoparticle based routes we assess the intrinsic potential of a nanoparticle precursor by focussing on the effectiveness of the doping [2,3].
Through in depth characterisation we correlate synthesis conditions to the TCO properties. Hence we try to understand and tackle the intrinsic challenges of solution processing and progress towards functional printed TCO layers competitive with sputtered coatings.
References
1. H. Damm, P. Adriaensens, C. De Dobbelaere, B. Capon, K. Elen, J. Drijkoningen, B. Conings, J.V. Manca, J. D’Haen, C. Detavernier, agusin, J. Hadermann, A. Hardy and M.K. Van Bael, Chemistry of Materials, 26, 20, 5839 (2014).
2. H. Damm, A. Kelchtermans, A. Bertha, F. Van den Broeck, K. Elen, J.C. Martins, R. Carleer, J. D’Haen, C. De Dobbelaere, J. Haderman, A. Hardy and M.K. Van Bael, RSC Advances, 3, 45, 23745 (2013)
3. A. Kelchtermans, K. Elen, K. Schellens, B. Conings, H. Damm, H.G. Boyen, J. D’Haen, P
Solution synthesis of Al doped ZnO transparent electrodes: mission impossible or need for more insight?
No full textTransparent conducting oxides (TCO) are gaining increasing importance, not only in solar panels, but also in various new thin film based technologies. The herewith increasing demand of TCO’s is associated with immense scientific and economic challenges: First, reliable synthesis routes have to be developed that allow mass production at justifyable cost. Solution based deposition is in this respect an appealing alternative to standard physical deposition methods, as they often require (high) vacuum conditions. Second, the vastly increasing demands for TCO materials motivate the search for cost-effective alternatives to Indium doped Tin Oxide (ITO). (Doped) zinc oxide (ZnO) is among such promising alternatives. Although the proposed routes and materials have important advantages, some crucial challenges jeopardize their success in e.g. energy applications.
We investigate and compare various approaches to synthesize Aluminium doped ZnO. A first route is based on precursor solutions comprising the dissolution of molecular precursors followed by solution deposition on a substrate. A thermal treatment is then needed to transform the molecular precursor into the desired (crystalline) oxide. A second route starts with the preparation of TCO nanoparticles, which are consecutively dispersed in a liquid before deposition and thermal treatment. We address experimental strategies towards optimizing the molecular precursor routes in terms of less toxic solvents and lower temperature thermal treatments [1]. For the nanoparticle based routes we assess the intrinsic potential of a nanoparticle precursor by focussing on the effectiveness of the doping [2,3].
Through in depth characterisation we correlate synthesis conditions to the TCO properties. Hence we try to understand and tackle the intrinsic challenges of solution processing and progress towards functional printed TCO layers competitive with sputtered coatings.
References
1. H. Damm, P. Adriaensens, C. De Dobbelaere, B. Capon, K. Elen, J. Drijkoningen, B. Conings, J.V. Manca, J. D’Haen, C. Detavernier, agusin, J. Hadermann, A. Hardy and M.K. Van Bael, Chemistry of Materials, 26, 20, 5839 (2014).
2. H. Damm, A. Kelchtermans, A. Bertha, F. Van den Broeck, K. Elen, J.C. Martins, R. Carleer, J. D’Haen, C. De Dobbelaere, J. Haderman, A. Hardy and M.K. Van Bael, RSC Advances, 3, 45, 23745 (2013)
3. A. Kelchtermans, K. Elen, K. Schellens, B. Conings, H. Damm, H.G. Boyen, J. D’Haen, P
Event Invitation: An Evening with Dr. Ken Robinson
No full textInvitation:
Guest speaker, Dr. Ken Robinson, author of “Out of Our Minds: Learning to be Creative, ” will speak on the importance of arts, the development of creativity, education, and the economy. And, introducing the inaugural DaVinci Scholars Awards program
Synthesis of Ceria Coatings on Soda-Lime Glass via Solution-Gel Process: The Role of Cerium Citrate Precursor Species
No full textThe solution-gel coating approach offers versatility in tailoring material composition and properties, allowing for the creation of uniform, homogeneous coatings on various substrates. 1, 2 The research presented can be related to the spray coating of spherically curved glass beads with ceria from a solution-gel precursor solution.
While significant research exists in sol-gel chemistry mechanisms, there remains a need for a more detailed understanding of how the specific chemical species in the precursor solution might influence the properties of the resulting coatings. This would enable a precise prediction and tailoring of the microstructure, morphology, and functional characteristics of ceria coatings obtained from these precursors by spray coating.
Citric acid is highly valued in solution-gel precursors as it chelates with metal ions, stabilizing them and enhancing the homogeneity of the coating. It can also form oxides at low temperatures. 3 However, the complexes formed are highly pH-dependent. A speciation plot was created to understand this and relate it to the coating characteristics, such as smoothness and homogeneity. Relevant species were determined by combining experimental potentiometry data with the speciation program Hyperquad2013. As the pH increases, the citrate ligands are deprotonated. Above pH 7 hydroxyl ions replace citrate ligands. ESI-MS data were obtained in addition to the speciation simulations to confirm the presence of simulated species in precursor solutions at a specific pH.
We speculate that the coating process and the resultant film properties are influenced by the cerium citrate species due to the variable chemical and physical properties of the species present at different pH levels. For example, we hypothesize that the coating uniformity and adherence are enhanced with increasing pH as a result of the increased number of hydroxyl ions in a species that reacts with surface hydroxyl functionalities by the formation of Ce-O-Si bonds. 2
References see attachment
Synthesis of Ceria Coatings on Soda-Lime Glass via Solution-Gel Process: The Role of Cerium Citrate Precursor Species
No full textThe solution-gel coating approach offers versatility in tailoring material composition and properties, allowing for the creation of uniform, homogeneous coatings on various substrates. 1, 2 The research presented can be related to the spray coating of spherically curved glass beads with ceria from a solution-gel precursor solution.
While significant research exists in sol-gel chemistry mechanisms, there remains a need for a more detailed understanding of how the specific chemical species in the precursor solution might influence the properties of the resulting coatings. This would enable a precise prediction and tailoring of the microstructure, morphology, and functional characteristics of ceria coatings obtained from these precursors by spray coating.
Citric acid is highly valued in solution-gel precursors as it chelates with metal ions, stabilizing them and enhancing the homogeneity of the coating. It can also form oxides at low temperatures. 3 However, the complexes formed are highly pH-dependent. A speciation plot was created to understand this and relate it to the coating characteristics, such as smoothness and homogeneity. Relevant species were determined by combining experimental potentiometry data with the speciation program Hyperquad2013. As the pH increases, the citrate ligands are deprotonated. Above pH 7 hydroxyl ions replace citrate ligands. ESI-MS data were obtained in addition to the speciation simulations to confirm the presence of simulated species in precursor solutions at a specific pH.
We speculate that the coating process and the resultant film properties are influenced by the cerium citrate species due to the variable chemical and physical properties of the species present at different pH levels. For example, we hypothesize that the coating uniformity and adherence are enhanced with increasing pH as a result of the increased number of hydroxyl ions in a species that reacts with surface hydroxyl functionalities by the formation of Ce-O-Si bonds. 2
References see attachment
Synthesis and in depth characterisation of ZnO:Al nanoparticles as building blocks for printed TCO layers
No full text
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