Day 2 :
VOJISLAV MITIĆ completed his B.Sc. from University of Nis in the year 1982, M.Sc. from University of Belgrade in the year 1990 and Ph.D. from University of Nis in the year 1995. Currently he is working as a Full Professor as a Faculty of Electronic Engineering, University of Nis.
The nature of ceramics grains contacts play an essential role in understanding complex electric and dielectric properties of electronic ceramics materials. Morphology of ceramics grains and pores as well as Brownian character of particle dynamics inside ceramics materials contributes to better understanding of the sintering process which is of basic importance in further electro-physical properties. Real inter-grain contact surfaces are highly irregular objects that can be described in the only adequate way, using fractal nature analysis. Using the method of fractal analysis, the micro-nanostructure configurations reconstruction, like shapes of grains pores or intergranular contacts is possible. Besides, we re-investigate intergranular capacity model as well as Heywang fractal modified model from the point of view of intergranular fractal formations. The area of grains’ surface is calculated by using fractal correction that expresses the irregularity of grains surface through fractal dimension. This leads towards a more exact calculates of ceramics’ electronics properties as well as more realistic understanding of electrical behavior of barium-titanate and other electronic ceramics materials and refractory ceramics, fly ashes, etc. In order to obtain an equivalent circuit model, which provides a more realistic representation of the electronic materials’ electrical properties, we have determined and implemented an intergranular contacts model for the BaTiO3 electrical properties characterization in this paper. On the basis of micro-nanostructure fractal relations, a prognosis of the electronic properties of material can be deduced. Consi¬dering the obtained results, the new frontiers for deeper and higher level electronics circuit microelectronic integration are established, which is what is practically leading towards the new frame of fractal electronics.
- Track: 1 Fundamentals fromTheory to Practice; Track: 2 Electro-Magnetic and Optical Ceramics and Devices; Track: 3 Bioceramics and Health; Track: 4 Ceramics Under Severe Environments and Refractories
Marius Stan is the National Technical Director of the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. He is also a Senior Computational Energy Scientist at Argonne National Laboratory, a Senior Fellow of the Computation Institute at University of Chicago, and a Senior Fellow of the Institute for Science and Engineering at Northwestern University. His main research interests include multi-scale and multi-physics models and simulations of heat and mass transport in ceramics and metals for energy applications.
Modern society has increasing energy needs that require new materials with significantly improved properties. Advanced mathematical modeling and high performance computer simulation, coupled with experimental validation, contribute to enhancing the understanding of the complex phenomena that occur in materials at multiple time and length scales. This presentation reviews recent computational materials science results focused on improving the understanding of heat and chemical (oxygen, fission products) transport in uranium oxide – a ceramic material of high importance for nuclear energy applications. After a brief description of the multi-scale methodology – density functional theory (DFT+U), molecular dynamics (MD), and continuum (FEM) methods – recent results capturing temperature effects and the impact of defects on oxygen diffusivity and thermal conductivity of UO2 are discussed, with an emphasis on the complezxity of the physics and chemistry of the material. The results show a strong driving force for oxygen interstitials to form clusters, wth significant impact on the properties of the UO2 fluorite phase and neighboring compounds. The diffusion properties are a function of the cluster size, with the large clusters exhibiting high mobility through a multi-step mechanism. Experimental validation is also examined, especially the need for dedicated validation experiments. The presentation ends with a discussion of opportunities in the high-performance computing space for improved simulations of heat and chemical species transport in ceramics in general, and in UO2 in particular.
Magdy Y. Abdelaal was born and obtained his PhD in 1991 from Mansoura University, Egypt in collaboration with FU-Berlin, Germany. He is a Professor of Polymer Chemistry at Mansoura University and at KAU, Saudi Arabia on sabbatical since 2004. He has cross-cooperation with many institutions including NIMC and Toyohashi University of Technology, Japan; LNF/INFN, Italy and most institutions in Egypt. He has published 45 papers in reputed journals and served as a reviewer for many international journals. His research focuses on polymers and their nano-composites in wastewater treatment, polymer recycling, pharmaceutical and biomedical applications and as templates for photonanocatalysts preparation.
Chitosan (CS) was included in the preparation of different metal oxides nanoparticles by using a modified sol-gel technique to improve the morphology of the obtained nanoparticles. Titanium oxide (TiO2) and Zirconium oxide (ZrO2) nanoparticles have been prepared separately in presence of CS and/or Palladium (Pd). Similar experiments were conducted in absence of CS to evaluate its impact on the nanoparticles morphology and the obtained nanoparticles have been characterized with XRD, TEM, UV/Vis, PI and BET techniques. The results revealed that CS can effectively prevent the agglomeration of the nanoparticles in both cases of TiO2 and ZrO2 and the nanoparticles are distributed in homogeneous domains within the matrix. Photo catalytic activity was investigated under visible light irradiation by using methylene blue (MB) and thiophene (TH) as model pollutants for TiO2 and ZrO2, respectively. UV-Vis spectroscopic investigation demonstrated that the composite’s ability to absorb visible light is greatly improved which is reflected on its efficacy to degrade the organic pollutants used. Recycling experiments confirmed the relative stability of the catalysts. They were reproducible without significant loss in their activity during the first five cycles.