International Journal of Materials Research, Sep 1, 2006
This paper deals with the densification and phase transformation of Si3N4 with additives of Li-ex... more This paper deals with the densification and phase transformation of Si3N4 with additives of Li-exchanged zeolite during pressureless sintering at significantly reduced temperatures. Dilatometric shrinkage data show that the first liquid forms as low as 1080 °C. Upon sintering at 1500 °C the bulk density increases to more than 95% of the theoretical density without phase transformation from α-S3N4 to β-Si3N4, i. e. the phase transformation lags behind the densification process. Above 1500 °C the secondary phase is completely converted into a glass and the α-to-β transformation takes place. Under these conditions the grain growth is anisotropic, leading to a microstructure which has potential for enhanced fracture toughness. The results show that a very effective low-temperature sintering additive for silicon nitride can be obtained from Li-exchanged zeolite.
Ca0.9Gd0.1MnO3 nanopowders with perovskite type crystal structure were synthesized by modified gl... more Ca0.9Gd0.1MnO3 nanopowders with perovskite type crystal structure were synthesized by modified glycine nitrate procedure. Nanopowders were prepared by combining glycine with metal nitrates and/or metal acetates in their appropriate stoichiometric ratios. Modification of the procedure was performed by partial replacement of nitrates by acetates, in order to control the burn-up reaction. Obtained Ca0.9Gd0.1MnO3 powders were calcinated in the temperature interval
Journal of Physics and Chemistry of Solids, Nov 1, 2018
Abstract Ab initio calculations using hybrid B3LYP functional were performed in order to investig... more Abstract Ab initio calculations using hybrid B3LYP functional were performed in order to investigate structural, electronic and mechanical properties of aluminum nitride as function of pressure. Electronic properties of the experimentally observed aluminum nitride modifications at standard and high pressures have been investigated. Furthermore, mechanical properties for each of the predicted and experimentally observed AlN modifications have been investigated in order to get insight into the phase stability. In addition, ductility/brittleness relationship, character of the bonding, and the relationship between calculated hardness Hv, Young's modulus E, bulk modulus B, and shear modulus K have been investigated. In this way, we address new possibilities for improving the mechanical and elastic properties of AlN based ceramic materials, as well as possible band gap tuning, which might have applications in optoelectronic devices.
This paper presents the technological process for obtaining basalt-stainless steel composite mate... more This paper presents the technological process for obtaining basalt-stainless steel composite materials and testing their physical and mechanical properties. The phases of the technological process consist of: milling, homogenization, pressing, and sintering to obtain composite materials with improved fracture toughness. Andesite basalt from the deposit site "Donje Jarinje", Serbia, was used as a matrix in the composites, while commercial austenitic stainless steel 316L in the amount of 0-30 wt.% was used as a reinforcement. Although the increase of 316L amount caused a continuous decrease in the relative density of sintered samples, the relative density of sample containing 30 wt.% of 316L was above 94%. The 316L grains, which possess a larger coefficient of thermal expansion than the basalt matrix, shrinking faster during cooling from sintering temperature resulting in the formation of compressive residual stress in the basalt matrix surrounding the spherical steel grains...
Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3P... more Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3PO4 at room temperature. X-ray powder diffraction analysis and Raman spectroscopy reviled that synthesized powder was single-phase. Using scanning electron microscopy analysis, it was found that the synthesized Ag3PO4 particles were near-spherical shape with an average diameter of 100 nm. The high value for the specific surface area of obtained powder was measured by Brunauer?Emmet?Teller method. Finally, the Ag3PO4 product was used as a photocatalyst for the photodegradation of crystal violet dye in an aqueous solution. Nanoemulsion strategy procedure provides a simple pathway to obtain a highly efficient single-phase Ag3PO4 photocatalyst.
International Journal of Materials Research, Sep 1, 2006
This paper deals with the densification and phase transformation of Si3N4 with additives of Li-ex... more This paper deals with the densification and phase transformation of Si3N4 with additives of Li-exchanged zeolite during pressureless sintering at significantly reduced temperatures. Dilatometric shrinkage data show that the first liquid forms as low as 1080 °C. Upon sintering at 1500 °C the bulk density increases to more than 95% of the theoretical density without phase transformation from α-S3N4 to β-Si3N4, i. e. the phase transformation lags behind the densification process. Above 1500 °C the secondary phase is completely converted into a glass and the α-to-β transformation takes place. Under these conditions the grain growth is anisotropic, leading to a microstructure which has potential for enhanced fracture toughness. The results show that a very effective low-temperature sintering additive for silicon nitride can be obtained from Li-exchanged zeolite.
Ca0.9Gd0.1MnO3 nanopowders with perovskite type crystal structure were synthesized by modified gl... more Ca0.9Gd0.1MnO3 nanopowders with perovskite type crystal structure were synthesized by modified glycine nitrate procedure. Nanopowders were prepared by combining glycine with metal nitrates and/or metal acetates in their appropriate stoichiometric ratios. Modification of the procedure was performed by partial replacement of nitrates by acetates, in order to control the burn-up reaction. Obtained Ca0.9Gd0.1MnO3 powders were calcinated in the temperature interval
Journal of Physics and Chemistry of Solids, Nov 1, 2018
Abstract Ab initio calculations using hybrid B3LYP functional were performed in order to investig... more Abstract Ab initio calculations using hybrid B3LYP functional were performed in order to investigate structural, electronic and mechanical properties of aluminum nitride as function of pressure. Electronic properties of the experimentally observed aluminum nitride modifications at standard and high pressures have been investigated. Furthermore, mechanical properties for each of the predicted and experimentally observed AlN modifications have been investigated in order to get insight into the phase stability. In addition, ductility/brittleness relationship, character of the bonding, and the relationship between calculated hardness Hv, Young's modulus E, bulk modulus B, and shear modulus K have been investigated. In this way, we address new possibilities for improving the mechanical and elastic properties of AlN based ceramic materials, as well as possible band gap tuning, which might have applications in optoelectronic devices.
This paper presents the technological process for obtaining basalt-stainless steel composite mate... more This paper presents the technological process for obtaining basalt-stainless steel composite materials and testing their physical and mechanical properties. The phases of the technological process consist of: milling, homogenization, pressing, and sintering to obtain composite materials with improved fracture toughness. Andesite basalt from the deposit site "Donje Jarinje", Serbia, was used as a matrix in the composites, while commercial austenitic stainless steel 316L in the amount of 0-30 wt.% was used as a reinforcement. Although the increase of 316L amount caused a continuous decrease in the relative density of sintered samples, the relative density of sample containing 30 wt.% of 316L was above 94%. The 316L grains, which possess a larger coefficient of thermal expansion than the basalt matrix, shrinking faster during cooling from sintering temperature resulting in the formation of compressive residual stress in the basalt matrix surrounding the spherical steel grains...
Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3P... more Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3PO4 at room temperature. X-ray powder diffraction analysis and Raman spectroscopy reviled that synthesized powder was single-phase. Using scanning electron microscopy analysis, it was found that the synthesized Ag3PO4 particles were near-spherical shape with an average diameter of 100 nm. The high value for the specific surface area of obtained powder was measured by Brunauer?Emmet?Teller method. Finally, the Ag3PO4 product was used as a photocatalyst for the photodegradation of crystal violet dye in an aqueous solution. Nanoemulsion strategy procedure provides a simple pathway to obtain a highly efficient single-phase Ag3PO4 photocatalyst.
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