58 results on '"Vujasin, Radojka"'
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52. Aging Effects in Irradiated MgH2; Connection to Hydrogen Production.
- Author
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KURKO, Sandra, MATOVIĆ, Ljiljana, VUJASIN, Radojka, MILANOVIĆ, Igor, RAŠKOVIĆ-LOVRE, Željka, IVANOVIĆ, Nenad, and NOVAKOVIĆ, Jasmina GRBOVIĆ
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ARGON ,X-ray diffraction ,MATERIAL fatigue ,SCANNING electron microscopy - Abstract
Copyright of Materials Science / Medziagotyra is the property of Kaunas University of Technology, represented by Prof. Rymantas Jonas Kazys and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
- Full Text
- View/download PDF
53. Changes in Storage Properties of Hydrides Induced by Ion Irradiation.
- Author
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NOVAKOVIĆ, Jasmina GRBOVIĆ, KURKO, Sandra, RAŠKOVIĆ-LOVRE, Željka, MILOŠEVIĆ, Sanja, MILANOVIĆ, Igor, STOJANOVIĆ, Zoran, VUJASIN, Radojka, and MATOVIĆ, Ljiljana
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STORAGE ,HYDRIDES ,HYDROGEN ,IONS ,IRRADIATION - Abstract
Copyright of Materials Science / Medziagotyra is the property of Kaunas University of Technology, represented by Prof. Rymantas Jonas Kazys and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
- Full Text
- View/download PDF
54. Hydrogen desorption properties of MgH2/LiAlH4 composites.
- Author
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Milanović, Igor, Milošević, Sanja, Matović, Ljiljana, Vujasin, Radojka, Novaković, Nikola, Checchetto, Riccardo, and Grbović Novaković, Jasmina
- Subjects
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HYDROGEN , *DESORPTION , *MAGNESIUM hydride , *LITHIUM aluminum hydride , *METALLIC composites , *MECHANICAL alloying - Abstract
Abstract: The hydrogen desorption properties of MgH2–LiAlH4 composites obtained by mechanical milling for different milling times have been investigated by Thermal Desorption Spectroscopy (TDS) and correlated to the sample microstructure and morphology analysed by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The MgH2–LiAlH4 composites show improved hydrogen desorption properties in comparison with both as-received and ball-milled MgH2. Mixing of MgH2 with small amount of LiAlH4 (5 wt.%) using short mechanical milling (15 min) shifts, in fact, the hydrogen desorption peak to lower temperature than those observed with both as-received and milled MgH2 samples. Longer mixing times of the MgH2–LiAlH4 composites (30 and 60 min) reduce the catalytic activity of the LiAlH4 additive as revealed by the shift of the hydrogen desorption peak to higher temperatures. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
55. Microstructure and hydrogen storage properties of MgH2–TiB2–SiC composites
- Author
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Milanović, Igor, Milošević, Sanja, Rašković-Lovre, Željka, Novaković, Nikola, Vujasin, Radojka, Matović, Ljiljana, Francisco Fernández, Jose, Sánchez, Carlos, and Grbović Novaković, Jasmina
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MICROSTRUCTURE , *HYDROGEN storage , *MAGNESIUM hydride , *TITANIUM diboride , *SILICON carbide , *COMPOSITE materials , *CHEMICAL kinetics - Abstract
Abstract: The influence of TiB2 and SiC ceramics on H-desorption kinetics from MgH2 based composites was investigated and correlated with the microstructure and morphology of the composites. The mechanism of desorption and the activation energy for desorption was investigated by applying non-isothermal kinetic analysis of thermodesorption spectra. It has been shown that TiB2 addition leads to significant decrease of the activation energy for desorption, while SiC addition has effect on the interface reaction between hydride and hydroxide. The mechanism of desorption change from Avrami–Erofeev n=3 for pure MgH2 to Avrami–Erofeev n=4 for composite materials. The change from 3 to 4 can be due to the modification of the nucleation process or a change in the dimensionality of the growth. Those high values of n discard a diffusion control as a rate limiting step. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
56. Influence of VO2 nanostructured ceramics on hydrogen desorption properties from magnesium hydride
- Author
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Milošević, Sanja, Rašković-Lovre, Željka, Kurko, Sandra, Vujasin, Radojka, Cvjetićanin, Nikola, Matović, Ljiljana, and Grbović Novaković, Jasmina
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VANADIUM oxide , *NANOSTRUCTURED materials , *CERAMIC materials , *MAGNESIUM hydride , *CHEMICAL kinetics , *MECHANICAL alloying , *METALLIC composites - Abstract
Abstract: The hydrogen desorption properties and kinetics of MgH2–VO2 composite prepared by mechanical milling of MgH2 and VO2 have been investigated. Structural characterization of produced nanocomposite was done by X-ray powder diffraction (XRD), particle size analysis and scanning electron microscopy (SEM). The structure and morphology of the composite have been correlated with hydrogen desorption properties investigated by differential thermal analysis (DTA). It has been shown that short mechanical milling of nanostructured VO2 and MgH2 leads to decrease of hydrogen desorption temperature of MgH2 by 80K. The mechanism of desorption has been changed from phase boundary reaction, spherical symmetry for untreated MgH2 to phase boundary reaction, cylindrical symmetry for the composite material. The activation energy for desorption has been reduced by adding VO2 ceramics as a catalyst. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
57. Influence of vacant CeO2 nanostructured ceramics on MgH2 hydrogen desorption properties
- Author
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Gulicovski, Jelena, Rašković-Lovre, Željka, Kurko, Sandra, Vujasin, Radojka, Jovanović, Zoran, Matović, Ljiljana, and Grbović Novaković, Jasmina
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CERIUM oxides , *NANOSTRUCTURED materials , *CERAMIC materials , *MAGNESIUM hydride , *HYDROGEN , *DESORPTION - Abstract
Abstract: The hydrogen desorption (HD) properties of MgH2-CeO2 composite prepared by mechanically milling of MgH2 and cubic CeO2nano have been examined. Morphology and microstructure of composites have been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), laser scattering analysis and correlated with desorption properties obtained by means of temperature programmed desorption (TPD). It has been shown that decrease of crystallite and particle size of the samples lead to significant lowering of desorption temperature. Further, the activation energy for desorption has been calculated using Kissinger equation. Obtained value of 60±10kJ/mol indicates that the activation energy of hydrogen desorption is sufficiently decreased by the catalytic effect of vacant CeO2 structure. Consequently the surface activation of sample plays a major role in HD reaction. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
58. Fast hydrogen sorption from MgH2–VO2(B) composite materials
- Author
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Nikola Novaković, Sanja Milošević, Radojka Vujasin, Ljiljana Matović, Luca Pasquini, Sandra Kurko, Jasmina Grbović Novaković, Milošević, Sanja, Kurko, Sandra, Pasquini, Luca, Matović, Ljiljana, Vujasin, Radojka, Novaković, Nikola, and Novaković, Jasmina Grbović
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Materials science ,Scanning electron microscope ,Composite number ,Analytical chemistry ,Energy Engineering and Power Technology ,Composite ,02 engineering and technology ,010402 general chemistry ,complex mixtures ,01 natural sciences ,Ball milling ,symbols.namesake ,Differential scanning calorimetry ,Desorption ,Phase (matter) ,VO2 (B) ,MgH2 ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Composite material ,Ball mill ,Composites ,Kinetic ,Renewable Energy, Sustainability and the Environment ,Sorption ,(de)sorption ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Kinetics ,symbols ,0210 nano-technology ,Raman spectroscopy - Abstract
The hydrogen sorption kinetics of MgH2-VO2(B) composites synthesised by mechanical milling have been studied. The microstructural properties of composites were characterized by means of X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), Particle size analysis (PSD), while sorption behaviour was followed by differential scanning calorimetry (DSC) and Sievert measurements. Results have shown that although desorption temperature reduction is moderate; there is a substantial improvement in hydrogen sorption kinetics. The complete desorption of pure MgH2 at elevated temperature takes place in more than 30 min while the composite fully desorbs in less than 2 min even at lower temperatures. It has been shown that the metastable gamma-MgH2 phase and the point defects have a decisive role in desorption process only in the first sorption cycle, while the second and the subsequent sorption cycles are affected by microstructural and morphological characteristics of the composite. (C) 2015 Elsevier B.V. All rights reserved.
- Published
- 2016
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