Year of publication
- Institute of Technical Sciences of the Serbian Academy of Sciences and Arts (96)
- University of Belgrade, Vinča Institute of Nuclear Sciences (42)
- University of Belgrade, Faculty of Agriculture (35)
- Serbian Academy of Sciences and Arts, Belgrade (30)
- University of Niš, Faculty of Electronic Engineering (22)
- University of Belgrade, Faculty of Mechanical Engineering (20)
- Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade (15)
- Institute for Multidisciplinary Research, Belgrade (10)
- University of Kragujevac, Faculty of Technical Sciences, Čačak (9)
- North Carolina Central University, Durham (7)
- Ferroelectric nanocomposites of polyvinylidene fluoride/polymethyl methacrylate blend and BaTiO3 particles: Fabrication of β-crystal polymorph rich matrix through mechanical activation of the filler (2014)
- Nanocomposites of polyvinylidene fluoride/polymethyl methacrylate (PVDF/PMMA) blend and mechanically activated barium titanate (BaTiO3) particles were prepared by melt mixing. Modification of filler by means of mechanical activation has a profound effect on the crystallization of PVDF in the blend matrix. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form. The introduction of activated particles reduces the overall crystallinity but slightly affects the crystallization and melting temperatures of the matrix. Dielectric spectroscopy revealed that at fixed filler content the dielectric constant of the blend increases with decreasing of the particle size (increasing of the activation time). A similar trend was observed for the storage moduli in dynamic mechanical analysis; the stiffness of the composite was higher when mechanically activated particles were used.
- Influence of Synthesis Parameters on Structure of 1-D TiO2 nanostructures (2015)
- The influence of electrochemical conditions and the heat treatment on the crystal structure and the microstructure evolution of TiO2 based nanotubes synthesized by the self-ordering anodization process is investigated in this work. The electrochemical anodization was performed at room temperature, for 30 minutes under 15, 20 and 25 V, with stirring. The as-anodized Ti foils were annealed in air at 450, 600, 650 and 700 °C for 30 minutes. The structure and the lattice dynamics of the samples has been studied by using XRD and Raman spectroscopy methods. The microstructure development of the 1-D TiO2 nanostructures has been analyzed by FESEM.
- Targeted Synthesis of Ceramic-Polymer Nanocomposites (2014)
- It is well known that materials used in nano-electro-mechanical systems (NEMS) must simultaneously satisfy numerous requirements for chemical, structural, mechanical and electrical properties. Taking into account that the application of targeted synthesis principles is fundamental for development of these materials, in this article the results of the investigation of the nano-scale grain size effects, grain/particle size induced structural transformations, the evolution of the particle structure during targeted synthesis process and microstructure modeling of ceramic-polymer nanocomposites, has been presented. The nanocomposite BT,ST/PVDF films were prepared by pulsed laser deposition (PLD) method and investigated by X-ray diffraction (XRD) method and Raman spectroscopy, while the microstructure morphology has been analyzed by scanning electron microscope (SEM). It was found that PLD of BT,ST on PVDF substrate offers a new set of opportunities for development of advanced flexible piezo-films for the next generation of NEMS, which applications span the aero-space industry, communications, defense systems, national security, health care, information technology and environmental monitoring.
- Piezoelectric polymer/ceramic nanostructures for mechanical energy harvesting (2013)
- Vibration-based mechanical energy is one of the most accessible energy source in the surroundings. Harvesting this type of energy exhibits a great potential for remote/wireless sensing, charging batteries, and powering electronic devices. Piezoelectric and ferroelectric materials, including PZT, BaTiO3, ZnO, polyvinylidene fluoride (PVDF), etc., can be used for converting ambient mechanical energy into electricity. Based on these materials, a variety of micro- or nanoelectromechanical systems can be developed for harvesting energies from random vibrations, mechanical waves, or body movements like walking, running, or typing. Recent investigations on nanocomposites of electroactive ceramics and ferroelectric polymers exploit this approach in order to produce new multifunctional materials for mechanical energy harvesting. Taking into account that mechanical activation is one of the methods for modification of physico-chemical properties of the filler, in this study we investigate the influence of mechanical activation of ZnO particles on structural properties of ZnO/polyvinylidene fluoride nanocomposites. The nanocomposite films were prepared by solution casting method and investigated by X-ray diffraction (XRD) method and Raman spectroscopy, while the microstructure morphology has been analyzed by scanning electron microscope (SEM). Presented results will enable optimization of PVDF processing techniques for the production of new mechanical energy harvesting devices.
- Analysis and modeling of sintering of Sr-hexaferrite produced by PIM technology (2011)
- The powder injection moulding (PIM) technology is lately becoming more and more significant due to complex design possibilities and good repeatability. This technology requires optimization of all steps starting with material and binder, injection, debinding and sintering parameters. Sintering is one of the key links in this technology. The powder injection moulding process is specific as during feedstock injection powder particles mixed into the binder do not come into mechanical contact. Shrinkage during sintering of PIM samples is high. In this work we have analyzed and modeled the sintering process of isotropic PIM samples of Sr-hexaferrite. The Master Sintering Curve (MSC) principle has been applied to analyze sintering of two types of PIM Sr-hexaferrite samples with completely removed binder and only the extraction step of the debinding procedure (thermal debinding proceeding simultaneously with sintering). Influence of the heating rate on resulting sample microstructures has also been analyzed. Influence of the sintering time and temperature was analyzed using three different phenomenological equations.
- Evaluation of Fly Ash Pysico-chemical Characteristics as Component for Eco-ceramic and Sintered Materials (2012)
- The aim of the presented study is to evaluate utilization potential of the fly ash which is the main residue from the coal combustion thermal-plants. Decades long high production of fly ash represents extreme hazard for the environment. The storage problem of this waste material is also alerting. Thus, recycling and reapplication of fly ash in construction materials industry is the only economic solution. The well-known examples of fly-ash reapplication as a component in cement, mortar, concrete, bricks and tiles are not enough in means of reusing extreme amounts of this waste material. Therefore, new applications in ash-based composites have to be developed: eco-ceramic materials and sintered materials for refractory performances. In this investigation, characterization of three different fly ash capacities was used as base for further fly ash utilization possibilities analysis. Accent was on the investigation of the fly ash mineralogical and chemical composition. Thermal stability of crystalline phases was investigated with DTA. Macro-performance was correlated with the microstructure of fly ash studied by means of XRD and SEM analysis. Furthermore, content of trace elements, physico-chemical characteristics and leaching toxicity tests were carried out. Comparing the properties of investigated fly ashes with standard values, it could be presumed that fly ash originating from Serbian power plants can be potentially useful for high value products - eco-ceramic and refractory/sintered materials manufacturing. Key words: fly ash, microstructure, potential reusing, eco-ceramic, sintering. Acknowledgements: This investigation was supported by Serbian Ministry of Science and Education and it was conducted under following projects: 172057 and 45008.
- Structural Investigation of Mechanically Activated Nanocrystalline BaTiO3 Powders (2011)
- In this article, in order to obtain tetragonal nanocrystalline BaTiO3, structural investigations of mechanically activated BaTiO3 powder have been performed. A mercury porosimetry analysis and scanning electron microscopy method have been applied for determination of the specific pore volume, porosity and microstructure morphology of the samples. The lattice vibration spectra of nonactivated and activated powders, their phase composition, lattice microstrains and the mean size of coherently diffracting domains were examined by Raman spectroscopy and the X-ray powder diffraction method. The average crystal structure of obtained nanocrystalline powders, estimated from X-ray diffraction data, gave evidence of retained, but slightly sustained tetragonality of powders, even for particles as small as ∼30 nm. Raman spectroscopy also gave clear evidence for local tetragonal symmetries, in particular through the presence of a band at ∼307 cm−1.
- Raman Responses in Mechanically Activated BaTiO3 (2014)
- The structure and lattice dynamics of mechanically activated BaTiO3 was investigated in this study. Phonon behavior and crystal structure stability of the obtained nanocrystalline BaTiO3 were discussed from the view point of crystallite size effects and microstrains induced by mechanical activation. A systematic study of Raman responses indicates that mechanical activation has a distinct influence on BaTiO3 lattice spectra affecting the intensity, width, and position of Raman modes. The measured Raman spectra were deconvoluted and phonon parameters were estimated. It has been established that applied mechanical activation leads to a significant decrease in the mean crystallites size, but nevertheless enables formation of tetragonal nanocrystalline BaTiO3.
- Tailoring self-ordering TiO2 nanotube arrays by oxidative anodization (2015)
- Having in mind that anodic oxidation method can be used for tailoring desired structure and morphology of TiO2, herein the synthesis of self-ordered TiO2 nanotubes via electrochemical anodization of high purity Ti foil is reported. The influence of synthesis parameters such as oxidative voltage, different electrolyte, annealing temperature and annealing atmosphere were explored and correlate with obtained TiO2 nanotube arrays. The results show that applied potential is the main factor that controls the diameter of the nanotubes, while annealing temperature influence on crystal type and morphology is related to different contents of electrolyte. Investigated method gives opportunity to enhanced performance of TiO2 nanotubes, providing many applications in different field.
- The influence of mechanical activation on the structure of ZnO (2013)
- In this paper, the authors investigated the influence of mechanicall activation of ZnO powder on crystal and micro structure. Because of its structure, ZnO could be used like filler in polymer ceramics nanocompozites. Performances of these material depend on filler morphology, surfaces, texture and size particle. According to this, ZnO powder was activated in a planetary ball mill for 2, 5, 10 and 30 minutes. Changes in crystal and micro structure were observed by SEM, XRD, Raman spectroscopy and UV-Vis Reflection. SEM micrographs show increase of agglomerates size with prolonged milling time. XRD patterns indicate that the peak intensities getting lower and expand with activation time. UV-Vis reflection shows that there is a clear difference in the spectra with increasing activation time. The results we got by the investigation of dinamical structure by Raman spectroscopy are in corelation with the other results of structures analysis. Results presented here enable further optimisation of the polymer nanocompozite based on ZnO and PVDF making process.