Showing papers by "Peter Baláž published in 2017"
TL;DR: In this article, a review of advances achieved in the field of mechanochemical synthesis of nanocrystalline binary, ternary and quaternary chalcogenides and their nanocomposites is provided.
Abstract: The aim of this paper on recent development in chalcogenide mechanochemistry is to provide a comprehensive review of advances achieved in the field of mechanochemical synthesis of nanocrystalline binary, ternary and quaternary chalcogenides and their nanocomposites. The synthetic approaches from elements and compounds are reviewed. The current focus of mechanochemical synthesis is on materials with potential utilization in future. In order to demonstrate the suitability of mechanochemically prepared chalcogenides for various applications, the concrete examples of the utilization of these materials in materials engineering, bioimaging and cancer treatment are provided. The possibility of scaling for industrial applications is also reviewed. The simplification of the synthesis processes with their reproducibility and easy way of operation, ecological safety and the product extraordinariness (nanoscale aspects) emphasizes the suitability of mechanochemistry application in chalcogenide synthesis.
69 citations
TL;DR: In this article, a bio-mechanochemical approach combining mechanochemistry (ball milling) and green synthesis for the first time, silver nanoparticles (Ag NPs) with antibacterial activity were successfully synthesized.
60 citations
TL;DR: The ZnS nanocrystals possessed interesting optical properties verified in vitro, and the biological activity of the cells was not influenced by nanoparticles, they did not cause cell death, and only the granularity of cells was increased as a consequence of cellular uptake.
Abstract: The ZnS nanocrystals were prepared in chitosan solution (0.1 wt.%) using a wet ultra-fine milling. The obtained suspension was stable and reached high value of zeta potential (+57 mV). The changes in FTIR spectrum confirmed the successful surface coating of ZnS nanoparticles by chitosan. The prepared ZnS nanocrystals possessed interesting optical properties verified in vitro. Four cancer cells were selected (CaCo-2, HCT116, HeLa, and MCF-7), and after their treatment with the nanosuspension, the distribution of ZnS in the cells was studied using a fluorescence microscope. The particles were clearly seen; they passed through the cell membrane and accumulated in cytosol. The biological activity of the cells was not influenced by nanoparticles, they did not cause cell death, and only the granularity of cells was increased as a consequence of cellular uptake. These results confirm the potential of ZnS nanocrystals using in bio-imaging applications.
37 citations
TL;DR: In this article, the dissolution rate of arsenic sulphide β-As4S4 has been increased by mechanical activation in a planetary ball mill, which is a challenge for the application in cancer research.
Abstract: Arsenic sulphide β-As4S4 has been modified by mechanical activation in a planetary ball mill. As a consequence, the solid-state properties and dissolution yield have been influenced. The following changes were observed: the increase of specific surface area, changes in the morphology (the formation of submicron particles), the occurrence of nanoparticles (21–31 nm), changes in crystal lattice parameters and changes in the Raman shift of particular vibrations. As a consequence of these changes, the dissolution rate of β-As4S4 has been increased, which is a challenge for the application in cancer research.
28 citations
TL;DR: The anti-cancer effects were tested on two melanoma cell lines, A375 and Bowes, with promising results, confirming increased efficiency of the samples containing both As4S4 and ZnS nanocrystals.
23 citations
TL;DR: The nanosuspensions were successfully used for in vitro studies on selected cancer cell lines and it was evidenced that the nanocrystals enter the cell and that they can serve as imaging agents in biomedical applications.
22 citations
TL;DR: A one-pot mechanochemical synthesis of the nanocomposite composed of stannite Cu2 FeSnS4 and rhodostanniteCu2FeSn3S8 nanocrystals using a planetary ball mill and elemental precursors results in unique nanostructures with interesting properties.
Abstract: In this study, we demonstrate a one-pot mechanochemical synthesis of the nanocomposite composed of stannite Cu2FeSnS4 and rhodostannite Cu2FeSn3S8 nanocrystals using a planetary ball mill and elemental precursors (Cu, Fe, Sn, S). By this approach, unique nanostructures with interesting properties can be obtained. Methods of XRD, Raman spectroscopy, UV-Vis, nitrogen adsorption, SEM, EDX, HRTEM, STEM, and SQUID magnetometry were applied. Quaternary tetragonal phases of stannite and rhodostannite with crystallite sizes 18–19 nm were obtained. The dominant Raman peaks corresponding to the tetragonal stannite structure corresponding to A-symmetry optical modes were identified in the spectra. The bandgap 1.25 eV calculated from UV-Vis absorption spectrum is very well-acceptable value for the application of the synthesized material. The SEM micrographs illustrate the clusters of particles in micron and submicron range. The formation of agglomerates is also illustrated on the TEM micrographs. Weak ferromagnetic properties of the synthesized nanocrystals were documented.
19 citations
TL;DR: In this article, the InAs/ZnS mixed nanocrystals were synthesized by dry high-energy milling approach in the first step and then the nanocrystal was subjected to wet ultra-fine milling in order to obtain a nanosuspension of chitosan-coated InAs and ZnS with bio-imaging properties.
Abstract: In this paper, InAs/ZnS mixed nanocrystals were synthesized by dry high-energy milling approach in the first step. The obtained nanocrystals were characterized from structural point of view by X-ray diffraction analysis and Raman spectroscopy, and from the morphological point of view by scanning electron microscopy. In the next step, the nanocrystals were subjected to wet ultra-fine milling in order to obtain a nanosuspension of chitosan-coated InAs/ZnS nanocrystals with bio-imaging properties. The stability of the nanosuspension was examined by zeta potential and particle size distribution measurements. The prepared nanosuspension was stable with high values of zeta potential. Its optical properties were also studied using UV–Vis and PL spectroscopies. The determined fluorescent properties confirming the potential in bio-imaging applications were verified on cancer cell lines Caco-2, HCT116, HeLa, and MCF7.
19 citations
TL;DR: In this article, the effect of milling speed on the explosive character of the reaction and phase composition of chalcocite was investigated, and the most drastic conditions favored the formation of the monoclinic phase with the lowest symmetry.
Abstract: Covellite, CuS and chalcocite, Cu2S nanoparticles prepared in the explosive manner from elemental precursors were further ball-milled in order to observe additional changes caused by mechanical action. Three phases of chalcocite were interchanging during milling, monoclinic one being major at the equilibrium after 30 min. In the case of covellite synthesis, milling for 15 min brought about a significant diminishment in the content of digenite, Cu1.8S, impurity. Covellite powder exhibited finer character than chalcocite, as documented by crystallite size, grain size and specific surface area analysis. Finally, the effect of milling speed on the explosive character of the reaction and phase composition of chalcocite was investigated. The most drastic conditions favored the formation of the monoclinic phase with the lowest symmetry and the time and intensity of the explosion was found to depend on the milling speed. The whole process is mechanically driven.
16 citations
TL;DR: In this paper, a modified x3-x2-coupling decomposition algorithm is applied to parameterize annihilation channels in three types of tetra-arsenic tetra sulfide As4S4 polymorphs composed by preferential β-As4S 4, realgar α-As 4S 4 and admixture of As 4S4 in the form of β-realgar, pararealgar and intermediate χ-phase subjected to mechanochemical ball milling in a water solution of polyvinylpyrrolidone (PVP).
15 citations
TL;DR: In this paper, a multifunctional As4S4/Fe3O4 nanocomposites prepared by high-energy mechanical milling are probed by complementary methods of positron annihilation lifetime (PAL) spectroscopy, supported by microstructure characterization using X-ray powder diffraction (XRPD) with analysis applied to the first sharp diffraction peak (FSDP), morphology studies by transmission electron microscopy (TEM) with energy-dispersive spectroscopic (EDS) and high-resolution TEM (HRTEM
09 Dec 2017
TL;DR: In this article, the synthesis of quaternary semiconductor nanocrystals of stannite Cu2FeSnS4/rhodostannite CFTS via mechanochemical route using Cu, Fe, Sn and S elements as precursors in one-pot experiments was demonstrated.
Abstract: In this study we demonstrate the synthesis of quaternary semiconductor nanocrystals of stannite Cu2FeSnS4/rhodostannite Cu2FeSn3S8 (CFTS) via mechanochemical route using Cu, Fe, Sn and S elements as precursors in one-pot experiments. Methods of X-ray diffraction (XRD), nitrogen adsorption, high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were applied to characterize properties of the unique nanostructures. Mechanochemical route of synthesis induced new phenomena like explosive character of reaction, where three stages could be identified and the formation of nanostructures 5–10 nm in size. By using XPS method, Cu(I), Fe(II), Sn(IV) and S(-II) species were identified on the surface of CFTS. The value of optical band gap 1.27 eV is optimal for semiconductors applicable as absorbers in solar cells. The significant photocatalytic activity of the CFTS nanocrystals was also evidenced. The obtained results confirm the excellent properties of the quaternary semiconductor nanocrystals synthesized from earth-abundant elements.
TL;DR: In this paper, the effective high-energy milling (HEM) treatment and utilization of chicken eggshells (ES) as a bio-waste waste have been investigated in environmental and economic interest.
Abstract: The main object of investigations in this work is the chicken eggshells. The effective high-energy milling (HEM) treatment and utilization of chicken eggshells (ES) as a bio-waste waste have been investigated in environmental and economic interest. The composition of the ES includes mainly inorganic (94 % calcium carbonate as calcite, 1 % calcium phosphate and 1 % magnesium carbonate) as well as organic matter (4 %). During HEM, the mechanical activation process takes place, which leads to improvement of materials properties. The HEM-activated ES samples were characterized by thermal analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. The decarbonization was carried out using the thermal methods with Ar flow gas. We established that the thermal properties of the ES samples change considerably due to HEM treatment. The changes appear as: (1) shifting of decarbonization temperature of HEM-activated samples to lower temperature of about 30 °C; (2) decrease in mass losses and temperatures of decomposition with the increasing milling time; and (3) decrease in DTA peak areas for the all HEM-activated samples. As was shown earlier, the HEM treatment has a beneficial effect on the application of the ES. They can be used as: sorbents and soil improvers (separately or as mixtures with apatite minerals or appropriate technogenic wastes, containing main for the plants nutrients—N, P, K, S, Ca et al.).
TL;DR: In this article, a modified x3-x2coupling decomposition algorithm is applied to parameterize expected annihilation channels in As4S4-PVP nanocomposites in respect to PVP matrix.
Abstract: Atomic-deficient nanostructurization in composites based on arsenic sulfide As4S4 polymorphs, such as (1) β-As4S4, (2) realgar α-As4S4, and (3) mixture of realgar, pararealgar, and intermediate χ-phase subjected to high-energy mechanochemical milling in polyvinylpyrrolidone (PVP) solution, are studied exploring the method of positron annihilation lifetime spectroscopy. Positron lifetime spectra reconstructed from unconstrained x3-term fitting procedure testify in a favor of mixed positron-positronium trapping in the studied composites. Modified x3-x2-coupling decomposition algorithm is applied to parameterize expected annihilation channels in As4S4-PVP nanocomposites in respect to PVP matrix. Interfacial free-volume voids between nanoparticles composed of arsenic sulfide crystallites embedded in PVP environment are defined as most favorable positron trapping sites, loosely packed in respect to variety of crystallographic polymorphs used for milling. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers
TL;DR: In this article, the use of elemental precursors (Cu, Fe, Sn, S) to obtain stannite forms by a solid-state one-pot mechanochemical synthesis was demonstrated.
Abstract: In this study we demonstrate the use of elemental precursors (Cu, Fe, Sn, S) to obtain stannite forms by a solid-state one-pot mechanochemical synthesis. In the processing route, we report the kinetics of the synthesis. For the characterization of the unique nanostructures, X-ray diffraction, specific surface area measurements and SQUID magnetometry methods were applied. CFTS polymorphs with the tetragonal body-centered structure with the average crystallite size 18–19 nm were obtained. The weak ferromagnetic properties of the quaternary nanocrystals after maximum milling time were also documented.
TL;DR: The calculated trapping parameters that were shown could be useful to characterize adequately the nanospace filling in As4S4/ZnS composites.
Abstract: Microstructure hierarchical model considering the free-volume elements at the level of interacting crystallites (non-spherical approximation) and the agglomerates of these crystallites (spherical approximation) was developed to describe free-volume evolution in mechanochemically milled As4S4/ZnS composites employing positron annihilation spectroscopy in a lifetime measuring mode. Positron lifetime spectra were reconstructed from unconstrained three-term decomposition procedure and further subjected to parameterization using x3-x2-coupling decomposition algorithm. Intrinsic inhomogeneities due to coarse-grained As4S4 and fine-grained ZnS nanoparticles were adequately described in terms of substitution trapping in positron and positronium (Ps) (bound positron-electron) states due to interfacial triple junctions between contacting particles and own free-volume defects in boundary compounds. Compositionally dependent nanostructurization in As4S4/ZnS nanocomposite system was imagined as conversion from o-Ps trapping sites to positron traps. The calculated trapping parameters that were shown could be useful to characterize adequately the nanospace filling in As4S4/ZnS composites.
TL;DR: In this article, the reduction of Chalcopyrite CuFeS2: Changes in Composition and Magnetic Properties P. Baláža,∗, A. Zorkovská, M. Tešinský, T. Osserov, G. Guseynova and T.I. Satpayev.
Abstract: Mechanochemical Reduction of Chalcopyrite CuFeS2: Changes in Composition and Magnetic Properties P. Baláža,∗, A. Zorkovská, M. Baláž, J. Kováč, M. Tešinský, T. Osserov, G. Guseynova and T. Ketegenov Institute of Geotechnics, SAS, Watsonova 45, 04001 Košice, Slovakia Institute of Experimental Physics, SAS, Watsonova 47, 04001 Košice, Slovakia K.I. Satpayev Kazakh National Research Technical University, Satpayev Str. 22a, 050013 Almaty, Kazakhstan Al-Farabi Kazakh National University, Al-Farabi Av. 71, 050040 Almaty, Kazakhstan
01 Jan 2017
TL;DR: In this paper, the authors reported relatively strong, compared to confined ZnS LO type phonon, Raman activities of combination modes away from the resonance in the strong confinement regime in QD, and found that off-resonance Raman spectroscopy can be used for quick estimation of the dimension of produced QDs.
Abstract: ZnS nanoparticles were synthesized mechanochemically by high-energy milling. Samples were produced in three different milling times. The morphology of samples has been investigated by scanning electron microscopy (SEM). X-ray diffraction (XRD) investigation of synthesized nanocrystals identified cubic structure, and crystallite size was estimated to 1.9 nm (5 min milling), 2.3 nm (10 min) and 2.4 nm (20 min). These dimensions ensure strong confinement regime. Raman spectroscopy studies (100–500 cm−1) have been performed. Excitation source was 514.5 nm (EL = 2.41 eV), implying that we are in off-resonance regime. Dominant spectral structures are registered in spectral region 130–180 cm−1, around 265 cm−1 and around 345 cm−1. First two are assigned as combination modes and mode at 345 cm−1 as confined ZnS LO type phonon. Absence of TO mode with visible excitation is consequence of poor scattering efficiency and anti-resonant behavior. We report relatively strong, compared to confined ZnS LO type phonon, Raman activities of combination modes away from the resonance in the strong confinement regime in ZnS quantum dots (QD). We find that off-resonance Raman spectroscopy can be used for quick estimation of the dimension of produced ZnS QDs. Sum of second-order Raman active modes centered at 265 cm−1 dominates over LO-like mode at 345 cm−1 in strong confinement regime.