Peter Baláž - Academia.edu (original) (raw)

Papers by Peter Baláž

Crystals, Dec 9, 2017

In this study we demonstrate the synthesis of quaternary semiconductor nanocrystals of stannite C... more In this study we demonstrate the synthesis of quaternary semiconductor nanocrystals of stannite Cu 2 FeSnS 4 /rhodostannite Cu 2 FeSn 3 S 8 (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.

CRC Press eBooks, May 18, 2023

Powder Technology, Jun 1, 2006

Nanocrystalline semiconductor particles MeS (Me=Pb, Zn, Cd, Cu) were successfully synthesized by ... more Nanocrystalline semiconductor particles MeS (Me=Pb, Zn, Cd, Cu) were successfully synthesized by the mechanochemical route from the corresponding metal acetates and sodium sulphide in an industrial eccentric vibratory mill. Structure properties of the as-prepared products were characterized by X-ray powder diffraction which reveals the crystalline nature of MeS nanoparticles. The methods of TEM, particle size analysis and low temperature nitrogen

Kovove Materialy-metallic Materials, 2002

DTU Orbit (11/12/2018) Preparation of cu/fes nanoparticles by mechanochemical reduction of copper... more DTU Orbit (11/12/2018) Preparation of cu/fes nanoparticles by mechanochemical reduction of copper sulphide The mechanochemical reduction of copper sulphide with elemental iron was studied. The methods of XPS, SEM, EDX, and low temperature nitrogen sorption were used to analyse the surface composition and the composite particles formed from elemental copper and hexagonal 2C-troilite. The study of the mechanism and kinetics of the mechanochemical reaction by magnetic measurements, XRD and Mossbauer spectroscopy has revealed the details of the process.The transformations of copper sulphide, the synthesis of cubic FeS and its transformation to the hexagonal form are associated with the primary mechanochemical reduction of copper sulphide by elemental iron. Platelets of Cu/FeS nanoparticles are formed as aggregates, tenths of micrometers in diameter. However, the average grain size of the freshly formed copper is between 10 and 25 nanometers depending on the milling conditions.

Advanced Powder Technology, Aug 1, 2018

ChemInform, Jul 10, 2007

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Czechoslovak Journal of Physics, Dec 1, 2004

The nanocrystalline pyrrhotite was prepared by high-energy milling of lead sulphide with elementa... more The nanocrystalline pyrrhotite was prepared by high-energy milling of lead sulphide with elemental Fe acting as reducing element. X-ray diffractometry, Mössbauer spectroscopy and VSM magnetometry were used for to determine the properties of nanocrystalline iron sulphide prepared by the corresponding mechanochemical reaction. Pyrrhotite Fe1-xS together with the residual Fe metal were identified by the X-ray diffractometry. The kinetic studies performed

Journal of Alloys and Compounds, May 1, 2007

The preparation of nanosized antimony (grain size 19nm) by high-energy milling of antimony sulphi... more The preparation of nanosized antimony (grain size 19nm) by high-energy milling of antimony sulphide Sb2S3 with elemental Fe as reducing element is reported. The mechanochemical reduction was performed in a planetary ball mill for 10–180min. The process is rather straightforward with elemental antimony and iron sulphide (pyrrhotite-4H) being the only solid-state products. The process kinetics as described by X-ray diffraction

Acta Physica Polonica A, 2020

Chalcopyrite CuFeS2, a ternary semiconductor, is an antiferromagnet with a promising thermoelectr... more Chalcopyrite CuFeS2, a ternary semiconductor, is an antiferromagnet with a promising thermoelectric potential. Since the thermoelectric efficiency of CuFeS2 is generally limited by high lattice thermal conductivity, it is highly desirable to lower the thermal conductivity without deterioration of other thermoelectric characteristics. Considering the interconnection between thermal conductivity, magnetic order and grain size in magnetic ceramics, we attempted to produce doped nanostructured chalcopyrite via mechanosynthesis and SPS sintering. We succeeded to prepare both n-and p-type nanostructured ceramics. We discussed the origin of highly depressed thermal conductivity with respect to the grain size and the magnetic properties, and confirm the high technological potential of high-energy milling with respect to thermoelectric potential of CuFeS2. Thermal conductivity was reduced by 35% compared to standard chalcopyrite. The maximum value of the thermoelectric figure of merit ZT was about 0.2, which is comparable to published data.

This review paper deals with the application of broad possibilities of mechanochemistry in minera... more This review paper deals with the application of broad possibilities of mechanochemistry in mineral processing, extractive metallurgy, chemical engineering, building industry, coal industry, materials engineering, agriculture, pharmacy and waste treatment. In several applications pilot plants units or full commercial units were successfully applied. The environmental aspects of these processes are particularly attractive. The main advantages in comparison with traditional technological procedures are decrease in number of technological stages, exclusion of operations that involve the use of solvents and gases and last but not the least the possibility obtaining a product in the metastable state which is difficult to obtain using traditional technological methods. There is a great potential of mechanochemistry in technology and several examples with a possibility for industrial applications are given. Gold and silver are frequently physically-locked within sulphides, may form defects in their structure or can be chemically bonded in the form of solid solutions or compounds [6-8]. Different types of associations of gold with sulphidic minerals are given in Fig. 2.

Metallurgical and Materials Engineering, 2014

This article reports on the hydrometallurgical production of synthetic anatase from ilmenite. Mec... more This article reports on the hydrometallurgical production of synthetic anatase from ilmenite. Mechanical activation followed by pressure leaching facilitates the leaching of ilmenite and the separation of titanium/iron by means of the synchronous hydrolysis of anatase. At 95% TiO2, the produced synthetic anatase fulfills the requirements for the aluminothermic production of titanium alloys.

Acta Physica Polonica A, 2014

Nanocrystalline powders of ZnAl2O4 and CdSe were prepared via mechanochemical synthesis. Powder s... more Nanocrystalline powders of ZnAl2O4 and CdSe were prepared via mechanochemical synthesis. Powder slurries were coated as thin lms on SiO2 thin layer chromatography (TLC) sheet by capillary method. The photocatalytic activity of the lm coating was tested in a self-made gas-phase at-plate continuous-ow photocatalytic reactor with toluene as model air contaminant. The tested nanocrystalline ZnAl2O4 turned out to be poor oxidation photocatalyst under UV irradiation. CdSe displays considerable photocatalytic activity under visible light, where TiO2 is inactive. The nonconventional one-step mechanochemical route to ZnAl2O4 and CdSe synthesis oers several advantages compared to traditional processing routes, including low-temperature solid state reactions at ambient temperature, absence of organic templates contamination and low expenses.

Journal of Nano Research, 2012

In this study, arsenic sulphide As4S4nanoparticles have been prepared, by high-energy wet milling... more In this study, arsenic sulphide As4S4nanoparticles have been prepared, by high-energy wet milling, in the presence of sodium dodecylsulphate, which acts a surfactant. Solid state properties of the nanoparticles were characterised by XRD, Raman scattering, specific surface area and particle size distribution. Changes in surface areas of the particles, in the 0.2 - 5.4 m2g-1range, and nanosize distributions, in the 100 - 250 nm range, characterise the surface and morphological properties of nanorealgar. Raman scattering revealed various species in the milled sample that indicate a disproportionate reaction (3As4S4→ 4As2S3+ 4As) occurring as a consequence of milling. Anticancer effects, of the milled species, were confirmed for the human multiple myeloma U266 and OPM1 cell lines. Dissolution experiments in simulated gastric fluid show a possibility for the application of the realgar nanoparticles as an oral dose in future arsenic drug cancer treatments.

Journal of Materials Science, Sep 9, 2016

In this paper, InAs/ZnS mixed nanocrystals were synthesized by dry high-energy milling approach i... more 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.

Advanced Powder Technology, Dec 1, 2017

Abstract By using a bio-mechanochemical approach combining mechanochemistry (ball milling) and gr... more Abstract By using 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. Concretely, eggshell membrane (ESM) or Origanum vulgare L. plant (ORE) and silver nitrate were used as environmentally friendly reducing agent and Ag precursor, respectively. The whole synthesis took 30 min in the former and 45 min in the latter case. The photon cross-correlation measurements have shown finer character of the product in the case of milling with Origanum . UV–Vis measurements have shown the formation of spherical NPs in both samples. TEM study has revealed that both samples are composites of nanosized silver nanoparticles homogenously dispersed within the organic matrices. It has shown that the size and size distribution of the silver nanoparticles is smaller and more uniform in the case of eggshell membrane matrix implying lower silver mobility within this matrix. The antibacterial activity was higher for the silver nanoparticles synthesized with co-milling with Origanum plant than in the case of milling with eggshell membrane.

Materials Science in Semiconductor Processing, Nov 1, 2014

The bulk and surface properties of mechanochemically synthesized ZnS nanoparticles were studied. ... more The bulk and surface properties of mechanochemically synthesized ZnS nanoparticles were studied. XRD, SEM, TEM (HRTEM), AFM, UV-VIS, low temperature nitrogen sorption as well as TPR characterization methods have been applied. Cubic ZnS nanocrystals (2-4 nm) with characteristic blue shift have been obtained by high-energy milling. There is an evidence of the nanocrystal aggregates formation in products of milling. The surface uniformity, homogeneity as well as enhanced uptake of hydrogen have been documented.

Journal of Alloys and Compounds, May 1, 2018

In this study, the mechanochemical synthesis of Co 9 S 8 nanoparticles from cobalt and sulphur by... more In this study, the mechanochemical synthesis of Co 9 S 8 nanoparticles from cobalt and sulphur by high-energy milling in a planetary mill in an argon atmosphere is reported. Structural characterization of the synthesized nanoparticles by XRD was performed. Co 9 S 8 nanoparticles crystallize in the cubic structure with the crystallite size of about 16 nm. The microstructure of the Co 9 S 8 nanoparticles was further studied using TEM, HRTEM and EDS-HAADF-STEM techniques. Co 9 S 8 nanoparticles consist of nanocrystals exhibiting size in the range of 10-30 nm that are densely aggregated into spherical-like objects. The highest specific surface area value observed was 4 m 2 g-1 and the pore properties of this sample are quite poor. The magnetic properties of mechanochemically synthesized nanoparticles were investigated using SQUID magnetometer. The room temperature magnetic data supported the paramagnetic spin structure of Co 9 S 8 nanoparticles. The transition from paramagnetic to weak ferromagnetic or ferrimagnetic behaviour was indicated from temperature dependence of magnetization.at cryogenic temperatures. It is demonstrated that mechanochemical synthesis can be successfully employed in the one-step solid-state preparation of Co 9 S 8 nanoparticles.

The Open Chemical Engineering Journal, Feb 14, 2008

Au-Ag noble metal wastes represent a wide range of waste types and forms with various ballast ele... more Au-Ag noble metal wastes represent a wide range of waste types and forms with various ballast elements and components. The thiourea process of gold and silver extraction from ores, concentrates or secondary raw materials consists of gold and silver leaching into the thiourea solution and the consequent precipitation of these metals from the solution. Due to the non-toxic character of thiourea it is the perspective alternative to the up to now most frequently used cyanide method. The thiourea leaching of gold and silver from electronic waste, goldsmith's waste and ceramic waste using crushing as the pretreatment step was investigated. For electronic waste, it was possible to achieve 97 % gold and 94 % silver recovery within 120 minutes of thiourea leaching. Up to 98 % of gold and 96 % of silver were recovered from goldsmith's waste after 60 minutes of leaching. In the case of ceramic waste, we achieved up to 98 % gold and 97 % silver extraction efficiency after only 45 minutes of leaching. In comparison with the classical cyanide leaching, thiourea leaching acts faster and without a harmful environmental impact.