S. Filipović

Serbian Academy of Sciences and Arts · Institute of Technical Sciences

The strength of zirconium diboride ceramics was tested by three different methods, 3‐point flexure, 4‐point flexure, and compression. Nearly full‐density ceramics were obtained by hot pressing commercial ZrB2 powder with the addition of .5 wt.% carbon as a sintering aid. The thermal properties and hardness were studied for ZrB2 milled with ZrB2 and...

To date, the thermal and electrical properties of three‐phase ceramics containing a boride phase, silicon carbide, and boron carbide have not been studied in detail. Further, the effect of the source of the boride powder has also not been investigated. This study produced three‐phase ceramics containing titanium diboride, silicon carbide, and boron...

This study presents an analysis of films which consist of two layers; one layer is PVDF as the matrix, along with fillers BaTiO3 (BT), and the second is one bacterial nanocellulose (BNC) filled with Fe3O4. The mass fraction of BT in PVDF was 5%, and the samples were differentiated based on the duration of the mechanical activation of BT. This innov...

Super‐hard (Hf,Mo,Ti,V,W)B2 was synthesized by boro‐carbothermal reduction and densified by spark plasma sintering. This composition was produced for the first time as a single‐phase ceramic in the present research. The optimized ceramic had a single hexagonal AlB2‐type crystalline phase with a grain size of 3.8 µm and homogeneous distribution of t...

Bacterial cellulose (BC) is a highly pure polysaccharide biopolymer that can be produced by various bacterial genera. Even though BC lacks functional properties, its porosity, three-dimensional network, and high specific surface area make it a suitable carrier for functional composite materials. In the present study, BC-producing bacteria were isol...

The need for improved functionalities in extreme environments is fuelling interest in high-entropy ceramics1–3. Except for the computational discovery of high-entropy carbides, performed with the entropy-forming-ability descriptor4, most innovation has been slowly driven by experimental means1–3. Hence, advancement in the field needs more theoretic...

Ceramic/polymer composites can be chemically stable, mechanically strong, and flexible, which make them candidates for electric devices, such as pressure or temperature sensors, energy storage or harvesting devices, actuators, and so forth. Depending on the application, various electrical properties are of importance. Polymers usually have low diel...

The hybrid multifunctional magnetic organic/inorganic composite materials, with addition of optimal filler type and quantities are attractive due to wide range of potential application, from various pressure sensors, through smart packaging, to tissue engineering and medicine. The structural, morphological and magnetic properties of polyvinylidene...

In the search for environmentally friendly materials with a wide range of properties, polymer composites have emerged as a promising alternative due to their multifunctional properties. This study focuses on the synthesis of composite materials consisting of four components: bacterial nanocellulose (BNC) modified with magnetic Fe3O4, and a mixture...

Final‐stage sintering was analyzed for nominally phase pure zirconium diboride synthesized by borothermal reduction of high‐purity ZrO2. Analysis was conducted on ZrB2 ceramics with relative densities greater than 90% using the Nabarro–Herring stress–directed vacancy diffusion model. Temperatures of 1900°C or above and an applied uniaxial pressure...

Multi-phase ceramics based on ZrB2, TiB2 and doped with CrB2 and SiC were prepared by powder metallurgy and hot pressing to explore the possibility of obtaining multi-scale microstructures by super-saturation of complex (Zr,Ti,Cr)B2 solid solutions. Core–shell structures formed in TiB2 grains, whereas ZrB2 appeared to form a homogeneous solid solut...

Magnesium aluminate has the spinel structure along with good mechanical, chemical, and thermal properties. Magnesium aluminate has a wide range of applications including refractory ceramics, optically transparent ceramic windows, and armors. Its low dielectric permeability and low loss tangent enable its applications for integrated electronic devic...

The authors investigated the influence of mechanical activation on the structure of SrTiO3 mixture with 6 wt.% Fe2O3. Powders were mechanically activated in a planetary ball mill with WC balls in time intervals from 0 to 120 minutes. XRD method was used for the identification of phase structure, while SEM and PSA were employed for monitoring of cha...

The manuscript shows the studies of structural and magnetic properties of BaTiO3/Fe2O3 samples prepared using five different chemical routes. We show that the undertaken processes leaded to the decoration of BaTiO3 grains with hematite nanoparticles, but not to a creation of a well-defined core-shell structure. These studies revealed that a strong...

The rise of innovation in the electrical industry is driven by the controlled design of new materials. The hybrid materials based on magnetite/nanocellulose are highly interesting due to their various applications in medicine, ecology, catalysis and electronics. In this study, the structure and morphology of nanocellulose/magnetite hybrid nanomater...

Due to the growing number of people infected with the new coronavirus globally, which weakens immunity, there has been an increase in bacterial infections. Hence, knowledge about simple and low-cost synthesis methods of materials with good structural and antimicrobial properties is of great importance. A material obtained through the combination of...

Magnesium aluminate and other alumina-based spinels attract attention due to their high hardness, high mechanical strength, and low dielectric constant. MgAl2O4 was produced by a solid-state reaction between MgO and α-Al2O3 powders. Mechanical activation for 30 min in a planetary ball mill was used to increase the reactivity of powders. Yttrium oxi...

Cellulose, as the main constituent of plants, is the most common natural material that is widely used. Bacterial cellulose (BC) is a polymer of β-1,4-glucan chains, extracellularly attached to bacterial cells. It possesses the same structure as plant cellulose but its application has many advantages. BC has tinner threads, better crystallinity, mec...

As one of the most common biopolymers on Earth, cellulose has found an important role in food industry, biomedicine andbiotechnology. The process of obtaining cellulose fibers is often followed with the presence of the byproduct, whose removal is required procedure. From that reason, the process of obtaining material on a bacterial cellulose (BC) b...

To investigate the magnetic behavior of starch-coated cobalt ferrites, well-established synthetic methods, i.e., coprecipitation, mechanochemical, ultrasonically assisted coprecipitation, microemulsion, and microwave-assisted hydrothermal syntheses were chosen for their preparation. The obtained materials had pure single-phase spinel structures. Sc...

Solid-state reaction between BaTiO3 and Fe2O3 was used to produce a multiferroic heterostructure composite. Commercial BaTiO3 and Fe(NO3)3•9H2O were suspended in ethanol for 30 minutes in an ultrasound bath. The prepared mixture was thermally processed at 300°C for 6 h. Sintering at 1300°C for 1 h resulted in a mixture of different phases, BaTiO3,...

Development in many areas of engineering and technology are closely linked to the development of new or improvement of existing materials. Having in mind wide use of bacterial nanocellulose (BNC) in various areas of everyday life, from biomedicine, ecology to electronics, BNC-based composites are becoming widely used and attracting the attention of...

We have developed rotationally symmetrical coaxial chambers for measurements of dielectric parameters of disk-shaped samples, in the frequency range from 1 MHz to several hundred MHz. The reflection coefficient of the chamber is measured and the dielectric parameters are hence extracted utilizing a high-accuracy quasistatic numerical model of the c...

Industrial/technological growth is directly connected with environmental pollution, but its influence can be minimized through pollution abatement approaches such as the treatment of industrial wastewater. In this study, novel porous amine-functionalized silicate minerals, specifically, cordierite was investigated for the removal of toxic heavy met...

To investigate the magnetic behaviour of starch coated cobalt ferrites, five well established synthetic methods, i.e. co-precipitation, mechanochemical, ultrasonically assisted co-precipitation, microemulsion, and microwave-assisted hydrothermal syntheses were chosen for the materials’ preparation. Obtained cobalt ferrites had pure single-phase spi...

Barium titanate (BaTiO3) attracts high scientific and technological attention due to good dielectric and electromechanical properties. Although BaTiO3 is one of the most frequently investigated ferroelectric materials, the need for finding new and/or improved synthesis methods of this material still exists. In this paper, a novel, mild synthesis ro...

The aim of the study was to investigate the influence of low heating temperatures with two different retention times to optimize the process for obtaining nanosized hydroxyapatite material that can possibly be used in the fields of biology and pharmacy. Nanosized hydroxyapatite was successfully obtained by wet chemical precipitation. The annealing...

Solid-state mechanical activation of MgO and α-Al2O3 powders was used to produce MgAl2O4. The cation site occupancy in the resulting MgAl2O4 spinel was investigated using different methods. Differential thermal analysis and thermal gravimetry showed that mechanical activation reduced the spinel formation temperature by around 200 °C, and the corres...

Alumina-based compounds have many technological applications and attract great attention even after decades of investigation, due to their good chemical, electrical, and mechanical properties. A mixture of several alumina modifications (α-, κ-, γ-Al2O3) doped with 1 wt% of Mn2O3 was used for this experiment. The powder was mechanically activated fo...

Multiferroic materials attracted a lot of attention in recent years because of their significant scientific interest and technological applications. The multiferroic core/shell powders have a better connectivity between the phases, resulting in superior dielectric and magneto electric properties. In this study, the influence of preparation conditio...

Magnesium aluminate, MgAl2O4 and other alumina-based spinels are ceramics with high hardness, high melting point and mechanical strenght. Spinels can also be used as dielectrics in microwave applications. The goal of this study was to examine the effects of mechanical activation and sintering temperatures on physico-chemical properties of spinel. M...

Single phase MgAl2O4 was made from a one-to-one molar ratio of MgO and Al2O3 powders mixed using ball-milling. Mixtures of MgO and Al2O3 were subsequently treated in planetary ball mill for 30, 60, 90 and 120 minutes in air. The aim of this study was to examine phase composition, microstructure, and densification behavior of sintered specimens. Aft...

Thermally activated processes in cordierite-based ceramics were investigated to determine the effect of the mechanical activation and the addition of TeO2 on kinetic and thermodynamic parameters of these processes. Using a combination of dilatometry and DTA measurements in the 100–1400 °C temperature range, it was established that both the mechanic...

Corundum (α-alumina) is a suiTab. material for usage in various industry fields owing to its chemical stability, electrical and mechanical features. It is known that properties of ceramics could be modified by addition of different oxides, as well as by changing the consolidation parameters. In this respect, alumina was doped with 1 wt.% of Cr2O3,...

In this paper, synthesis of porous wollastonite-based ceramics was reported. Ceramic precursor, methylhydrocyclosiloxane, together with micro-sized CaCO3, was used as starting material. After 20 min of ultrasound treatment, and calcination at 250 oC for 30 min, yeast as a pore-forming agent was added to the as-obtained powders. Sintering regime was...

In this study, porous macro- and micro-cellular wollastonite-based ceramics was synthesized. A ceramic precursor, methylhydrocyclosiloxane, together with micro-sized CaCO3, was used as a starting material. After 20 min of ultrasound treatment, and calcination at 250 °C for 30 min, different pore-forming agents were added to the as-obtained powders....

The intensive progress in electronics, especially telecommunication and mobile phone in 1990s, was the main driving force for the extensive research and development of microwave ceramics. These materials are often used in manufacturing resonators and antennas, filters and oscillators, etc. For suitable usage of these components, their dielectric pr...

In the present study the effect of preparation conditions on microstructure and electrical properties of MgTiO3 ceramics was investigated. Mixture of MgO and TiO2 powders was subjected to mechanical activation for different time periods. Two types of sintering (two-step and HIP sintering) were performed on green bodies prepared by cold isostatic pr...

Post-sintering of magnesium titanate ceramics by hot isostatic pressing (HIP) in an oxygen-free atmosphere significantly alters various electrical properties of the product. In particular, the sintered material becomes a semiconductor. The aims of this paper are: to extend our investigations of the electrical properties of this material by expandin...

The mechanical activation can help reduce production costs and modify cordierite-based materials. In this study, the structure and electrical properties of the mechanically activated MgO-Al2O3-SiO2 system have been analyzed. The mixtures of MgO-Al2O3-SiO2 powders were mechanically activated in a planetary ball mill for time periods ranging from 0 t...

The aim of this study is to explore the influence of the processing route on the structural and physical properties of bulk MgTiO3 ceramics. Commercially available MgO and TiO2 powders were mechanically activated in a planetary ball mill. Green bodies were formed by an isostatic pressure of 300 MPa. The sintering of these samples was done either by...

Cordierite-based ceramic materials are attracting much interest for their various applications in industry, for manufacturing multilayer circuit boards, catalytic converters, filters, thermal insulation, kiln furniture, components of portable electronic devices, etc. In order to reduce production costs and modify cordierite-based materials, mechani...

Cordierite 2MgO+2Al2O3+5SiO2 is frequently used ceramic material, that is commonly used as a carrier of electrical components due to its low dielectric constant (~ 5), and low temperature thermal expansion coefficient (20·10-7 oC-1). In order to accelerate the process of sintering, 5.00 mass% TeO2 was added to the starting mixtures. System was test...

We present two coaxial chambers for measurements of the complex permittivity of solid and liquid samples, in a frequency range that is in the transition between lower frequencies, where parallel-plate capacitor techniques are used, and higher (microwave) frequencies, where antennas, open coaxial lines, and waveguides are employed. Using a network a...

Since cordierite, 2MgO·2Al2O3·5SiO2 (MAS), is a very useful high-temperature ceramic material, it is important to decrease its sintering temperature. In order to accelerate the process of sintering, 5.00 mass% MoO3 was added to the starting mixtures. The mechanical activation of the starting mixtures was performed in a high-energy ball mill in time...

Commercially available ZnO powder was mechanically activated in a planetary ball mill. In order to investigate the specific surface area, pore volume and microstructure of non-activated and mechanically activated ZnO powders the authors performed N 2 physisorption, SEM and TEM. Crystallite size and lattice microstrain were analyzed by X-ray diffrac...

Since cordierite, 2MgO⋅2Al2O3⋅5SiO2 (MAS), is a very usefull high-temperature ceramic material, it is important to decrease its sintering temperature. In order to accelerate the process of sintering, 5.00 mass % MoO3 was added to the starting mixtures. The mechanical activation of the starting mixtures was performed in a high energy ball mill in ti...

Commercially available ZnO powder was mechanically activated in a planetary ball mill. In order to investigate the specific surface area, pore volume and microstructure of non-activated and mechanically activated ZnO powders the authors performed N2 physisorption, SEM and TEM. Crystallite size and lattice microstrain were analyzed by X-ray diffract...

Due to its characteristics, cordierite, 2MgO·2Al2O3·5SiO2, is a high-temperature ceramic material of a great scientific interest. Mechanical activation of the starting mixtures containing 5.00 mass% TiO2 was performed in a high-energy ball mill for 10 minutes. The compaction pressure varied from 0.5 to 6tcm-2 (49-588 MPa). The sintering process was...

The aim of this paper was investigation of structural and electrical properties of magnesium titanate ceramic obtained mechanochemically and subjected to two stage sintering process. Mixtures of MgO and TiO2 were treated in a planetary ball mill for several time intervals ranging from 0 to 160 minutes. Powders prepared in this way were two stage si...

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 t...

In this article, the advantages of combined sintering in comparison with the conventional one, of mechanically activated magnesium titanate ceramic were investigated. The stoichiometric mixtures of MgO and TiO2 were mechano-chemically activated for 0, 10, 40, 80 and 160 minutes by ball milling and then isostatically pressed (CIP) to form green bodi...

The aim of this paper was mechanochemical preparation of magnesium titanates. Powder mixtures of starting oxides MgO and TiO2 were mechanically activated in a planetary ball mill for the time interval from 0 to 160 minutes. Structural, stereological, thermal characterizations were performed on produced powders. The effects of activation on morpholo...

Strontium-titanate powder was mechanically activated in a planetary ball mill for 0, 5, 10, 30, 60, 90 and 120 minutes. Non-isothermal sintering of non-activated and activated SrTiO3 powder samples in the temperature interval from 50 to 1300 0C with three different heating rates (10, 15 and 20 0C/min) was investigated on a dilatometer. X-ray powder...

In this article the influence of ball miling process on structure of MgO–TiO2 system, as well as the electrical properties of samples after sintering, was investigated. The mixtures of MgO–TiO2 powders were mechanically activated in a planetary ball mill for the time period from 0 to 120 min. The influence of mechanical activation and sintering on...

Mixtures of MgO-TiO 2 powders were mechanically activated in a planetary ball mill for a time interval from 0 to 120 minutes. The influence of the mechanical activation on the phase composition and crystal structure have been analyzed by X-ray diffraction (XRD), while the effect of the activation and sintering process on the microstructure was inve...

Three-component oxide mixtures were prepared containing MgO, Al 2O 3 and SiO 2 in a 2 : 2 : 5 ratio with addition of 10% Bi 2O 3. The mixtures were mechanically activated in a range from 5 to 240 min in a mill with ceramic balls, and sintered in the range 1173–1573 K. In order to determine the structure transformations, sintered products were analy...

Due to its outstanding electrical characteristics, such as the low temperature expansion coefficient, low dielectric constant and good mechanical properties, cordierite, 2MgO⋅2Al2O3⋅ 5SiO2, is a very attractive high-temperature ceramic material. In order to accelerate the process of sintering, 2.50 mass% Bi2O3 has been added to the starting mixture...

Starting mixtures of BaCO3, ZnO, and TiO2 powders are mechanically activated in a planetary ball mill for various periods of time. The powders obtained are sintered isothermally at 1100°C for 120 min. Non-isothermal sintering process is followed by measurements with a sensitive dilatometer, as well. Results of microstructure characterization using...

Barium-Strontium-Titanate Ba0.77Sr0.23TiO3 was prepared from starting materials BaCO3, SrCO3 and TiO2 through solid-state reactions. Mixtures of these oxides are mechanically activated in a high-energy planetary ball mill at different time intervals from 0 to 120 minutes. In order to obtain information on phase composition, crystal structure was de...

Mixtures of BaCO3, ZnO and TiO2 powders, with molar ratio of 1:2:4, were mechanically activated for 20, 40 and minutes in a planetary ball mill. The resulting powders were compacted into pellets and isothermally sintered at 1250 degrees C for 2h with a heating rate of 10 degrees C/min. X-ray diffraction analysis of obtained powders and sintered sam...

Mixtures of MgO-TiO2 powders were mechanically activated in planetary ball mill for time interval from 0 to 120 minutes. The influence of mechanical activation on phase composition and crystal structure was analyzed by XRD, while the effect of activation and sintering process on microstructure was investigated by scanning electron microscopy. Using...

Ba0.8Sr0.2TiO3 was prepared from the starting materials BaCO3, SrCO3 and TiO2 through solid state reaction. Mixture of these oxides was mechanically activated using a high-energy ball mill at different time intervals from 0 to 120 minutes. The crystal structure was determined by X-ray diffraction to obtain information about the composition of phase...

The base mix refractory concrete is corundum-based, containing corundum as refractory aggregate and CAC as hydraulic binder, with a spinel as an additive. The authors investigated the dehydration reactions which occur from the moment when water is added (at the beginning of components mixing), to the moment when installed refractory concrete lining...

According to its exceptional electrical characteristics, such as low temperature expansion coefficient, low dielectric constant and good mechanical properties, cordierite, 2MgO⋅2Al2O3⋅5SiO2, represents very attractive ceramic material in the field of high temperatures. In order to accelerate the process of sintering, 1 mass% Bi2O3 has been added to...

The aim of this work was an investigation of structural and electrical properties of sintered barium-zinc-titanate ceramics. Mixtures of BaCO 3, ZnO and TiO2 were mechanically activated in a planetary ball mill up to 80 minutes and sintered isothermally in air for 120 minutes at 1300 °C. The phase composition in the BaCO3-ZnO-TiO2 system after mill...

In this article the influence of mechanical activation on sintering process of magnesium-titanate and barium-zinc-titanate ceramics has been investigated. Both non-activated and mixtures treated in planetary ball mill for 80 minutes were sintered at 1100 degrees C and 1300 degrees C. The influence of mechanical activation on phase composition and c...

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. T...

Mixtures of BaCO3–ZnO–TiO2 were mechanically activated using high-energy planetary ball mill during 20, 40 and 80 min. As the time of mechanical activation increased, the decrease in particle size was observed. The effect of milling on microstructure was investigated by scanning electron microscopy, as well. Sintering process was performed in air a...

The aim of this work was to analyse the kinetics and microstructure evolution of ZnO sintering process. ZnO powder was isothermally sintered (15, 30, 60, 90 and 120 min) in the temperature range from 8000C to 12000C. The values of Lenel parameter were calculated and used for the analysis of the densification and mass transport processes. Using scan...

Mixtures of MgO-TiO2 were mechanically activated using high-energy planetary ball mill during 5, 10, 20, 40, 80 and 120 minutes. Sintering process was preformed in air at 1100o-1400oC for 2h. The decrease in powder’s particle size was noticed as the time of mechanical activation increased and confirmed by particle size analyzer. XRD analyses were p...