Metal-Like Thermal Conductivity Possessed By Atmosphere Assisted Synthesis Of Spark Plasma Sintered Mayenite (Ca12Al14O33)

Mayenite (Ca12Al14O33) samples have been synthesized in ambient air, argon, and nitrogen atmospheres to vary the defect chemistry and to investigate its role in thermal conductivity. Highly dense sintered pellets (SEM) were obtained through spark plasma sintering and the X-ray diffractograms revealed predominantly mayenite phase with the presence of a minor amount of secondary phases. Thermal conductivity was measured for the sintered samples and it was observed that mayenite synthesized in nitrogen atmosphere exhibited a colossal value of 579 Wm-1K-1 at room temperature close to that of cubic-BN, comparable with that of metals.Supplementary material: [https://vinar.vin.bg.ac.rs/handle/123456789/9937

Metal-Like Thermal Conductivity Possessed By Atmosphere Assisted Synthesis Of Spark Plasma Sintered Mayenite (Ca12Al14O33): Supporting Information

Supporting information of the article Metal-Like Thermal Conductivity Possessed By Atmosphere Assisted Synthesis Of Spark Plasma Sintered Mayenite (Ca12Al14O33).Supplementary material for: [https://vinar.vin.bg.ac.rs/handle/123456789/9936

Combined magnetic and structural characterization of hidrothermal bismuth ferrite (BiFeO3) nanoparticles

Bismuth ferrite (BiFeO3) was synthesized by hydrothermal method. The crystal and magnetic structures of BiFeO3 have been studied by means of X-ray diffraction and neutron powder diffraction at ambient temperature. Microstructure was analysed by scanning electron microscopy. Quantitative phase analysis by the Rietveld method was conducted and crystallite sizes of 27 nm were determined from the XRD line broadening. The magnetic structure of BiFeO3 is described by the G-type antiferromagnetic order with magnetic peak located at 4.6 Å and a noticeable magnetic contribution to a reflection located at 2.4 Å in the diffraction pattern. The values of the ordered magnetic moment of Fe ions μFe=3.8(1) μB, obtained at ambient conditions, are consistent with those determined earlier. The magnetic moments in the crystal plane z = const are arranged in parallel, changing the direction from [100] to [ 110 ] when moving from one to the other z = const plane. © 2018 Authors. Published by the International Institute for the Science of Sintering

High-density ceramics obtained by andesite basalt sintering

In the present study, andesite basalt originated from the deposit site “Donje Jarinje”, Serbia, was examined as a potential raw material for high-density ceramics production. The production of high-density ceramics included dry milling, homogenization, cold isostatic pressing and sintering in the air. To determine the optimal processing parameters the sintering was conducted at 1040, 1050, 1060, 1070 and 1080°C, and afterwards the sintering duration was varied from 30 to 240min at the optimal sintering temperature of 1060°C. Characterization of the starting and sintered materials included the estimation of particle size distribution, density, hardness and fracture toughness complemented with X-ray diffraction, optical light microscopy, scanning electron microscopy and energy dispersive spectroscopy analysis. Phase transformations did not occur during processing in the investigated temperature range from 1040 to 1080°C. The obtained research results showed that 99.5% of relative density and the highest hardness and fracture toughness values of 6.7GPa and 2.2MPa•m1/2, respectively, were achieved for the andesite basalt sintered at 1060°C for 60min in the air. The results of the present study confirmed that the sintered andesite basalt can be used as a high-density ceramic material for various industrial applications

Computational Discovery of New Feasible Crystal Structures in Ce3O3N

Oxynitrides of cerium are expected to have many useful properties but have not been synthesized so far. We identified possible modifications of a not-yet-synthesized Ce3O3N compound, combining global search (GS) and data mining (DM) methods. Employing empirical potentials, structure candidates were obtained via global optimization on the energy landscape of Ce3O3N for different pressure values. Furthermore, additional feasible structure candidates were found using data mining of the ICSD database. The most promising structure candidates obtained were locally optimized at the ab initio level, and their E(V) curves were computed. The structure lowest in total energy, Ce3O3N-DM1, was found via local optimization starting from a data mining candidate and should be thermodynamically metastable up to high pressures

Luminescence properties of Eu3+ activated Y2MoO6 powders calcined at different temperatures

In the last decade, an immense progress has been made in white LEDs, mainly due to the development of red-emitting phosphors. In this paper, we report on the synthesis of Eu3+ activated Y2MoO6 by a self-initiated and self-sustained method. The obtained powder was calcined at various temperatures in the 600–1400 °C range and examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy (PL). The results revealed that all powders are single phase Y2MoO6:Eu3+, with particle size in the nanorange at lower treatment temperatures (600 and 800 °C) and in the microrange at higher calcination temperatures (1000–1400 °C). The obtained powders are promising materials for white light-emitting diodes as they can efficiently absorb energy in 324–425 nm region (near-UV to blue light region) and emit at 611 nm in the red region of the spectrum, while exhibiting high thermal and chemical stability

Andesite Basalt as a Natural Raw Material for Obtaining Glass-Ceramics

The industrial requirements in the 21st century are environmentally friendly and light construction materials with good physical-mechanical properties manufactured from cheap natural raw materials available in large quantities. One of these materials is basalt. Basalt is a natural igneous rock of volcanic origin, with a significant amount in Serbia. Basalt belongs to the group of non-hazardous and eco-friendly materials. Andesite basalt aggregate from the "Donje Jarinje" site, Serbia, was used as the starting natural raw material for obtaining the glass-ceramic material. The aggregate is from 2 to 5 mm in size. The aggregate was milled in the tungsten-carbide vibrating cup mill for 30 min to obtain a fine powder for synthesis. The homogenization of andesite basalt powder and binder was carried out in the mortar and pestle for 10 min. The paraplast was used as a binder with a content of 0.6 wt.%. After that, uniaxial pressing of the powder at a pressure of 50 MPa was performed. A forming green compact, cold isostatic pressing was performed with a pressure of 230 MPa to increase its density. The sintering was carried out at the temperature of 1060 °C for 60 min in the air. The sintered glass-ceramic sample was a relative density of 99.5%, a macrohardness of 6.7 GPa and a fracture toughness of 2.2 MPa·m1/2 [1]. The andesite basalt powder was characterized using the laser light diffraction method, X-ray diffraction method and scanning electron microscopy. Sintered glassceramic material was characterized using the X-ray diffraction method, Archimedes principle, scanning electron and optical light microscopy and the Vickers hardness test. The glass-ceramic material obtained by sintering andesite basalt powder could be used for various industrial applications in the civil engineering, mechanical, chemical, and petrochemical industries, as well as for the making of containers to store nuclear waste.VII Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbi

Luminescence Properties Of Eu3+ Doped Mayenite Under High Pressure

Europium doped mayenite (C12A7) powders of different concentrations (0.5, 1.0, 1.5, and 2.0 at.%) have been synthesized by a modified glycine/nitrate procedure - MGNP). Obtained samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE- SEM), and steady-state photoluminescence spectroscopy. The effect of doping concentration on photoluminescence properties of Eu3+ doped mayenite was studied and discussed. With the increasing of Eu3+ doping concentration, the red-emitting intensity exhibited behavior that increased firstly and then decreased. The optimal Eu3+ ion concentration is found to be 1.5%. High-pressure luminescence was measured in a Betsa high-pressure membrane diamond anvil cell up to 23 GPa

Sinteza vlakana magnezijum-oksida i magnezijum-hidroksida korišćenjem paukove mreže kao matrice

Spider silk fibers, collected from Pholcus Phalangioides spider were used as a template for obtaining magnesium oxide (MgO, periclase) as well as magnesium hydroxide (Mg(OH)2, brucite) fibers. Magnesium oxide fibers were obtained in a simple manner by heat induced decomposition of magnesium salt (MgCl2) in the presence of the spider silk fibers, while magnesium hydroxidefibers were synthesized by hydration of MgO fibers at 50 °C, 70°C and 90 °C, for 48 and 96 h. According to Scanning electron microscopy (SEM), dimensions of spider silk fibers determined the dimension of synthesized MgO fibers, while for Mg(OH)2 fibers, the average diameter was increased with prolonging the hydration period. The surface of Mg(OH)2 fibers was noticed to be covered with brucite in a form of plates. X-ray diffraction (XRD) analysis showed that MgO fibers were single-phased (the pure magnesium oxide fibers were obtained), while Mg(OH)2 fibers were two- or single-phased brucite depending on incubation period, and/or incubation temperature.Vlakna paukove mreže sakupljena od Pholcus phalangioides pauka korišćena su kao matrica za dobijanje vlakana magnezijum oksida (MgO, periklas) i magnezijum-hidroksida (Mg(OH)2, brucit). Vlakna magnezijum oksida jednostavno su dobijena termičkim razlaganjem soli magnezijuma (MgCl2) u prisustvu vlakana paukove mreže, dok su vlakna magnezijum hidroksida sintetisana hidratacijom MgO vlakana na temperaturama: 50, 70 i 90 °C u trajanju od 48 i 96 h. Na osnovu rezultata skenirajuće elektronske mikroskopije (SEM), veličina sintetisanih MgO vlakana bila je određena dimenzijama vlakana pauka, dok je za Mg(OH)2 vlakna prosečan dijametar rastao sa produženjem perioda hidratacije. Na površini Mg(OH)2 vlakana uočeni su tabličasti kristali brucita. Difrakcija X zraka (XRD) pokazala je da su vlakna periklasa jednofazna (dobijen je čist magnezijum-oksid), dok su brucitna vlakna bila dvofazna ili jednofazna, u zavisnosti od inkubacionog perioda i/ili teperature na kojoj je vršena inkubacija

High-entropy spinel oxides: fundamentals, synthesis and characterization

High-entropy spinel oxides (HESOs) are oxides with 5 or more cations with the general formula AB2O4 and the spinel ( Fd 3m ) structure. Due to their unique structure and properties, HESOs have shown great potential in various technological applications, i.e. they can be used as catalysts, adsorbents and photocatalysts. Since the first successful synthesis in 2018, researchers have been experimenting with different precursors and synthesis methods. However, further research is still needed in order to fully understand their capabilities and exploit their properties. The aim of this research is to synthesize novel HESOs using the self-propagating room temperature (SPRT) method, which is time and cost-effective and has not been utilized so far. Our results indicate that chlorides are not good precursors, since the formation of spinel structure has not been achieved. On the other hand, the use of nitrates has successfully led to a primary spinel ( Fd 3m ) phase. Still, certain issues persist, as secondary phases are commonly formed, especially in the presence of Mg or Cu. A potential solution that could ensure the formation of a single phase is the use of quenching from high temperatures (1000 °C), instead of gradual cooling