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BACKGROUND: Self‐propagating high‐temperature synthesis was used to create mesoporous CeO2 and MgO powders as well as nanocomposites based on them for efficient degradation of organic dyes. RESULTS: It has been investigated how magnesium oxide and cerium oxide interact to affect the crystal structure, morphology and microstructure of the materials produced. It was assumed that CeO2 forms on the surface of MgO while the material's developed surface is preserved. The values of the specific surface area and average pore diameter of the studied samples depend on the composition and vary in the ranges of 16–41 m2 g−1 and 11.919 nm, respectively. CONCLUSION: It has been established that the sizes of CeO2 crystallites in the composition of nanocomposites change insignificantly and range from 6.5 to 7.4 nm. The photocatalytic activity of the studied samples is at least two times higher compared to analogs. The samples MgO–CeO2 (30 mol%) and MgO–CeO2 (50 mol%) showed the maximum photodegradation efficiency of acid telon blue and direct bright blue dyes at levels of 98.5% and 92.5%, respectively. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Magnesium-aluminum oxynitride MgAlON has garnered significant attention in recent years due to its unique properties and potential applications. Herein, we report a systematic study on the synthesis of MgAlON with tunable composition by employing the combustion method. The Al/Al2O3/MgO mixture was combusted in nitrogen gas, and the effects of Al nitriding and oxidation by Mg(ClO4)2 on the exothermicity of the mixture, combustion kinetics, and phase composition of combustion products were investigated. Our results demonstrate that the MgAlON lattice parameter can be controlled by varying the AlON/MgAl2O4 ratio in the mixture, which corresponds to the MgO content in the combustion products. This work provides a new pathway for tailoring the properties of MgAlON, which may have significant implications in various technological applications. In particular, we reveal the dependence of the MgAlON lattice parameter on the AlON/MgAl2O4 ratio. The limitation of the combustion temperature by 1650 °C resulted in obtaining submicron powders with a specific surface area of about 3.8 m/g2. [ABSTRACT FROM AUTHOR]

The present work reports the direct production of a high-entropy (HE) intermetallic CoNi0.3Fe0.3Cr0.15Al material with a B2 structure from mechanically activated elemental powder mixtures. Fast and efficient combustion synthesis (CS), spark plasma sintering (SPS), and reactive SPS (RSPS) methods were used to synthesize the HE powders and bulks. The formation of the main B2 phase along with some amounts of secondary BCC and FCC phases are reported, and L12 intermetallic (CS scheme) and BCC based on Cr (CS + SPS and RSPS schemes at 1000 °C) were observed in all samples. The interaction between the components during heating to 1600 °C of the mechanically activated mixtures and CS powders has been studied. It has been shown that the formation of the CoNi0.3Fe0.3Cr0.15Al phase occurs at 1370 °C through the formation of intermediate intermetallic phases (Al9Me2, AlCo, AlNi3) and their solid solutions, which coincidences well with thermodynamic calculations and solubility diagrams. Compression tests at room and elevated temperatures showed that the alloy obtained by the RSPS method has enhanced mechanical properties (σp = 2.79 GPa, σ0.2 = 1.82 GPa, ε = 11.5% at 400 °C) that surpass many known alloys in this system. High mechanical properties at elevated temperatures are provided by the B2 ordered phase due to the presence of impurity atoms and defects in the lattice. [ABSTRACT FROM AUTHOR]

In this work silicon carbide (SiC) sub-micron powders were synthesized using four different combustion routes, which include the following reactive systems: Si/C/Teflon (T); Si/C/N 2 (N); Si/C mechanically activated composite particles (MA) and reduction SiO 2 /Mg/C reaction (R). The specific surface area of the as-synthesized SiC T , SiC N , SiC MA and SiC R powders are: 4 ± 0.5; 17 ± 2; 20 ± 2 and 145 ± 5 m 2 /g respectively. These powders were subjected to spark plasma sintering (SPS) without any additives at 2073 K for 10 min. The densification kinetics for each powder were measured and discussed. The obtained ceramics possess a relative density in the range 80–95% and Vickers micro-hardness ( H v ) from 7 to 20 GPa. To illustrate the capability of the method, essentially pore-free ceramics were prepared from SiC MA powder by 1 h SPS without additives at 2273 K, with H v = 24 GPa and fracture toughness K 1C = 3–5 MPa m 1/2 . [ABSTRACT FROM AUTHOR]

Groundwater is one of the cleanest natural sources of drinking water available, which, at the same time, often requires deironing – removal of the dissolved iron ions – before the water could be used. In this paper, there are describe the preparation, characterization, and deironing properties of surface-modified refractory chamotte granules, used as active components of fillers for deironing filters. For this research, chamotte surface modification was made by solution combustion synthesis (SCS) approach of an aqueous solution of synthetic iron nitrate and citric acid with the different iron-to-chamotte ratios. An iron-rich precipitate from deironing filters was used as a source of iron for the preparation of a precursor solution. Obtained materials were characterized using diffraction, spectroscopic and microscopic methods. The SCS modification resulted in the formation of layers of hematite Fe 3 O 4 nanocrystallites of ~5–15 nm on the surface of refractory chamotte granules. It was shown the effect of the dose of iron nitrate on the absorbed iron oxide species content on the surface of the modified chamotte granules and its influence on the surface and operational characteristics. Pilot-plant deironing tests showed that an increase in the concentration of iron on the chamotte granules surface from 5.8 wt% for unmodified samples, to 19.0, 48.7, and 55.8 wt% for the modified ones, led to the respective increase in the deironing efficiency from 41% to 65%, 73% and 78%, respectively. [Display omitted] • Solution combustion synthesis proposed for chamotte granules surface modification. • Iron-containing sediments used as an efficient modifier of water deironing filters. • Modification of chamotte increases the efficiency of water deironing on 45–78%. • Surface modification does not affect the operational characteristics of filters. [ABSTRACT FROM AUTHOR]

Oxides are attractive and promising compounds for application as thermoelectric materials owing to thermal and chemical stability, cost-effectiveness, and environmental safety. In this work, CaMnO 3 perovskite hollow spheres were synthesized by spray solution combustion synthesis. The effect of the fuel glycine on the phase composition, morphology, and microstructure of CaMnO 3 was studied, and the influence of synthesis parameters on the characteristics of the sintered materials was investigated. The porous CaMnO 3 (porosity 10–20%) forms by pressureless sintering at 1473 K, which is accompanied by the precipitation of marokite CaMn 2 O 4. It is possible to alter the porosity level as well as marokite and pore size in the CaMnO 3 /CaMn 2 O 4 composite by tailoring the fuel amount, which, in turn, affects the thermoelectric properties. The zT value of 0.13 at 1073 K, to the best of our knowledge, is the highest zT reported for the undoped CaMnO 3 material. • Hollow Spheres of CaMnO 3 Produced via Spray Solution Combustion Synthesis (SSCS). • Increasing fuel during SSCS reduced wall thickness of hollow spheres from 140 to 40 nm. • Excess fuel negatively affected CaMnO 3 uniformity after sintering. • Pressureless sintering yields bulk homogeneous CaMnO 3 + 10 vol% CaMn 2 O 4 + 22% pores. • Porosity and marokite of CaMnO 3 perovskite increase zT value at 1073 K to 0.13. [ABSTRACT FROM AUTHOR]

[Display omitted] • (Ta,Ti,Nb,Zr) and Mo-, Hf-, W-containing high-entropy carbides obtained by SCS-SPS. • All ceramics oxidizes in a three-stage process during non-isothermal heating. • Formation of ZrO 2 , Me 2 Me 6 O 17 , and MeMe 2 O 7 oxides are limited reaction on each stage. • Mo-, and Hf-based ceramics oxidation follows logarithmic law for isothermal heating. • Formation of Me 2 Me 6 O 17 oxides defines high oxidation resistance of carbide ceramics. Medium- and high-entropy carbides (MECs and HECs) have a wide range of advanced applications and, in many cases, outperform monocarbides. However, the behavior, oxidation mechanisms, and factors defining oxidation resistance of some popular HECs at high temperatures have not been studied in detail yet. In this study, the oxidation behavior of MEC and HECs including (Ta,Ti,Nb,Zr)C, (Ta,Ti,Nb,Zr,Mo)C, (Ta,Ti,Nb,Zr,Hf)C, and (Ta,Ti,Nb,Zr,W)C was investigated under both non-isothermal and isothermal conditions at temperatures up to 1200 °C, and a possible oxidation path was described. It was found that under non-isothermal heating conditions, the oxidation of HECs occurred in three stages, each governed by first-order chemical reactions, and was limited by the formation of ZrO 2 , Me 2 Me 6 O 17 , and MeMe 2 O 7 oxides, respectively. In the case of isothermal heating, the oxidation of (Ta,Ti,Nb,Zr)C, (Ta,Ti,Nb,Zr,Mo)C, and (Ta,Ti,Nb,Zr,Hf)C follows a logarithmic law and was limited by the formation of a protective Me 2 Me 6 O 17 layer. In contrast, isothermal oxidation of (Ta,Ti,Nb,Zr,W)C followed a linear law due to the formation of volatile WO 3. The results of the study have a high potential for practical application for the production of HEC ceramics for various high-temperature purposes and could be used for further understanding of functional characteristics and development of the new ceramic compositions. [ABSTRACT FROM AUTHOR]

By a combination of mechanical activation, combustion synthesis, and spark plasma sintering methods, bulk materials in the Hf-Zr-C-N system with various Hf/Zr atomic ratios were produced. The mechanical activation process in a low-energy mode (350 rpm) for 90 min resulted in the formation of layered Hf/Zr/C composite particles 10–30 μm in size, depending on the Hf/Zr ratio. The diffraction spectra of the as-synthesized powders were described by several isomorphic (Hf,Zr)(C,N)ss cubic phases with different nitrogen content. Spark plasma sintering contributed to the homogenization of the chemical composition and allowed production of the dense (∼98%) single-phase hafnium-zirconium carbonitrides with an FCC structure. The bulk ceramics exhibited superior hardness (∼17 GPa) and fracture toughness (∼5 MPa m1/2), relative to (Hf,Zr)C carbides prepared by similar methods. [ABSTRACT FROM AUTHOR]