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A series of double-perovskite oxides Sr2Sr1-xCaxTeO6 (0 ≤ x ≤ 1) samples have been prepared in order to study the effect of composition on phase formation and the related optical properties. The objective of this work is to study the possibility of calcium insertion with different percentages since calcium in known to enhance the electrical properties. In this work a well detailed structure and phase transitions investigation of the compounds were conducted and probed by X-ray diffraction and Raman spectroscopy techniques at room temperature. Both Rietveld refinements and Raman studies revealed that two phase transitions took place as the calcium amount x increases; a first from a triclinic to a hexagonal in the range 0.1 < x < 0.25 and a second from the hexagonal to a monoclinic structure in the range 0.5 < x < 0.6. The optical absorption α(λ) was also determined as a function of calcium content in the series samples using UV-vis analysis. It was revealed that a remarkable change occured in the cut-off wavelength, confirming the sequence of phase transitions C1 → R 3 ¯ m → P21/n. The optical band gap measurements showed that the triclinic Sr3TeO6 and the monoclinic Sr2CaTeO6 phases have band gap values of 2.75 and 2.81 eV, respectively. When the calcium increased to x = 0.25 (Sr2.75Ca0.25TeO6), remarkable decrease of the band gap value was observed, with Eg = 2.627 eV. [ABSTRACT FROM AUTHOR]

This study shows the effects of heat treatment on the manganese steel which microstructure consists essentially of 18.447% of manganese, 0.745% of chromium, and 1.169% of carbon. The techniques used are: X-ray diffraction, optical microscope, scanning electron microscope.After heat treatment at 600 °C and 1050 °C for 30 minutes, metallurgical analysis will connect the microstructural changes occurring during the temperature maintenance to the mechanical behavior of the material. The characterization of the microstructures and the surface morphology of the alloy before and after the heat treatment determine that this treatment process favors the dispersion of carbides in the austenitic matrix and the appearance of precipitates which causes structural hardening. [ABSTRACT FROM AUTHOR]

Ceramics of Sr2CaFe2WO9 and Sr2PbFe2TeO9 double perovskites have been prepared in polycrystalline form by solid-state technique, in the air. The crystalline structure was analyzed using X-ray powder diffraction (XRPD) at room temperature. Rietveld analysis of XRPD patterns show that both compounds adopt a tetragonal structure with space group I4/m, with unit cell parameters a = 5.5453(1) Å, c = 7.8389(1) Å for Sr2CaFe2WO9, and a = 5.5994(15) Å, c = 7.8979(30) Å for Sr2PbFe2TeO9. A certain degree of anti-site disordering of W and/or Te and Fe on the B –sites have been detected, indicating the presence of a partial amount of W and/or Te at Fe positions and vice versa. [ABSTRACT FROM AUTHOR]

This work is aimed at investigating the microstructure and mechanical properties of as-cast Al-Cd alloys system were prepared by casting technique. The Al-Cd binary aluminium alloy was analyzed by employing Rockwell hardness HRF, metallograph, XRD, SEM and EDS methods. Evolution of hardness confirmed that the studied alloys are age-hardenable alloys. The as-cast Al-2%Cd alloy is the one who present the mechanical properties (48,75HRF) improved compared to other studied alloy. The results of XRD and optical microscope revealed the presence of the one main phase a-Al of a crystalline structure CFC and there is no new phase formed. [ABSTRACT FROM AUTHOR]

The superalloy Hastelloy G30 (trademark of Haynes International, Inc.) is an alloy with a high proportion of nickel, characterized by a high corrosion resistance in environments containing extra oxidizing acids. The alloy consists essentially of 43% of nickel with a proportion of chromium which varies from 28 to 31.5% and from 13 to 17% for iron. Its matrix is austenitic and its structure is face-centered cubic. The objective of this work is to treat the alloy G30 thermally at 4 different temperatures 700 °C, 800 °C, 900 °C and 1000 °C for 3 hours. Indeed, we followed the progression of structural and mechanical properties. The micro structural evolution influence slightly on the mechanical properties of the alloy G30: hardness of the alloys treated at 700 °C and 800 °C is equal to 46 HRF and that of the alloys treated at 900 °C and 1000 °C is 46.25 HRF. The images obtained by optical microscopy revealed the presence of carbides at the joints and inside the grains .The X-ray diffraction spectra obtained after the isothermal treatments showed the presence of peaks of the precipitates and the peaks of the austenite phase. [ABSTRACT FROM AUTHOR]

The study back to the equilibrium state of Pb-Cd-Bi alloys was carried out by various experimental techniques such as hardness, microhardness, optical microscopy and X-ray diffraction. Two structural states were considered: raw casting alloy and rehomogenized alloy, their compositions are: Pb2% Cd1% Bi; Pb2% Cd2% Bi; Pb2% Cd3%Bi and Pb3.2% Cd2% Bi. The experimental temperatures are 20 °C and 80 °C. The latter one was chosen because it corresponds to the temperature of ripening of battery grids and the hot temperature for battery working. In general, the addition of bismuth accelerates the kinetics of transformation and hardness increases. While the addition of cadmium slightly increases the hardness and accelerates kinetics. The aging, which is the hardening step of the alloy, is still characterized by a discontinuous reaction and a hardening processing, while the overaging is characterized by a softening discontinuous precipitation. [ABSTRACT FROM AUTHOR]

Double-perovskite oxide Sr2MgTeO6 has been synthetized, and its crystal structure was probed by the technique of X-ray diffraction at room temperature. The structure is monoclinic, space group I2/m. Temperature-induced phase transitions in this compound were investigated by Raman spectroscopy up to 550 °C. Two low-wavenumber modes corresponding to external lattice vibrations merge at temperature of around 100 °C, indicating a phase transition from the monoclinic (I2/m) to the tetragonal (I4/m) structure. At 300 °C, changes in the slopes of temperature dependencies of external and O-Te-O bending modes are detected and interpreted as a second phase transition from the tetragonal (I4/m) to the cubic (Fm-3m) structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • PWS waste successfully utilized as inorganic foaming agent for porous acid geopolymers. • Optimized formulation: 16 wt% PWS, 10 M phosphoric acid, and 0.88 L/S ratio achieved best performance. • Enhanced thermal insulation: PWS addition reduced thermal conductivity to 0.076 W/m.K. • Trade-off between porosity and compressive strength: Increased porosity (29.4 %) at 13.8 MPa compressive strength. • Potential for cost-effective, eco-friendly thermal insulation materials in building applications. This study explores the potential utilization of phosphate washing sludge (PWS), a calcium carbonate-rich by-product of phosphate mining, as an inorganic foaming agent in the production of porous acid-based geopolymers. The investigation focused on evaluating the impact of various factors, including phosphoric acid concentration (ranging from 8 M to 12 M), liquid/solid (L/S) ratio (0.8 to 1.2), and the amount of PWS added (ranging from 0 wt% to 50 wt%), on the properties of the resulting geopolymers, such as porosity, density, thermal conductivity, and compressive strength. To optimize the formulation and processing parameters of porous acid-based geopolymers, a surface response methodology using statistical modeling was employed. This approach facilitated a systematic examination of the different factors influencing the properties of geopolymers. The raw materials involved in the study, namely kaolinitic clay, PWS, and the produced geopolymers, were characterized using various techniques such as X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Scanning Electron Microscope coupled with Energy Dispersive X-Ray (SEM/EDX), laser particle size analysis, and mapping. The results revealed that the combination of a phosphoric acid concentration of 10 M, a L/S ratio of 0.88, and the addition of 16 wt% PWS yielded the best performance in terms of porosity, compressive strength, and thermal conductivity, with values of 29.4 %, 13.8 MPa, and 0.0931 W/m.K, respectively. Additionally, a mathematical model was developed to predict optimal parameter combinations for desired performance characteristics. This research holds promise for the development of cost-effective thermal insulation materials for building applications. [ABSTRACT FROM AUTHOR]

In advancing sodium-ion battery technology, we introduce a novel application of Na 3 NiZr(PO 4 ) 3 with a NASICON structure as an anode material. This research unveils, for the first time, its exceptional ability to maintain high specific capacity and unprecedented cycle stability under extreme current densities up to 1000 mA·g -1 , within a low voltage window of 0.01-2.5 V. The core of our findings lies in the material's remarkable capacity retention and stability, which is a leap forward in addressing long-standing challenges in energy storage. Through cutting-edge in situ/operando X-ray diffraction analysis, we provide a perspective on the structural evolution of Na 3 NiZr(PO 4 ) 3 during operation, offering deep insights into the mechanisms that underpin its superior performance.

Lithium-ion batteries (LIBs) have gained considerable attention from the scientific community due to their outstanding properties, such as high energy density, low self-discharge, and environmental sustainability. Among the prominent candidates for anode materials in next-generation LIBs are the spinel ferrites, represented by the MFe 2 O 4 series, which offer exceptional theoretical capacities, excellent reversibility, cost-effectiveness, and eco-friendliness. In the scope of this study, Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 nanoparticles were synthesized using a sol-gel synthesis method and subsequently coated with a carbon layer to further enhance their electrochemical performance. TEM images confirmed the presence of the carbon coating layer on the Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 /C composite. The analysis of the measured X-ray diffraction (XRD) and Raman spectroscopy results confirmed the formation of nanocrystalline Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 before coating and amorphous carbon in the Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 /C after the coating. The Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 anode material exhibited a much higher specific capacity than the traditional graphite material, with initial discharge/charge capacities of 1275 and 874 mA h g -1 , respectively, at a 100 mA g -1 current density and a first coulombic efficiency of 68.54%. The long-term cycling test showed a slight capacity fading, retaining approximately 85% of its initial capacity after 75 cycles. Notably, the carbon-coating layer greatly enhanced the stability and slightly increased the capacity of the as-prepared Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 . The first discharge/charge capacities of Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 /C at 100 mA g -1 current density reached 1032 and 723 mA h g -1 , respectively, and a first coulombic efficiency of 70.06%, with an increase of discharge/charge capacities to 826.6 and 806.2 mA h g -1 , respectively, after 75 cycles (with a capacity retention of 89.7%), and a high-rate capability of 372 mA h g -1 at 2C. Additionally, a full cell was designed using a Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 /C anode and an NMC811 cathode. The output voltage was about 2.8 V, with a high initial specific capacity of 755 mA h g -1 at 0.125C, a high rate-capability of 448 mA h g -1 at 2C, and a high-capacity retention of 91% after 30 cycles at 2C. The carbon coating layer on Ni 0.5 Mg 0.5 Fe 1.7 Mn 0.3 O 4 nanoparticles played a crucial role in the excellent electrochemical performance, providing conducting, buffering, and protective effects.

This work synthesized a novel chitosan-loaded MgAl-LDH (LDH = layered double hyroxide) nanocomposite, which was physicochemically characterized, and its performance in As(V) removal and antimicrobial activity was evaluated. Chitosan-loaded MgAl-LDH nanocomposite (CsC@MgAl-LDH) was prepared using cross-linked natural chitosan from shrimp waste and modified by Mg-Al. The main mechanisms predominating the separation of As(V) were elucidated. The characteristic changes confirming MgAl-LDH modification with chitosan were analyzed through Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis-differential thermal analysis, and Brunauer-Emmett-Teller measurements. Porosity and the increased surface area play an important role in arsenic adsorption and microbial activity. Adsorption kinetics follows the general order statistically confirmed by Bayesian Information Criterion differences. To understand the adsorption process, Langmuir, Freundlich, and Liu isotherms were studied at three different temperatures. It was found that Liu's isotherm model was the best-fitted model. CsC@MgAl-LDH showed the maximum adsorption capacity of 69.29 mg g -1 toward arsenic at 60 °C. It was observed that the adsorption capacity of the material rose with the increase in temperature. The spontaneous behavior and endothermic nature of adsorption was confirmed by the thermodynamic parameters study. Minimal change in percentage removal was observed with coexisting ions. The regeneration of material and adsorption-desorption cycles revealed that the adsorbent is economically efficient. The nanocomposite was very effective against Staphylococcus aureus and Bacillus subtilus ., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

In this work, a cost-effective chitin-based magnesium oxide (CHt@MgO) biocomposite with excellent anionic methyl orange (MO) dye removal efficiency from water was developed. The CHt@MgO biocomposite was characterized by FT-IR, XRD, SEM-EDX, and TGA/DTG. Results proved the successful synthesis of CHt@MgO biocomposite. Adsorption of MO on the CHt@MgO biocomposite was optimized by varying experimental conditions such as pH, amount of adsorbent (m), contact time (t), temperature (T), and initial MO concentration ( C o ). The optimized parameters for MO removal by CHt@MgO biocomposite were as follows: pH, 6; m, 2 g/L; t, 120 min. Two common isotherm models (Langmuir and Freundlich) and three kinetic models (pseudo-first-order (PFO), pseudo-second-order (PSO), and intraparticle diffusion (IPD)) were tested for experimental data fitting. Results showed that Langmuir and PFO were the most suitable to respectively describe equilibrium and kinetic results on the adsorption of MO adsorption on CHt@MgO biocomposite. The maximum Langmuir monolayer adsorption capacity ( q m ) on CHt@MgO biocomposite toward MO dye was 252 mg/g at 60 °C. The reusability tests revealed that CHt@MgO biocomposite possessed high (90.7%) removal efficiency after the fifth regeneration cycle.

In this study, sulfated and carboxylated cellulose nanocrystals (CNC) have been produced from newly identified cellulose-rich bio-sourced material, namely Juncus plant. The Juncus plant stems were firstly subjected to chemical treatments to produce purified cellulose microfibers (CMF) with an average diameter of 3.5 µm and yield of 36%. By subjecting CMF to sulfuric and citric/hydrochloric mixture acids hydrolysis, sulfated CNC (S-CNC) and carboxylated CNC (C-CNC) have been produced with a diameter of 7.3 ± 2.2 and 6.1 ± 2.8 nm, and a length of 431 ± 94 and 352 ± 79 nm, respectively. These newly extracted S-CNC and C-CNC exhibited a crystallinity of 81% and 83% with cellulose I structure and showed high thermal stability (>200 °C). Herein, this newly identified Juncus plant, which is a naturally-derived source, could be used as a valuable alternative to conventional sources such as wood and cotton for nanocellulose production. We speculate that the determined high thermal stability, the large aspect ratio and high crystallinity will allow the use of the extracted CNC as nano-reinforcing agents in polymers that require processing temperatures of up to 200 °C. Owing to their surface functionalities (sulfated or carboxylated surface groups), the here produced CNC could be used as nano-additives or nano-reinforcing agents for water-soluble bio-polymers in order to produce bio-nanocomposites by solvent casting techniques., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, sunflower oil cake (SOC) was identified as bio-sourced material for cellulose nanocrystals (CNC) production using chemical treatments followed by sulfuric acid hydrolysis. The hydrolysis was performed at 64% acid concentration, a temperature of 50 °C and at two different hydrolysis times, 15 min (CNC 15 ) and 30 min (CNC 30 ). It was found that CNC exhibited a diameter of 9 ± 3 nm and 5 ± 2 nm, a length of 354 ± 101 nm and 329 ± 98 nm, a crystallinity of 75% and 87%, a surface charge density of ~1.57 and ~1.88 sulfate groups per 100 anhydroglucose units and a zeta potential value of -25.6 and -30.7 mV, for CNC 15 and CNC 30 , respectively. The thermal degradation under nitrogen atmosphere started at 225 °C (CNC 15 ), which is relatively higher than the temperature for sulfuric acid hydrolyzed CNC from other sources. Due to a high importance of CNC application in aqueous systems, the rheological behaviour of CNC suspensions at various concentrations was evaluated by the steady shear viscosity measurements and the oscillatory dynamic tests. The results showed that the CNC suspensions exhibited a gel-like behaviour at very low CNC concentrations (0.1-1%) wherein a strong CNC entangled network is formed. Polymer nanoreinforcing capability of the newly produced CNC was also investigated in this study. CNC filled PVA nanocomposite films were produced at various CNC contents (1, 3, 5 and 8 wt%) and their mechanical and transparency properties were investigated, resulting in transparent nanocomposite materials with strong mechanical properties. The study suggested other possibilities to utilize agricultural wastes from SOC for CNC production with potential application as reinforcement in polymer nanocomposites., (Copyright © 2019 Elsevier B.V. All rights reserved.)