Nominal Composition Research Articles

In situ X-ray diffraction studies on nominal composition of C2Li under high pressure and temperature

Superdense phase between graphite and Li metal, C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li, has been significant in the research on both lithium-ion batteries (LIBs) and graphite intercalated compounds (GICs). However, a detailed method for synthesizing C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li remains unknown owing to the limited information regarding C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li and difficulties in distinguishing C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li from C6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{6}$$\\end{document}Li. Thus, we performed in situ X-ray diffraction measurements on samples with the nominal composition of C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li under high pressures and temperatures of up to 10 GPa and 400 ∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{\\circ }\\hbox {C}$$\\end{document}, respectively. We employed two types of C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li samples; one was a mixture of C6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{6}$$\\end{document} graphite powder and Li metal (C6+3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{6}+3$$\\end{document}Li), and the other was a mixture of C6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{6}$$\\end{document}Li and Li metal in which the C6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{6}$$\\end{document}Li was prepared by the electrochemical discharge (reduction) reaction that occurs in LIBs. Considering changes in the d-value based on the 001 diffraction peak from C6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{6}$$\\end{document}Li or C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li, C6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{6}$$\\end{document}Li + 2Li is suitable for synthesizing C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{2}$$\\end{document}Li, although the nonaqueous electrolyte used for the electrochemical reaction should be removed to avoid structural transformations to lower-stage compounds such as C12\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{12}$$\\end{document}Li and C18\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {C}_{18}$$\\end{document}Li during the heating. These findings pave the way toward a method for synthesizing C2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{2}$$\\end{document}Li, which could increase the energy density of LIBs and establish GICs with novel physical and electronic properties.

The Influence of Surface Segregation on the Anodizing of AlSi11Cu2(Fe) Diecastings

A positive segregation is usually formed on the casting surfaces produced by high-pressure die casting (HPDC). In diecast Al-Si-Cu alloy components, this segregation shows a higher content of Si compared to the nominal composition of the alloy and it drastically affects the anodizing response of the casting surface. In the present work, HPDC components were produced by AlSi11Cu2(Fe) alloy, grit-blasted, and then anodized in a sulfuric acid electrolyte at the temperature of -4.5°C. Before the anodizing process, some regions of the casting were also milled, in order to completely remove the surface segregation. Microstructural investigations were carried out on grit-blasted and milled surfaces to characterize the initial substrates before anodizing, and to study their effect on the growth of the anodic layer. Scratch and wear tests were also performed to investigate the surface mechanical properties after anodizing. The results show that the surface segregation and the rough surface present on grit-blasted substrate leads to the formation of a thin and homogeneous anodic layer. On the contrary, a thicker and scalloped oxide film is formed on the milled surfaces. After anodizing, grit-blasted surfaces show lower wear and scratch resistance than milled substrates. The presence of surface segregation prevents the thickening of the anodic layer, negatively affecting the surface wear resistance due to the reduced oxide thickness.

Cu-doped nanocomposite Pr2Fe14B/α-Fe ribbons with high (BH)max

Abstract The melt-spun ribbons of nominal composition Pr9Fe84.2-xB6.2P0.3Zr0.3Cux (x=0, 0.5, 1, 2) were prepared at wheel speeds of 21, 27, 30, and 33 ms-1. The XRD patterns show that as the wheel speed increases, the crystallinity of the 2:14:1 hard phase decreases, while that of the α-Fe soft phase increases. The (BH)max, remanence, and coercivity are improved from 63 kJm-3, 0.85 T, and 515 kAm-1 for the Cu-free ribbons to 171 kJm-3, 1.08 T, and 684 kAm-1 with x=0.5. The high squareness ratio of Jr/Js ~ 0.82 at 0.5 at. % Cu (27 ms-1) indicates strong exchange coupling due to small grain sizes of 15 and 30 nm for soft and hard magnetic phases, respectively. The SEM images revealed smooth morphology and uniform element distribution at 0.5 at. % Cu (27 ms-1), contributing to the high magnetic properties. The low recoil permeability (μ rec ) value of 5.466×10-4 to 1.970×10-4 $\frac{T}{k A m^{-1}}$ confirms the strong exchange coupling with x=0.5 (27 ms-1). The initial magnetization curves show that the coercivity mechanism of the Cu-free alloy evolves from the nucleation of the reverse domain to the domain wall pinning as the wheel speed increases, resulting in a high coercivity value of 818 kAm-1 (33 ms-1). Conversely, for the Cuadded alloy, the coercivity mechanism changes from pinning to the nucleation of the reverse domain from low to high wheel speed.

Electrochemical Impedance Spectroscopy Study of Ceria- and Zirconia-Based Solid Electrolytes for Application Purposes in Fuel Cells and Gas Sensors

In this study, the structural and electrochemical properties of commercial powders of the nominal compositions Ce0.8Gd0.2O1.9, Sc0.1Ce0.01Zr0.89O1.95, and Sc0.09Yb0.01Zr0.9O1.95 were investigated. The materials are prospective candidates to be used in electrochemical devices, i.e., gas sensors and fuel cells. Based on a comparison of the EIS spectra in different atmospheres (synthetic air, 3000 ppm NH3 in argon, 10% H2 in argon), the reactions on the three-phase boundaries were proposed, as well as the conduction mechanisms of the electrolytes were described. The Ce0.8Gd0.2O1.9 material is a mixed ionic–electronic conductor, which makes it suitable for anode material in fuel cells. Moreover, it exhibits an apparent and reversible response for ammonia, indicating the possibility of usage as an NH3 gas-sensing element. In zirconia-based materials, electrical conduction is realized by oxygen ion carriers. Among them, the most promising from an applicative point of view seems to be Sc0.09Yb0.01Zr0.9O1.95, showing a high, reversible reaction with hydrogen.

Broad-Temperature Thermoelectric Figure of Merit Enhancement in Unconventional n-Type Bi2Te2.3Se0.7 Alloys.

Bi2Te2.7Se0.3-based alloys are conventional n-type thermoelectric materials for solid-state cooling and heat harvest near room temperature; high thermoelectric performance over a wide temperature range and superior mechanical properties are essential for their use in practical thermoelectric devices. In this work, we demonstrated that decent thermoelectric performance can also be realized in an unconventional composite with a nominal composition of Bi2Te2.3Se0.7 since the emergence of a Bi2Te2Se phase with Se ordered occupation could induce an enlargement of the electronic band gap. Follow-up Cu/Na codoping could generate a dynamic optimization of carrier concentration, significantly broadening the temperature range of high thermoelectric performance. Further B incorporation and annealing treatment resulted in obvious grain refinement and stacking fault structures, which help pushing the ultimate maximal figure of merit up to ∼1.3 at 423 K with an average value of ∼1.2 at 300-573 K. This work might provide insights for further research on bismuth tellurides and other thermoelectric materials.

Effect of Cr on nano-indentation Young's modulus and hardness of the β-Ti phase in equilibrium with α2-Ti3Al and γ-TiAl phases in Ti-Al-Cr alloys

Young's modulus and hardness of the constituent phases of β-Ti (bcc or B2), in equilibrium with α2-Ti3Al (D019) and γ-TiAl (L10) phases in Ti-Al-Cr ternary alloys were quantitatively evaluated in terms of the chemical composition analysis and nano-indentation method, in order to identify the Cr concentration dependence on the mechanical properties of the β phase. An alloy with a nominal composition of Ti-43Al-3Cr (at.%) decomposes into the three phases of β, α2, and γ by equilibrium heat treatment at 1373 K, with chemical composition of Ti-37.2Al-5.2Cr, Ti-38.9Al-2.2Cr, and Ti-47.4Al-1.4Cr, respectively. The β phase shows a Young's modulus of 141 ± 5 GPa, smaller and less orientation dependent than the other two phases of α2 (174 ± 9 GPa) and γ phases (164 ± 15 GPa). In contrast, the β phase has a hardness of 5.9 ± 0.3 GPa, slightly softer than the α2 phase (6.4 ± 0.8 GPa) but much harder than the γ phase (3.7 ± 0.6 GPa). The alloys Ti-44Al-4Cr and Ti-45Al-6Cr consist of two phases of β and γ phases, and the chemical composition of the β phase in these two alloys is Ti-36.5 Al-8.5 Cr and Ti-36.3 Al-13.9 Cr, respectively, with nearly the same Al concentration. The Young's modulus and hardness of the β phase with the latter composition become 158 GPa and 6.7 GPa, respectively, with increasing Cr content. These results found that the effect of solid solution Cr on the Young's modulus for β phase is relatively weak, and that on the hardness is strong, in comparison with that for the other two phases.

First‐Principle Investigation of zb‐TiGe: A Promising Narrow Bandgap Semiconductor

Using first‐principle calculations, a new compound semiconductor based on titanium (Ti) is predicted. It has been observed that Ti when alloyed with germanium (Ge) can crystallize in the zincblende symmetry, and exhibits semiconducting nature with a narrow bandgap. To test the robustness of the semiconducting nature, the structural properties and electronic band structure have been modeled using three different exchange–correlation functionals, namely, local density approximation, generalized gradient approximation, and Perdew‐Burke‐Ernzerhof for solids. With a nominal composition of 1:1, TiGe exhibits a direct bandgap of 0.58 eV at the “X” point of the Brillouin zone. From lattice dynamics, the structural stability of the compound has been established. The new semiconductor is characterized in detail for its electronic band structure, carrier effective mass, charge density distribution, and linear optical properties. Zb‐TiGe exhibits large effective mass for conduction band holes and tentatively becomes a prototype system to study heavy holes resulting in carrier condensation at the bottom of the conduction band. The linear optical properties of the TiGe are found to be suitable for photosensitive devices in the infrared region. In addition, TiGe may find application in deep‐UV and far‐UV regions because of the surface plasmon resonance at 6.4 eV.

Gradient distribution of cations in rhabdophane La0.27Y0.73PO4·nH2O nanoparticles

The structure of gradient rhabdophane nanoparticles of variable composition (La,Y)PO4·nH2O obtained by precipitation is considered. According to the data of HAADF TEM and EDX mapping using the Abel inversion procedure, it was shown that there is an inhomogeneous distribution of yttrium and lanthanum atoms in the particles from the central part to the periphery. At the same time, the nominal composition of both individual nanoparticles and the entire sample meets the value specified during synthesis within the error of the method – La0.27Y0.73PO4·nH2O. According to SAXS data, it was determined that in the particles of (La,Y)PO4·nH2O, there is a redistribution of scattering densities, which is caused by an increase in the fraction of YPO4 in the peripheral region of the particles. The observed effect of the distribution of cations over the particle made it possible to determine the size of the gradient layer, which reaches 50 % of the total particle size.

Effect of Electroslag Remelting on the Microstructure and Ballistic Penetration Characteristics of an Austenite‐Based Lightweight Steel

Herein, the effects of electroslag remelting (ESR) and impurities in ESR slag on the composition, microstructure, and properties of lightweight steel with a nominal composition in wt% of Fe‐20Mn‐10Al‐1.5C are studied. These results can provide a reference for the production of such steels using ESR and the design of the composition of such steels. The results show that ESR can make the contents of Si increase and that of S decrease, make the grain size decrease, make the phase transformation of austenite at about 540 °C change from spinodal decomposition to ordered transformation, make the contents of MnS and SiO2 and inclusions greater than 5 μm decrease, make the distribution of inclusions homogenize, and make the shape of inclusions change from long strip with sharp corners to spherical shape. ESR can improve its strength, plasticity, and antiballistic penetration properties.

Novel Eu3+-Doped Glasses in the MoO3-WO3-La2O3-B2O3 System: Preparation, Structure and Photoluminescent Properties.

Novel multicomponent glasses with nominal compositions of (50-x)MoO3:xWO3:25La2O3:25B2O3, x = 0, 10, 20, 30, 40, 50 mol% doped with 3 mol % Eu2O3 were prepared using a conventional melt-quenching method. Their structure, thermal behavior and luminescent properties were investigated by Raman spectroscopy, differential thermal analysis and photoluminescence spectroscopy. The optical properties of the glasses were investigated by UV-vis absorption spectroscopy and a determination of the refractive index. Physical parameters such as density, molar volume, oxygen molar volume and oxygen packing density were determined. The glasses are characterized by a high glass transition temperature. Raman analysis revealed that the glass structure is built up mainly from tetrahedral (MoO4)2- and (WO4)2- units providing Raman bands of around 317 cm-1, 341-352 cm-1, 832-820 cm-1 and 928-935 cm-1. At the same time, with the replacement of MoO3 with WO3 some fraction of WO6 octahedra are produced, the number of which increases with the increasing WO3 content. A strong red emission from the 5D0 level of Eu3+ ions was registered under near-UV (397 nm) excitation using the 7F0 → 5L6 transition of Eu3+. Photoluminescence (PL) emission gradually increases with increasing WO3 content, evidencing that WO3 is a more appropriate component than MoO3. The integrated fluorescence intensity ratio R (5D0 → 7F2/5D0 → 7F1) was calculated to estimate the degree of asymmetry around the active ion, suggesting a location of Eu3+ in non-centrosymmetric sites. All findings suggest that the investigated glasses are potential candidates for red light-emitting phosphors.

Tailoring sub-5 nm Fe-doped CeO2 nanocrystals within confined spaces to boost photocatalytic hydrogen evolution under visible light

This work aimed to study the efficiency of the reverse micelle (RM) preparation route in the syntheses of sub-5 nm Fe-doped CeO2 nanocrystals for boosting the visible-light-driven photocatalytic hydrogen production from methanol aqueous solutions. The effectiveness of confining precipitation reactions within micellar cages was evaluated through extensive physicochemical characterization. In particular, the nominal composition (0–5 mol% Fe) was preserved as ascertained by ICP-MS analysis, and the absence of separate iron-containing crystalline phases was supported by X-ray diffraction. The effective aliovalent doping and modulation of the optical properties were investigated using UV-Vis, Raman, and photoluminescence spectroscopies. 2.5 mol% iron was found to be an optimal content to achieve a significant decrease in the band gap, enhance the concentration of oxygen vacancy defects, and increase the charge carrier lifetime. The photocatalytic activity of Fe-doped CeO2 prepared at different Fe contents with RM preparation was studied and compared with undoped CeO2. The optimal iron load was identified to be 2.5 mol%, achieving the highest hydrogen production (7566 μmol L−1 after 240 min under visible light). Moreover, for comparison, the conventional precipitation (P) method was adopted to prepare iron containing CeO2 at the optimal content (2.5 mol% Fe). The Fe-doped CeO2 catalyst prepared by RM showed a significantly higher hydrogen production than that obtained with the sample prepared by the P method. The optimal Fe-doped CeO2, prepared by the RM method, was stable for six reuse cycles. Moreover, the role of water in the mechanism of photocatalytic hydrogen evolution under visible light was studied through the test in the presence of D2O. The obtained results evidenced that hydrogen was produced from the reduction of H+ by the electrons promoted in the conduction band, while methanol was preferentially oxidized by the photogenerated positive holes.

Cobalt-free spinel–layered structurally integrated Li0.8Mn0.64Ni0.183Fe0.091O2 cathodes for lithium-ion batteries

Cobalt-free, Li-rich layered-spinel structurally integrated positive electrode (cathode) materials for lithium-ion batteries (LIBs), with nominal composition 0.6(Li1.2Mn0.56Fe0.08Ni0.16O2) 0.4(LiFe0.2Mn1.4Ni0.4O4) which can otherwise be written as Li0.8Mn0.64Ni0.183Fe0.091O2 (FeSL) are synthesized via simple citric acid-assisted sol-gel route. Four different final annealing temperatures (550 °C, 650 °C, 750 °C, and 850 °C) were chosen to investigate their influence on electrochemical performance. The obtained composite materials contain spinel (space group Fd3¯m) as well as Li-rich layered phases (space group C2/m) as revealed by X-ray diffraction (XRD), HRTEM and cyclic voltammetry investigations. The excellent electrochemical performance of the composite material could be attributed to the structural stability achieved by the integration of spinel and layered components. Selected synthesized composite materials exhibit high discharge capacities close to 200 mAh g−1. The FeSL750 shows better capacity retention (92(3)% at the 50th cycle and 82(5)% at the 70th cycle) and rate capability than the FeSL550 and FeSL650 samples. However, the FeSL850 sample shows different charge-discharge behaviour. The charge capacity corresponding to FeSL850 is found to increase up to the 20th cycle, then stabilizes and displays a capacity retention of almost 100 % at the 50th cycle and 91(1)% at the 70th cycle. The electrochemical mechanism of FeSL750 was elucidated via in operando XAS investigations, which reveal electrochemical activity from all transition metals.

Flux growth of Cs1-xRbxBF3 (B = Ca, Sr) crystals by the micro-pulling-down method

The possibility of growing Cs1-xRbxBF3 (B = Ca, Sr) crystals by micro-pulling-down was investigated due to their potential for application in ultrafast scintillation detectors. A LiF flux was applied to lower the melting point and therefore suppress evaporation of CsF from the melt. Suitable growth conditions were obtained through careful choice of the hot zone elements. A crucible with minimal nozzle length improved mass transport and an afterheater with four windows provided a steep temperature gradient. Inclusion and crack-free crystals of Cs1-xRbxCaF3 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, and 1) and CsCa1-xSrxF3 (x = 0, 0.1, and 0.25) were grown under optimized conditions. Despite the hygroscopic nature of the heavy alkali metal fluorides, all the grown crystals are non-hygroscopic which significantly improves their application potential. Growth of CsCa1-xSrxF3 crystals with higher Sr concentration was complicated by the low solubility of SrF2 in the LiF-CsF melt and the hygroscopic nature of the CsSrF3. The formation of solid solution in the Cs1-xRbxCaF3 and CsCa1-xSrxF3 systems was investigated through the dependence of lattice parameters on nominal composition.

Enhanced electrochemical performance of garnet Li7La3Zr2O12 electrolyte by efficient incorporation of LiCl

Garnet-type Ta-doped Li7La3Zr2O12 (LLZO) lithium-ion-conducting ceramic electrolytes has become the promising and critical candidate for developing the high-energy-density all-solid-state lithium batteries, due to the satisfied Li+ conductivity, stability against metallic lithium anode, and the feasible preparation under ambient air. Here, to further increase the lithium-ion conductivity of LLZO comparable to that of the commercial organic liquid electrolytes, lithium chloride (LiCl) is effectively introduced to synthesize the garnet-type ceramic electrolytes with the nominal composition (Li6.5La3Zr1.5Ta0.5O12)1-x–(LiCl)x (x = 0, 5mol%, 10mol%, 15mol%, 20mol%, and 25mol%) via high-temperature calcination process. The cubic structure with highly conductive performance is confirmed from X-ray diffraction measurement as well as Raman spectra analysis. Structural information is observed according to field emission scanning electron microscope equipped with energy dispersive spectrometer and density measurements. Among above investigated ceramic compositions, the prepared (Li6.5La3Zr1.5Ta0.5O12)0.85–(LiCl)0.15 ceramic electrolyte sheet sintered at 1200 °C for 12h presents the room-temperature Li-ion conductivity of 1.22 × 10−3 S·cm−1 by alternating current (AC) impedance analysis along with the corresponding activation energy of 0.262eV through Arrhenius equation calculation. The electronic conductivity measurements are also done by direct-current polarization to confirm the ionic nature for all investigated ceramics. Furthermore, the Li|(Li6.5La3Zr1.5Ta0.5O12)0.85–(LiCl)0.15 |Li symmetric batteries can possess the small interfacial resistance of 92.3 Ω cm2 and stably run for 1000 h at 0.1 mA cm−2 without a short circuit at room temperature. The hybridized lithium-sulfur battery with (Li6.5La3Zr1.5Ta0.5O12)0.85–(LiCl)0.15 electrolyte delivered excellent initial room-temperature discharge capacity of 1204mAh·g−1 and 1152 mAh·g−1 under the current density of 0.1C and 0.2C respectively, large coulombic efficiency, and great cycling stability. Moreover, the lithium-sulfur batteries also can show excellent cycling performances under different current densities and a good capacity recoverability. The above investigation results suggest that the low-melting-point LiCl incorporation in Li6.5La3Zr1.5Ta0.5O12 electrolyte is an effective measurement to synthesize the cubic and dense Li-stuff garnet ceramic sheets for the high-performance rechargeable next-generation solid-state batteries.

High-pressure behavior of high-entropy A2B2O7 pyrochlore

A single high-entropy pyrochlore-type compound (A2B2O7) was successfully synthesized, incorporating 8 different rare-earth cations at the A site and 2 different metal cations at the B site in equiatomic amounts [(8A1/8)2(2B1/2)2O7]. Powders with a nominal composition of (La1/8Sm1/8Nd1/8Pr1/8Y1/8Gd1/8Dy1/8Yb1/8)2(Hf1/2Zr1/2)2O7 were fabricated by glycine nitrate procedure (GNP). The GNP process yielded powders with low crystallinity and after subsequent calcination, a well crystalline ceramic powders were formed. The phase evolution was initially analyzed using X-ray diffraction (XRD). In situ high-pressure X-ray diffraction was employed to investigate the structural stability and high-pressure behavior of the A2B2O7 pyrochlore up to 25.8 GPa. Theoretical investigations of the high-entropy pyrochlore systems were performed and showed good agreement with the experimentally obtained results.

A new aspect of the effect of fluorine doping on structural and superconducting properties in the Bi2Sr1.6La0.4CuO5+δ(O1-xFx) ceramic system

In this study, ceramic samples with the nominal composition Bi2Sr1.6La0.4CuO5+δ(O1-xFx) (where x = 0, 0.2 and 0.4) were synthesized using the solid-state reaction method to investigate the effects of fluorine anionic doping on the Bi-2201 system's structural, microstructural, and superconducting properties. X-ray diffraction analysis (XRD) confirmed the Bi-2201 phase in all samples and total incorporation of fluorine. Doping with fluorine reduced orthorhombicity, leading to an orthorhombic-tetragonal transition. Scanning electron microscopy (EDS) revealed changes in grain shape and size, while energy dispersive x-ray analysis (EDAX) confirmed fluorine incorporation. DC-electrical resistivity measurements showed that fluorine doping decreased the critical transition temperature TC (Onset), with a greater decrease observed at higher fluorine concentrations. The resistivity increase in the normal state of the sample with x = 0.4 was also noted. The conduction mechanism above TC (Onset) = 26.10 K followed the Arrhenius law, indicating thermally activated behavior due to a band gap.

Ti4Fe2C0.82O0.18.

The phase with composition Ti4Fe2C0.82O0.18, tetra-titanium diiron carbide oxide, was unexpectedly synthesized by high-pressure sinter-ing (HPS) of a stoichiometric mixture with nominal composition Ti2Fe. The Ti4Fe2C0.82O0.18 phase crystallizes in the Fd m space group and can be considered as the Ti2Fe structure filled with C and O atoms co-occupying the same octa-hedral void [occupancy ratio 0.82 (7):0.18 (7)]. The Ti4Fe2C0.82O0.18 phase is isotypic with Ti4Ni2C and Ti4Fe2O0.407, and is the first example where C and O atoms co-occupy the same site in filled Ti2Fe structures.

Structural evolution and mechanical properties of 9Cr ferritic/martensitic ODS steels developed by a direct powder forging route

ABSTRACT A nominal composition of mechanically alloyed Fe-9Cr-2W-0.2Ti-0.12C-0.35Y2O3 steel powders was consolidated via a direct powder forging route. The powder-forged samples exhibited an equiaxed grain structure with the formation of Y-Ti-O (Y2Ti2O7 or YTiO3) complex oxides and the absence of prior particle boundaries. The powder-forged samples were further heat treated, i.e. cooled at three different rates, i.e. furnace cooling, air cooling, and water quenching, followed by tempering for the air-cooled and water-quenched samples. The tensile strength at room temperature for water-quenched and normalised samples was comparable, whereas the ductility for the normalised samples was higher, while at high temperature, a good combination of strength and ductility was achieved in the tempered air-cooled samples among all the heat-treated samples. The mechanical properties achieved in the present study were at par and superior in some cases to those reported in literature. The absence of prior particle boundaries network, almost full density and equiaxed grains indicated that the powder forging route can emerge as an alternative consolidation technique to HIP and hot extrusion for the consolidation of powder metallurgy oxide dispersion strengthened steels for nuclear applications.

PREPARATION AND ACELLULAR IN-VITRO BIOACTIVITY OF SOLID STATE SINTERED 45S5 BIOACTIVE CERAMICS USING BIO-WASTES AS ALTERNATIVE RESOURCES FOR BIOMEDICAL APPLICATIONS

In this research, rice husk ash (RHA) and eggshell ash (EGA) were used as biogenic materials for total replacement of pure quartz (SiO2) and calcium oxide (CaO) respectively in the traditional 45S5 bioactive glass composition by powder metallurgy route. Body formulation with nominal composition 45% RHA (SiO2), 24.5 EGA (CaO), 24.5% Na2O and 6% P2O5 was composed. The batch material was properly mixed with addition of 2% PVA (Polyvinyl alcohol) as binder and compacted at 70 MPa to produce compact samples of 40 x 20 mm. The samples were then allowed to dry in an ambient temperature followed by sintering at 1000°C for 2 h, then allowed to cool to room temperature. Selected samples were immersed inside prepared simulated body fluid (SBF – pH 7.4) at 37 °C for 5, 9, and 18h respectively. Physical, microstructure and phase evaluation were conducted to examine the developed bio-ceramic. The results showed the bio-waste based 45S5 bioceramic has bulk density and porosity of 1.02 g/cm3 and 62% respectively while deposits of carbonate-hydroxyapatite were found to increase with immersion period showing good bioactivity and affirm that the developed bio-waste based bioceramics are bioactive and can find suitable application bone repair.

Granite waste as a source of network former for soda-lime glass production: Evaluation of their potential use in proportions higher than 70%

Granites correspond to around 40% of the Brazilian ornamental stones production. However, there is a negative environmental impact due to the large amounts of waste produced. In this work, we evaluate the potential use of granite waste in proportions higher than 70% as an alternative raw material for soda-lime glass production. The glasses were produced by the conventional melt-quenching method. The nominal compositions were 70%, 75%, and 80% (wt%) of waste and complementary amounts of sodium and calcium carbonates. The glasses presented chemical composition compatible to soda-lime glasses and good optical quality, allowing up to 70% light transmission. Thus, the glasses produced proved to be efficient in immobilizing granite waste, which contributes to reducing environmental impacts.