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Solids, Volume 6, Issue 1 (March 2025) – 5 articles

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13 pages, 3935 KiB  
Article
Mechanochemical Synthesis of High-Entropy Layered Double Hydroxide MgCoNi/AlFeY
by Olga Kokoshkina, Maksim Yapryntsev and Olga Lebedeva
Solids 2025, 6(1), 5; https://doi.org/10.3390/solids6010005 - 2 Feb 2025
Viewed by 301
Abstract
In the present study, the possibility of synthesizing high-entropy hexacationic layered double hydroxide MgCoNi/AlFeY via mechanochemical synthesis was demonstrated. In the synthesis, the activation rate, activation time, and NaOH amount were varied. The main synthesis stages were as follows: the mechanical activation of [...] Read more.
In the present study, the possibility of synthesizing high-entropy hexacationic layered double hydroxide MgCoNi/AlFeY via mechanochemical synthesis was demonstrated. In the synthesis, the activation rate, activation time, and NaOH amount were varied. The main synthesis stages were as follows: the mechanical activation of salts, NaOH addition, washing with distilled water before achieving neutral pH, and drying at 100 °C. The stage of aging in aqueous solution was omitted. During the synthesis, the activation conditions were varied, the activation time ranged from 1 to 120 min, the rotation speed of the ball mill was changed from 200 to 400 rpm, and the ratio values of sodium hydroxide weight to the mass of cations were specified as 1.0, 1.5, or 2.0. The samples were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy combined with an energy-dispersive analyzer, thermal analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy. The following optimal synthesis conditions for obtaining single-phase sample were determined: an activation rate of 300 rpm, an activation time of 30 min, and an m(cation)-to-m(NaOH) ratio of 1:1. Full article
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20 pages, 16756 KiB  
Article
About the Rare-Earth Metal(III) Bromide Oxoarsenates(III) RE5Br3[AsO3]4 with A- (RE = La and Ce) or B-Type Structure (RE = Pr, Nd, Sm–Tb) and RE3Br2[AsO3][As2O5] (RE = Y, Dy–Yb)
by Ralf J. C. Locke, Florian Ledderboge, Felix C. Goerigk, Frank C. Zimmer and Thomas Schleid
Solids 2025, 6(1), 4; https://doi.org/10.3390/solids6010004 - 15 Jan 2025
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Abstract
The monoclinic rare-earth metal(III) bromide oxoarsenates(III) RE5Br3[AsO3]4 of the A-type (RE = La and Ce) crystallize in the space group C2/c with the lattice parameters a = 1834.67(9) pm, b = 553.41(3) pm, [...] Read more.
The monoclinic rare-earth metal(III) bromide oxoarsenates(III) RE5Br3[AsO3]4 of the A-type (RE = La and Ce) crystallize in the space group C2/c with the lattice parameters a = 1834.67(9) pm, b = 553.41(3) pm, c = 1732.16(9) pm and β = 107.380(3)° for La5Br3[AsO3]4 and a = 1827.82(9) pm, b = 550.67(3) pm, c = 1714.23(9) pm and β = 107.372(3)° for Ce5Br3[AsO3]4 with Z = 4, while, for the B-type (RE = Pr, Nd and Sm–Tb), they prefer the space group P2/c with lattice parameters from a = 881.23(5) pm, b = 547.32(3) pm, c = 1701.14(9) pm and β = 90.231(3)° for Pr5Br3[AsO3]4 to a = 875.71(5) pm, b = 535.90(3) pm, c = 1643.04(9) pm and β = 90.052(3)° for Tb5Br3[AsO3]4 with Z = 2. The closely related rare-earth metal(III) bromide oxoarsenates(III) RE3Br2[AsO3][As2O5] crystallize in the triclinic space group P1¯ with lattice parameters from a = 539.15(4) pm, b = 870.68(6) pm, c = 1092.34(8), α = 90.661(2)°, β = 94. 792(2)° and γ = 90.223(2)° for Dy3Br2[AsO3][As2O5] to a = 533.56(4) pm, b = 869.61(6) pm, c = 1076.70(8), α = 90.698(2)°, β = 94.785(2)° and γ = 90.053(2)° for Yb3Br2[AsO3][As2O5] with Z = 2. All three structures have the same building units with [REO8]13− and [REO4Br4]9− polyhedra as well as isolated ψ1-tetrahedral [AsO3]3− anions in common, with the exception that, in the latter two, ψ1-[AsO3]3− tetrahedra linked by a corner form a pyroanionic [As2O5]4− entity. A- and B-type differ in the stacking sequence of their 2{[(RE3)Ot4/1(Br1)v1/2(Br2)e3/3]6.5−} layers. While the former have an ABC sequence, the latter exhibit an AAA variant. In the triclinic structures, the (RE3)3+ sites are thinned out, while the As3+ sites are simultaneously enriched, resulting in the mentioned condensed units. Full article
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22 pages, 17837 KiB  
Article
In-Situ Cure-Induced Strain Measurements Using Optical Fiber Bragg Gratings for Residual Stress Determinations in Thermosets
by Lars P. Mikkelsen, Jesper K. Jørgensen, Ulrich A. Mortensen and Tom L. Andersen
Solids 2025, 6(1), 3; https://doi.org/10.3390/solids6010003 - 9 Jan 2025
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Abstract
A small experimental setup for in-situ measurement of the load-transferring strains during the curing process of thermosets is proposed. Combining the output from an unconstrained and a kinematically constrained setup, it is possible to design a cure profile for the first time, lowering [...] Read more.
A small experimental setup for in-situ measurement of the load-transferring strains during the curing process of thermosets is proposed. Combining the output from an unconstrained and a kinematically constrained setup, it is possible to design a cure profile for the first time, lowering the residual stresses in the final product while keeping the cure time short based on the output from a few simple experiments. The stress relaxation during the curing process under a kinetically constrained condition is accounted for by comparing the final cure-induced strain during a kinetically unconstrained and constrained cure experiment. The constrained polymer is curing between two laminates where the constraining layer is removed after finalizing the cure profile, making it possible to measure the final cure-induced strain for that case as well. The temperature at which the load-transferring point is reached is found to be a key process parameter from which the final cure-induced strains can be predicted for the unconstrained case. From the corresponding constrained cure experiments, the final residual stresses can be measured. Full article
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15 pages, 2623 KiB  
Article
Impact of Vanadium and Zirconium Contents on Properties of Novel Lightweight Ti3ZryNbVx Refractory High-Entropy Alloys
by Noura Al-Zoubi, Amer Almahmoud and Abdalla Obeidat
Solids 2025, 6(1), 2; https://doi.org/10.3390/solids6010002 - 2 Jan 2025
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Abstract
This research explores the physical properties of refractory high-entropy alloys Ti3ZryNbVx (0.5 ≤ x ≤ 3.5; 1 ≤ y ≤ 2), utilizing the first-principles exact muffin-tin orbitals method, in addition to the coherent potential approximation. We examine the [...] Read more.
This research explores the physical properties of refractory high-entropy alloys Ti3ZryNbVx (0.5 ≤ x ≤ 3.5; 1 ≤ y ≤ 2), utilizing the first-principles exact muffin-tin orbitals method, in addition to the coherent potential approximation. We examine the atomic size difference (δ), the valence electron concentration (VEC) and the total energy of the body-centered cubic (bcc), the face-centered cubic (fcc) and the hexagonal close-packed (hcp) lattices, revealing a disordered solid solution with a bcc lattice as the stable phase of these alloys. The stability of the bcc Ti3ZryNbVx alloys increases with the addition of vanadium, and slightly decreases with increasing Zr concentration. All the investigated RHEAs have densities less than 6.2 g/cm3. Adding V to the Ti-Zr-Nb-V system reduces the volume and slightly enhances the density of the studied alloys. Our results show that increasing V content increases the tetragonal shear modulus C′, which assures that V enhances the mechanical stability of the bcc phase, and also increases the elastic moduli. Moreover, all the examined alloys are ductile. Vickers hardness and bond strength increase as V concentration increases. In contrast, decreasing Zr content reduces the density and increases the hardness and the bond strength of the present RHEAs, potentially resulting in systems with desirable mechanical properties and lower densities. These findings provide theoretical insights into the behavior of RHEAs, and emphasize the necessity for additional experimental investigations. Full article
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17 pages, 6287 KiB  
Article
A Quaternary Solid Dispersion System for Improving the Solubility of Olaparib
by Tae-Han Yun, Jeong-Gyun Lee, Kyu-Ho Bang, Jung-Hyun Cho and Kyeong-Soo Kim
Solids 2025, 6(1), 1; https://doi.org/10.3390/solids6010001 - 2 Jan 2025
Viewed by 722
Abstract
To improve the low solubility of poorly water soluble olaparib, in the following study, we prepared olaparib-loaded quaternary solid dispersions with hypromellose, Tween 20 or Labrasol, and colloidal silica. The solubility of olaparib with various types of surfactants was evaluated to select the [...] Read more.
To improve the low solubility of poorly water soluble olaparib, in the following study, we prepared olaparib-loaded quaternary solid dispersions with hypromellose, Tween 20 or Labrasol, and colloidal silica. The solubility of olaparib with various types of surfactants was evaluated to select the most suitable surfactant to effectively enhance its solubility, and subsequently, olaparib-loaded quaternary solid dispersions were prepared through spray drying. The physicochemical properties of the prepared olaparib-loaded quaternary solid dispersions were investigated using scanning electron microscopy, flowability, powder X-ray diffraction, and Fourier-transform infrared spectroscopy. The particle size of the olaparib-loaded quaternary solid dispersions was smaller and more spherical compared to the olaparib drug powder and maintained an amorphous state, and olaparib exhibited no intermolecular interactions with other excipients within the solid dispersion. Additionally, they exhibited enhanced flow properties compared to the olaparib drug powder. The results of subsequent kinetic solubility tests and dissolution tests demonstrated that the surfactant influenced the enhancement of the solubility and drug release of olaparib. Therefore, olaparib-loaded quaternary solid dispersions, characterized by enhanced solubility, will be beneficial for the oral delivery of poorly soluble olaparib. Full article
(This article belongs to the Special Issue Amorphous Materials: Fabrication, Properties, and Applications)
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