Solids, Volume 6, Issue 1 (March 2025) – 14 articles

Carbonized polymer dots (CPDs) have emerged as a fascinating class of functional nanomaterials with unique physicochemical properties. However, the mechanisms governing their formation and photoluminescence remain a subject of intense debate. In this study, we conducted a systematic comparison of the structural, morphological, and optical properties of CPDs synthesized using various methods, revealing the self-assembly characteristics of low-molecular-weight CPDs with relatively complex structures. Through comprehensive structural, morphological, and optical analyses, we found that CPDs with fewer endogenous derivatives exhibited pronounced concentration-dependent self-assembly, leading to larger particle sizes and enhanced fluorescence emission at higher concentrations. In contrast, CPDs with higher proportions of endogenous derivatives showed limited self-assembly due to complex supramolecular interactions between the derivatives and polymer chains. Remarkably, the removal of endogenous derivatives using a ternary solvent extraction method significantly enhanced the self-assembly and fluorescence of the CPDs. These findings highlight the critical role of endogenous derivatives in modulating the self-assembly and photophysical properties of CPDs, paving the way for future advancements in this field. Full article

Large organic molecules and metal complexes are promising candidates for organic electronics, optoelectronics, and spintronics, with interfaces to metals being critical. Clean preparation in ultra-high vacuum (UHV) is ideal, but many systems are fragile and cannot be thermally sublimed. This study details the preparation of thin films of the metallacrown Cu(II)[12-MC_Cu(II)N(Shi)-4] (short: CuCu4) from the liquid phase using electrospray injection (ESI) and, in particular, liquid injection (LI). Both methods produce films with intact CuCu4 complexes, but they differ in the amount of co-adsorbed solvent molecules. Enhancements using an argon stream perpendicular to the molecular beam significantly reduce these contaminants. An additional effect occurs due to the counterions (HNEt₃)₂ of CuCu4. They are co-deposited by LI, but not by ESI. The advantages and limitations of the LI method are discussed in detail. The CuCu4 films prepared by different methods were analyzed with infrared (IR) spectroscopy, ultraviolet and X-ray photoelectron spectroscopy (UPS, XPS), and scanning tunneling microscopy (STM). For thicker films, ex situ and in situ prepared CuCu4 films to exhibit similar properties, but for studying interface effects or ultrathin films, in situ preparation is necessary. Full article

We report the topochemical solid-state polymerization of different series of symmetrical diacetylenes (DAs) and asymmetrical chlorodiacetylenes (ClDAs), whose members differ in their alkyl spacing lengths of one to four methylene units (n = 1, 2, 3, 4) between the diyne and carbamate functionalities. Structure determination by single-crystal X-Ray diffraction (SCXRD) confirms that in each of these series, at least 50% of the analyses show monomers with a particular stacking pattern presenting two potential directions of polymerization simultaneously. An organization of a crystalline polydiacetylene (PDA) with an oblique chain orientation with respect to the network of cooperatives hydrogen bonds is rather rare in the literature (only two cases), and here we have obtained two more examples of this type of structural motif (supported by SCXRD analysis of the polymer). Orientation control is essential to optimize the performance of conjugated polymers, and a spacer length modification strategy presents a potential way to achieve this in the case of PDA. Full article

Magnesium and its rare-earth alloys are extensively studied for their lightweight properties and high specific strength, making them attractive for aerospace, automotive, and biomedical applications. However, their hexagonal close-packed structure leads to a strong basal texture, limiting plasticity and formability at room temperature. Considerable research has been devoted to texture control strategies, including alloying, thermomechanical processing, and recrystallization mechanisms, yet a comprehensive understanding of their effects remains an ongoing research focus. This review summarizes recent advances in texture regulation of rare-earth magnesium alloys, focusing on the role of RE elements (Gd, Y, Nd, Ce) and non-RE elements (Zn, Ca) in modifying basal texture and enhancing mechanical properties. The influence of key processing techniques, such as extrusion, rolling, equal channel angular pressing, and rotary shear extrusion, is discussed in relation to their effects on recrystallization behavior. Additionally, the mechanisms governing texture evolution, including continuous dynamic recrystallization, discontinuous dynamic recrystallization (DDRX), and particle-stimulated nucleation, are critically examined. By integrating recent findings, this review provides a systematic perspective on alloying strategies, processing conditions, and recrystallization pathways, offering valuable insights for the development of high-performance magnesium alloys with improved formability and mechanical properties. Full article

With the rapid increase in polyethylene terephthalate (PET) usage in recent years, recycling has become indispensable in mitigating environmental damage and safeguarding natural resources. In this context, this study presents a methodology for valorizing PET waste through phase transfer catalytic hydrolysis conducted at a low temperature (80 °C) and atmospheric pressure, with the goal of recovering the terephthalic acid (TPA) monomer. The recovered TPA monomer was subsequently utilized as a precursor for the synthesis of metal–organic frameworks (MOFs). Tributylhexadecyl phosphonium bromide (3Bu6DPB) was selected as the phase transfer catalyst due to its efficiency and sustainability. The process parameters, including the concentration of NaOH, the wt.% of catalyst to PET, and the concentration of PET in the solution, were varied to optimize the hydrolysis reaction. The Taguchi design methodology with an L9 (3^3) orthogonal array was employed to analyze the influence of these factors on the depolymerization time. The analysis of variance (ANOVA) results revealed that the concentration of NaOH was the most significant factor, contributing to 93.3% of the process efficiency, followed by the wt.% of the catalyst to PET (6.5%). The findings also demonstrated that the concentration of NaOH had the greatest impact (Δ = 4.27, rank = 1), while the concentration of PET had the smallest effect (Δ = 0.16, rank = 3). The optimal conditions for PET depolymerization were achieved in 75 min with 20 g/100 mL of NaOH, 12 wt.% of catalyst to PET, and 5 g/100 mL of PET. The recovered TPA monomer was further employed as an organic ligand to synthesize Fe(III)-TPA MOFs under mild conditions (80 °C for 24 h). The X-ray diffraction (XRD) analysis revealed the simultaneous formation of MOF-235(Fe) and MIL-101(Fe), two multifunctional materials with diverse properties and applications. This study highlights an efficient approach for producing low-cost MOFs while promoting urban waste recycling, contributing to an integrated strategy for PET recycling and resource valorization. Full article

This study explores the potential of utilizing circulating fluidized bed boiler fly ash (CFBFA) in the production of composite gravels, with the aim of achieving performance comparable to natural gravel while promoting sustainability. CFBFA, activated by hydrated lime and gypsum, was investigated for its pozzolanic reaction and carbonation curing under simulated coal-fired power plant flue gas conditions (80 °C, 0.4 MPa, 15% CO₂, 85% N₂). The study focused on optimizing the ratios of gypsum and hydrated lime in CFBFA-based cementitious materials, with the goal of enhancing their mechanical properties and understanding the underlying hydration and carbonation mechanisms. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the mineral composition and microstructure of the composite gravels. The results revealed that the optimal gypsum-to-hydrated lime ratio for CFBFA composite gravels is 2:1, achieving a compressive strength of 9.01 MPa after 28 days of carbonation curing. Carbonation curing accelerated hydration, improving the material’s strength, stability, and microstructure. Additionally, the production of CFBFA composite gravels demonstrated significant environmental benefits, reducing Cumulative Energy Demand (CED) by 86.52% and Global Warming Potential (GWP) by 87.81% compared to cement road base materials. This research underscores the potential of CFBFA as a sustainable construction material, with insights into improving its mechanical performance and expanding its large-scale use through carbonation curing with flue gas. Full article

Titanium nitride (TiN) is an advantageous material for plasmonic applications and is suitable for extreme conditions in which conventional plasmonic materials such as gold (Au) cannot be utilized. In this study, TiN and Au nanodisk arrays with different lattice spacing (Λ) were fabricated using the electron beam lithography (EBL) method to increase the quality factor of TiN. At a period of 550 nm, the TiN nanodisk arrays demonstrate a higher sensitivity, 412.79 nm·RIU⁻¹, with the plasmonic resonance wavelength shifting from 883 nm (n = 1.3335) to 915 nm (n = 1.4069) in the NIR region. The surface lattice resonance (SLR) properties of the produced TiN nanodisk arrays were investigated in detail with Au nanodisk arrays. The TiN nanodisk arrays caused sharp plasmon resonances by creating a localized plasmon vibration mode coupled with the diffractive grazing wave excited by the incident light. The transmission dips obtained at narrower full width at half maximum (FWHM) values caused at least an almost 10-fold improvement in the quality factor compared to localized surface plasmon resonance (LSPR) dips. This study is significant for assessing the surface plasmon resonance characteristics of TiN and Au nanodisk arrays across various periods and indices. Full article

Austenitic stainless steel SS316LN is used as the material of construction of the vessel and core components of fast breeder reactors, which operate at an elevated temperature of 550 °C. For design and integrity analysis using the finite element method, material models, such as Johnson–Cook and Ramberg–Osgood, are widely used. However, the temperature- and strain-rate-dependent plasticity and damage parameters of these models for this material are not available in the literature. Moreover, the method of evaluation of temperature and strain-rate-dependent plasticity parameters, in literature, has some major shortcomings, which have been addressed in this work. In addition, a new optimization-based procedure has been developed to evaluate all nine plasticity and damage parameters, which uses results of combined finite element analysis and experimental data. The procedure has been validated extensively by testing tensile specimens at different temperatures, by testing notched tensile specimens of different notch radii, and by carrying out high strain-rate tests using a split Hopkinson pressure bar test setup. The parameters of the Johnson–Cook material model, evaluated in this work, have been used in finite element analysis to simulate load-displacement behavior and fracture strains of various types of specimens, and the results have been compared with experimental data in order to check the accuracy of the parameters. The procedure developed in this work shall help the researchers to adopt such a technique for accurate estimation of both plasticity and damage parameters of different types of material models. Full article

This review provides an analysis of non-perovskite hybrid halides of coinage metals templated by metal–organic cations (CCDC November 2023). These materials display remarkable structural diversity, from zero-dimensional molecular complexes to intricate three-dimensional frameworks, allowing fine-tuning of their properties. A total of 208 crystal structures, comprising haloargentates, mixed-metal haloargentates, and halocuprates, are categorized and examined. Their potential in photocatalysis is discussed. Special attention is given to the structural adaptability of these materials for the generation of functional interfaces. This review highlights key compounds and aims to inspire further research into optimizing hybrid halides for advanced technological applications. Full article

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

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 P$\overline{1}$ 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 $\begin{array}{c}2\\ \infty \end{array}${[(RE3)O$\begin{array}{c}t\\ 4/1\end{array}$(Br1)$\begin{array}{c}v\\ 1/2\end{array}$(Br2)$\begin{array}{c}e\\ 3/3\end{array}$]^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

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

This research explores the physical properties of refractory high-entropy alloys Ti₃Zr_yNbV_x (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 Ti₃Zr_yNbV_x 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

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