Alkali Metal Research Articles

Pop the bubbles and let the current flow: mechanochemistry of micron and nano-sized openings in dielectric layers

Thin or ultra-thin dielectric layers have been widely used in various applications such as capacitors, piezo-electrics, and solar cells. This study explains the mechanism and chemistry of creating nano- and micron-sized openings in atomic-layer-deposited aluminum oxide-based dielectric layers using the alkali metal salt selenization technique. The necessary components for this mechanism are excess methyl groups present in the dielectric layer, supply of selenium and alkali metals, and a minimum annealing temperature. It is shown and explained that to create openings in the dielectric layer, heavier alkali halide metal salts require less energy, or - in other words - a lower annealing temperature. The overall hypothesis is explained via a thermodynamic approach with supportive thermochemical reactions. Thus, an easy way to engineer the dielectric layer to form openings at low temperatures is presented, beneficial for various applications like photovoltaics, optoelectronics, or micro-electro-mechanical systems (MEMS).

Technology of production of aluminosilicate refractories for units processing fluorinated waste

The aluminium production process through the electrolysis of cryolite-alumina melts involves a series of interconnected, sequential, and parallel technological operations, each defined by a specific level of engineering and technological advancement. The development of the modern aluminum industry is closely tied to the adoption of resource-efficient and environmentally friendly technologies, which focus on recycling secondary materials and industrial waste. Fluorinated carbon-based materials release fluorine into the gas phase at relatively low temperatures when heated, and in thermal units processing fluorinated waste, this fluorine, along with alkali metals, will remain in the gas phase. To enhance the durability of furnace linings against the corrosive atmosphere, refractories with the highest possible density (low porosity) and a high concentration of mullite in the matrix (the finely ground component of the batch) are required. These properties can only be achieved in refractory products produced by the semi-dry pressing method, which ensures high grain packing density and leads to the formation of a ceramic mullite bond after firing.

Complexes of Alkaline Earth Metal Ions with the Cyclodimethylsiloxane ligands D7, D8 and D9 (D = Me2SiO)

We present complexes of alkaline earth metal ions with the large cyclodimethylsiloxane D7, D8 and D9. The compounds prepared are [Mg(D7)(H2O)2][GaI4]2 (1), [Ca(D8)][GaI4]2 (2), [Sr(D8)][GaI4]2 (3), [Ba(D8)][GaI4]2 (4), [Ca(D9)][GaI4]2 (5), [Sr(D9)][GaI4]2 (6) and [Ba(D9)][GaI4]2 (7). Single‐crystal X‐ray diffraction and multinuclear NMR spectroscopy were used to analyze the prepared compounds and coordination modes in the solid state and in solution.

Phase Behavior and Atomic Dynamics in Rb x Na1-x : Insights from Machine Learning Interatomic Potentials based on Ab Initio Molecular Dynamics

Abstract Liquid alkali metal alloys have garnered significant attention because of their potential applications in coolant systems and batteries, driven by the need for environmental conservation and technological development. However, research on these complex systems is limited, necessitating a deeper understanding to ensure their safe and effective utilization. This study presents a comprehensive investigation of the factors that determine the phase diagram of Rb x Na1-x . By reproducing the experimental results using the thermodynamic integration method and machine learning interatomic potentials based on ab initio molecular dynamics simulations, we uncovered the delicate balance between the energy and entropy contributions that influence the phase stability of these liquid metal alloys. Further analysis of the liquid phase revealed the crucial roles of volume and atomic mass. Additionally, the coordination numbers of the atoms revealed distinct clustering behaviors, where Na atoms tended to avoid proximity to other Na atoms, whereas Rb atoms exhibited a strong tendency to cluster together. Moreover, the diffusion dynamics further illustrated the asymmetry in the behavior of Rb and Na, with Rb showing increased diffusion at higher concentrations and Na exhibiting higher diffusion at lower concentrations. These findings offer significant insights into the phase stability and the dynamic and structural properties of these complex liquid metal alloys.

Mandible composition and properties in two selected praying mantises (Insecta, Mantodea)

AbstractInsects process their food with their cuticle‐based mouthparts. These feeding structures reflect their diversity and can, in some cases, showcase adaptations in material composition, mechanical properties, and shape to suit their specific dietary preferences. To pave the way to deeply understand the interaction between mouthparts and food and to determine potential adaptations of the structures to the food, this study focuses on the mandibles of two praying mantis species. Gongylus gongylodes feeds mainly on Diptera, and Sphodromantis lineola forages on larger prey. Employing scanning electron microscopy, the mandibular morphologies were analyzed. The degree of the cuticle tanning was tested using confocal laser scanning microscopy. Furthermore, the contents of transition and alkaline earth metals in the mandible cuticle were studied using energy‐dispersive X‐ray spectroscopy and the mechanical properties tested by nanoindentation. We found that S. lineola mandibles show pronounced gradients of Young's modulus and hardness from the basis to the tip, which might be an adaptation against high stresses during biting and chewing. G. gongylodes, in contrast, did not show pronounced gradients, which may indicate that there is less stress involved in feeding—necessary to test in future studies. The mechanical properties of manidibles in both species are related to the degree of cuticle tanning but also positively correlate with the content of magnesium. These findings enrich our understanding of insect cuticle biology but also present new sets of data on praying mantis structures.

Halogens and Alkali Metals Adsorbed Uni-axially Strained ZnS Sphalerite Monolayer for Application in Optoelectronics

Halogens and Alkali Metals Adsorbed Uni-axially Strained ZnS Sphalerite Monolayer for Application in Optoelectronics

SYNTHESIS AND RADIOGRAPHY OF NEW ZIRCON-MANGANITES OF LANTHANUM AND ALKALINE EARTH METALS AND CALCULATION OF THEIR THERMODYNAMIC PROPERTIES

Annotation. The synthesis of LaMeIIZrMnO6 compounds (MeII – Mg, Ca, Sr, Ba) was carried out using ceramic technology in the range of 800-1200оС by the interaction of lanthanum (III) oxides of the " extra clean." qualification, zirconium (IV), manganese (III) and magnesium, calcium, strontium and barium carbonates of the " clean for analysis " brand.". The weights of the starting materials were weighed with an accuracy of up to the fourth decimal place. Stoichiometric amounts of the starting materials were carefully ground in an agate mortar, then poured into alund crucibles and subjected to heat treatment for solid-phase interaction in air in the "SNOL" furnace. X-ray methods have established that all synthesized zircon-manganites crystallize in cubic symmetry with the following lattice parameters: LaMgZrMnO6 – а = 13,46 ±0,02 Å; V0 = 2437,86 ±0,05 Å3; Z = 4; V° elem cell = 609,47 ± 0,02 Å3; r x-ray = 4,42 g/сm3; r picn = 4,35 ± 0,07 g/сm3; LaCaZrMnO6 – а = 14,50 ± 0,02Å; V0 = 3048,63 ± 0,06 Å3; Z = 4; V° elem cell = 762,16 ± 0,02 Å3; r x-ray = 3,67 g/сm3; r picn = 3,62 ± 0,05 g/сm3; LaSrZrMnO6 – а = 14,56 ± 0,02 Å; V0 = 3087,52 ±0,06 Å3; Z = 4; V° elem cell = 771,88 ± 0,02 Å3; r x-ray. = 4,03 g/сm3; r picn.= 3,99 ± 0,04 g/сm3, LaBaZrMnO6 – а = 14,79 ± 0,02Å; V0 = 3233,45 ± 0,06 Å3; Z = 4; V° elem cell = 808,36 ± 0,02 Å3; r x-ray = 4,25 g/сm3; r picn= 4,19 ± 0,05 g/сm3. It was found that with an increase in the ionic radii in the Mg® Ca®Sr®Ba series, the values of the parameter "a", the volumes of lattices and elementary cells of zircono-manganites increase. The calculation of the temperature dependence of the heat capacity and the standard heat capacity by indirect methods is carried out. The equations of temperature dependences of the investigated zircon-manganites of lanthanum and alkaline earth metals are derived.

Heavy Alkaline Earth Cyclic (Alkyl)(Amino)Carbene Complexes Supported by Aryl-Silyl Amides.

A series of 8 trigonal planar, heavy alkaline earth (AE = Ca-Ba) metal complexes containing cyclic (alkyl)(amino)carbene (CAAC) ligands were prepared from AE bis(amide) species. Complexation can be achieved by first generating the free carbene in situ or by direct addition of the free carbene, with the former route giving rise to unexpected mixed-amide AE complexes. The frontier molecular orbitals of the highly equatorial, 3-coordinate AE-CAAC species were also probed computationally, revealing the lowest unoccupied molecular orbital (LUMO) consisting predominantly of the π* system located on the carbene ligand.

Calcium Sulfide Based Nanophosphors-A Review on Synthesis Techniques, Characterization and Applications.

Calcium sulfide (CaS) is a widely investigated alkaline earth sulfide nanophosphor with promising applications in optoelectronics and biomedical fields due to its excellent photoluminescence properties. The selection of the synthesis method is a crucial factor in determining the efficacy of nanophosphors for various applications. This review provides a comprehensive overview of the various synthesis techniques employed to develop CaS nanophosphors, including solvothermal, alkoxide, sol-gel, microwave, wet chemical co-precipitation, solid-state diffusion, and single-source precursor methods. The structural and optical properties of CaS nanophosphors are discussed in detail, highlighting the influence of different dopants on the emission color, which can be tuned from blue to red. The review also explores the potential applications of CaS nanophosphors in optoelectronics and biomedicine. This review serves as a valuable resource for researchers interested in developing CaS nanophosphors for various optoelectronic and biomedical applications, providing insights into the latest advancements and future prospects in this field.

Coordination Compounds of Alkali and Rare Earth Metals Based on Centrosymmetric Chlorine-Substituted Bis-Mercaptooxazole. Synthesis, Structure, and Luminescence

New coordination polymers were synthesized. A ditopic centrosymmetric organic ligand containing oxazole heterocycles, 4,8-dichlorobenzo[1,2d:4,5d´]bis(oxazole)-2,6(3H,7H)-dithione (H2L), was prepared and structurally characterized. It was shown that deprotonated H2L forms non-luminescent binuclear molecular complexes Li2L(THF)6 (I) and Na2L(DME)4 (II) with alkali metals, while complexes of H2L with lanthanides are ionic compounds [Ln(DMSO)8][L]1.5 (Ln = Nd (III), Yb (IV)) exhibiting moderate metalcentered emission in the near-infrared (IR) range, despite the absence of coordination of the ligand L to lanthanide ions. The molecular structures of H2L·2DMSO and I–III were established by X-ray diffraction (CCDC no. 2320461 (H2L·2DMSO), 2320462 (I), 2320463 (II), 2320464 (III)).

Co-Catalyzed Suzuki-Miyaura Coupling of Organoboronic Acids and Alkynyl Chlorides Using Potassium Bicarbonate as Base.

Organoboronic acids, some of the most common and widely used organoboron compounds, have not yet been used in the cobalt-catalyzed cross coupling reactions, despite cobalt demonstrating good reactivity with zinc reagents, Grignard reagents, and metal organoborates that are formed by n-butyl lithium or alkaline metal alkoxide salts and organoboron esters. Herein, a highly efficient and practical cobalt-catalyzed coupling reaction of aryl/alkenyl boronic acids and alkynyl chloride under mild reaction conditions is reported. The advantages of the organoboronic acids, along with a broad functional group compatibility and the reaction's tolerance to moisture and air, enable this reaction to be a synthetically useful protocol for the construction of a C(sp2)-C(sp) bond. Lastly, the synthesis of two natural products and a key intermediate of roxadustat was effectively accomplished using the methodology to construct the critical alkynyl-aryl bond.

Tunable magnetism by nonmagnetic-doping in 2D flexible alkaline-earth metal halofluoride XYF (X = Ca/Sr/Ba, Y = Cl/Br/I) with ultra-wide bandgap

Tunable magnetism by nonmagnetic-doping in 2D flexible alkaline-earth metal halofluoride XYF (X = Ca/Sr/Ba, Y = Cl/Br/I) with ultra-wide bandgap

Effect of alkali metal sulfates on hydration properties of alpha-calcium sulfate hemihydrate for 3D printing

Three-dimensional printing (3DP) technology is an important means of achieving decorative convenience, personalization, and functional integration for future building construction. However, the setting time and hydration process of calcium sulfate hemihydrate (HH) present chanllenges for the 3DP application. This study aims to investigate the accelerating effect of alkali metal sulfates accelerators on the hydration transformation of HH into calcium sulfate dihydrate (DH). The setting time, conductivity, Ca2+ ion concentration, size distribution, and zeta (ζ) potential of gypsum slurries with different accelerators were measured. The results demonstrated that the accelerators significantly enhanced the hydration process of αlpha-calcium sulfate hemihydrate (α-HH). On the effect of accelerators, the setting times of gypsum slurries containing 30 wt% lithium sulfate (LS), sodium sulfate (NS) and potassium sulfate (KS) were accelerated by 82.56 %, 86.06 % and 97.13 %, respectively, compared to the control sample. The crystal particle sizes of hydration products decreased, and the absolute values of ζ potential increased to 1.85 mV, 3.1 mV, and 5.3 mV, respectively. The X-ray photoelectron spectroscopy (XPS) analysis revealed a shift in the peak values of the hardened specimens towards higher electric fields. This was accompanied by improved ion dispersion within the slurry, resulting in enhanced supersaturation of calcium sulfate dihydrate and crystallization of the crystal nuclei. Thus, the suitable accelerators can effectively achieve rapid solidification and hardening of high-fluidity gypsum slurries.

Feasibility Study on Geothermal Dolomite Reservoir Reinjection with Surface Water in Tianjin, China

Reinjection is thought to be the most effective way to maintain reservoir pressure and production capacity for hydrothermal resources. The use of external water injection to replenish deep geothermal reservoirs is a new approach in China to addressing the problems of declining groundwater levels and energy depletion caused by the excessive and uneven exploitation of geothermal resources. However, the key challenge and focus of the feasibility assessment of this method lies in the chemical compatibility of the external water with the native geothermal reservoir water and surrounding rocks. In this paper, we discuss the geochemical response of a dolomite reservoir to lake water injection based on experiments on water–rock interaction in the Wumishan formation in the Dongli Lake area of Tianjin. The results show that after reactions with dolomite, the TDS of the reacted water decreases, indicating the occurrence of precipitation. According to the calculation results obtained using the PHQREEC program, the precipitation amount is found to be quite limited. Geochemical analysis indicates that at the initial stage of the reactions, plagioclase dissolves and releases alkaline metals like Ca-, Na-, SiO2- and Al-bearing compositions, leading to the oversaturation and precipitation of dolomite and calcite. As the reaction progresses, a portion of the dolomite dissolves, while the calcite continues to precipitate at a later stage. Illite precipitates and its effects on reservoir structure depend on its shape. Based on the experimental data, it can be concluded that the dolomite reservoir will be slightly affected by the reinjection of lake water; however, it is still a good method for the sustainable development of geothermal resources.

Machine Learning and First-Principle Predictions of Materials with Low Lattice Thermal Conductivity

We performed machine learning (ML) simulations and density functional theory (DFT) calculations to search for materials with low lattice thermal conductivity, κL. Several cadmium (Cd) compounds containing elements from the alkali metal and carbon groups including A2CdX (A = Li, Na, and K; X = Pb, Sn, and Ge) are predicted by our ML models to exhibit very low κL values (<1.0 W/mK), rendering these materials suitable for potential thermal management and insulation applications. Further DFT calculations of electronic and transport properties indicate that the figure of merit, ZT, for the thermoelectric performance can exceed 1.0 in compounds such as K2CdPb, K2CdSn, and K2CdGe, which are therefore also promising thermoelectric materials.

Alkali and alkaline earth metals induced n-type surface transfer doping of diamond: A first-principles calculation

The advancement of diamond-based electronic devices is hindered by the n-type doping in diamond, which is a major challenge for diamond. Surface transfer doping is an effective way for modulating the surface conductivity. In this study, we propose and select eight kinds of alkali and alkaline earth metals with low electronegativities as n-type surface dopants on F-terminated diamond using first-principles calculations. Our results reveal n-type doping is realized on diamond surface, and a negative correlation between the electronegativity of metal dopants and areal electron density. High areal electron densities of 2.975 × 1013 and 3.102 × 1013cm-2 and room-temperature electron mobilities of 1102 and 1152 cm2 V-1 s-1 are obtained on Rb and Cs doped diamond surfaces, respectively. Our findings provide a way for designing of n-type diamond, and it is helpful for the understanding of the surface doping mechanism for semiconductors.

Enhancing radiation shielding efficiency through modifiers in potassium incorporated phospho-tellurite glasses

The current research mainly focuses to delve a prime set of Potassium incorporated phospho-tellurite glasses fabricated by the melt quenching way for radiation prevention applications. In this consideration, the alkaline earth metals such as MgO, CaO, SrO and BaO which acts as modifiers are enclosed separately within the glass network. The crafted glasses indicated by the empirical formula 49P2O5+20TeO2+10K2CO3+10MO+10ZnF+1Dy2O3 (where M = MgO, CaO, SrO, BaO) and these developed glasses were characterized by numerous methods. XRD, FTIR approach was conducted for structural investigation. The functional groups and the corresponding bands associated are analyzed through the FTIR results for the quenched glass samples. The radiation shielding properties of the glasses were calculated using Phy-X software. The Ba-glass has the highest MAC values at most energy, specifically at low and high energies. The LAC values of the Ba glass at the same respective energies are equal to 77.884, 7.881, 0.269, 0.129, and 0.085 cm−1. Similarly, other parameters like LAC and HVL are already prove the efficiency of the Ba containing glass to shield the gamma rays. At 0.15 MeV, the TVL values of the glasses are equal to 3.029, 2.972, 2.897, and 2.387 cm at 2.828, 2.875, 2.979, and 3.004 g/cm3.

Coordination chemistry of a weakly coordinating carbanion

Carbanions are typically highly reactive species but can be efficiently stabilized to even function as stable weakly coordinating anions (WCA). We now report on the coordination chemistry of the recently introduced allyl anion 1, stabilized by ArF (ArF = 3,5-bis(trifluoromethyl)phenyl), triflyl substituents, with various s-block metals. A systematic crystallographic study on the s-block metal salts (Li-Cs, Ca) showed that the alkali metals have minimal impact on the anion, as indicated by the similar structural properties compared to the phosphonium salt of 1. In contrast, the calcium complex showed a slightly more pronounced distortion of the allyl symmetry due to stronger Ca–O interactions with the triflyl group. Additionally, the significance of the allyl moiety in stabilizing the carbanionic charge in 1 was demonstrated by comparing the structural parameters and charge distribution with those of an analogous C1-anion. Overall, these studies confirm the enhanced stability of 1 and its weak coordination tendency

New insights of emerald geographic origin determination based on the infrared spectroscopy of D2O and HDO molecules

Emerald geographic origin determination in laboratories typically relies on the microscopic features of inclusions, ultraviolet through visible and near-infrared (UV-Vis-NIR) spectroscopy, and trace element chemistry measured by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). Infrared (IR) spectroscopy, a non-destructive technique, has played a minor role in this process. This work conducts a systematic examination of emerald samples from twelve origins, encompassing spectroscopic, and trace element analyses. For the first time, IR absorptions related to D2O and HDO molecules within the 2600–2850cm–1 range for from multiple origins (333 emerald samples) were recorded, assigned, and classified. These IR absorptions, controlled by the concentrations of deuterium (D) and alkali metals (primarily sodium) within channels, reveal three distinct patterns and derived four groups that serve as strong evidence for origin determination. Emeralds from Zambia group display the most prevalent HDO-dominant IR-pattern I characterized by the pronounced absorption peak of Type II HDO at 2672cm–1; Panjshir (Afghanistan) and Swat (Pakistan) emeralds exhibit the transitional type IR-Pattern II with overall five peaks and obvious 2808cm–1 peak; D2O-dominant IR-Pattern III is featured by marked absorption band at 2740cm–1, and can be further subdivided into two subtypes (IIIa and IIIb). IR-Pattern IIIb is currently only found in Nigerian emeralds, characterized by strong broad band of Type I D2O due to enriched deuterium and obvious absorption of Type I HDO at 2685cm–1 due to depleted sodium. Furthermore, this research updates the classification of UV-Vis-NIR spectra, unveils the trace element features, and presents effective compositional diagrams. This contribution enriches and expands existing techniques and provides new insights for emerald origin determination.

A new strategy toward synthesis of novel bifunctional N- and S-bearing sorbent for platinum(IV) removal from aqueous solutions and acidic leaching residue of Pt/Al2O3 catalyst

Strong incentive politics have been elaborated for promoting the recovery of precious metals from secondary resources. Solid leaching generates acidic effluents that can be pre-treated using precipitation steps for partial separation before applying sorption for metal recovery from mild acidic solutions. For this purpose, a new sorbent was designed bearing numerous N- and S-bearing reactive groups with good affinity for platinum (as chloroanionic species). Thiazole precursors were first reacted before being grafted (by free radical reaction) with triallyl cyanurate (to form CTTR sorbent). The material was characterized by a series of analytical tools (SEM, BET, FTIR, XPS, TGA, elemental analysis, and titration). The effect of pH combined with FTIR and XPS spectroscopy analyses allowed identifying the mechanisms involved in metal binding: (a) electrostatic attraction of chloroplatinate anions with protonated amine groups (especially in acidic conditions), (b) while at moderate acidic pH metal sorption proceeds through ligand exchange and chelation onto N-based and S-based groups. Optimum sorption was found at pH close to 4 (near pHpzc value). Under selected experimental conditions, the equilibrium was reached in 25–35 min. The pseudo-first order rate equation fitted well experimental profile (though the resistance to intraparticle diffusion contributes to the kinetic control). The maximum sorption capacity at room temperature reached up to 1.58 mmol Pt g−1 (at pH 4). The sorption isotherm was successfully fitted by the Temkin equation. The sorption is spontaneous and exothermic (with reduction in maximum sorption capacity reaching up to 25 %, when temperature increases to 50 °C). Optimum platinum desorption was obtained with 0.3 M HCl solution (with solid/liquid ratio 1.67 g L−1) for complete desorption and enrichment factor close to 4.6. Complete desorption was maintained over 5 cycles, while the sorption efficiency decreased by less than 3.5 % at the fifth cycle. The sorbent showed remarkable stability for PGMs (Pd(II) in addition to Pt(IV)) against alkali-earth elements or base metals (from equimolar synthetic solutions); the selectivity is driven by the preference of the reactive groups (soft base and intermediary base) for soft PGM metals against hard and borderline metal ions; this selectivity is also affected by metal speciation (formation of chloro-anionic species). The valorization of platinum from non-compliant Pt/Al2O3 catalyst was investigated after leaching with aqua regia. Platinum was precipitated from the leachate with ammonium chloride. In a second step, aluminum was removed by precipitation at pH 5. The residual solution was then treated by adsorption on CTTR: optimum separation between Pt and Al was achieved at pH ≈ 3.