Interstitial Solution Research Articles

The influence of hydroxyalkyl methylcellulose on early skin formation in cement‐based tile adhesive

AbstractThe effect of cellulose ethers (CE) with same water retention (WR) level but different molecular weight on the early skin formation of cement adhesive mortars was studied. In drymix mortars CE provide WR higher molecular weight and dosage of CE both improve WR. In this study all CE concentrations were adjusted to provide same WR independently from molecular weight of CE. Adjusted concentrations were obtained from zero‐shear viscosities measured in aqueous CE solutions.Measurements with cement‐based mortars identified the interstitial pore solution viscosity to determine WR level. Data show comparable WR for equal interstitial pore solutions, independently from the molecular weight of the CE if its concentration was adjusted accordingly. However, for cement adhesive mortars formulated with CE having different molecular weight which all provide equal WR, early skin formation was found to vary notably. Higher dosed low molecular weight CE outperforms CE with lower dosage but high molecular weight. This effect can be explained through the formation of a CE containing layer upon evaporation of water from the water‐air interface of the mortar.

Effects of silicon and neodymium additions on microstructures and mechanical properties of CoCrNi medium entropy alloy films

A series of (CoCrNi)100–x–ySixNdy medium entropy alloy films (MEAFs) with manipulated metalloid element, Si, and rare earth element, Nd, was synthesized using magnetron three-target co-sputtering. A transition from single FCC phase to the coexistence of FCC CoCrNi, HCP CoCrNi and HCP NdNi5 phases was observed in XRD and TEM diffraction patterns with the increasing Nd content for Si content of ∼0.7 at.%, and the SEM and TEM images showed the refined columnar grains. The hardness and compressive yield strength reached the maxima of 10.29 and 4.27 GPa, respectively, in Si0.61Nd5.14 film due to the solid solution strengthening, grain refinement and precipitation strengthening. However, The films exhibited a transition from fully crystalline to crystalline within the amorphous matrix in XRD and TEM results with the increasing Si content for Nd content of ∼2.6 at.%, and the columnar structure disappeared in the SEM and TEM images. The hardness and yield strength increased slightly to the maxima of 9.75 and 4.10 GPa, respectively, in Si0.76Nd2.91 film attributed mainly to the interstitial solid solution strengthening. Discussion on (CoCrNi)100–x–ySixNdy MEAFs showed the optimized mechanical properties in Si0.61Nd5.14 film, indicating that precipitation strengthening and grain refinement could be the major strengthening mechanisms in this system.

Yield stress of in-situ polymerization modified cement paste

Achieving desired yield stress is crucial for various construction processes, especially in the emerging 3D concrete printing. In this paper, we present the possibility of enhancing yield stress of cement paste through in-situ polymerization and uncover the mechanisms of in-situ polymerized polymers. We investigate the effects of two types of in-situ polymerized polymer, sodium polyacrylate (PAAS) and polyacrylamide (PAM), on the yield stress, interstitial solution viscosity, and flocculated structure, as well as their adsorption behaviors on the surface of cement particles. The results show that the yield stresses of both in-situ polymerization modified cement pastes are raised considerably at high polymer concentration, which can be attributed to the dual roles of generated polymers. On the one hand, the absorbing polymers can bridge cement particles together, resulting in an augmentation in the interparticle forces. On the other hand, the non-adsorbing polymers remaining in the interstitial solution interact with each other and create a robust polymer network that can effectively withstand the external stresses. The former mechanism emerges as the dominant contributor to the enhanced yield stress of cement paste modified with in-situ polymerized PAAS, attributed to the Freundlich multilayer adsorption behavior of PAAS amplifying the bridging effect of polymers. While in-situ polymerized PAM predominantly assume the latter role, largely due to the remarkable length of their chain structure and the abundant residual polymers in the interstitial solution, which greatly intensities the interaction between polymers.

Efficient ab initio stacking fault energy mapping for dilute interstitial alloys

Density Functional Theory (DFT) is the prevalent first principles computational method for determining the stacking fault energy (SFE) of face centered cubic (fcc) metals and alloys. Due to several theoretical and computational challenges, SFE determination for interstitial alloys with alloying elements such as carbon, nitrogen, and hydrogen, has so far been limited to few studies at relatively high interstitial content. We propose a new method, rooted in the axial interaction model, that allows rapid and robust mapping of SFE for virtually arbitrary interstitial contents. Instead of computing the total energy of a very large supercell to represent dilute interstitial solutions, representative interstitial-affected and bulk regions are treated separately at the equivalent volume. The SFE is obtained by balancing the SFE values of the regions with a lever rule approach. The method matches SFE values from the axial interaction model within ≤4 mJ.m−2 error, as validated for non-magnetic fcc Fe-N and paramagnetic fcc Fe-N and AISI 304 alloys. The significantly reduced computational workload and equidistant SFE mapping vs. interstitial content down to extremely low values allows accurate fitting of the SFE vs. interstitial content with only few datapoints. This further improves the computational efficiency. So far DFT-based SFE mapping was limited to purely substitutional alloys; we demonstrate the first-time DFT-based SFE mapping in fcc AISI 304 vs. N and Ni, revealing a non-additive contribution of N and Ni to the SFE. Finally, the remaining challenges and future application for high-throughput DFT SFE computation in interstitial alloys is discussed.

Effect of sulfate on the compatibility between polycarboxylate superplasticizer and cement-based materials with or without silica fume

Polycarboxylate superplasticizer (PCE) is a crucial raw material used for preparing concrete. However, there has always been a compatibility issue between PCE and different types of cementitious materials due to their varying qualities. In concrete raw materials, the types and contents of sulfates have a significant impact on compatibility, and it is well-established that a competitive adsorption exists between PCE and sulfate ions solubilized in the interstitial solution of cement paste, which may cause a loss of the dispersing properties. However, previous studies focused on the effect of sulfate on the compatibility between PCE and cement, and there was a lack of research on silica fume. In this study, the workability of fresh cement and cement-silica fume paste and the mechanical properties of harden mortar were evaluated in the presence of different concentrations of five types of sulfates (Na2SO4, K2SO4, MgSO4, KAl(SO4)2, and CaSO4·2H2O) added in aqueous solution. The results show that soluble sulfates have a more adverse effect on the compatibility between PCE and cement-based materials with or without silica fume than slightly sulfate. And the effects of different sulfates on saturation points of PCE in cementitious materials and the mechanical properties of cement and cement-silica fume mortar are various. Finally, it is important to note that a high sulfate content in the solution can lead to salt precipitation of PCE, which is highly undesirable.

Divalent ion partitioning through dense ion exchange membranes

Understanding the mechanism behind the permeation of multivalent ions through ion exchange membranes remains an ongoing challenge. Here we address this knowledge gap by presenting a molecular theory to elucidate the influence of counterion condensation and electrosteric effects on the (multivalent) divalent counterion permeation through such membranes. Building upon published experimental data (Galizia et al., 2017), we analyze the energetic tendencies of divalent counterions to associate with the fixed charge groups and their entropic preferences to disassociate to gain translational freedom, allowing us to quantitatively assess the partitioning of divalent ions at two distinct levels. (i) The global partitioning between the external 2:1 salt solution and the membrane, and (ii) the local partitioning within the interstitial solution and the crosslinked polymeric chains within the membrane. Notably, our observations reveal that the global partitioning of divalent counterions does not differ when the membranes operate separately in magnesium chloride (MgCl2) and calcium chloride (CaCl2) solutions. However, at the local partitioning level, we identify a higher preference for calcium counterions to associate with the fixed charge groups than magnesium ions. This preference arises from calcium ions’ more favorable charge density (physical size), facilitating their association/pairing with the fixed charge groups. The key takeaway message from this work is that when dealing with multivalent ions, we must downlevel our investigation, looking at how the counterions relax between the interstitial solution and the crosslinked polymeric chains and, in return, comprehending how it ultimately controls the global transport property of these membranes (such as their Donnan potential and water uptake).

Role of Interstitial Solid Solutions in the Formation of the Active Component of Supported Palladium Catalysts for the Selective Hydrogenation of Acetylene to Ethylene

Role of Interstitial Solid Solutions in the Formation of the Active Component of Supported Palladium Catalysts for the Selective Hydrogenation of Acetylene to Ethylene

Observation of hybrid solid solution and superior energy storage in 0.8Ba(Zr0.35Ti0.65)O3-0.2ZnO films

Unusual substitutional and interstitial solid solutions were observed in (1−x)Ba(Zr0.35Ti0.65)O3-xZnO thin films, where one Zn2+ cation substituted one B-site Zr4+/Ti4+ site and two Zn2+ cations substituted one A-site Ba2+ site simultaneously. Such a hybrid solid solution with an appropriate ZnO content remarkably increases both the electric breakdown strength (Eb) by widening the bandgap and the energy storage efficiency (η) by suppressing the hysteresis of the ferroelectric loop. As a result, the films with x = 0.2 show superior energy storage performance with a recoverable energy storage density (Wrec) of 130.3 J/cm3 and η of 89.1%. This work confirms the feasibility of forming an unconventional hybrid solid solution, which may shed light on further work on perovskite oxides with improved ferroic functionalities.

Comparative analysis and modification of evaluation methods for the pozzolanic reactivity of natural volcanic powders

Rapid and accurate assessment of the pozzolanic reactivity of natural volcanic powders (NVPs) is crucial for their practical application in cement-based materials. In this paper, six conventional pozzolanic reactivity evaluation methods were carried out on three collected NVPs. It was found that various evaluation methods give different ranking of the pozzolanic reactivity of the tested materials, owing to the changes in the test conditions. In addition, based on the R3 pozzolanic reactivity test method standardized in ASTM C1897-20, a modified R3 method by adjusting the usage of sulfate and alkali was proposed. Analysis of hydration products confirmed that the proposed modified R3 method can effectively simulate the interstitial solution of the NVPs-cement composite system within 24 h, and the accuracy of pozzolanic reactivity evaluation of NVPs with low reactivity was greatly improved.

Study on the influence of oxygen content evolution on the mechanical properties of tantalum powder fabricated by laser powder bed fusion

In this work, the influence of reuse times on the properties of tantalum powder and its laser powder bed fusion (LPBF) product was investigated. For this purpose, a batch of tantalum powder was reused up to 16 times, and the particle size distribution, flowability, surface topography, and other characteristics of the powder were studied after different reuse times. The mechanical properties of the finished product samples were also tested. Results from the powder reuse showed that the particle size distribution of tantalum powder changed from 30.1 μm to 33.8 μm, and the oxygen content increased from 310 ppm to 450 ppm. The density and fracture strain of tensile specimens decreased from 16.57 g/cm3 to 16.48 g/cm3 and from 37.9% to 11.6%, respectively. The ultimate tensile strength and microhardness decreased after reaching a peak, ranging from 504 MPa to 614 MPa, and 227 HV to 245 HV, respectively. In addition, it was found that the oxides were mainly tantalum pentoxide, along with monovalent and bivalent oxides. The change in tensile properties was likely related to the interstitial solution of oxygen atoms. This study provides a reference for the reusability of LPBF tantalum powder.

Understanding the temperature-dependent workability of cement paste with polycarboxylate superplasticizer

This paper aims to clarify the role of polycarboxylate superplasticizer (PCE) on the workability of cement paste under different temperatures ranging from 5 to 35 °C. The temperature-induced change in the aggregate morphology of PCE has been studied to reveal its dispersion efficiency, given its surfactant nature. The results indicate that the workability of cement paste with PCE gradually increases with a rise in temperature, and a similar trend is observed in quartz powder paste, where the effect of hydration can be disregarded. The improvement in dispersing efficiency of PCE is attributed to it being adsorbed as aggregates in both cement and quartz powder systems. Usually, the concentration of PCE in the cement interstitial solution exceeds the critical micellar concentration (CMC), which results in PCE aggregating in size but exhibiting numerous reconstituted branch chains. These findings suggest that cement hydration was not a dominant factor affecting the workability of cement paste at an early stage (within 10 min) with temperature rise, which makes PCE aggregate and enhances its dispersion efficiency in cement-based materials.

NaHCO3 synergistic electrokinetics extraction of F, P, and Mn from phosphate ore flotation tailings

In this study, the NaHCO3 synergistic electrokinetic method was used to remove F, P, and Mn from phosphate ore flotation tailings (PTs). First, using PHREEQC simulation calculations, the occurrence forms of P, F, and Mn in the PTs were determined. Thereafter, under various electrokinetic treatment conditions, the variation trends between pH and the different forms of various elements in interstitial solutions of the PTs were analyzed. The influence of various electrokinetic treatment methods on conductivity and pH distribution was thoroughly investigated. The difference in P concentration between the cathode and anode chambers was 21.42 mg/L, the removal efficiency of Mn was 71.43 %, and the leaching of F was inhibited. Dissolved impurities migrated to the electrode chamber during electrokinetic treatment primarily because of electromigration and electro-osmotic flow. During the 1.00 M NaHCO3-enhanced electrokinetic treatment in the cathode chambers, in 360 min, P and F concentrations increased from 3.51 mg/L to 57.28 mg/L and 2.073 mg/L to 29.38 mg/L, respectively. Solution-precipitation of hydroxide or carbonate minerals was determined to be an important mechanism for P, F, and Mn stabilization. This study demonstrated that the NaHCO3 synergistic electrokinetic method is suitable for removing F, P, and Mn from PTs. The findings of this study provide insights for developing novel technologies for the clean treatment and high-value utilization of PTs.

Gorevsky polymetallic deposit (Siberia, Russia): mineral composition of ores and features of ore deposition

The paper shows the genetic diversity of the structure and mineral composition of the ores of the Gorevsky Pb-Zn deposit, reveals the main signs of synchronous deposition of ore matter from near-bottom ore-bearing solutions associated with sedimentation processes in the sedimentary basin, considers textural and structural features and mineral associations of ores accompanying various metamorphism processes and postmagmatic processes. A model of the initially primary sedimentary-diagenetic origin of the ores of the Gorevsky Pb-Zn deposit under the conditions of catagenesis and the important role of the processes of redistribution and redeposition of the ore substance by interstitial solutions of the primary ore material is detailed. The study is based on the method of detailed study of the textural and structural features of ores in polished and polished samples. microstructural and mineral features and composition of ore and non-metallic minerals using modern methods of studying the substance. The bulk of the ores of the Gorevsky deposit demonstrate the textural and structural features of synsedimentary deposits, which are simultaneous with the host carbonaceous-micaceous-siliceous-carbonate rocks and retain these main structural features both at the macro and micro levels. The results obtained are compared and analyzed in comparison with other polymetallic deposits in Russia and in other regions of the world

Rationality of two-phase coexistence with no element segregation in a CuZr-based amorphous alloy composite

Here, the structure features of Cu62Zr34.4Al3Nb0.6 amorphous alloy composites (AACs) are studied by combining experimental characterization with first-principles calculation. Element segregation, which is common in conventional alloy materials, does not occur in two phases (crystalline and amorphous phase) of the AACs due to complex solid solution. The lattice parameters, electron distribution, charge transfer and electrical potential, which are directly related to atomic bonding and lattice parameters of different structures, are obtained by calculating the various types of structural models, including interstitial solid solution, substitutional solid solution, B2 and amorphous phase. Finally, the formation and stability of solid solution in crystalline phase and amorphous phase are elucidated by first-principles calculation. The work has important guiding significance for understanding the two-phase structure and solidification mechanism in AACs materials.

Structural changes in polycrystalline indium oxide after irradiation with xenon ions

Changes in the structure of polycrystalline indium oxide after irradiation with xenon ions with energies of 140 and 300 keV have been studied. It has been found that irradiation with xenon ions leads to a change in the chemical composition of indium oxide, accompanied by phase transformations, an increase in the reflective intensity of X-ray lines of the indium oxide structure, and an increase in the unit cell parameter over the depth of the sample. The X-ray method was used to separate the elastic and inelastic effects of xenon ions on the structure of indium oxide. The concentration of xenon ions, dissolved over the depth of the sample, was determined as a function of the irradiation energy. A structural model of the dissolution of xenon ions in the indium oxide lattice is presented, which explains the formation of an ionic bond of xenon with indium and oxygen atoms and anionic vacancies. The intercalation of xenon ions into the octahedral positions of indium oxide leads to the formation of an interstitial solid solution based on indium oxide along the depth of the sample. It has been found that the energy of defect formation in the structure of indium oxide after irradiation of the samples depends on the dose of xenon ions and the irradiation energy. The experimental and theoretical calculations were made to determine the lattice parameter and ionic radius of xenon in the XeO 2 compound, and the correct mechanism for the formation of an interstitial solid solution based on indium oxide was found. A mathematical model has been calculated that explains the increase in the reflective X-ray intensity of indium oxide lines over the depth of the sample after irradiation with xenon ions. Ill. 9. Ref. 18. Tab. 3.

Surface hardening of Al0.1CoCrFeNi and Al0.5CoCrFeNi high-entropy alloys by low-temperature gaseous carburization

The effect of low-temperature gaseous carburization on AlxCoCrFeNi high-entropy alloys (HEAs) (x = 0.1 and 0.5) was investigated. The results show that low-temperature gaseous carburization can be successfully applied to surface hardening of AlxCoCrFeNi HEAs. After carburization, a hardened case is formed in the surface region of HEAs, which shows that the maximum nano-hardness varies from 12.9 to 11.9 GPa and is accompanied by a case depth ranging from 16 to 10 μm when the Al content is changed from x = 0.1 (2.4 at.%) to x = 0.5 (11.1 at.%). The surface hardness originates from a hard carbide-free carbon-enriched case. For carburized Al0.1CoCrFeNi the case is a single-phase supersaturated interstitial solid solution of C atoms in FCC (expanded FCC). For carburized Al0.5CoCrFeNi the case is a dual-phase and consists of expanded FCC phase and a supersaturated interstitial solid solution of C atoms in BCC (expanded BCC). Increasing the Al content reduces the potential for surface hardening by low-temperature gaseous carburization, because the Al-stabilized BCC phase has a relatively low capacity to dissolve C atoms, despite a high Cr content.

High energy storage performance in Sr0.64Bi0.18Na0.18TiO3-ZnO hybrid solid solution ceramics

Ceramic-based capacitors with excellent recoverable energy storage density (Wrec) and efficiency (η) are greatly desired for pulsed capacitors but challenge as well. In this work, the high energy storage performance with an Wrec of 5.1 J/cm3, an η of 93.4%, and an ultrafast discharge–charge speed t0.9 of 72 ns is achieved in unusual interstitial and substitutional hybrid solid solution of Sr0.64Bi0.18Na0.18TiO3-ZnO (SBNT-Zn), in which two Zn2+ ions occupy one A-site, while one Zn2+ ion occupies one B-site of ABO3 perovskite lattice simultaneously. The addition of Zn2+ increases lattice distortion and breaks long-range ferroelectric order, resulting in more highly dynamic polar nanoregions, higher relaxation behaviors as well as larger polarization (ΔP). Moreover, the extraordinary hybrid solid solution configuration enhances the bandgap of SBNT-Zn and ZnO as a sintering aid refines grain size, both help to enhance electric breakdown strength. This work affirms the feasibility and reliability of forming a hybrid solid solution to develop high-performance ferroelectric materials.

Hydrothermal Synthesis and Photocatalytic Properties of Cobalt-Doped Tungsten Oxide

Hexagonal tungsten trioxide–base interstitial solid solutions of general formula CoxWO3, where 0.01 ≤ x ≤ 0.09, were prepared hydrothermally. The dopant homogeneity extent was found to depend on рН in the working solution. Interstitial solid solutions with the highest Co2+ concentrations were formed at рН of 2.3. The CoxWO3 samples with a fiber-like morphology with a fiber diameter of ca. 40 nm, which were prepared at рН of 2.3, had the highest specific surface area, equal to 38.6 m2/g. The key parameter for the stability of the CoxWO3 crystal structure appeared to be ammonium ions residing in the hexagonal channels of the crystal structure. When tested as photocatalysts of 1,2,4-trichlorobenzene oxidation under the UV light, the prepared samples showed high chloroarene conversions and low selectivities to yield a wide range of organic compounds, including chlorine-free ones.

Migration and solidification behavior of the semivolatile heavy metal elements Zn and Cd during high ferrite cement clinker (HFCC) calcination

The use of solid waste to produce low carbon, high ferrite cement clinker (HFCC) with favorable durability delivers potential application prospects. However, the semivolatile heavy metals Zn and Cd in solid waste not only restrict its utilization ratio but also cause potential environmental pollution. In this study, the migration and solidification behavior of Zn and Cd during calcination and their action mechanisms on phase reconstruction are systematically studied. The reaction sequence and conditions of Zn were revealed by experimental tests and phase diagram simulation. Zn2+ will firstly solidify in the C2S phase by the solid-phase reaction. After liquid phase forms, Zn2+ is more inclined to substitute Fe3+ in the C4AF phase with 4-coordination in the [FeO4]. Only a small amount of Zn2+ enters the C3A and C3S phases in the form of interstitial solid solution. Zn promotes the formation of the liquid phase and C3S phase. And HFCCs indicate a favorable solidification effect on Zn. While due to low volatilization temperature and high volatility of Cd, even at a low sintering temperature, the HFCC cannot greatly reduce the volatilization of Cd. Cd2+ mainly exists in HFCC by substituting Ca2+ in the C3S, C2S and C4AF phases with a 6-coordination number in [CaO6] to form the spatial configuration of octahedral complexes.

An exceptionally strong, ductile and impurity-tolerant austenitic stainless steel prepared by laser additive manufacturing

The effective strategy for structural steel with excellent tolerance of impurities is to increase solidification rate to prevent the formation of segregation and intermetallic during fabrication.Carbon (C) and oxygen (O) as impurities in austenitic stainless steel are often controlled at extremely low levels to ease their detrimental effects on toughness and corrosion resistance. Hence, high-quality austenitic stainless steels are poor in impurity tolerance and moderate in strength. Here, we use laser additive manufacturing successfully engineering C, N and O with high contents as interstitial atoms coordinated with Cr in the form of short-range ordered assembly in steel, and develop an impurity-tolerant supersaturated austenitic stainless steel with an ultrahigh strength of 961±40 MPa, a good ductility (37.5 ± 3%), an enhanced corrosion resistance (0.0745 Ecorr/V) and acceptable thermal stability up to 500 °C. First-principles calculations indicate that a coordinated hexahedron C4Cr4, as a stable unit in the austenite, can be assembled via three basic types of stacking. With the presence of N and O, N1C6Cr8, O1C6Cr7 and O1C6Cr8 are also stable coordination assembly units. Such short-range ordered assembly of interstitial atoms can produce significant super-saturated interstitial solid solution strengthening, which is responsible for the enhancement of tensile strength while maintaining ductility. The novel approach in engineering impurities by laser additive manufacturing may open up a new avenue in developing advanced high-impurity-tolerance steels for potential industrial applications at a low cost.