Structure Of Solid-liquid Interface Research Articles

Structure of Solid-Liquid Interface and Tribology

Structure of Solid-Liquid Interface and Tribology

Precipitation characteristics and growth mechanism of Fe and Cr from liquid lead-bismuth eutectic by quenching in liquid nitrogen

The compatibility of structural steels with liquid lead-bismuth eutectic (LBE) restricts the development of the lead-cooled fast reactor (LFR) and the accelerator driven sub-critical (ADS) system. During the reactor operation, alloying elements in steel can dissolve into LBE. The dissolved alloying elements could precipitate in cold parts of the reactor due to the decrease in solubility, which can cause pipe clogging and worsen heat transfer. Therefore, it is necessary to study their precipitation characteristics to provide a reference for the filtration process. In this paper, Fe, Cr, and a mixture of Fe and Cr were added to liquid LBE at 1173 K and quenched in liquid nitrogen to study their precipitation characteristics. The scanning electron microscope (SEM) and field-emission scanning electron microscope (FESEM) were used to analyze the morphology, and the phase structure was identified by an X-ray diffractometer. The chemical compositions of precipitates were analyzed by an energy dispersive spectrometer (EDS, Esprit Compact, Bruker) and an electron probe microanalyzer (EPMA, EPMA-8050 G, Shimadzu). The solid-liquid interface structure and growth mechanism of precipitates were also discussed. The difference in growth mechanisms resulted in various morphologies for the precipitates. There were three morphologies of precipitates: faceted dendrite, polyhedron (cube, octahedron, and hopper), and seaweed dendrite. All the precipitates in LBE have a faceted growth character except the seaweed dendrites, irrespective of their morphology. The growth of Fe, Cr, and Cr-Fe faceted dendrites originated from continuous growth followed by lateral growth. On the contrary, the cubic and octahedral precipitates were controlled by the spiral growth mechanism, and the growth mechanism of hopper crystals was two-dimensional nucleation. The formation of seaweed dendrites was caused by a strong local undercooling of nonfaceted dendrites.

Sapphire crystal growth and solid–liquid interface structure: An investigation by molecular dynamic simulation and Czochralski growth

Sapphire has increasing demand toward optoelectrical devices like LED; its big challenge is to find reasonable growth mechanisms for high quality large size single crystals. In this paper, we proposed both theoretical and experimental studies to clarify multiscale behaviors within the Al2O3 growth system. Molecular dynamics simulation for sapphire crystal growth along c-, a-, and m-axes, and solid–liquid interface structure, and grown 2″ sapphire via the Czochralski method along the c-axis, were reported herein. Our studies show that α-Al2O3 growth behaviors along different crystal directions are different, which is different from the amorphous Al2O3 phase transition at the various α-Al2O3 planes. α-Al2O3 crystal growth in the c-axis system may be a complex process involving solid–liquid and solid–solid transformations, rather than a single solid–liquid transformation that happened in the systems growing along the a- and m-axes. Within the time scale of simulation, the crystals cannot be grown by the lattice period of the seed crystal along the c-axis and transform into γ-Al2O3 rather than α-Al2O3, while it is opposite along the a- and m-axes. This may be the microscopic reason why it is difficult to grow sapphire along the c-axis in the experiment. An abrupt change in the interfacial structure is the key reason to inhibit the transformation of liquid Al2O3 into α-Al2O3 along the c-axis.

Distribution Characteristics of Multiphysics around the Bubble on the Surface of Photoelectrode

In the heterogeneous photocatalytic reaction systems, the evolution of bubbles on the catalyst surface is a complex process that depends on multiple factors, such as the solid–liquid interface structure, solution properties of the reaction system, and multiphysics interactions, and directly affects energy and mass transport processes. This study investigated the multiphysics distribution around a bubble and the bubble detachment characteristics on the surface of a TiO2 photoelectrode during photoelectrocatalytic water splitting. The bubble diameter had an effect on the distribution of the light field in the system, affecting the temperature and flow distributions of the electrolyte around the bubble. Marangoni convection was induced by the inhomogeneous temperature distribution along the bubble interface, which enhanced the heat and mass transfer near the reaction site. It was also demonstrated that an increase in laser power increased Marangoni convection on the bubble surface, thus delaying bubble detachment. A force model for predicting the bubble detachment diameter that considered the coupling effect between the light, temperature, and flow fields was developed. The predicted bubble detachment diameters agreed well with the experimental results within an error of ±10%.

Solid-Liquid Interface Structure of Muscovite Mica in SrCl2 and BaCl2 Solutions.

The structure of the solid–liquid interface formed by muscovite mica in contact with two divalent ionic solutions (SrCl2 and BaCl2) is determined using in situ surface X-ray diffraction using both specular and non-specular crystal truncation rods. The 0.5 monolayer of monovalent potassium present at the surface after cleavage is replaced by approximately 0.25 monolayer of divalent ions, closely corresponding to ideal charge compensation within the Stern layer in both cases. The adsorption site of the divalent ions is determined to be in the surface ditrigonal cavities with minor out-of-plane relaxations that are consistent with their ionic radii. The divalent ions are adsorbed in a partly hydrated state (partial solvation sphere). The liquid ordering induced by the presence of the highly ordered crystalline mica is limited to the first 8–10 Å from the topmost crystalline surface layer. These results partly agree with previous studies in terms of interface composition, but there are significant differences regarding the structural details of these interfaces.

In-situ mass-electrochemical study of surface redox potential and interfacial chemical reactions of Li(Na)FePO4 nanocrystals for Li(Na)-ion batteries

In this work, an in-situ experimental mass-electrochemical investigation of the LiFePO4 (LFP) and NaFePO4 (NFP)electrolyte interfacial chemical reactions and surface redox potential is achieved by adopting electrochemical quartz crystal microbalance (EQCM) to monitor the mass change trend. In organic electrolyte, LFP (NFP) cathode's mass decreases/increases during the charge/discharge process because of deintercalation/intercalation of Li (Na) ions, which is an normal phenomenon which is generally known. However, the mass-potential curve for LFP nanocrystals in aqueous electrolyte show an anomalous mass change interval (AMCI) around 3.42V (vs. Li/Li+) where the cathode's mass increase in the charging process and mass decrease in the discharging process, which doesn’t obey the normal law of mass change. Through density functional theory (DFT) calculations, we gain a microscopic picture of the solid-liquid interface structure with a reconstructed LFP (010)/H2O and NFP (010)/H2O interface. Taken together, it's concluded that the surface redox potential of LFP is around 3.31V, which is lower than the bulk potential (3.42V) and the desolvation/solvation rate of surficial Li-ion is lower than the bulk Li-ion diffusion rate. While for NFP, it's surface redox potential is almost the same as the bulk one.

Solid-Liquid Interface Structure of Muscovite Mica in CsCl and RbBr Solutions.

The solid-liquid interface formed by single terminated muscovite mica in contact with two different ionic solutions is analyzed using surface X-ray diffraction. Specular and nonspecular crystal truncation rods of freshly cleaved mica immersed in CsCl or RbBr aqueous solution were measured. The half monolayer of the surface potassium ions present after the cleavage is completely replaced by the positive ions (Cs+ or Rb+) from the solution. These ions are located in the ditrigonal surface cavities with small outward relaxations with respect to the bulk potassium position. We find evidence for the presence of a partly ordered hydration shell around the surface Cs+ or Rb+ ions and partly ordered negative ions in the solution. The lateral liquid ordering induced by the crystalline surface vanishes at distances larger than 5 Å from the surface.

An in situ correlative STEM-EDS and HRTEM based nanoscale chemical characterization of solid-liquid interfaces in an aluminium alloy.

The chemistry and the structure of solid-liquid interface in an Al-Si based alloy during high temperature phase transformation were characterized at nanoscale using scanning Transmission Electron Microscopy-EDS and HRTEM. Such studies were until recently limited by large sample drift associated with conventional heating holders. This study was made possible thanks to the modern low-drift MEMS-chip based localized heating technology. The results reveal that (i) the structural interface between solid (111) oriented Si phase and the liquid phase (i.e. decay of crystalline order) coexisting at 600°C is 3.2 nm wide (ii) the STEM-EDS chemical maps show inhomogeneous distribution of the elements with the solid phase being rich in Si and the liquid phase rich in Al (iii) the HRTEM and the HAADF images display respectively dark and bright intensity bands along the interface which could be due to apparent enrichment of Cu at the interface region resulting in enhanced amplitude-contrast (darker band in HRTEM) and Z-contrast (bright band in HAADF) and (iv) intriguingly, the concentration profiles within (i.e. compositional width) and across the solid-liquid interface display element-specific complex and asymmetric variation in the chemical widths.

Atomic layering and misfit-induced densification at the Si(111)/In solid–liquid interface

We report on the solid–liquid interface structure between Si(111) substrates and indium at temperatures just above its melting point. At similar metal–semiconductor interfaces, liquid density enhancements have been observed by Reichert et al. [1]. Our surface x-ray diffraction study reveals that there is pronounced layering of the liquid near the interface. The data allow for identifying both layering length scales: the interlayer distance of 2.2Å̊ and the decay length of approximately 15Å̊. Furthermore do we find the very first layer of indium adjacent to the Si(111) to be partially laterally ordered at the substrate's hollow sites. We introduce a hard sphere packing model that can explain the experimentally observed layering distance and anisotropic order. This packing also reveals that due to the misfit between the size of the indium atoms and the periodicity of the substrate, the indium atoms can pack together closer than in the bulk liquid. These results show that the lateral interaction between the substrate and the liquid directly influences the layering distance and that the resulting packing can account for part of the previously observed enhanced densities.

Interfacial reaction between Co–Cr–Mo alloy and liquid Al

The interfacial reaction between Co–Cr–Mo alloy and liquid Al was investigated using immersion tests. Microstructure characterization indicated that the Co–Cr–Mo alloy was corroded by liquid Al homogeneously, with the formation of a (Co,Cr,Mo)2Al9 layer close to alloy matrix and “(Cr,Mo)7Al45+Al” layer close to Al. Kinetics analysis showed that the corrosion of the Co–Cr–Mo alloy followed a linear relationship with the immersion duration. Compared with pure Co–liquid Al reaction system, the alloying of Cr and Mo changed the solid–liquid interface structure, but the corrosion of the solid metal was still dominated by the dissolution of an intermetallic layer.

Evaluation on Solid-Liquid Interface Structure of Altered Rock Based on Hydrothermal Flow Experiments

Evaluation on Solid-Liquid Interface Structure of Altered Rock Based on Hydrothermal Flow Experiments

Towards an atomic-scale understanding of crystal growth in solution

Our understanding of crystal growth continues to increase thanks to progress in theoretical models, computer simulations and experimental techniques. A discussion of the state-of-the-art in morphology prediction and of the determination of the solid-liquid interface structure using X-ray diffraction shows, however, that there is still a large gap between experiment and theory. We expect that computer modelling, in the form of both Molecular Dynamics simulations and first-principle calculations, will play a crucial role in filling this gap.

PH-dependent liquid order at the solid-solution interface ofKH2PO4crystals

We have determined the solid-liquid interface structure of the {101} and {100} faces of $\mathrm{K}{\mathrm{H}}_{2}\mathrm{P}{\mathrm{O}}_{4}$ (KDP) crystals in contact with a growth solution for three different pH values. Using surface x-ray diffraction data we find in all cases several liquid layers with varying degrees of lateral and perpendicular order. The structural changes are large for the {101} face and small for the {100}, which correlates with the changes in the macroscopic growth velocity of these faces. The changes at the {101} face are likely due to the pH-dependent competition between ${\mathrm{K}}^{+}$ and ${\mathrm{H}}_{3}{\mathrm{O}}^{+}$ bonding. For the highest pH value crystalline preordering is observed.

Solid-liquid Interface Energy of Metals at Melting Point and Undercooled State

By investigating the effects of the configurational entropy, the vibrational entropy and the bonding strength of solid-liquid atoms on the structure of solid-liquid interface, a model for the interface energy of rough solid-liquid interface has been developed. From present model, the non-dimensional solid-liquid interface energies for metals at melting point are predicted to be 0.66‐0.73, which are almost equal to the experimental result (0.66‐0.75) obtained from grain boundary method. The solid-liquid interface energy decreases with increasing undercooling. At the maximum undercoolings that metals have reached, the non-dimensional solid-liquid interface energies predicted from present model are equal to 0.52‐0.56. They are near to the experimental results (0.49‐0.57) obtained from nucleation undercooling method. The predicted results of solid-liquid interface energy for metals from present model are in very good agreement with the experimentally measured results at melting point and undercooled state.

Effect of anorthite liquid on the abnormal grain growth of alumina

A small amount of anorthite (2CaO·Al2O3SiO2) powder was placed on the top-center of the pure Al2O3 powder compact and then sintered at 1600°C. During sintering some grains grew extensively along the radial direction from the liquid source. By considering an atomically smooth solid–liquid interface structure of alumina, grain growth controlled by 2-dimensional (2-D) nucleation was suggested. The elongation has been explained in terms of nucleation advantage of grain-boundary re-entrant edges (GBRE) formed dominantly at non-basal planes.

Effect of sintering temperature on the secondary abnormal grain growth of BaTiO3

When BaTiO3 specimens containing a small amount of excess TiO2 were sintered for more than 15 h, some grains grew abnormally to several millimeters in size. This phenomenon may be referred to as the secondary abnormal grain growth (SAGG) because it occurred from a large and uniform grain structure (average grain size: 70 μm) after completion of primary abnormal grain growth. SAGG was observed only at a very narrow temperature range between 1360 and 1370°C, where the solid–liquid interface structure was atomically smooth. Almost all the secondary abnormal grains contained the (111) double twin, which provides the persistent twin-plane re-entrant edge (TPRE). During SAGG, the growth of matrix grains was strongly suppressed and material transfer occurred preferentially to the grains with a (111) double twin.

Spatial structure of solid-liquid interface near melting temperature

In this paper we discuss the solid-liquid interface which emerges from our dislocation theory of melting. We analyse how the dislocation order parameter varies across this interface and study the stability o the obtained solutions. We calculate the correlation radius and discuss physical characteristics of the system as functions of the coupling parameter.