Concentration Gradients Of Elements Research Articles

Development of diverse aluminium concentration gradient profiles in Ni-rich layered cathodes for enhanced electrochemical and thermal performances

Nickel (Ni)-rich cathodes with elemental concentration gradients within particles have attracted great interest due to their considerably enhanced interfacial stability and electrochemical performance for advanced Li-ion batteries.

Numerical Simulation Study of Seafloor Hydrothermal Circulation Based on HydrothermalFoam: A Case Study of the Wocan-1 Hydrothermal Field, Carlsberg Ridge, Indian Ocean

Deep-sea hydrothermal circulation plays a pivotal role in the material and energy exchange in deep-sea environments, exerting significant influence on the evolution of seawater chemistry and global climate dynamics. Based on existing data and assumptions, this study presents a numerical model tailored for the hydrothermal circulation in the Wocan-1 Hydrothermal Field, Carlsberg Ridge, Indian Ocean. The model successfully simulates the hydrothermal circulation patterns within the oceanic crust, providing detailed insights into temperature distribution, flow field structures, and elemental concentration gradients. Through data analysis of the simulation results, we inferred the depth and temperature of potential heat sources within the Wocan-1 hydrothermal field. The maximum temperature of the heat source Tmax = 823K (550 °C) and the depth of the heat source h = 1 km are possible results. To deepen understanding of the heat source’s impact on fluid temperatures, a sensitivity analysis was conducted. The findings show a positive correlation between both the heat source’s temperature and its depth with the fluid temperature at vent outlets. Regarding elemental transport, this paper offers a preliminary exploration of the kinetic processes in hydrothermal circulation and presents an empirical relationship linking elemental concentrations at the bottom to those at the vent: Cvent = 0.26 Cboundary. This study enhances current numerical models for hydrothermal vents, offering valuable insights for future work and utilization in the Wocan-1 hydrothermal field, and potentially in any other hydrothermal field.

Formation, Microstructure, and Properties of Dissimilar Welded Joint between CrMnFeCoNi and Fe.

This research explores the welding process of a high-entropy CrMnFeCoNi alloy with iron, unraveling the intricate chemical compositions that materialize in distinct regions of the weld joint. A mid-wave infrared thermal camera was deployed to monitor the cooling sequences during welding. A thorough analysis of the metallographic sample from the weld joint, along with measurements taken using a nano-hardness indenter, provided insights into the hardness and Young's modulus. The element distribution across the weld joint was assessed using a scanning electron microscope equipped with an EDS spectrometer. Advanced techniques such as X-ray diffraction and Mössbauer spectroscopy underscored the prevalence of the martensitic phase within the weld joint, accompanied by the presence of bcc (iron) and fcc phases. In contrast, Young's modulus in the base metal areas displayed typical values for a high-entropy alloy (202 GPa) and iron (204 GPa). The weld joint material displayed substantial chemical heterogeneity, leading to noticeable concentration gradients of individual elements. The higher hardness noted in the weld (up to 420 HV), when compared to the base metal regions (up to 290 HV for CrMnFeCoNi alloy and approximately 150 HV for iron), can be ascribed to the dominance of the martensitic phase. These findings provide valuable insights for scenarios involving diverse welded joints containing high-entropy alloys, contributing to our understanding of materials engineering.

Analysis of inhomogeneities in Nb3Sn wires by combined SEM and SHPM and their impact on J c and T c

We demonstrate the combined use of scanning electron microscopy (SEM) and scanning Hall probe microscopy (SHPM) to analyse inhomogeneities in Nb3Sn wires. Inhomogeneities of the A15 phase in Nb3Sn sub-elements of a Ti-alloyed Restacked Rod Process wire and a Ta-alloyed Powder-In-Tube wire are investigated. Microstructural features are examined by SEM, elemental concentration gradients by energy dispersive x-ray spectroscopy (EDX) and the superconducting properties by SHPM. Correlations between the results are analysed to gain information about the impact of inhomogeneities in the microstructure on the superconducting properties. We find considerable differences in geometry and performance between sub-elements, as well as compositional and geometric inhomogeneities of the A15 phase inside single sub-elements. Additionally, simulations of the influence of Sn concentration gradients on the critical current density J c are performed. We also demonstrate the viability of SHPM and EDX for determining the dependence of the critical temperature T c on the Sn concentration and discuss possible performance gains by a reduction of inhomogeneities in Nb3Sn wires.

АКТИВАЦІЯ ПРОЦЕСІВ МАСОПЕРЕНОСУ ПРИ ДИФУЗІЙНОМУ ЗВАРЮВАННІ У ТЛІЮЧОМУ РОЗРЯДІ

The paper examines the effect of ion treatment of contacting surfaces on the activation of mass transfer processes during diffusion welding of metals. Using the example of welding titanium alloys, stainless steel with armco-iron and steel 45, it was determined that the preliminary ion cleaning of the welded surfaces in a glow discharge in an argon environment significantly reduces the time of the incubation period associated with the diffusional absorption of oxygen layers adsorbed on the surface, and provides a reduction in time isothermal aging until the maximum strength of the connection is reached.It is also shown that to ensure the strength of the welded joint at the level of strength of the base metal, it is sufficientto form a transition layer with a thickness of 3...4 microns, which experiences the largest plastic deformations at the first stage of welding. A further increase in the thickness of the transition layer practically does not lead to an increase in strength.Ionic activation of the surfaces to be joined, which is carried out in a vacuum chamber immediately before welding, provides an increase in the diffusion coefficient in the transition zone by approximately three times compared to standard surface preparation by washing them in solvents, and by almost two orders of magnitude compared to the self-diffusion coeffi-cient of the elements. It was established that when welding stainless steel with steel 45, the efficiency of ion activation of surfaces decreases, which is due to the reductive nature of the interaction of carbon contained in the composition of steel 45 in a significant amount, with oxides in the welding zone.It is shown that the most effective application of ionic activation of surfaces during diffusion welding of metals that arehomogeneous or similar in chemical composition, when there is no such important factor of intensification of mass transfer processes as the concentration gradient of elements in the welding zone, as well as metals that contain a small amount of reducing elements, in particular, carbon

In situ preparation of double gradient anode materials based on polysiloxane for lithium-ion batteries.

Although silicon has a high volumetric energy density as an anode material for Li-ion batteries, its volumetric expansion and sluggish Li+ migration kinetics need to be urgently addressed. In this work, cage-like structure materials (HRPOSS) derived from the in situ hydrogen reduction of polyhedral oligomeric silsesquioxane (T8-type POSS) were constructed as an Si@C anode for Li-ion batteries. Benefiting from the intriguing features of the Si/N double gradient and even-distributed silicon, HRPOSS-6 exhibited faint volume changes and fast ion-electron kinetics. Moreover, the uniformly immobilized nano-silicic and concentration gradient were favorable for accelerated ion migration. Therefore, HRPOSS-6 exhibited good electrochemical performances given that its cage structure could relieve the volume expansion. HRPOSS-6 demonstrated a high reversible capacity of 1814.1 mA h g-1 and long cycling performance after 200 cycles with 635 mA h g-1 at a current density of 0.5 A g-1. Accordingly, this Si/C/N composite exhibited great potential for high energy Li-ion batteries, where the corresponding full-cell (HRPOSS-6//LiNi0.6Co0.2Mn0.2O2) showed a cycle life of 200 cycles with over 80% capacity retention at rate of 1C. This work exploits the concentration gradients of dual elements for the capacity improvement of Si anodes and offers insight into the development of high-performance Si@C anode materials for advanced Li-ion batteries.

Physicochemical Aspects of Oxidative Consolidation Behavior of Manganese Ore Powders with Various Mn/Fe Mass Ratios for Pellet Preparation.

With the depletion of rich manganese ore resources, plentiful manganese ore powders with various Mn/Fe mass ratios are produced. The physicochemical aspects of oxidative consolidation behavior of manganese ores with various Mn/Fe mass ratios were investigated in this work to determine whether manganese ore powders with high iron content (Fe-Mn ore) can be prepared as high-quality pellets. Physicochemical properties of the pellets were investigated, including cold compression strength (CCS), phase transformation, microstructural evolution, Vickers hardness (HV), porosity, and lattice parameter. CCS testing indicated that the strength of roasted Fe-Mn ore pellets was observably lower than that of pure hematite or manganese ore pellets. Phase and morphology results showed that in Fe-Mn ore pellets, an Mn ferrite phase was generated between hematite and pyrolusite particles. However, newborn Mn ferrites and hematite had an obvious crystal boundary in the crystallographic particles. Moreover, poorly crystallized Mn ferrite particles were evident, along with Mn and Fe element concentration gradients, due to the inadequate diffusion of metal ions. This resulted in poor mechanical properties of the Fe-Mn ore pellets. A temperature over 1275 °C and a roasting time of 15 min is required for the oxidative consolidation of Fe-Mn ores. In such optimized cases, Mn, Fe, O, and Al elements were uniformly distributed in the well-crystallized Mn ferrite grains, which provided favorable mineralogy for the consolidation of Fe-Mn ore powders.

Permanent signatures of birth and nursing initiation are chemically recorded in teeth

In 2013 we presented a model for identifying nursing behavior from primate teeth based on rapid postnatal concentration changes in the non-essential trace element barium. Here we leverage the permanent neonatal (birth) line in the enamel of several dozen primate M1 cusps to compare pre- and postnatal trends in barium, zinc, strontium, and oxygen, as each element is believed to evince developmental patterning. Barium and zinc are the most consistent biomarkers of nursing initiation; a majority of M1 cusps shows concentration increases from prenatal to postnatal enamel, whereas strontium shows decreases or no change with similar frequency. Exceptions to the pattern of barium increase occurred in cusps that had been mineralizing for less than three weeks, suggesting that subsequent enamel maturation has only a minor impact on detecting real time events. Oxygen isotope compositions (δ18O) show rapid and marked fluctuations (∼1–2‰) within two weeks of birth in 93% of M1 cusps (n = 27/29). This is likely due to measurements of hypomineralized perinatal enamel and physiological changes in the body water of newborn infants. Ongoing work integrating elemental concentration gradients with isotopic variation will help establish the degree to which milk intake may cause elevated δ18O in teeth. We show that chemical identification of pre-to postnatal transitions may be robust to slight planar deviations that commonly obscure growth increments under light microscopy, and could help validate the identification of potential neonatal lines, making this approach a useful complement to bioarchaeological studies and public health investigations.

Dissimilar diffusion bonding behaviour of Ti2AlNb alloy and TiBw/Ti64 composites using the Ti interlayer

The Ti2AlNb alloy and TiBw/Ti64 composites were successfully bonded using a Ti interlayer at 900°C–1050°C for 20–80 min. The interface of the joints showed a layered microstructure. Moreover, the width of the diffusion zone gradually increased from 30 to 58 µm owing to sufficient atomic diffusion and phase transition at higher bonding temperatures with longer bonding times. The elemental concentration gradients caused by atomic diffusion promoted the precipitation of the O phase (Zone I) and the growth of the lamellar α phase (Zone II). A well-bonded joint was obtained and showed the highest shear strength of 460.9 MPa. Microcracks emerged in the diffusion zone and propagated into the TiBw/Ti64 substrate during the shear test, and the fracture mechanism inside the composites was intergranular ductile fracture mode.

Oxidation behavior of recast layer of air-film hole machined by EDM technology of Ni-based single crystal blade and its effect on creep strength

High temperature oxidation behavior of recast layer of film cooling hole (made by EDM) of Ni-based single crystal turbine blade was investigated by virtue of XRD, SEM, TEM and EDS. The element redistribution results in the loss of Al element in the recast layer, which inhibits the formation of protective oxide and accelerates the oxidation rate obviously. The concentration gradient of solute elements is large in recast layer. The diffusion path and distance of solute elements at different locations are not consistent. When the solute elements distribution is uneven, they can react with O at different speeds at the same time. The oxidation heat affected layer below the recast layer is significantly thicker than that of the substrate, whose strength is also lower than substrate. The creep behaviors were investigated in particular after oxidation for 0 h, 200 h and 800 h. The oxidation of recast layer significantly promotes creep fracture.

Permanent Signatures of Birth and Nursing Initiation are Chemically Recorded in Teeth

In 2013 we presented a model for identifying nursing behavior from primate teeth based on rapid postnatal concentration changes in the non-essential trace element barium. Here we leverage the permanent neonatal (birth) line in the enamel of several dozen primate M1 cusps to compare pre- and postnatal trends in barium, zinc, strontium, and oxygen, as each element is believed to evince developmental patterning. Barium and zinc are the most consistent biomarkers of nursing initiation; a majority of M1 cusps show concentration increases from prenatal to postnatal enamel, whereas strontium shows no change or decreases with equal frequency. Exceptions to the pattern of barium increase occurred in cusps that had been mineralizing for less than three weeks, suggesting that subsequent enamel maturation has only a minor impact on detecting real time events. Oxygen isotope compositions (δ18O) show marked fluctuations (~ 1–2 ‰) within a few weeks of birth in 92% of M1 cusps (n = 22/24). This is likely due to measurements of hypomineralized perinatal enamel, as well as physiological changes in the body water of newborn infants. Ongoing work integrating elemental concentration gradients with isotopic variation will help establish the degree to which milk intake may cause elevated δ18O in teeth. We show that chemical identification of pre- to postnatal transitions may be robust to slight planar deviations that often obscure growth increments under light microscopy, and could help validate the identification of potential neonatal lines, making this approach a useful complement to bioarchaeological studies and public health investigations.

Interfacial structure and formation mechanism of tungsten/steel HIP diffusion bonding joints using Ni interlayer

Tungsten and steel were successfully bonded using hot isostatic pressing (HIP) diffusion bonding with Ni interlayer. The influences of surface roughness, post-weld heat treatment (PWHT) and interlayer thickness on the properties of W/steel joint were researched, and the interfacial structure as well as the formation mechanism was investigated systematically. The results indicated that, the interfacial structure of the joint is steel/diffusion layer/reaction layer/W. The number of voids at the interface will be decreased greatly by reducing the roughness of the surfaces to be joined, which leads to the compactness of joints improving obviously. For the joints with thin (5-20μm) interlayers, after PWHT, the brittle reaction layer will further grow into W substrate and reduce the joint strength. While for those joints with thick (30-80μm) interlayers, PWHT is beneficial to increase the thickness of the helpful diffusion layer which shows the positive effect on the joint strength. A surprising result in this work is that, due to the different element concentration gradients, the structure of reaction layers is various with different interlayer thickness. With the very thin (≤20μm) interlayer, the reaction layer is a double-layer structure including W2Ni(Fe) layer and sublayer. When the thickness of the interlayer is 30μm, it is a W2Ni(Fe) single-layer structure. As the interlayer thickness increases to 50μm, the reaction layer shows a WNi and W2Ni double-layer structure. While when the interlayer thickness further increases to and above 80μm, it is a W2Ni and sublayer structure. Among the layers mentioned above, the sublayer close to W substrate is the decisive area to influence joint strength.

From Micro to Nano: Material Characterization Methods for Testing of Nuclear Core and Structural Materials

Nuclear grade fuel claddings act as a barrier against release of fuel particles into the coolant water during nuclear power plant operation, handling, and wet or dry storage of the spent fuel rods. The integrity of claddings is always a critical issue during the reactor operation, storage, or loss of coolant accidents (LOCA). After Fukushima disaster, cladding materials are widely studied, as the neutron transparent zirconium (Zr)-based alloys or accident tolerant fuel claddings, which should reduce the high-temperature oxidation rate of Zr-based alloys and enhance the accident tolerance. One part of the long-term investigation of Zr-based claddings in the Research Center Řež contributes to the characterization of material behavior after creep testing and high-temperature oxidation, i.e., conditions that may occur during reactor operation or storage of the spent fuel. Then, the microstructure response can be investigated by means of standard as well as advanced microscopy methods. In this study, we introduce the methodology of the cladding microstructure complex characterization demonstrated on the reference (nonirradiated) Zr-1%Nb alloy after creep testing. In the Zr-1%Nb microstructure, the hydrogen is present under some conditions as the hydride phases ZrH or ZrH2 that cause the mechanical properties degradation. As well, the hydride reorientation can pose a risk. Therefore, currently used methods of hydrides evaluation are presented. Furthermore, we introduce the microstructure analysis of the zircalloy-4 cladding after high-temperature oxidation at the temperature 1300 °C simulating LOCA. For this study, the new automatic chemical analysis procedure was developed. The main issue is the determination of the oxygen concentration and alloying elements behavior after critical increase of oxygen in the Zr-alloy tube at LOCA, also concerning the hydrogen content in the microstructure. Based on the element concentration gradients, the phase transitions from the oxide ZrO2 to the prior β-Zr can be determined and contributes to the phase diagrams experimental verification. In our contribution, the significant role of the electron microscopy methods “from micro to nano-scale” in the nuclear research is emphasized in these two research topics.

Trace element diffusion and kinetic fractionation in wet rhyolitic melt

Piston-cylinder experiments were run to determine the chemical diffusivities of 21 trace elements (Sc, V, Y, Zr, Nb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Hf, Th and U) in hydrous rhyolitic melts at 1 GPa pressure and temperatures from 850 to 1250 °C. Diffusion couple glasses were doped with trace elements in low concentrations to characterize the diffusivities of all cations in a single experiment. Laser ablation ICP-MS was used to evaluate the trace element concentration gradients that developed in the silicate glasses. All calculated diffusion coefficients correspond to the temperature dependence D = D0exp(-Ea/RT). Rhyolite liquids contained either ∼4.1 wt% or ∼6.2 wt% dissolved H2O; separate Arrhenius relationships are produced for each melt composition. Trace element diffusivities in the melt with 6.2 wt% H2O are roughly two times higher than those in the less hydrous melt.Calculated trace element diffusion coefficients cover nearly two orders of magnitude at a given temperature. The high field strength elements are the slowest diffusers, followed by the transition metals and heavy rare earth elements. The light rare earth elements have the fastest diffusion rates in hydrous rhyolitic melt. The measured diffusion coefficients range down to values sufficiently low to preclude diffusive homogenization over geochemically realistic time scales in some cases. The substantial differences in the diffusivities of individual cations may result in fractionated trace element signatures in rhyolite melt pockets. A simple model is used to explore the potential for kinetic fractionation of REE during growth of an apatite crystal in a diffusive boundary layer locally saturated in P2O5. The faster-diffusing light REE are more efficiently transported away from the crystal interface than the slower-moving heavy REE. Diffusion effects will enrich the melt boundary layer in slow-moving HREE relative to the faster LREE. The kinetic fractionation of REE in the melt growth medium will result in a precipitated apatite crystal with a disequilibrium trace element composition.

Influence of chemical compositions of anterior chamber aqueous humour and blood serum on the secretion of intraocular fluid

to identify the standard chemical composition of anterior chamber aqueous humour (AH) using energy dispersive spectrometer (EDS) integrated in scanning electron microscope (SEM); to study the influence of concentration gradient of chemical elements between aqueous humor and blood serum (BS) on the secretion of intraocular fluid (IOF) at normal and increased intraocular pressure (IOP). The study involved two groups of patients consisting of 33 people (33 eyes) each. The 1st group included patients with cataract and normal IOP (control), the 2nd group included patients with POAG and decompensated IOP. The samples (AH and BS) were taken during surgeries and studied using Oxford X-Max50 EDS integrated in EVO LS10 SEM. The concentration ratios (mmol/l) of AH/BS for Na at normal IOP was 1.472/1.278, for K - 0.106/0.035. In cases with POAG with decompensated IOP, the concentration ratio of Na was 1.424/1.248, K - 0.114/0.036. The concentration ratio of N between AH in cases with decompensated IOP and AH of normotonic eyes was 1.151/0.960, for S - 0.020/0.012. Consistent excess of Na and K concentrations in AH compared to BS indicates active participation of these osmotically active elements in the normal process of intraocular fluid secretion. The absence of significant differences in the ratios of Na and K in AH and BS at normal and decompensated IOP indicates low significance of these elements for pathological hypersecretion of intraocular fluid. Increased concentration of N in AH eyes with decompensated IOP compared with AH at normal IOP indicates possible involvement of nitrogen-containing osmotically active substances in the abnormal hypersecretion of intraocular fluid.

Micro-structure of ITO ceramics sintered at different temperatures and its effect on the properties of deposited ITO films

Structural characterizations of two ITO ceramics that were respectively sintered at 1560°C and 1600°C were focused on and the results indicate that the lower sintering temperature is good for ITO ceramics to have the triangle fine grains, larger elemental concentration gradients of indium and tin and more content of In4Sn3O12 phase which displays the stronger grain orientation growth along the crystallographic direction of [0-11]. ITO films with 100nm thickness deposited at 25°C–230°C were used to investigate the effect of micro-structure on the film properties. Grain orientation growth of In4Sn3O12 phase is conductive to form ITO films of columnar structure. Otherwise, uniform micro-structure and higher solubility of SnO2 in In2O3 main phase contribute to deposit ITO films of higher sheet resistance, less thickness uniformity and higher transmittance at 25°C, smaller etching angle and lower etching rate at 230°C.

Correlation of Interface Impurities and Chemical Gradients with High Magnetoelectric Coupling Strength in Multiferroic BiFeO3-BaTiO3 Superlattices.

The detailed understanding of magnetoelectric (ME) coupling in multiferroic oxide heterostructures is still a challenge. In particular, very little is known to date concerning the impact of the chemical interface structure and unwanted impurities that may be buried within short-period multiferroic BiFeO3-BaTiO3 superlattices during growth. Here, we demonstrate how trace impurities and elemental concentration gradients contribute to high ME voltage coefficients in thin-film superlattices, which are built from 15 double layers of BiFeO3-BaTiO3. Surprisingly, the highest ME voltage coefficient of 55 V cm-1 Oe-1 at 300 K was measured for a superlattice with a few atomic percent of Ba and Ti that diffused into the nominally 5 nm thin BiFeO3 layers, according to analytical transmission electron microscopy. In addition, highly sensitive enhancements of the cation signals were observed in depth profiles by secondary ion mass spectrometry at the interfaces of BaTiO3 and BiFeO3. As these interface features correlate with the ME performance of the samples, they point to the importance of charge effects at the interfaces, that is, to a possible charge mediation of ME coupling in oxide superlattices. The challenge is to provide cleaner materials and processes, as well as a well-defined control of the chemical interface structure, to push forward the application of oxide superlattices in multiferroic ME devices.

Effect of Powder-Feeding Modes During Plasma Spray on the Properties of Tungsten Carbide Composite Coatings

A WC-reinforced composite coating was fabricated on the surface of 45 steel samples by plasma, cladding process with WC powder added to the molten pool synchronously or in the tail of the molten pool. The microstructure, phase composition, and element distribution in the coating were analyzed. The results show that the undissolved WC particles and crystallized carbide (WC, W2C) were distributed uniformly in the sub-eutectic matrix in both cases. Fewer of the WC particles are dissolved in the matrix when they are injected into the tail of the molten pool. There are fewer needle-like tungsten carbide formations seen in the composite coating fabricated by back-feeding process than in that formed by synchronous feeding. The former results in a finer microstructure and a higher concentration gradient of elements near the interface between the WC particles and the coating matrix.

Characterization of cesium diffusion behavior into granite matrix using Rutherford backscattering spectrometry

The characterization of radionuclide diffusion behavior is necessary for performance assessment of granite as a geological barrier for high-level radioactive waste disposal. Rutherford backscattering spectrometry (RBS), a novel nuclear ion-beam technique, was selected in this study because it is suitable for analyzing the concentration gradients of heavy elements in a well-defined matrix and allows measuring diffusion coefficients on a micrometer scale. In this study Cs was selected to represent Cs-135 (a key radionuclide in high-level waste) diffusion in granite. The Cs energy spectrum and concentration deep profile were analyzed and the diffusion coefficient of Cs in granite for three different locations were determined, which were 2.06×10−19m2s−1, 3.58×10−19m2s−1, and 7.19×10−19m2s−1-19m2s–19m2s−1, respectively, which were of a similiar order of magnitude. Results from other studies are also compared and discussed in this paper.

Diffusive fractionation of trace elements in basaltic melt

The chemical diffusivities of 25 trace elements (Sc, V, Rb, Sr, Y, Zr, Nb, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Hf, Ta, Th, and U) in basaltic melt were measured in diffusion couple experiments performed at 1 GPa pressure and temperatures from 1250 to 1500 °C. Trace element concentration gradients developed in the glasses were simultaneously characterized using laser ablation ICP/MS to create an internally consistent data set. A ratio-fitting technique was employed to accurately determine the relative diffusivities of the rare earth elements (REE). All diffusion coefficients conform to the expected Arrhenius relation D = D0exp(−Ea/RT), where the constant log(D0, m2/s) ranges from −3.81 to −5.11 and Ea ranges from 161.73 to 223.81 kJ/mol. The slowest diffusivities are obtained for the high-field-strength elements; the fastest diffusivities are obtained for the low-field-strength elements. Trace element diffusion in MORB follows the compensation law, where log D0 is linearly correlated with Ea. Arrhenius parameters for diffusion of trivalent REE monotonically increase from La to Lu and are near-linear functions of bond strength (the variation in Arrhenius parameters means that the diffusivities decrease monotonically from La to Lu at a given T). The new data for trace element diffusion in basaltic melt can be used to explore the potential for diffusive fractionation of trace elements using kinetic models. Concentrations of the slower-diffusing heavy REE may be altered relative to those of the faster-diffusing light REE as a diffusive boundary layer develops in melt–melt and crystal–melt systems. The results indicate that diffusion in basalt can be an effective mechanism to fractionate trace elements from one another.