Memory Seeds Enable High Structural Phase Purity in 2D Perovskite Films for High-Efficiency Devices
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99 GENERAL AND MISCELLANEOUS↗
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Predicting phase transformation kinetics during metal additive manufacturing using non-isothermal Johnson-Mehl-Avrami models: Application to Inconel 718 and Ti-6Al-4V
Here, a computational model was developed to predict solid-state phase transformation kinetics within mechanical parts during metal additive manufacturing processes. This model is a modified version of the Johnson-Mehl-Avrami model for non-isothermal phase transformations that can be applied to various material systems undergoing solid-state phase transformations. Using the thermal history of an additive manufacturing fabricated mechanical part, along with the necessary thermodynamic data and kinetic information as inputs, the model outputs the history of phase fraction evolution during the build process. The model was applied to an Inconel 718 part built by powder bed fusion and a Ti-6Al-4V part built by directed energy deposition. Microstructure characterization and mechanical testing were performed for the validation of the model.
36 MATERIALS SCIENCE↗
Rare earth ion-adsorption clays in the presence of iron at basic pH: Adsorption mechanism and extraction method
In this work, the uptake mechanism and influence of iron (Fe) co-adsorption on the binding of rare-earth elements (REEs) on kaolinite have been investigated. REEs and varying concentrations of Fe were co-adsorbed onto kaolinite at pH 10.5. Inductively coupled plasma mass spectrometry (ICP-MS), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize how Fe co-adsorption influenced the uptake mechanism of REEs on kaolinite. Elemental analysis by ICP-MS revealed that the REE concentrations on kaolinite were unaffected by the presence of Fe. Crystal structure of kaolinite, determined by PXRD, was not altered after REE and Fe co-adsorption. XPS suggests that the adsorbed Fe is in the form of FeOOH, while the greatly attenuated REE XPS signals upon Fe co-adsorption implies that REEs are encapsulated by Fe species. Based on these results, we conclude that FeOOH layers were formed on top of REEs on the surface of kaolinite. Synthesized REE-Fe-kaolinite samples respond poorly to ion-exchange leaching, indicating that Fe is detrimental to the REE ion-exchange efficiency. The inhibition of ion-exchange REE extraction appears to be due to the passivating FeOOH layers. In contrast to ion-exchange methods, reductive leaching was found to dissolve the FeOOH passivating layers and liberate REEs such that they became available for ion-exchange leaching.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Sodium intercalation in the phosphosulfate cathode NaFe 2 (PO 4 )(SO 4 ) 2
The compound NaFe 2 (PO 4 )(SO 4 ) 2 is successfully synthesized via a solid state reaction route and its crystal structure is determined using powder X-ray diffraction data. NaFe 2 (PO 4 )(SO 4 ) 2 phase is also characterized by cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy. NaFe 2 (PO 4 )(SO 4 ) 2 crystallizes with the well-known NASICON-type structure. SAED and HRTEM experiments confirm the structural model, and no ordering between the PO 4 -3 and SO 4 -2 polyanions is detected. The electrochemical tests indicate that NaFe 2 (PO 4 )(SO 4 ) 2 is a 3 V sodium intercalating cathode. The electrical conductivity is relatively low (2.2 × 10 -6 Scm -1 at 200 °C) and the obtained activation energy is ~0.60eV. The GITT experiments indicate that the diffusivity values are in the range of 10 -11 -10 -12 cm 2 /s within the measured sodium concentrations.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Reinforcing blade-cast photocatalytic-titania thin film by titanate nanotubes
Highlights: • Suspension-based photocatalysts are inferior to thin-films due to separation issues. • Hydrothermal TiO{sub 2} nanotubes and sol-gel Ti(n-OBu){sub 4} blends were tape casted on glass. • Optimum blend composition yields mechanical stability due to the tubes reinforcing effect. • At optimum gel content the nanotube bundles are smoothed without stabilizers added. • Surface accessibility and mass transfer dominate the photocatalytic dye degradation. - Abstract: Titanate nanotubes/titania gel blends were prepared as composite sol-gel material, deposited on a glass substrate using a doctor blade and calcined in order to create thin films. In order to get an insight in titania nanotubes’ ability to reinforce thin films, drying control chemical agents were not used. The effects of titanate nanotubes to titanium n-butoxide ratio on surface morphology, phase composition, mechanical stability and photocatalytic activity were studied. Characterization of the thin films was carried out by means of optical and scanning electron microscopy, powder X-ray diffraction, synchrotron radiation grazing incidence X-ray diffraction and mechanical stability testing. Photocatalytic properties of the obtained thin films were evaluated on the basis of methylene blue degradation. Moderate blends exhibit favourable microstructural features while the dye degradation rate was greater for films with a greater amount of titanate nanotubes.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
CMAS behavior of yttrium aluminum garnet (YAG) and yttria-stabilized zirconia (YSZ) thermal barrier coatings
Calcium magnesium aluminosilicate (CMAS) that is formed from the ingested deposits in gas turbines degrades thermal barrier coatings (TBCs), especially for the most widely used material; yttria-stabilized zirconia (YSZ). In the present work, we examine the behavior of yttrium aluminum garnet (YAG) as an alternative material for TBCs. CMAS interaction studies were conducted by making composite pellets of YAG-CMAS and YSZ-CMAS powders. These pellets, after being subjected to heat treatment between 1100 °C and 1500 °C were characterized by X-ray Diffraction (XRD), scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS), which showed YAG to be almost inert to CMAS whereas YSZ exhibited significant phase changes. To test the behavior of TBCs with YAG and 8YSZ as the topcoat material in a CMAS environment, cyclic furnace tests were conducted in which a controlled amount of CMAS was applied and then the samples were cycled to failure. In addition, to simulate the continuous accumulation of CMAS expected in service, a cyclic furnace test was devised in which a small dose of aqueous solution of CMAS was applied on TBC specimens at the start of every cycle until the samples were cycled to failure. In all these tests YAG TBCs outperformed YSZ in terms of durability. In conclusion, the mechanisms of CMAS attack are described and the relative resistance of YAG and YSZ is shown to be consistent with the Optical Basicity (OB) theory.
36 MATERIALS SCIENCE↗
Crystal structures of tricalcium citrates
The crystal structures of calcium citrate hexahydrate, calcium citrate tetrahydrate, and anhydrous calcium citrate have been solved using laboratory and synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Both the hexahydrate and tetrahydrate structures are characterized by layers of edge-sharing Ca coordination polyhedra, including triply chelated Ca. An additional isolated Ca is coordinated by water molecules, and two uncoordinated water molecules occur in the hexahydrate structure. The previously reported polymorph of the tetrahydrate contains the same layers, but only two H 2 O coordinated to the isolated Ca and two uncoordinated water molecules. Anhydrous calcium citrate has a three-dimensional network structure of Ca coordination polyhedra. The new polymorph of calcium citrate tetrahydrate is the major crystalline phase in several commercial calcium supplements.
Kaduk, James A.↗
Cold Spray Field Deployment Evaluation for Double-Shell Tank 241-AN-105
This report highlights the documentation that supported Cold Spray field deployment in double-shell tank (DST) 241-AN-105 (AN-105) in July of 2025. This work was a collaborative effort between VRC Metal Systems (VRC), Robotic Technologies of Tennessee (RTT), the Hanford Tank Waste Operation and Closure (H2C) Chief Technology Office, H2C Tank Farm Projects Engineering, H2C Tank and Pipeline Integrity (TAPI) and H2C Ultrasonic Testing (UT) Operations & Support. Since 2019, the Chief Technology Office has been developing Cold Spray technology for refurbishing Hanford’s DSTs (RPP-RPT-65015). This technology is particularly relevant for addressing localized corrosion within the annulus of the DSTs by propelling metal powder particles at supersonic speeds to targeted areas. This process results in high-quality coatings characterized by high bond strength and low porosity result.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Fabrication and Thermoelectric Characterization of Transition Metal Silicide-Based Composite Thermocouples
Metal silicide-based thermocouples were fabricated by screen printing thick films of the powder compositions onto alumina tapes followed by lamination and sintering processes. The legs of the embedded thermocouples were composed of composite compositions consisting of MoSi2, WSi2, ZrSi2, or TaSi2 with an additional 10 vol % Al2O3 to form a silicide–oxide composite. The structural and high-temperature thermoelectric properties of the composite thermocouples were examined using X-ray diffraction, scanning electron microscopy and a typical hot–cold junction measurement technique. MoSi2-Al2O3 and WSi2-Al2O3 composites exhibited higher intrinsic Seebeck coefficients (22.2–30.0 µV/K) at high-temperature gradients, which were calculated from the thermoelectric data of composite//Pt thermocouples. The composite thermocouples generated a thermoelectric voltage up to 16.0 mV at high-temperature gradients. The MoSi2-Al2O3//TaSi2-Al2O3 thermocouple displayed a better performance at high temperatures. The Seebeck coefficients of composite thermocouples were found to range between 20.9 and 73.0 µV/K at a temperature gradient of 1000 °C. There was a significant difference between the calculated and measured Seebeck coefficients of these thermocouples, which indicated the significant influence of secondary silicide phases (e.g., Mo5Si3, Ta5Si3) and possible local compositional changes on the overall thermoelectric response. The thermoelectric performance, high sensitivity, and cost efficiency of metal silicide–alumina ceramic composite thermocouples showed promise for high-temperature and harsh-environment sensing applications.
47 OTHER INSTRUMENTATION↗
Syntheses and characterization of isotopically labeled 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)
Synthesis and characterization of chemical analogues of TATB, where specific atoms in the structure have been isotopically substituted, are reported. 15 N, 2 H, and 18 O have replaced the naturally occurring isotope distributions in the amino and/or the nitro attendant sites and 13 C has replaced the carbon in the ring structure. A modified wet-amination method was used to produce the analogues, and the isotopic replacements were performed by selective choice of labeled precursors. Four 15 N-labeled compounds (N replaced in the amino and nitro positions), two deuterium-labeled compounds (hydrogens replaced on the amino groups), and one 13 C-labeled compound (C in the ring substituted) were synthesized of high isotopic and chemical purity. One partially labeled 18 O-labeled compound (O in the nitro position) was a result of incomplete labeling due to exchange reactions during synthesis. The compounds were characterized by various spectroscopic methods – mass spectrometry (MS), solid-state nuclear magnetic resonance (SS-NMR), infrared (FTIR), powder x-ray diffraction (PXRD), and differential scanning calorimetry (DSC), depending upon the substitution. In conclusion, these compounds have been critical to the efforts in understanding the decomposition pathways of TATB when exposed to abnormal thermal environments.
36 MATERIALS SCIENCE↗
Autogenous healing of Engineered Cementitious Composites (ECC) based on MgO-fly ash binary system activated by carbonation curing
Developing self-healing of concrete cracks represents a critical approach for extending material longevity. If demonstrated on concretes with CO 2 stored through carbonation curing, self-healing can further mitigate infrastructure lifecycle emissions. In this study, the self-healing process is investigated on novel Engineered Cementitious Composites (ECC) based on binary blends of reactive MgO cement and siliceous fly ash activated by carbonation. The self-healing was observed under cyclic wetting and drying exposures and was characterized by measurements of resonance frequency, optical microscopy and X-ray computed microtomography (XCT). Thermogravimetric analysis, X-ray powder diffraction and scanning electron microscopy were employed to assist in identifying healing products and mechanisms. It was found that micro-cracks could be autogenously filled in 7 wet-dry cycles, as evidenced by over 95% recovery of resonance frequency and healed crack appearance under optical microscopic observation. Nevertheless, the composite mechanical performance, particularly tensile strength and ductility, did not fully recover with respect to the uncracked specimens. The inadequate post-healing mechanical properties were consistent with XCT observations that indicated low material densities in the cracked area. Based on the chemical and microstructural characterizations, it was determined that nesquehonite crystallites were responsible for the crack filling. Although the nesquehonite filled cracks will be less permeable to invasion of reactive fluids, novel strategies are needed to establish more robust healing capability to completely restore the crack bridging and composite tensile performance.
36 MATERIALS SCIENCE↗
High-Throughput Microstructural Characterization and Process Correlation Using Automated Electron Backscatter Diffraction
The need to optimize the processing conditions of additively manufactured (AM) metals and alloys has driven advances in throughput capabilities for material property measurements such as tensile strength or hardness. High-throughput (HT) characterization of AM metal microstructure has fallen significantly behind the pace of property measurements due to intrinsic bottlenecks associated with the artisan and labor-intensive preparation methods required to produce highly polished surfaces. This inequality in data throughput has led to a reliance on heuristics to connect process to structure or structure to properties for AM structural materials. In this study, we show a transformative approach to achieve laser powder bed fusion (LPBF) printing, HT preparation using dry electropolishing and HT electron backscatter diffraction (EBSD). This approach was used to construct a library of > 600 experimental EBSD sample sets spanning a diverse range of LPBF process conditions for AM Kovar. This vast library is far more expansive in parameter space than most state-of-the-art studies, yet it required only approximately 10 labor hours to acquire. Build geometries, surface preparation methods, and microscopy details, as well as the entire library of >600 EBSD data sets over the two sample design versions, have been shared with intent for the materials community to leverage the data and further advance the approach. Using this library, we investigated process–structure relationships and uncovered an unexpected, strong dependence of microstructure on location within the build, when varied, using otherwise identical laser parameters.
Characterization and Analytical Technique↗
Quantitative Analysis of the Morphology of {101} and {001} Faceted Anatase TiO 2 Nanocrystals and Its Implication on Photocatalytic Activity
The atomistic structure and morphology (shape and size) of nanomaterials have strong influences on their physical and chemical properties. However, many characterization techniques focus exclusively on one length-scale regime or another when developing quantitative morphology/structural models. In this article, we demonstrate that powder X-ray diffraction and neutron pair distribution function (PDF) can be used to obtain accurate average morphology and atomistic structure of {001} and {101} faceted anatase TiO 2 nanocrystals based on differential evolution refinements using Debye scattering equation calculations. It is also demonstrated that the morphology polydispersity of TiO 2 nanocrystals can be effectively obtained from the diffraction data via a numerical refinement routine. The morphology refinement results are in good agreement with those from transmission electron microscopy and the modeling of small angle neutron scattering data. This method is successfully used to quantify the facet-specified photocatalytic hydrogen evolution activity of anatase TiO 2 nanocrystals with different {001} to {101} ratios. It is found that the sample with an intermediate amount of both {001} and {101} facets shows the best photocatalytic hydrogen evolution reaction (HER) activity. It is expected that the simultaneous structure and morphology refinement technique can be generally used to study the relationship between morphology and functionality of nanomaterials.
36 MATERIALS SCIENCE↗
Quantitative Microstructural Characterization of Plutonium Oxalate Auto-Degradation and Evidence for PuO2 Nanocrystal Formation
It has been known since the 1950s that plutonium oxalate powders change color and lose mass over time when stored at room temperature in air. Despite several studies monitoring these changes, there are still discrepancies in the literature regarding the speciation of intermediate and final products that result from this decomposition. Presented here for the first time is a comprehensive series of time-resolved powder X-ray diffraction experiments coupled with solid-state optical spectroscopy and electron microscopy of aged plutonium (III) and (IV) oxalate powders. These data provide fresh insight into the chemical and structural changes that occur in these solids over time at room temperature and represent new evidence suggesting both plutonium (III) and plutonium (IV) oxalates decompose to form nanocrystalline plutonium oxide in the solid state.
Corbey, Jordan F.↗
Characterization and nondestructive inspection of additively manufactured materials
Additively manufactured (AM) components often exhibit significant discontinuities and indications without a clear understanding of how they might affect the mechanical properties of a part during qualification and service. This uncertainty is unacceptable for the design and manufacturing of most aerospace components. Current research in both mechanical testing and nondestructive evaluation involves developing methods for characterizing and inspecting AM components as the use of such materials continues to rise. Although several AM manufacturing methods have been developed in recent decades, this paper focuses on AM production-ready processes for a direct metal laser sintering (DMLS) powder bed fusion machine and will provide background on Sandia National Laboratories’ research efforts in this area. Tensile bar samples manufactured using the DMLS powder bed fusion method were inspected in this study, and the results of ultrasonic spectroscopy for assessing internal flaws will be presented. A combination of material property evaluation, microstructural characterization, and nondestructive inspection techniques will also be described. Finally, the results obtained from these material evaluation methods assist in determining inspection limits and methods for qualifying AM materials.
36 MATERIALS SCIENCE↗
Influence of Water, Vacuum, and Temperature on Surface Conditions of a Zeolite‐based Molecular Sieve
Molecular sieves such as zeolite-based materials are ubiquitous in industrial separation processes. However, there is a significant gap in understanding the surface properties and adsorption mechanisms for commercial zeolites, as most research focuses on pure zeolite powders rather than industrially relevant forms. Here, this work addresses this gap in understanding by employing advanced characterization techniques, including positron annihilation spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, liquid nitrogen sorption, and Fourier-transform infrared spectroscopy, to investigate the adsorption and desorption behavior of water in commercial zeolite 13X. Our research reveals insights into the pore-filling mechanisms, the impact of material binders on adsorption properties, and the dynamics of hydration and drying processes for zeolites. Monitoring changes on a minute scale allowed the distinction between fast and slow processes leading to sample drying. The identification of positronium bound to Na + ions indicated that water molecules remain in the vicinity of Na + ions after air-drying zeolite 13X. These findings highlight the importance of various environmental conditions in restoring zeolite properties to baseline after hydration, with significant implications for optimizing industrial processes. This work sets the direction for further research aimed at developing more efficient and robust separation techniques.
Beads Binder↗
Geochemical and microbial characteristics of seepage water and mineral precipitates in a radwaste disposal facility impacted by seawater intrusion and high alkalinity
The construction of an underground facility can dramatically change the quality, flow direction, and level of groundwater. It may also impact subsurface microbial composition and activity. Groundwater quality was monitored over eight years in two observational wells near an underground disposal facility on the east coast of South Korea. The results showed dramatic increases in dissolved ions such as O 2 , Na, Ca, Mg, and SO 4 during facility construction. Seepage water samples downgradient from the silos and tunnels, and precipitates deposited along the seepage water flow path were collected to determine the impact inside the disposal facility. X-ray analysis (powder X-ray diffraction (pXRD) and X-ray absorption fine structure (XAFS)) were used to characterize the mineral precipitates. Microbial community composition was determined by 16S rRNA gene sequencing. The seepage water composition was of two types: Ca-Cl and Ca-Na-HCO 3 . The ratio of Cl and δ 18 O showed that the Ca-Cl type seepage water was influenced by groundwater mixed with seawater ranging from 2.7% to 15.1%. Various sulfate-reducing bacteria were identified in the Ca-Cl type seepage water, exhibiting relatively high sulfate content from seawater intrusion. Samples from the Ca-Na-HCO 3 type seepage water had an extremely high pH (>10) and abundance of Hydrogenophaga. The precipitates observed along the flow path of the seepage water included calcite, ferrihydrite, green rust, and siderite, depending on seepage water chemistry and microbial activity. This study suggests that the construction of underground structures creates distinct, localized geochemical conditions (e.g., high alkalinity, high salinity, and oxic conditions), which may impact microbial communities. These biogeochemical changes may have undesirable large-scale impacts such as water pump clogging. Overall, an understanding of the process and long-term monitoring are essential to assess the safety of underground facilities.
54 ENVIRONMENTAL SCIENCES↗
Controlled Growth of Ceria Nanoarrays on Anatase Titania Powder: A Bottom-up Physical Picture
The leading edge of catalysis research motivates physical understanding of the growth of nanoscale oxide structures on different supporting oxide materials that are themselves also nanostructured. This research opens up for consideration a diverse range of facets on the support material, versus the single facet typically involved in wide-area growth of thin films. In this paper, we study the growth of ceria nanoarchitectures on practical anatase titania powders as a showcase inspired by recent experiments. Density functional theory (DFT)-based methods are employed to characterize and rationalize the broad array of low energy nanostructures that emerge. Using a bottom-up approach, we are able to identify and characterize the underlying mechanisms for the facet-dependent growth of various ceria motifs on anatase titania based on formation energy. These motifs include 0D clusters, 1D chains, 2D plates, and 3D nanoparticles. Finally, the ceria growth mode and morphology are determined by the interplay of several factors including the role of the common cation valence, the interface template effect for different facets of the anatase support, enhanced ionic binding for more compact ceria motifs, and the local structural flexibility of oxygen ions in bridging the interface between anatase and ceria structures.
36 MATERIALS SCIENCE↗