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PmS3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Pm3+ is bonded to twelve equivalent S1- atoms to form a mixture of distorted face and corner-sharing PmS12 cuboctahedra. There are six shorter (2.86 Å) and six longer (3.24 Å) Pm–S bond lengths. S1- is bonded in a 2-coordinate geometry to four equivalent Pm3+ atoms.
PaPmO4 is Fluorite-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Pa5+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Pa–O bond lengths are 2.32 Å. Pm3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Pm–O bond lengths are 2.42 Å. O2- is bonded to two equivalent Pa5+ and two equivalent Pm3+ atoms to form a mixture of edge and corner-sharing OPm2Pa2 tetrahedra.
MgPm2Se4 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent Se2- atoms to form MgSe4 tetrahedra that share corners with twelve equivalent PmSe6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Mg–Se bond lengths are 2.65 Å. Pm3+ is bonded to six equivalent Se2- atoms to form PmSe6 octahedra that share corners with six equivalent MgSe4 tetrahedra and edges with six equivalent PmSe6 octahedra. All Pm–Se bond lengths are 2.95 Å. Se2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three equivalent Pm3+ atoms.
PaPmO4 is Fluorite-derived structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Pa5+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Pa–O bond lengths are 2.31 Å. Pm3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Pm–O bond lengths are 2.43 Å. O2- is bonded to two equivalent Pa5+ and two equivalent Pm3+ atoms to form a mixture of edge and corner-sharing OPm2Pa2 tetrahedra.
PmSe2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Pm3+ is bonded in a 9-coordinate geometry to nine Se+1.50- atoms. There are a spread of Pm–Se bond distances ranging from 2.98–3.22 Å. There are two inequivalent Se+1.50- sites. In the first Se+1.50- site, Se+1.50- is bonded in a 5-coordinate geometry to four equivalent Pm3+ and one Se+1.50- atom. The Se–Se bond length is 2.55 Å. In the second Se+1.50- site, Se+1.50- is bonded to five equivalent Pm3+ atoms to form a mixture of distorted edge and corner-sharing SePm5 trigonal bipyramids.
PmSe3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pm3+ is bonded to twelve Se1- atoms to form distorted PmSe12 cuboctahedra that share corners with four equivalent PmSe12 cuboctahedra, edges with eight equivalent PmSe12 cuboctahedra, edges with sixteen equivalent SePm4Se8 cuboctahedra, faces with four equivalent PmSe12 cuboctahedra, and faces with eight equivalent SePm4Se8 cuboctahedra. There are four shorter (2.94 Å) and eight longer (3.40 Å) Pm–Se bond lengths. There are two inequivalent Se1- sites. In the first Se1- site, Se1- is bonded to four equivalent Pm3+ and eight Se1- atoms to form distorted SePm4Se8 cuboctahedra that share corners with twelve equivalent SePm4Se8 cuboctahedra, edges with eight equivalent PmSe12 cuboctahedra, edges with eight equivalent SePm4Se8 cuboctahedra, faces with four equivalent PmSe12 cuboctahedra, and faces with ten equivalent SePm4Se8 cuboctahedra. There are four shorter (2.94 Å) and four longer (3.40 Å) Se–Se bond lengths. In the second Se1- site, Se1- is bonded in a square co-planar geometry to four equivalent Pm3+ and eight equivalent Se1- atoms.
MgPmS3 is Ilmenite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Mg2+ is bonded to six S+1.67- atoms to form distorted MgS6 octahedra that share corners with four equivalent PmS6 pentagonal pyramids, edges with three equivalent MgS6 octahedra, and edges with four equivalent PmS6 pentagonal pyramids. There are a spread of Mg–S bond distances ranging from 2.55–2.88 Å. Pm3+ is bonded to six S+1.67- atoms to form distorted PmS6 pentagonal pyramids that share corners with four equivalent MgS6 octahedra, edges with four equivalent MgS6 octahedra, an edgeedge with one PmS6 pentagonal pyramid, and a faceface with one PmS6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 38–48°. There are a spread of Pm–S bond distances ranging from 2.74–2.99 Å. There are two inequivalent S+1.67- sites. In the first S+1.67- site, S+1.67- is bonded in a 4-coordinate geometry to two equivalent Mg2+ and two equivalent Pm3+ atoms. In the second S+1.67- site, S+1.67- is bonded to two equivalent Mg2+ and two equivalent Pm3+ atoms to form edge-sharing SPm2Mg2 trigonal pyramids.
Pm2(WO4)3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Pm3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Pm–O bond distances ranging from 2.39–2.51 Å. There are two inequivalent W6+ sites. In the first W6+ site, W6+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of W–O bond distances ranging from 1.78–2.16 Å. In the second W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.80 Å) and two longer (1.85 Å) W–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Pm3+ and two equivalent W6+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Pm3+ and one W6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Pm3+ and one W6+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Pm3+ and one W6+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Pm3+ and one W6+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Pm3+ and one W6+ atom.
MgPm2S4 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent S2- atoms to form MgS4 tetrahedra that share corners with twelve equivalent PmS6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Mg–S bond lengths are 2.53 Å. Pm3+ is bonded to six equivalent S2- atoms to form PmS6 octahedra that share corners with six equivalent MgS4 tetrahedra and edges with six equivalent PmS6 octahedra. All Pm–S bond lengths are 2.83 Å. S2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three equivalent Pm3+ atoms.
PmP3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pm3+ is bonded to twelve P1- atoms to form a mixture of corner, edge, and face-sharing PmP12 cuboctahedra. There are four shorter (2.81 Å) and eight longer (3.12 Å) Pm–P bond lengths. There are two inequivalent P1- sites. In the first P1- site, P1- is bonded in a 8-coordinate geometry to four equivalent Pm3+ and four equivalent P1- atoms. All P–P bond lengths are 2.81 Å. In the second P1- site, P1- is bonded in a square co-planar geometry to four equivalent Pm3+ atoms.
PmAu3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pm3+ is bonded in a distorted body-centered cubic geometry to fourteen Au1- atoms. There are eight shorter (3.05 Å) and six longer (3.52 Å) Pm–Au bond lengths. There are two inequivalent Au1- sites. In the first Au1- site, Au1- is bonded to four equivalent Pm3+ and four equivalent Au1- atoms to form a mixture of distorted face, edge, and corner-sharing AuPm4Au4 tetrahedra. All Au–Au bond lengths are 3.05 Å. In the second Au1- site, Au1- is bonded in a 8-coordinate geometry to six equivalent Pm3+ and eight equivalent Au1- atoms.
Balance of plant of a High-Temperature gas-cooled Reactor – Pebble bed Module (HTR-PM) is modeled using RELAP-7. The model includes the primary helium loop where the heat produced by the core is transferred to a helical-coil steam generator and the secondary loop where super-heated steam is fed to a turbine to extract power. The steam is then condensed to subcooled water and pumped back into the steam generator. Results demonstrate that RELAP-7 has the capability to model different regimes encountered in two-phase flow with wall boiling, superheated steam, subcooled liquid and condensation. RELAP-7 also has the capability of modeling different fluids with their own specific models in a very flexible way, without any code change. This also demonstrates the capability of modeling the transfer of fission power into electrical power.
To understand how the composition of novel lubricant additives and their ash interact with gasoline particulate filters (GPFs), an accelerated aging protocol was conducted using three lubricant additive formulations and two GPF types. The additive packages (adpaks) consisted of Ca+Mg detergent in a 3:1 or 0:1 ratio and an anti-wear component—either zinc dialkyl dithiophosphate (ZDDP) or a novel phosphonium-phosphinate ionic liquid (IL) substitute. The particulate sampling captured amount/compositions of particulate matter (PM) generated, total particulate number, and size distribution. Five ash loadings were completed. GPF position and adpak composition affected the backpressure, ash composition, ash morphology, and captured mass. The particulate sampling indicated that the ash component consisted primarily of particles less than 50 nm in size and that the Mg-only adpak resulted in more particulate of 50–400 nm in size. Postmortem materials characterization indicated GPFs in the underfloor position had deeper penetration of ash into the walls compared to the close-coupled position. Additionally, the Mg-only adpak had a higher filter collection efficiency (>90%) and the ash particles consisted of a higher concentration of dense ash material. In contrast, four of the 3:1 Ca:Mg lubricant adpaks resulted in a collection efficiency of only 40–50%. Although the collection efficiency was higher with the Mg-only adpak, the ash layer in the GPF was not thicker, nor was the penetration into the wall more significant, and surprisingly the full useful life (FUL) backpressure was lower than with Ca:Mg adpaks. The higher density of the Mg-derived ash was the only detectable difference. A possible explanation of this observation is that Mg ash has a lower melting point and is more susceptible to densification during combustion or GPF regeneration. The substitution of IL in place of the ZDDP did not lead to any notable changes in collection efficiency or location of the ash.
A Serpent model of the HTR-PM equilibrium core was developed for use in cross section prepa-ration studies in order to guide methods development for the Griffin reactor multiphysics applica-tion. The model includes detailed isotopics for 10 distinct pebble burnup groups in 126 core zoneswith unique fuel and moderator temperatures obtained from a coupled neutronics-thermal-fluidsequilibrium core calculation using Griffin-Pronghorn. A sensitivity study of the fuel and mod-erator temperatures for various core regions was performed with the MOOSE stochastic tools.The results show that the uncertainties are, not unexpectedly, dominated by the value of the fluidtemperature and that the power level, heat transfer coefficient and effective conduction to neigh-boring pebbles and fluid constitute, at best, second order effects. The temperature uncertaintyrange varies from 28 K to 57 K at the core entry and exit planes, respectively, but these val-ues are probably higher. We still have to quantify the significance of these uncertainties in thepreparation of cross sections, which will be postponed for future work. In addition, we verifythat the single effective pebble approach works well for the preparation of region averaged crosssections in the infinite domain approximation. Nevertheless, there are significant discrepanciesin the cross sections when compared to the multi-pebble model. This could affect the predictionof peak values and in the depletion calculation. We conclude that is highly desirable for futurestudies with Griffin to be able to handle both the ?effective? pebble approximation and the multi-pebble approach for the various pebble burnup groups. This enables Griffin users the flexibilityto perform higher-fidelity studies. Finally, we initiate the preparation of cross sections for variouscore regions from the full core Serpent reference model. We quantify the differences in 26 groupcross sections from infinite domain models. These reference cross sections will serve to validatethe double heterogeneity, self-shielding, and spectrum-correction methods in Griffin.
Overview of the PM-HIP work performed on stainless steel 316H as part of the microreactor program. High temperature mechanical testing was performed, with concerns identified with the creep-fatigue performance. Variations in feedstock and processing parameters did not conclusively identify the primary factor in the reduced creep-fatigue performance.
An electronic-structure-centered perspective is presented on permanent-magnet (PM) design, highlighting two key levers, that is, saturation magnetization (M s ), governed by 3d-band filling and exchange physics, and magnetocrystalline anisotropy energy (MAE), arising from spin-orbit coupling (SOC) on anisotropic orbital populations. Reviewing current practices, including DFT-based MAE/J ij extraction, atomistic-spin and micromagnetic modeling, and high-throughput machine learning (ML) pipelines, three bottlenecks limiting predictive discovery is identified that is i) electronic-structure accuracy for small MAE (sensitive to functional choice, Hubbard U, and many-body effects), ii) finite-temperature and kinetic realism (phonon/magnon renormalization, ordering kinetics), and iii) descriptor and multiscale decoupling (lack of SOC-weighted and orbital-resolved fingerprints). Deep dives into the electronic-structure of Nd─Fe─B and Fe─N show how these fingerprints govern magnetic performance, motivating DFT- and quantum-mechanics-based descriptors for discovery. Unbiased, structure-driven exploration, coupled with high-throughput simulations, ML, generative AI, and reasoning models, accelerates candidate identification and propagates insights across scales. Addressing supply-chain risks, on future needs of designing “critical-element-free” magnets with tailored microstructure and high energy products is emphasized. By integrating electronic fingerprints, AI reasoning, and multiscale modeling, a practical roadmap is provided for rare-earth-lean or rare-earth free, high-performance, sustainable PMs.
Since graphene, a variety of 2D materials have been fabricated in a quest for a tantalizing combination of properties and desired physiochemical behavior. 2D materials that are piezoelectric, i.e., that allow for a facile conversion of electrical energy into mechanical and vice versa, offer applications for sensors, actuators, energy harvesting, stretchable and flexible electronics, and energy storage, among others. Unfortunately, materials must satisfy stringent symmetry requirements to be classified as piezoelectric. Here, 2D ultrathin single-crystal molybdenum oxide (MoO 2 ) flakes that exhibit unexpected piezoelectric-like response are fabricated, as MoO 2 is centrosymmetric and should not exhibit intrinsic piezoelectricity. However, it is demonstrated that the apparent piezoelectricity in 2D MoO 2 emerges from an electret-like behavior induced by the trapping and stabilization of charges around defects in the material. Arguably, the material represents the first 2D electret material and suggests a route to artificially engineer piezoelectricity in 2D crystals. Specifically, it is found that the maximum out-of-plane piezoresponse is 0.56 pm V -1 , which is as strong as that observed in conventional 2D piezoelectric materials. The charges are found to be highly stable at room temperature with a trapping energy barrier of ≈2 eV.
Achieving substantial electrostrain alongside a large effective piezoelectric strain coefficient (d 33 *) in piezoelectric materials remains a formidable challenge for advanced actuator applications. Here, in this work, a straightforward approach to enhance these properties by strategically designing the domain structure and controlling the domain switching through the introduction of arrays of ordered {100}<100> dislocations is proposed. This dislocation engineering yields an intrinsic lock-in steady–state electrostrain of 0.69% at a low field of 10 kV cm -1 without external stress and an output strain energy density of 5.24 J cm -3 in single-crystal BaTiO 3 , outperforming the benchmark piezoceramics and relaxor ferroelectric single-crystals. Additionally, applying a compression stress of 6 MPa fully unlocks electrostrains exceeding 1%, yielding a remarkable d 33 * value over 10 000 pm V -1 and achieving a record-high strain energy density of 11.67 J cm -3 . Optical and transmission electron microscopy, paired with laboratory and synchrotron X-ray diffraction, is employed to rationalize the observed electrostrain. Phase-field simulations further elucidate the impact of charged dislocations on domain nucleation and domain switching. These findings present an effective and sustainable strategy for developing high-performance, lead-free piezoelectric materials without the need for additional chemical elements, offering immense potential for actuator technologies.