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Cr3Pt crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Cr is bonded in a 6-coordinate geometry to two equivalent Cr and four equivalent Pt atoms. Both Cr–Cr bond lengths are 2.34 Å. All Cr–Pt bond lengths are 2.61 Å. Pt is bonded to twelve equivalent Cr atoms to form a mixture of face and edge-sharing PtCr12 cuboctahedra.
PtSi3 crystallizes in the hexagonal P6_3/mmc space group. The structure is one-dimensional and consists of two PtSi3 ribbons oriented in the (0, 0, 1) direction. Pt4+ is bonded in a 6-coordinate geometry to six equivalent Si+1.33- atoms. All Pt–Si bond lengths are 2.52 Å. Si+1.33- is bonded in a 8-coordinate geometry to two equivalent Pt4+ atoms.
TcPt crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Tc2+ is bonded in a 6-coordinate geometry to six equivalent Pt2- atoms. All Tc–Pt bond lengths are 2.76 Å. Pt2- is bonded to six equivalent Tc2+ and six equivalent Pt2- atoms to form a mixture of distorted corner, edge, and face-sharing PtTc6Pt6 cuboctahedra. All Pt–Pt bond lengths are 2.78 Å.
PtMo crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Mo2+ is bonded in a 6-coordinate geometry to six equivalent Pt2- atoms. All Mo–Pt bond lengths are 2.79 Å. Pt2- is bonded to six equivalent Mo2+ and six equivalent Pt2- atoms to form a mixture of face, edge, and corner-sharing PtMo6Pt6 cuboctahedra. All Pt–Pt bond lengths are 2.82 Å.
This comprehensive investigation examines the structure–property relationships in two nuclear alloy systems—Alloy 709 (A709) austenitic stainless steel and Grade 92 (G-92) ferritic/martensitic (F/M) steel—manufactured via directed energy deposition (DED) for sodium-cooled fast reactor applications. This study establishes the fundamental mechanisms for controlling microstructures for optimizing the mechanical performance of additively manufactured nuclear materials through systematic heat treatment optimization and multiscale characterization. As-deposited A709 steel develops a complex multiscale strengthening architecture consisting of a fine cellular solidification structure with diameter of 2-3 µm within10–50 µm grains, elevated dislocation densities from rapid thermal cycling, and grain boundary precipitates that activate concurrent Hall–Petch, dislocation, and precipitation hardening mechanisms to achieve exceptional properties [yield strength (YS): 603 MPa, ultimate tensile strength (UTS): 844 MPa, Vickers hardness: 220 HV] that achieve a 44% superior strength compared to that of the wrought material. Heat treatments produce different results. Solution annealing (SA) dissolves the cellular structure and reduces the hardness to 190 HV. Precipitation treatment (PT) keeps the cellular structure but adds carbides, allowing the hardness to reach 205 HV. The best approach combines both treatments (SA+PT) and creates uniform precipitate distributions with M 23 C 6 carbides at the grain boundaries and MX carbonitrides in the matrix, achieving a hardness of 195 HV. However, directional differences persist, with a 12%–15% strength variation between orientations due to the inherited layered microstructural architecture that survives aggressive heat treatment. While tensile testing at 550°C demonstrates 40%–50% thermal softening with dynamic strain aging, DED A709 steel still maintains a 71% higher YS than that of the wrought material. Ion irradiation studies (100–400 dpa) of DED A709 steel reveal progressive radiation damage with increasing void density and radiation-induced segregation causing nickel enrichment and chromium depletion, which will ultimately compromise mechanical properties. As-deposited G-92 exhibits exceptional strength (UTS: 1650–1700 MPa, 430 HV) through a complex microstructure containing both ferrite and martensite phases, a high geometrically necessary dislocation (GND) density (17.04×10 14 /m 2 ), and fine carbides. Heat treatments create distinct changes. Normalizing produces fresh martensite with the highest hardness (460 HV) and an increased GND density (20.23×10 14 /m 2 ). Tempering develops dual precipitation systems and reduces the hardness to 290 HV. The optimal approach uses sequential normalizing plus tempering, achieving balanced properties with the lowest hardness (250 HV) and a reduced GND density (11.01×10 14 /m 2 ). A processing-dependent anisotropy is observed: horizontal specimens achieve superior ductile behavior, while vertical specimens exhibit brittle failure. A tempering heat treatment successfully mitigates this anisotropic behavior by transforming the hard martensitic as-deposited structure into tempered martensite enabling both horizontal and vertical specimens to exhibit similar stress–strain characteristics with visible necking behavior. Remarkably, testing at 550°C reveals a reversal in the anisotropy, where as-deposited specimens achieve near isotropy with superior thermal stability (a 15%–20% strength reduction), while tempered specimens develop an orientation dependence with a 25%–30% strength reduction. Both alloy systems demonstrate that DED processing creates specimens with a superior strength through refined microstructural features, though with distinct strengthening mechanisms—austenitic through cellular structures and precipitates versus F/M through phase transformations and precipitates. Heat treatment optimization requires alloy-specific approaches, with A709 benefiting from controlled precipitation while G-92 requires careful phase transformation control. The results show that DED manufacturing can produce nuclear materials with exceptional performance, but directional effects and temperature-dependent behavior must be carefully considered for reactor component design and qualification.
The performance of catalysts made out of Pt supported on TiO 2 thin films grown on SBA-15 (a silica mesoporous material) by atomic layer deposition (ALD) was characterized systematically by combining in situ infrared absorption spectroscopy (IR) with other techniques including electron microscopy and adsorption−desorption isothermal measurements. The titania films in the resulting high-surface-area catalysts were evenly distributed throughout the inner surface of the SBA-15 mesopores, and their thickness could be controlled at a submonolayer level, with 3 to 4 TiO 2 ALD cycles needed for the complete coverage of the silica sites. The titania films could be deposited either before or after adding the metal (Pt), which was dispersed in the form of small nanoparticles (NPs) approximately 4−6 nm in diameter, in order to exert some control on the density and nature of the Pt/TiO 2 interface sites. One important lesson deriving from this work is that such an order of deposition leads to significantly different catalysts in spite of the fact that most of their structural properties are similar. If the Pt is deposited on the titania films, the resulting metal NPs are slightly smaller than those grown on silica and display CO adsorption sites with lower surface Pt coordination numbers. On the other hand, when TiO 2 is deposited on the Pt/SBA-15 starting material, some titania grows on the metal and partially blocks its surface while also creating new interface sites where CO binds more weakly and displays lower C−O stretching frequencies. In terms of catalytic performance, the results from in situ IR CO site titration and kinetic measurements combined suggest a mechanism where CO first adsorbs on Pt atop sites and then migrates to Pt/TiO 2 interface sites, where oxidation takes place. Both types of sites appear to be similar in all the catalysts tested, but catalytic performance could be optimized by tuning their surface densities. Maximum catalytic activity was obtained when the TiO2 films were deposited first and with TiO 2 coverages of at least half a monolayer, that is, after at least 2 ALD cycles.
LiPtO2 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Li sites. In the first Li site, Li is bonded to six O atoms to form LiO6 octahedra that share corners with six PtO6 octahedra, edges with six LiO6 octahedra, and edges with six PtO6 octahedra. The corner-sharing octahedra tilt angles range from 4–9°. There are a spread of Li–O bond distances ranging from 2.12–2.35 Å. In the second Li site, Li is bonded to six O atoms to form LiO6 octahedra that share corners with six PtO6 octahedra, edges with six equivalent LiO6 octahedra, and edges with six PtO6 octahedra. The corner-sharing octahedra tilt angles range from 5–6°. There are two shorter (2.20 Å) and four longer (2.34 Å) Li–O bond lengths. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded to six O atoms to form PtO6 octahedra that share corners with six LiO6 octahedra, edges with six LiO6 octahedra, and edges with six PtO6 octahedra. The corner-sharing octahedra tilt angles range from 4–7°. There are a spread of Pt–O bond distances ranging from 2.08–2.18 Å. In the second Pt site, Pt is bonded to six O atoms to form distorted PtO6 octahedra that share corners with six LiO6 octahedra, edges with six LiO6 octahedra, and edges with six equivalent PtO6 octahedra. The corner-sharing octahedra tilt angles range from 6–9°. There are four shorter (2.26 Å) and two longer (2.33 Å) Pt–O bond lengths. There are two inequivalent O sites. In the first O site, O is bonded to three Li and three Pt atoms to form a mixture of edge and corner-sharing OLi3Pt3 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. In the second O site, O is bonded to three Li and three Pt atoms to form a mixture of edge and corner-sharing OLi3Pt3 octahedra. The corner-sharing octahedra tilt angles range from 0–5°.
Ba6Ti5PtO18 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are six inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, corners with three equivalent TiO6 octahedra, faces with seven BaO12 cuboctahedra, a faceface with one PtO6 octahedra, and faces with six TiO6 octahedra. The corner-sharing octahedral tilt angles are 12°. There are a spread of Ba–O bond distances ranging from 2.90–2.95 Å. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form distorted BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, corners with three equivalent TiO6 octahedra, faces with seven BaO12 cuboctahedra, faces with three equivalent PtO6 octahedra, and faces with four TiO6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are a spread of Ba–O bond distances ranging from 2.84–3.08 Å. In the third Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, corners with three equivalent PtO6 octahedra, faces with seven BaO12 cuboctahedra, and faces with seven TiO6 octahedra. The corner-sharing octahedral tilt angles are 10°. There are a spread of Ba–O bond distances ranging from 2.90–2.94 Å. In the fourth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form distorted BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, corners with three equivalent TiO6 octahedra, faces with seven BaO12 cuboctahedra, and faces with seven TiO6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are a spread of Ba–O bond distances ranging from 2.80–3.06 Å. In the fifth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.86–2.98 Å. In the sixth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, faces with three equivalent PtO6 octahedra, and faces with five TiO6 octahedra. There are nine shorter (2.90 Å) and three longer (3.01 Å) Ba–O bond lengths. There are five inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three equivalent TiO6 octahedra, corners with three equivalent PtO6 octahedra, and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–9°. There are three shorter (1.90 Å) and three longer (2.11 Å) Ti–O bond lengths. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–9°. There are three shorter (1.92 Å) and three longer (2.11 Å) Ti–O bond lengths. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent TiO6 octahedra, faces with seven BaO12 cuboctahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedral tilt angles are 9°. There are three shorter (1.89 Å) and three longer (2.12 Å) Ti–O bond lengths. In the fourth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent TiO6 octahedra, faces with seven BaO12 cuboctahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are three shorter (1.92 Å) and three longer (2.08 Å) Ti–O bond lengths. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent TiO6 octahedra, faces with seven BaO12 cuboctahedra, and a faceface with one PtO6 octahedra. The corner-sharing octahedral tilt angles are 9°. There are three shorter (1.89 Å) and three longer (2.13 Å) Ti–O bond lengths. Pt4+ is bonded to six O2- atoms to form PtO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent TiO6 octahedra, faces with seven BaO12 cuboctahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are three shorter (2.01 Å) and three longer (2.09 Å) Pt–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two Ti4+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+, one Ti4+, and one Pt4+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Ti4+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Ti4+ atoms. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Ti4+ atoms. In the sixth O2- site, O2- is bonded to four Ba2+, one Ti4+, and one Pt4+ atom to form a mixture of distorted face and corner-sharing OBa4TiPt octahedra. The corner-sharing octahedra tilt angles range from 6–60°.
X-ray absorption spectroscopy (XAS) coupled with highly intense pulses from an X-ray-free electron laser (XFEL) can be used to track ultrafast chemical dynamics. Nonetheless, measurements for dilute samples (≤1 mM) have been exceptionally challenging, as scattering background signals dominate over the sample’s X-ray fluorescence. We show that femtosecond time-resolved XAS measurements of sub-millimolar transition metal solutions are now possible at the Linac Coherent Light Source (LCLS) using a high-throughput polycapillary XAS spectrometer, designed, developed, and commissioned at LCLS and the Stanford Synchrotron Radiation Lightsource (SSRL). The instrument integrates three polycapillary optics that collect and collimate X-ray fluorescence emitted from the interaction point with a high solid angle. X-ray collimated fluorescence is then selectively diffracted by coupled graphite analyzer crystals. As a result, the contribution of scattered photons is suppressed. Experiments at the Pt L 3 -edge on 0.1 mM aqueous K 2 PtCl 6 (delivered via a 100 μm liquid jet) were successfully performed in the laser pump X-ray probe configuration at the LCLS XCS and XPP instruments. We report the transient spectra of hexachloroplatinate within the first 10 ps after a 266 nm photoexcitation. We observed a short-lived reduced intermediate (≈2 ps). The polycapillary X-ray spectrometer at LCLS now enables the efficient study of the dynamics of ultradilute transition metals in solution. This capability opens the door to investigating plasmonic systems, photocatalysts, enzymes, and other scarce and dilute samples.
Supported metal single atom catalysts (SACs) present an emerging class of low-temperature catalysts with high reactivity and selectivity, which, however, face challenges on both durability and practicality. Herein, we report a single-atom Pt catalyst that is strongly anchored on a robust nanowire forest of mesoporous rutile titania grown on the channeled walls of full-size cordierite honeycombs. This Pt SAC exhibits remarkable activity for oxidation of CO and hydrocarbons with 90% conversion at temperatures as low as ~160 °C under simulated diesel exhaust conditions while using 5 times less Pt-group metals than a commercial oxidation catalyst. Such an excellent low-temperature performance is sustained over hydrothermal aging and sulfation as a result of highly dispersed and isolated active single Pt ions bonded at the Ti vacancy sites with 5 or 6 oxygen ions on titania nanowire surfaces.
CePt2Au3 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. Ce3+ is bonded in a 6-coordinate geometry to six equivalent Pt2- atoms. There are two shorter (3.15 Å) and four longer (3.24 Å) Ce–Pt bond lengths. Pt2- is bonded to three equivalent Ce3+, two equivalent Pt2-, and seven Au+0.33+ atoms to form a mixture of face, edge, and corner-sharing PtCe3Pt2Au7 cuboctahedra. There are one shorter (2.76 Å) and one longer (2.78 Å) Pt–Pt bond lengths. There are a spread of Pt–Au bond distances ranging from 2.73–3.22 Å. There are two inequivalent Au+0.33+ sites. In the first Au+0.33+ site, Au+0.33+ is bonded in a 6-coordinate geometry to six equivalent Pt2- atoms. In the second Au+0.33+ site, Au+0.33+ is bonded in a 6-coordinate geometry to four equivalent Pt2- and two equivalent Au+0.33+ atoms. There are one shorter (2.73 Å) and one longer (2.75 Å) Au–Au bond lengths.
Zr7Pt10 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are four inequivalent Zr+2.86+ sites. In the first Zr+2.86+ site, Zr+2.86+ is bonded in a 10-coordinate geometry to ten Pt2- atoms. There are a spread of Zr–Pt bond distances ranging from 2.88–2.98 Å. In the second Zr+2.86+ site, Zr+2.86+ is bonded in a body-centered cubic geometry to eight Pt2- atoms. There are four shorter (2.81 Å) and four longer (2.82 Å) Zr–Pt bond lengths. In the third Zr+2.86+ site, Zr+2.86+ is bonded in a distorted body-centered cubic geometry to eight Pt2- atoms. There are a spread of Zr–Pt bond distances ranging from 2.79–2.85 Å. In the fourth Zr+2.86+ site, Zr+2.86+ is bonded in a 7-coordinate geometry to seven Pt2- atoms. There are a spread of Zr–Pt bond distances ranging from 2.83–2.92 Å. There are three inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 6-coordinate geometry to six Zr+2.86+ atoms. In the second Pt2- site, Pt2- is bonded in a 1-coordinate geometry to five Zr+2.86+ atoms. In the third Pt2- site, Pt2- is bonded in a 6-coordinate geometry to six Zr+2.86+ atoms.
PtIn6Ge2O9 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pt2- is bonded to six equivalent In2+ atoms to form PtIn6 octahedra that share corners with six equivalent OIn6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Pt–In bond lengths are 2.67 Å. In2+ is bonded in a 6-coordinate geometry to one Pt2- and five O2- atoms. There are four shorter (2.35 Å) and one longer (2.45 Å) In–O bond lengths. Ge4+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Ge–O bond lengths are 1.78 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to six equivalent In2+ atoms to form OIn6 octahedra that share corners with six equivalent PtIn6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent In2+ and one Ge4+ atom.
Two-dimensional (2D)-structured photocatalysts with atomically thin layers not only have the potential to enhance hydrogen generation efficiency but also allow more direct investigations of the effects of surface terminations on photocatalytic activity. In this work, taking 2D Bi 2 WO 6 as a model, we found that the configuration of bilayer Bi 2 O 2 sandwiched by alternating WO 4 layers enabled the thermodynamic driving potential for photocatalytic hydrogen evolution. Without Pt deposition, the H 2 generation efficiency can reach to 56.9 μmol/g/h by 2D Bi 2 WO 6 as compared with no activity of Bi 2 WO 6 nanocrystals under simulated solar light. This configuration is easily functionalized by adsorption of Cl – /Br – to form Bi–Cl/Bi–Br bonds, which leads to the decrease of recombination in photogenerated charge carriers and narrower band gaps. This work highlights an effective way to design photocatalysts with efficient hydrogen evolution by tuning the surface terminations.
Tb3(PtIn3)4 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are three inequivalent Tb sites. In the first Tb site, Tb is bonded in a 3-coordinate geometry to six equivalent Pt and twelve In atoms. There are three shorter (3.19 Å) and three longer (3.56 Å) Tb–Pt bond lengths. There are a spread of Tb–In bond distances ranging from 3.40–3.61 Å. In the second Tb site, Tb is bonded in a 4-coordinate geometry to three Pt and ten In atoms. There are one shorter (3.01 Å) and two longer (3.05 Å) Tb–Pt bond lengths. There are a spread of Tb–In bond distances ranging from 3.26–3.37 Å. In the third Tb site, Tb is bonded in a 12-coordinate geometry to six equivalent Pt and twelve In atoms. All Tb–Pt bond lengths are 3.69 Å. There are six shorter (3.45 Å) and six longer (3.52 Å) Tb–In bond lengths. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 9-coordinate geometry to three Tb and six In atoms. There are a spread of Pt–In bond distances ranging from 2.75–2.79 Å. In the second Pt site, Pt is bonded in a 8-coordinate geometry to three Tb and six In atoms. There are a spread of Pt–In bond distances ranging from 2.73–2.82 Å. There are eight inequivalent In sites. In the first In site, In is bonded in a 2-coordinate geometry to three Tb and two equivalent Pt atoms. In the second In site, In is bonded in a distorted bent 150 degrees geometry to three Tb and two equivalent Pt atoms. In the third In site, In is bonded in a 3-coordinate geometry to three equivalent Tb, three equivalent Pt, and one In atom. The In–In bond length is 3.04 Å. In the fourth In site, In is bonded in a 3-coordinate geometry to three Tb and three Pt atoms. In the fifth In site, In is bonded in a 2-coordinate geometry to three Tb and two equivalent Pt atoms. In the sixth In site, In is bonded in a 4-coordinate geometry to three equivalent Tb and one In atom. In the seventh In site, In is bonded in a 2-coordinate geometry to two equivalent Tb, two equivalent Pt, and two equivalent In atoms. Both In–In bond lengths are 3.49 Å. In the eighth In site, In is bonded in a 6-coordinate geometry to six equivalent In atoms.
Engineering surface defects on metal oxide supports could help promote the dispersion of active sites and catalytic performance of supported catalysts. Herein, a strategy of ZrO 2 doping was proposed to create rich surface defects on CeO 2 (CZO) and, with these defects, to improve Pt dispersion and enhance its affinity as single sites to the CZO support (Pt/CZO). The strongly anchored Pt single sites on CZO support were initially not efficient for catalytic oxidation of CO/C 3 H 6 . However, after a simple activation by H 2 reduction, the catalytic oxidation performance over Pt/CZO catalyst was significantly boosted and better than Pt/CeO 2 . Pt/CZO catalyst also exhibited much higher thermal stability. The structural evolution of Pt active sites by H 2 treatment was systematically investigated on aged Pt/CZO and Pt/CeO 2 catalysts. With H 2 reduction, ionic Pt single sites were transformed into active Pt clusters. Much smaller Pt clusters were created on CZO (ca. 1.2 nm) than on CeO 2 (ca. 1.8 nm) due to stronger Pt-CeO 2 interaction on aged Pt/CZO. Consequently, more exposed active Pt sites were obtained on the smaller clusters surrounded by more oxygen defects and Ce 3+ species, which directly translated to the higher catalytic oxidation performance of activated Pt/CZO catalyst in vehicle emission control applications.
Herein, a device study using technology computer-aided design simulation to theoretically analyze the electrical performance of ultrawide-bandgap boron nitride (BN)-based vertical junction devices is performed, including h-BN Schottky diode, h-BN pn diode, and h-BN/AlN pn diode; this is also the first demonstration of the BN power devices in simulation. The material properties of BN are defined with recently reported data, and the physical mechanisms of the device performance are systematically investigated. Additionally, the h-BN junctions in this simulation shows excellent performance, especially for breakdown behaviors. Schottky diode shows a turn-on voltage of 0.6 V for Pt Schottky contact and breakdown voltages over 450 V for 5 μm, 6 × 10 15 cm –3 p-type-doped drift layer; The h-BN pn diode shows a turn-on voltage of 6 V and breakdown voltages over 3 kV with a critical electric field of 13.6 MV cm –1 for 2.5 μm, 2 × 10 16 cm –3 p-type-doped drift layer. The h-BN/AlN heterojunction pn diode shows a turn-on voltage of 5.8 V and breakdown voltage over 2 kV for 2.5 μm, 2 × 10 16 cm –3 n-type-doped AlN drift layer. Herein, an understanding of the device principles of vertical BN junctions is provided, which can serve as a reference for the future development of robust BN power electronics.
Bi2Pt crystallizes in the trigonal P31m space group. The structure is two-dimensional and consists of one Bi2Pt sheet oriented in the (0, 0, 1) direction. Pt2- is bonded in a 6-coordinate geometry to six Bi1+ atoms. There are a spread of Pt–Bi bond distances ranging from 2.77–2.87 Å. There are three inequivalent Bi1+ sites. In the first Bi1+ site, Bi1+ is bonded in a 3-coordinate geometry to three equivalent Pt2- atoms. In the second Bi1+ site, Bi1+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent Pt2- atoms. In the third Bi1+ site, Bi1+ is bonded in a distorted T-shaped geometry to three equivalent Pt2- atoms.