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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Zr(MnSn)6 by Materials Project

ZrMn6Sn6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Zr is bonded to eight Sn atoms to form distorted edge-sharing ZrSn8 hexagonal bipyramids. There are two shorter (2.94 Å) and six longer (3.12 Å) Zr–Sn bond lengths. Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.72–2.80 Å. There are three inequivalent Sn sites. In the first Sn site, Sn is bonded in a 12-coordinate geometry to three equivalent Zr and six equivalent Mn atoms. In the second Sn site, Sn is bonded in a 6-coordinate geometry to six equivalent Mn atoms. In the third Sn site, Sn is bonded in a 7-coordinate geometry to one Zr and six equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr(TlSe)4 by Materials Project

Zr(TlSe)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six Se2- atoms to form ZrSe6 octahedra that share corners with four TlSe5 square pyramids, edges with two ZrSe6 octahedra, and edges with six TlSe5 square pyramids. There are a spread of Zr–Se bond distances ranging from 2.68–2.82 Å. In the second Zr4+ site, Zr4+ is bonded to six Se2- atoms to form ZrSe6 octahedra that share corners with four TlSe5 square pyramids, edges with two ZrSe6 octahedra, and edges with six TlSe5 square pyramids. There are a spread of Zr–Se bond distances ranging from 2.68–2.83 Å. In the third Zr4+ site, Zr4+ is bonded to six Se2- atoms to form ZrSe6 octahedra that share corners with four TlSe5 square pyramids, edges with two equivalent ZrSe6 octahedra, and edges with six TlSe5 square pyramids. There are two shorter (2.73 Å) and four longer (2.76 Å) Zr–Se bond lengths. There are ten inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to five Se2- atoms to form distorted TlSe5 square pyramids that share corners with two equivalent ZrSe6 octahedra, corners with two equivalent TlSe5 square pyramids, edges with three ZrSe6 octahedra, and edges with three TlSe5 square pyramids. The corner-sharing octahedra tilt angles range from 14–18°. There are a spread of Tl–Se bond distances ranging from 3.03–3.46 Å. In the second Tl1+ site, Tl1+ is bonded to five Se2- atoms to form distorted TlSe5 square pyramids that share corners with two ZrSe6 octahedra, corners with two equivalent TlSe5 square pyramids, edges with three ZrSe6 octahedra, and edges with three TlSe5 square pyramids. The corner-sharing octahedra tilt angles range from 7–9°. There are a spread of Tl–Se bond distances ranging from 3.07–3.44 Å. In the third Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.01–3.33 Å. In the fourth Tl1+ site, Tl1+ is bonded to five Se2- atoms to form distorted TlSe5 square pyramids that share corners with two ZrSe6 octahedra, corners with two equivalent TlSe5 square pyramids, edges with three ZrSe6 octahedra, and edges with three TlSe5 square pyramids. The corner-sharing octahedra tilt angles range from 10–11°. There are a spread of Tl–Se bond distances ranging from 3.05–3.50 Å. In the fifth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.03–3.42 Å. In the sixth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.02–3.46 Å. In the seventh Tl1+ site, Tl1+ is bonded to five Se2- atoms to form distorted TlSe5 square pyramids that share corners with two ZrSe6 octahedra, corners with two equivalent TlSe5 square pyramids, edges with three ZrSe6 octahedra, and edges with three TlSe5 square pyramids. The corner-sharing octahedra tilt angles range from 10–14°. There are a spread of Tl–Se bond distances ranging from 3.03–3.43 Å. In the eighth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 2.99–3.35 Å. In the ninth Tl1+ site, Tl1+ is bonded in a rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.01–3.47 Å. In the tenth Tl1+ site, Tl1+ is bonded to five Se2- atoms to form distorted TlSe5 square pyramids that share corners with two ZrSe6 octahedra, edges with three ZrSe6 octahedra, and edges with four TlSe5 square pyramids. The corner-sharing octahedra tilt angles range from 15–19°. There are a spread of Tl–Se bond distances ranging from 3.04–3.46 Å. There are ten inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to one Zr4+ and five Tl1+ atoms to form a mixture of distorted edge and corner-sharing SeZrTl5 octahedra. The corner-sharing octahedra tilt angles range from 8–17°. In the second Se2- site, Se2- is bonded to two equivalent Zr4+ and four Tl1+ atoms to form a mixture of distorted edge and corner-sharing SeZr2Tl4 octahedra. The corner-sharing octahedra tilt angles range from 5–19°. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to two Zr4+ and four Tl1+ atoms. In the fourth Se2- site, Se2- is bonded to two Zr4+ and four Tl1+ atoms to form distorted SeZr2Tl4 octahedra that share corners with three SeZrTl5 octahedra and edges with six SeZr2Tl4 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. In the fifth Se2- site, Se2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the sixth Se2- site, Se2- is bonded to two Zr4+ and four Tl1+ atoms to form distorted SeZr2Tl4 octahedra that share corners with three SeZrTl5 octahedra and edges with eight SeZr2Tl4 octahedra. The corner-sharing octahedra tilt angles range from 8–17°. In the seventh Se2- site, Se2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the eighth Se2- site, Se2- is bonded to one Zr4+ and five Tl1+ atoms to form a mixture of distorted edge and corner-sharing SeZrTl5 octahedra. The corner-sharing octahedra tilt angles range from 8–16°. In the ninth Se2- site, Se2- is bonded to one Zr4+ and five Tl1+ atoms to form a mixture of distorted edge and corner-sharing SeZrTl5 octahedra. The corner-sharing octahedra tilt angles range from 0–19°. In the tenth Se2- site, Se2- is bonded to two Zr4+ and four Tl1+ atoms to form a mixture of distorted edge and corner-sharing SeZr2Tl4 octahedra. The corner-sharing octahedra tilt angles range from 5–14°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr(TlS)4 by Materials Project

Zr(TlS)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with three TlS5 square pyramids, edges with two ZrS6 octahedra, and edges with six TlS5 square pyramids. There are a spread of Zr–S bond distances ranging from 2.54–2.68 Å. In the second Zr4+ site, Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with four TlS5 square pyramids, edges with two ZrS6 octahedra, and edges with four TlS5 square pyramids. There are a spread of Zr–S bond distances ranging from 2.54–2.70 Å. In the third Zr4+ site, Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with two equivalent TlS5 square pyramids, edges with two equivalent ZrS6 octahedra, and edges with four TlS5 square pyramids. There are a spread of Zr–S bond distances ranging from 2.59–2.63 Å. There are ten inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two equivalent ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and an edgeedge with one TlS5 square pyramid. The corner-sharing octahedra tilt angles range from 15–18°. There are a spread of Tl–S bond distances ranging from 2.88–3.40 Å. In the second Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and edges with three TlS5 square pyramids. The corner-sharing octahedral tilt angles are 7°. There are a spread of Tl–S bond distances ranging from 2.94–3.43 Å. In the third Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.88–3.24 Å. In the fourth Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and edges with two TlS5 square pyramids. The corner-sharing octahedra tilt angles range from 9–10°. There are a spread of Tl–S bond distances ranging from 2.92–3.48 Å. In the fifth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.92–3.42 Å. In the sixth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.90–3.46 Å. In the seventh Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and edges with three TlS5 square pyramids. The corner-sharing octahedra tilt angles range from 11–15°. There are a spread of Tl–S bond distances ranging from 2.89–3.37 Å. In the eighth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.88–3.26 Å. In the ninth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.89–3.43 Å. In the tenth Tl1+ site, Tl1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Tl–S bond distances ranging from 2.91–3.41 Å. There are ten inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the second S2- site, S2- is bonded to two equivalent Zr4+ and four Tl1+ atoms to form distorted SZr2Tl4 octahedra that share a cornercorner with one SZrTl5 octahedra and edges with two SZr2Tl4 octahedra. The corner-sharing octahedral tilt angles are 19°. In the third S2- site, S2- is bonded in a 6-coordinate geometry to two Zr4+ and four Tl1+ atoms. In the fourth S2- site, S2- is bonded to two Zr4+ and four Tl1+ atoms to form distorted SZr2Tl4 octahedra that share a cornercorner with one SZr2Tl4 octahedra and edges with three SZrTl5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the sixth S2- site, S2- is bonded in a 6-coordinate geometry to two Zr4+ and four Tl1+ atoms. In the seventh S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the eighth S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the ninth S2- site, S2- is bonded to one Zr4+ and five Tl1+ atoms to form a mixture of distorted corner and edge-sharing SZrTl5 octahedra. The corner-sharing octahedra tilt angles range from 0–19°. In the tenth S2- site, S2- is bonded in a 6-coordinate geometry to two Zr4+ and four Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr(Zn10Cu)2 by Materials Project

ZrCu2Zn20 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Zr is bonded in a 4-coordinate geometry to sixteen Zn atoms. There are twelve shorter (3.03 Å) and four longer (3.04 Å) Zr–Zn bond lengths. Cu is bonded to twelve Zn atoms to form CuZn12 cuboctahedra that share corners with six equivalent CuZn12 cuboctahedra, edges with eighteen equivalent ZnZrZn10Cu cuboctahedra, and faces with six equivalent ZnZrZn10Cu cuboctahedra. There are six shorter (2.49 Å) and six longer (2.79 Å) Cu–Zn bond lengths. There are three inequivalent Zn sites. In the first Zn site, Zn is bonded in a 2-coordinate geometry to two equivalent Cu and six equivalent Zn atoms. There are two shorter (2.64 Å) and four longer (2.79 Å) Zn–Zn bond lengths. In the second Zn site, Zn is bonded to one Zr, one Cu, and ten Zn atoms to form ZnZrZn10Cu cuboctahedra that share corners with fifteen equivalent ZnZrZn10Cu cuboctahedra, edges with two equivalent ZnZrZn10Cu cuboctahedra, edges with three equivalent CuZn12 cuboctahedra, a faceface with one CuZn12 cuboctahedra, and faces with fifteen equivalent ZnZrZn10Cu cuboctahedra. There are a spread of Zn–Zn bond distances ranging from 2.55–2.96 Å. In the third Zn site, Zn is bonded in a 2-coordinate geometry to two equivalent Zr and twelve equivalent Zn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr(Fe2P)2 by Materials Project

Zr(Fe2P)2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Zr is bonded to six equivalent P atoms to form a mixture of distorted edge and corner-sharing ZrP6 octahedra. The corner-sharing octahedral tilt angles are 41°. There are two shorter (2.76 Å) and four longer (2.79 Å) Zr–P bond lengths. Fe is bonded in a 3-coordinate geometry to three equivalent P atoms. There are one shorter (2.26 Å) and two longer (2.30 Å) Fe–P bond lengths. P is bonded in a 9-coordinate geometry to three equivalent Zr and six equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Neural network potential for Zr–Rh system by machine learning

Zr–Rh metallic glass has enabled its many applications in vehicle parts, sports equipment and so on due to its outstanding performance in mechanical property, but the knowledge of the microstructure determining the superb mechanical property remains yet insufficient. Here, we develop a deep neural network potential of Zr–Rh system by using machine learning, which breaks the dilemma between the accuracy and efficiency in molecular dynamics simulations, and greatly improves the simulation scale in both space and time. Here, the results show that the structural features obtained from the neural network method are in good agreement with the cases in ab initio molecular dynamics simulations. Furthermore, we build a large model of 5400 atoms to explore the influences of simulated size and cooling rate on the melt-quenching process of Zr 77 Rh 23 . Our study lays a foundation for exploring the complex structures in amorphous Zr 77 Rh 23 , which is of great significance for the design and practical application.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Radionuclide incorporation in negative thermal expansion α-Zr(WO 4 ) 2 : A density functional theory study

The incorporation of uranium, plutonium and technetium in the negative thermal expansion (NTE) α-Zr (WO 4 ) 2 has been investigated within the framework of density functional theory (DFT). It is found that the vacancy formation energies of the charged vacancies are overall larger than that of its counterpart neutral Frenkel defects and Schottky defects. DFT calculations suggest that U and Pu substitutions for the Zr site are preferred in α-Zr (WO 4 ) 2 . In case of Tc substitution, both Tc(IV) for the Zr site and Tc(VII) for the W site are considered under oxygen-poor and oxygen-rich conditions, while Tc(VII) substitution can be improved significantly by including Y 2 O 3 (charge compensation).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Mechanical, corrosion, and wear properties of biomedical Ti–Zr–Nb–Ta–Mo high entropy alloys

The microstructures, mechanical, corrosion, and wear behaviors of the Ti x ZrNbTaMo (x = 0.5, 1, 1.5, and 2, molar ratio) high entropy alloys (HEAs) were studied in this work. It was found that the Ti–Zr–Nb–Ta–Mo HEAs showed a dendrite structure with two body-centered-cubic (BCC) solid solution phases. The Ti 0.5 ZrNbTaMo HEA exhibited a high hardness of about 500 HV, high compressive strength approaching 2,600 MPa, and large plastic strain of over 30%. Furthermore, the highly-protective oxide films formed on the surface of Ti–Zr–Nb–Ta–Mo HEAs in the phosphate buffer saline (PBS) solution, which resulted in the high corrosion resistance of the HEAs. The Ti–Zr–Nb–Ta–Mo HEAs exhibited the greater dry- and wet-wear resistance than that of the traditional biomedical Ti6Al4V alloy. The results also indicated that with the decrease in the Ti content, the wear resistance of the Ti–Zr–Nb–Ta–Mo HEAs in the PBS solution improved. Finally, the Ti 0.5 ZrNbTaMo alloy presented the highest corrosive wear resistance among the four HEAs owing to its combination of good mechanical properties and high chemical stability.

36 MATERIALS SCIENCE↗
DOE OSTI2020

The strong influence of Ti, Zr, Hf solutes and their oxidation on microstructure and performance of Nb 3 Sn superconductors

The strong influence of Ti, Zr, Hf solutes and their oxidation on microstructure and performance of Nb 3 Sn superconductors Over the last few years a new type of Nb 3 Sn superconducting composite based on the internal oxidation approach has emerged and has demonstrated performance significantly superior to conventional Nb 3 Sn. It requires a supply of O and the use of a Nb alloy – Nb-X, where X is a solute element that can be selectively oxidized to form oxide particles within the Nb 3 Sn. Such oxide particles not only refine Nb 3 Sn grain size, but also have the proper size to act as artificial pinning centers (APC) directly restraining fluxon motion, and thus dramatically improve superconducting properties. In this article we show that the size and volume fraction of the oxide particles determine both the levels of grain refinement and the shift in the peak field of the flux pinning force (F p -B) curve. Additionally, we explore the factors influencing these microstructure and properties, which we find include: selection of the solute element X, solute content, O content, and heat treatment. For the selection of X, we searched the periodic table for all promising candidates but focused down on the group-IVB elements (Ti, Zr, Hf) here as the drawability of Nb 3 Sn wires made from Nb-Ti, Nb-Zr, and Nb-Hf alloys has been demonstrated in the past few decades. We found that while internally oxidizing Nb-1.5at.%Ti led to negligible grain refinement and F p -B peak shift, Nb-Zr alloys led to much more dramatic results, and internally oxidizing Nb-Hf alloys led to the strongest grain refinement and F p -B peak shift. For Hf alloying in particular, we compared our internal oxidation method with another method for grain refinement, which uses Hf alloying itself without oxidation, and found that internal oxidation led to much stronger grain refinement and F p -B peak shift. We also found that higher solute content and lower reaction temperature led to stronger grain refinement and F p -B peak shift. We conclude with a discussion of the possible mechanisms for the influence of these factors.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Effect of alloying with Sc, Nb and Zr on reduction-diffusion synthesis of magnetically hard Sm(Fe,Co,Ti) 12 -based monocrystalline powders

Powders of Sm(Fe,Co) 11.2 Ti 0.8 alloys modified with Sc, Nb and Zr, as well as with additional Ti were prepared by reducing mechanically activated raw oxides with Ca metal in the furnace preheated to 990–1250 °C. Expansion of the crystal lattice upon introduction of Nb or additional Ti implies that atoms of these elements replace the smaller Fe atoms in the tetragonal ThMn 12 -type structure. On the other hand, contraction of the lattice upon introduction of Sc or Zr was smaller than what was expected for replacement of the Sm atoms, which suggests that the Sc and Zr atoms replace both the Sm and Fe atoms. Washing away the reduction byproducts expands the crystal lattice of the 1:12 particles and increases their coercivity. The lattice expansion associated with the washing is believed to be caused by interstitial H atoms; more research, however, is needed to establish the mechanism(s) of the washing effect on the coercivity. The earlier reported development of a high coercivity in zirconium-modified monocrystalline particles achieved by increasing the reduction annealing temperature to ≈1200 °C was similarly characteristic of the particles modified with Sc (the coercivity reaches 11.5 kOe) and Nb (8.1 kOe), but not for the particles prepared with additional Ti where the maximum coercivity of 8.3 kOe develops for a lower annealing temperature. Furthermore, it is concluded that Sc, Nb and Zr modify the high-temperature phase equilibria of the Sm(Fe,Co) 11.2 Ti 0.8 alloys allowing for an effective high-temperature processing, whereas the alloy coercivity increases with the synthesis temperature through a different, still unknown mechanism which may involve suppression of the defects specific to the 1:12 crystals.

36 MATERIALS SCIENCE↗
DOE OSTI2020

The effect of Zr on precipitation in oxide dispersion strengthened FeCrAl alloys

Oxide dispersion strengthened (ODS) FeCrAl alloys are promising candidate materials for advanced nuclear reactor applications requiring high-temperature strength, corrosion resistance, and irradiation tolerance. As these alloys have increased in compositional complexity through attempts to use highly reactive elements such as Zr to refine particle sizes and optimize nanoprecipitate dispersion characteristics, much debate has ensued as to the effects of these alloying element additions on alloy properties. In an attempt to reconcile differences in nanoprecipitate distributions reported in the literature over the past decade, a detailed investigation of a recently developed ODS FeCrAl alloy with nominal composition Fe–10Cr-6.1Al-0.3Zr+0.3Y 2 O 3 is presented here using a combination of atom probe tomography (APT), scanning/transmission electron microscopy (S/TEM), and computational thermodynamics modeling. It is illustrated that based on the amount of Zr available in the lattice, Zr competes with Al and Cr to form carbides and nitrides as opposed to oxygen-rich precipitates. This alloy system has a high number density (>10 23 m -3 ) of ~2–4 nm diameter (Y,Al,O)-rich nanoprecipitates, but it is shown that due to the compositional spread and unknown partitioning of Al between the matrix and precipitates, significant challenges still exist for quantifying the exact compositions of these precipitates using APT. However, the noted compositional spread is supported by identified complex oxides yttrium aluminum monoclinic (YAM) and yttrium aluminum garnet (YAG) using S/TEM. As a result of these findings, researchers developing ODS FeCrAl with reactive element additions must pay careful attention to C and N impurities when optimizing reactive element additions.

electron microscopy↗
DOE OSTI2025

Zr 3 Mn 3 Sn 4 Ga: A new hetero-kagome bilayer antiferromagnet

Here, we report the magnetic and electrical transport properties of single-crystalline Zr 3 Mn 3 Sn 4 Ga, featuring two distinct kagome lattices: a non-magnetic breathing Zr 3 Sn 4 lattice and a magnetic intact Mn 3 Ga lattice. The material undergoes an antiferromagnetic phase transition at T N = 87 K, with neutron diffraction confirming commensurate ordering characterized by k = (1/3,1/3,0). Transport measurements show metallic behavior, a resistivity anomaly near T N , and 12% magnetoresistance at 2 K under 9 T. Deviations from the conventional second-order power law, along with negative magnetoresistance and nonlinear Hall slope variations near T N , suggest strong magneto-electronic coupling. Resonant photoemission spectroscopy identifies Zr 4d and Mn 3d orbitals as dominant contributors to the valence band, linking the material’s unique electronic properties to its kagome layers. Zr 3 Mn 3 Sn 4 Ga offers a valuable platform to study interactions between magnetism and topological electronic bands in hetero-kagome systems using the co- existence of magnetic and non-magnetic kagome layers and its tunable electronic structure.

Crystal structure↗
DOE OSTI2025

Node-Solution Microenvironment Governs the Selectivity of Thioanisole Oxidation within Catalytic Zr-Based Metal–Organic Framework

Lewis acidic metal oxides, including zirconia (ZrO 2 ), are catalytically active toward oxidative reactions in the presence of sacrificial oxidants like t-butyl hydroperoxide (TBHP). The structural ambiguity and heterogeneity of the ZrO 2 surface impose challenges to chemists in understanding the reaction mechanism down to atomic-level precision. The inorganic, Zr-oxo nodes of many crystalline metal–organic frameworks (MOFs) structurally mimic ZrO 2 . Herein, we report three novel findings: (A) Zr-based MOF, Zr-MOF-808 is catalytically competent in activating TBHP to induce oxygen atom transfer (OAT) reactions to a model substrate, thioanisole, at room temperature, (B) its reaction mechanism can be derived with greater structural precision owing to the crystallinity of the MOF, and (C) the node-binding agent and other reaction conditions significantly impact the selectivity between the singly oxidized methyl phenyl sulfoxide vs the doubly oxidized sulfone. These findings suggest that both the activity and selectivity of OAT reactions within Zr-MOF-808 are governed by the chemistry occurring at the interface of the node and the surrounding reaction medium. Implications of these findings in OAT reactions and other MOF/metal oxide-catalyzed relevant catalysis are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Lead-free Zr-doped ceria ceramics with low permittivity displaying giant electrostriction

Electrostrictors, materials developing mechanical strain proportional to the square of the applied electric field, present many advantages for mechanical actuation as they convert electrical energy into mechanical, but not vice versa. Both high relative permittivity and reliance on Pb as the key component in commercial electrostrictors pose serious practical and health problems. Here we describe a low relative permittivity (<250) ceramic, Zr x Ce 1-x O 2 (x < 0.2), that displays electromechanical properties rivaling those of the best performing electrostrictors: longitudinal electrostriction strain coefficient ~10 -16 m 2 /V 2 ; relaxation frequency ≈ a few kHz; and strain ≥0.02%. Combining X-ray absorption spectroscopy, atomic-level modeling and electromechanical measurements, here we show that electrostriction in Zr x Ce 1-x O 2 is enabled by elastic dipoles produced by anharmonic motion of the smaller isovalent dopant (Zr). Unlike the elastic dipoles in aliovalent doped ceria, which are present even in the absence of an applied elastic or electric field, the elastic dipoles in Zr x Ce 1-x O 2 are formed only under applied anisotropic field. The local descriptors of electrostrictive strain, namely, the cation size mismatch and dynamic anharmonicity, are sufficiently versatile to guide future searches in other polycrystalline solids.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Single-atom Zr promoter boosts oxygen activation on ceria-supported Pt catalysts

Activation of surface lattice oxygen and chemisorbed oxygen on catalyst surfaces constitutes a pivotal step in heterogeneous oxidative catalysis. Herein, we report a strategy for enhancing oxygen activation by rational design of catalysts with single-atom promoters. Single-site Zr species in CeO 2 (Zr 1 -CeO 2 ) are synthesized using the atom-trapping method. The Zr 1 -CeO 2 -supported Pt catalyst exhibits enhanced catalytic performance over the CeO 2 -supported Pt catalyst in the oxidation of CO, C 3 H 8 , and C 3 H 6 , achieving significantly lower T 50 values (temperature required to reach 50% conversion). This enhanced catalytic activity is attributed to the formation of an asymmetric Zr 1 -O-Pt 1 structure, which favors the activation of the adjacent surface lattice oxygen and chemisorbed molecular oxygen. This work exemplifies that incorporating single-site atoms into oxide support facilitates oxygen activation, providing new insights into the role of atomically dispersed promoters in heterogeneous catalysis.

Science & Technology - Other Topics↗
DOE OSTI2020

X-ray and neutron scattering measurements of ordering in a Cu 46 Zr 54 liquid

The structural evolution of the equilibrium and supercooled Cu 46 Zr 54 liquids was investigated with a combination of elastic neutron scattering (with isotopic substitution) and synchrotron x-ray scattering studies. The partial pair correlation functions were determined over a wide temperature range (~270 °C). These show that the Cu–Cu and Zr–Zr ordering increases as the temperature decreases, while the Cu–Zr ordering decreases. We note this surprising result is in contradiction with the results from molecular dynamics studies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Ferro-ionic states and domains morphology in Hf x Zr 1–x O 2 nanoparticles

Unique polar properties of nanoscale hafnia-zirconia oxides (Hf x Zr 1–x O 2 ) are of great interest for condensed matter physics, nanophysics, and advanced applications. These properties are connected (at least partially) to the ionic–electronic and electrochemical phenomena at the surface, interfaces, and/or internal grain boundaries. Here, we calculated the phase diagrams, dielectric permittivity, spontaneous polar, and antipolar ordering, as well as the domain structure morphology in Hf x Zr 1–x O 2 nanoparticles covered by ionic–electronic charge originating from surface electrochemical adsorption. We revealed that the ferro-ionic coupling supports the polar long-range order in nanoscale Hf x Zr 1–x O 2 , induces, and/or enlarges the stability region of the labyrinthine domains toward smaller sizes and smaller environmental dielectric constant at low concentrations of the surface ions. The ferro-ionic coupling causes the transition to the single-domain ferro-ionic state at high concentrations of the surface ions. We predict that the labyrinthine domain states, being multiple-degenerated, may significantly affect the emergence of the negative differential capacitance state in the nanograined/nanocrystalline Hf x Zr 1–x O 2 films.

36 MATERIALS SCIENCE↗
DOE OSTI2021

High pressure stability of β-Zr: no evidence for isostructural phase transitions

Isostructural transitions have been reported to occur in several pure elements; however, most of these have been disproven. Zr is one of those elements which remains controversial with two reports of an isostructural bcc-to-bcc transition at ~56–60 GPa at an ambient temperature and a more recent report proposing a second bcc-to-bcc transition at 110 GPa. Here, we report a detailed experimental and theoretical study of zirconium in the pressure region of the proposed isostructural transition(s). We conducted three room temperature static compression experiments using Ne as a pressure transmitting medium up to 80 GPa. We see no evidence for an isostructural transition finding a smooth compression curve for β-Zr. We determined the theoretical volume, elastic parameters, and Poisson’s ratio for β-Zr up to 717 GPa and no obvious anomalies are identified. Furthermore, our new results join the growing body of evidence that does not find evidence of isostructural transitions in β-Zr.

36 MATERIALS SCIENCE↗