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

Materials Data on Sr(CoGe)2 by Materials Project

Sr(CoGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Co and eight equivalent Ge atoms. All Sr–Co bond lengths are 3.41 Å. All Sr–Ge bond lengths are 3.25 Å. Co is bonded to four equivalent Sr and four equivalent Ge atoms to form a mixture of distorted edge, corner, and face-sharing CoSr4Ge4 tetrahedra. All Co–Ge bond lengths are 2.35 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Sr and four equivalent Co atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(ZnGe)2 by Materials Project

Sr(ZnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Zn and eight equivalent Ge atoms. All Sr–Zn bond lengths are 3.46 Å. All Sr–Ge bond lengths are 3.40 Å. Zn is bonded to four equivalent Sr and four equivalent Ge atoms to form a mixture of distorted face, edge, and corner-sharing ZnSr4Ge4 tetrahedra. All Zn–Ge bond lengths are 2.62 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Sr, four equivalent Zn, and one Ge atom. The Ge–Ge bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(AgSn)2 by Materials Project

Sr(AgSn)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Ag and eight equivalent Sn atoms. All Sr–Ag bond lengths are 3.77 Å. All Sr–Sn bond lengths are 3.66 Å. Ag is bonded in a 12-coordinate geometry to four equivalent Sr and four equivalent Sn atoms. All Ag–Sn bond lengths are 2.81 Å. Sn is bonded in a 9-coordinate geometry to four equivalent Sr, four equivalent Ag, and one Sn atom. The Sn–Sn bond length is 2.85 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(AgGe)2 by Materials Project

Sr(AgGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Ag and eight equivalent Ge atoms. All Sr–Ag bond lengths are 3.54 Å. All Sr–Ge bond lengths are 3.42 Å. Ag is bonded in a 12-coordinate geometry to four equivalent Sr and four equivalent Ge atoms. All Ag–Ge bond lengths are 2.70 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Sr, four equivalent Ag, and one Ge atom. The Ge–Ge bond length is 2.49 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(CdGe)2 by Materials Project

Sr(CdGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Cd and eight equivalent Ge atoms. All Sr–Cd bond lengths are 3.74 Å. All Sr–Ge bond lengths are 3.48 Å. Cd is bonded to four equivalent Sr and four equivalent Ge atoms to form a mixture of distorted corner, edge, and face-sharing CdSr4Ge4 tetrahedra. All Cd–Ge bond lengths are 2.84 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Sr, four equivalent Cd, and one Ge atom. The Ge–Ge bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(InCu)2 by Materials Project

Sr(CuIn)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Cu and eight equivalent In atoms. All Sr–Cu bond lengths are 3.37 Å. All Sr–In bond lengths are 3.64 Å. Cu is bonded in a 9-coordinate geometry to four equivalent Sr, one Cu, and four equivalent In atoms. The Cu–Cu bond length is 2.50 Å. All Cu–In bond lengths are 2.75 Å. In is bonded to four equivalent Sr and four equivalent Cu atoms to form a mixture of distorted edge, face, and corner-sharing InSr4Cu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(GaRh)2 by Materials Project

Sr(RhGa)2 is alpha Pu-derived structured and crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. Sr is bonded in a 6-coordinate geometry to eight equivalent Rh and ten equivalent Ga atoms. There are four shorter (3.31 Å) and four longer (3.53 Å) Sr–Rh bond lengths. There are a spread of Sr–Ga bond distances ranging from 3.38–3.77 Å. Rh is bonded in a 4-coordinate geometry to four equivalent Sr and four equivalent Ga atoms. There are two shorter (2.44 Å) and two longer (2.49 Å) Rh–Ga bond lengths. Ga is bonded in a 4-coordinate geometry to five equivalent Sr and four equivalent Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(AlGa)2 by Materials Project

Sr(GaAl)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Ga and eight equivalent Al atoms. All Sr–Ga bond lengths are 3.38 Å. All Sr–Al bond lengths are 3.54 Å. Ga is bonded in a 9-coordinate geometry to four equivalent Sr, one Ga, and four equivalent Al atoms. The Ga–Ga bond length is 2.59 Å. All Ga–Al bond lengths are 2.66 Å. Al is bonded to four equivalent Sr and four equivalent Ga atoms to form a mixture of distorted edge, face, and corner-sharing AlSr4Ga4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(Mg4Al3)4 by Materials Project

Sr(Mg4Al3)4 crystallizes in the cubic I-43m space group. The structure is three-dimensional. Sr is bonded in a 12-coordinate geometry to four equivalent Mg and twelve equivalent Al atoms. All Sr–Mg bond lengths are 3.33 Å. All Sr–Al bond lengths are 3.28 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 10-coordinate geometry to one Sr, three equivalent Mg, and six equivalent Al atoms. All Mg–Mg bond lengths are 3.04 Å. All Mg–Al bond lengths are 3.22 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five equivalent Al atoms. There are two shorter (3.12 Å) and four longer (3.19 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 2.86–3.18 Å. Al is bonded in a 11-coordinate geometry to one Sr, seven Mg, and three equivalent Al atoms. There are one shorter (2.74 Å) and two longer (2.84 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(ClO)2 by Materials Project

Sr(OCl)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to two equivalent O and six equivalent Cl atoms. Both Sr–O bond lengths are 3.08 Å. There are a spread of Sr–Cl bond distances ranging from 2.95–3.07 Å. O is bonded in a water-like geometry to one Sr and one O atom. The O–O bond length is 1.24 Å. Cl is bonded in a distorted trigonal non-coplanar geometry to three equivalent Sr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr by Materials Project

Sr crystallizes in the hexagonal P6/mmm space group. The structure is one-dimensional and consists of one Sr ribbon oriented in the (0, 0, 1) direction. Sr is bonded in a linear geometry to two equivalent Sr atoms. Both Sr–Sr bond lengths are 4.60 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Pressure‐Dependent “Insulator–Metal–Insulator” Behavior in Sr‐Doped La 3 Ni 2 O 7

Abstract Recently, superconductivity at high temperatures is observed in bulk La 3 Ni 2 O 7−δ under high pressure. However, the attainment of high‐purity La 3 Ni 2 O 7−δ single crystals remains a formidable challenge. Here, the crystal structure and physical properties of single crystals of Sr‐doped La 3 Ni 2 O 7 synthesized at high pressure (20 GPa) and high temperature (1400 °C) are reported. Through single crystal X‐ray diffraction, it is shown that high‐pressure‐synthesized paramagnetic Sr‐doped La 3 Ni 2 O 7 crystallizes in an orthorhombic structure with Ni─O─Ni bond angles of 173.4(2)° out‐of‐plane and 175.0(2)°and 176.7(2)°in plane. The substitution of Sr alters in band filling and the ratio of Ni 2+ /Ni 3+ in Sr‐doped La 3 Ni 2 O 7 , aligning them with those of “La 3 Ni 2 O 7.05” , thereby leading to significant modifications in properties under high pressure relative to the unsubstituted parent phase. At ambient pressure, Sr‐doped La 3 Ni 2 O 7 exhibits insulating properties, and the conductivity increases as pressure goes up to 10 GPa. However, upon further increasing pressure beyond 10.7 GPa, Sr‐doped La 3 Ni 2 O 7 transits back from a metal‐like behavior to an insulator. The insulator–metal–insulator trend under high pressure dramatically differs from the behavior of the parent compound La 3 Ni 2 O 7−δ , despite their similar behavior in the low‐pressure regime. These experimental results underscore the considerable challenge in achieving superconductivity in nickelates.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Tracking natural CO 2 migration through a sandstone aquifer using Sr, U and C isotopes: Chimayó, New Mexico, USA

The geochemical and isotopic characteristics of groundwaters in Chimayó, New Mexico, reflect processes that affect water quality in the Tesuque Aquifer, which overlies a leaking natural CO 2 source in a structurally complex region. In this study, select isotopes (δ 13 C, 87 Sr/ 86 Sr, 234 U/ 238 U) are applied to groundwaters to better understand CO 2 transport mechanisms and related water-rock interactions that impact Chimayó groundwater. Carbon stable isotope ratios of dissolved inorganic carbon (DIC; δ 13 CDIC = -15.10‰ to 4.50‰) identify a distinct source of upward-migrating CO 2 that interacts with the groundwater. Additionally, groundwater 87 Sr/ 86 Sr compositions (0.7098 to 0.7154) reflect intrusion of varying amounts of saline water associated with the high CO 2 source, while 234 U/ 238 U ratios corroborate presence of deep groundwater and suggest impacts from distinctive natural uranium sources are affecting groundwater. Previous work proposed two CO 2 transport mechanisms at the site: (1) dissolved in deep brine that underlies the aquifer and (2) in the gas phase; this study uses isotope mixing models to identify wells that are affected by these CO 2 transport mechanisms and demonstrates that both transport mechanisms are associated with impaired groundwaters. Overall, this study demonstrates that applying multiple isotope systems (δ 13 CDIC, 87 Sr/ 86 Sr, 234 U/ 238 U) is a dynamic tool for identifying and measuring the impact of CO 2 leakage from a sequestration site.

58 GEOSCIENCES↗
DOE OSTI2023

Tuning the Radius Ratio to Enhance Thermoelectric Properties in the Zintl Compounds AM 2 Sb 2 (A = Ba, Sr; M = Zn, Cd)

Five novel Zintl phase solid solutions in the Ba 1–x Sr x Zn 2–y Cd y Sb 2 (0 ≤ x ≤ 0.13(1); 0 ≤ y ≤ 0.32(2)) system were successfully synthesized by the molten Pb metal-flux method, and the powder X-ray diffraction and single-crystal X-ray diffraction analyses proved that all five title compounds adopted the BaCu 2 S 2 -type phase having the orthorhombic Pnma space group (Z = 4, Pearson code oP20) with five crystallographically independent atomic sites. The previously studied BaCu 2 S 2 -type antimonides demonstrated a limited tolerance for doping in contrast to the CaAl 2 Si 2 -type antimonides. To understand the relatively narrower phase width and limited dopability of the title BaCu 2 S 2 -type phase than the CaAl 2 Si 2 -type phase in the overall Ba 1–x Sr x Zn 2–y Cd y Sb 2 system, the radius ratio of cations and anionic elements r + /r – for two structure types were thoroughly investigated. For the first time, the r + /r – ratio was identified as a critical factor for the phase selectivity: (1) r + /r – > 1 favored the BaCu 2 S 2 -type phase, and (2) r + /r – < 1 favored the CaAl 2 Si 2 -type phase. Further, we also revealed the structural transformation mechanism from the more widely observed CaAl 2 Si 2 -type phase to the title BaCu 2 S 2 -type phase as the relatively larger cationic elements were introduced to the system. A series of DFT calculations using the three hypothetical models indicated that a resonance peak near EF in the density of states curves was descended from the relatively flat band structure at several special symmetry points rationalizing the enhanced Seebeck coefficients of Ba 0.94(1) Sr 0.06 Zn 1.86(3) Cd 0.14 Sb 2 and Ba 0.96(1) Sr 0.04 Zn 1.68(2) Cd 0.32 Sb 2 . Electron localization function analysis rationalized the correlation between the polarity change of anionic Zn/Cd–Sb bonds and the charge carrier mobility on the anionic frameworks. Temperature-dependent thermoelectric properties were studied for the four title compounds, and the results proved that the Sr and Cd doping in the title Ba 1–x Sr x Zn 2–y Cd y Sb 2 system successfully enhanced the ZT values through the increased Seebeck coefficients and the reduced total thermal conductivities.

36 MATERIALS SCIENCE↗
DOE OSTI2022

2D Homologous Series SrFM n BiS n +2 (M = Pb, Ag 0.5 Bi 0.5 ; n = 0, 1) and Commensurately Modulated Sr 2 F 2 Bi 2/3 S 2

In this work, we report three new mixed-anion two-dimensional (2D) compounds: SrFPbBiS 3 , SrFAg 0.5 Bi 1.5 S 3 , and Sr 2 F 2 Bi 2/3 S 2 . Their structures as well as the parent compound SrFBiS 2 were refined using single-crystal X-ray diffraction data, with the sequence of SrFBiS 2 , SrFPbBiS 3 , and SrFAg 0.5 Bi 1.5 S 3 defining the new homologous series SrFM n BiS n+2 (M = Pb, Ag 0.5 Bi 0.5 ; n= 0, 1). Sr 2 F 2 Bi 2/3 S 2 has a different structure, which is modulated with a q vector of 1/3b* and was refined in superspace group X2/m(0 β 0)00 as well as in the 1x3x1 superstructure with space group C2/m (with similar results). Sr 2 F 2 Bi 2/3 S 2 features hexagonal layers of alternating [Sr 2 F 2 ] 2+ and [Bi 2/3 S 2 ] 2- , and the modulated structure arises from the unique ordering pattern of Sr 2+ cations. SrFPbBiS 3 , SrFAg 0.5 Bi 1.5 S 3 , and Sr 2 F 2 Bi 2/3 S 2 are semiconductors with band gaps of 1.31, 1.21, and 1.85 eV, respectively. The latter compound exhibits room temperature red photoluminescence at ~ 700 nm.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Unveiling Swift Heavy Ion Track Morphology in Sr-Based High-Entropy Perovskites

The incorporation of multiple cations on a single lattice site in the high-entropy oxides is considered the key driving factor for modifying the known atomic-level response to energetic ion irradiation due to the presence of structural disorder; however, these effects are not well-understood yet. In this work, we present atomic-level insight into irradiation-induced nanoscale phase transformations in a perovskite-structured high-entropy oxide, Sr(Zr 0.2 Sn 0.2 Ti 0.2 Hf 0.2 Nb 0.2 )O 3 (Sr(HE)O 3 ), subjected to 774 MeV swift Xe heavy ions, where damage is dominated by inelastic ion−lattice interactions. While these ions generally are known to create nanoscale disordered channels, “ion tracks”, along the penetration direction in the material, this study shows the formation of discontinuous and partially recrystallized ion tracks in Sr(HE)O 3 . Compared to SrTiO 3 irradiated under identical energy loss conditions, the ion tracks in Sr(HE)O 3 exhibit significantly reduced diameters and a markedly different interfacial structure. Notably, the crystalline−amorphous interface in Sr(HE)O 3 shows minimal lattice distortion, confined to approximately 2−3 monolayers, in contrast to the extended disordered shell commonly observed in SrTiO 3 . Using in situ atomic-resolution electron microscopy, we further demonstrate that the amorphous/disordered regions within Sr(HE)O 3 ion tracks remain highly stable under electron irradiation, whereas tracks in SrTiO 3 readily recrystallize. This enhanced stability is attributed to the dominance of structural and chemical complexity arising from multiple B-site cations, which suppress defect migration and templated recrystallization driven by electronic excitations and local heating. Overall, this study highlights how high-entropy oxide chemistry fundamentally reshapes irradiation damage evolution, offering insights into defect formation and phase stability under extreme conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Ba 1−x Sr x FeO 3−δ as an improved oxygen storage material for chemical looping air separation: a computational and experimental study

Chemical looping air separation (CLAS) is a promising technology to generate oxygen-rich gas streams to enable efficient carbon dioxide capture during fossil fuel combustion or gasification. CLAS relies on the capture and release of oxygen from the atmosphere using the redox properties of an oxygen-selective solid oxide carrier. This study investigates the redox characteristics of Ba 1−x Sr x FeO 3−δ (0.0 ≤ x ≤ 0.417, 0.0 ≤ δ ≤ 0.5) using a combination of density functional theory (DFT) calculations and experimental verification using X-ray diffraction, thermogravimetric analysis, and oxygen-temperature-programmed desorption. The DFT computed energies of the Ba 1−x Sr x FeO 3−δ perovskites reveal a composition-dependent transition from hexagonal to cubic phases as the Sr-concentration or oxygen vacancy concentration increases. Oxygen vacancy formation energies of the cubic perovskites are found to be lower than those of their hexagonal counterparts. A low oxygen diffusion barrier of ∼1 eV combined with the thermodynamic preference of Ba 1−x Sr x FeO 3−δ compositions that form in a cubic phase suggests them as promising candidates for oxygen storage applications. The experimental results corroborate this finding by identifying Ba 0.75 Sr 0.25 FeO 3−δ in the cubic phase as an optimal composition offering low-temperature oxygen storage capacities comparable to that of the state-of-the-art Sr 0.75 Ca 0.25 FeO 3−δ perovskite oxygen storage material at 325 °C and 350 °C.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

First-principles thermodynamic assessment of Sr-containing secondary phase formation in strontium-substituted lanthanum manganites for solid oxide cell applications

Sr-secondary phase formation is a potentially significant degradation mode with direct impact upon solid-oxide cell (SOC) commercial viability. A first-principles based thermodynamic study was performed for La 1−x Sr x MnO 3±δ (LSM) perovskites to assess their stability against formation of different Sr-secondary phases, including SrO, SrCrO 4 , SrSO 4 , SrCO 3 , and Sr(OH) 2 , for SOC applications. The Sr-secondary phase formation reaction free energies were determined via a thermodynamic model by combining ab initio lattice dynamics calculations for the solid phases and ab initio thermodynamic data for the gas phases. The current approach expands the previously reported thermodynamic modeling studies by integrating first-principles based point defect equilibria into the thermodynamic analysis. The modeling results obtained using this new approach indicate an increased tendency to form the SrO oxide upon decreasing the oxygen partial pressure. Additionally, the enhancing factors to form the Sr-related secondary phase from the associated SrO activity in LSM are further quantified by considering the equilibrium of SrO reacting with the contaminant gas species as a function of temperature and pressure.

defect thermodynamics modeling↗