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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Comparative study of three yttrium organometallic compounds for the stabilization of the cubic phase in YSZ deposited by PE-CVD

In this work, the efficiencies of three organometallic yttrium precursors used to produce YSZ coatings by plasma-enhanced chemical vapor deposition were studied. Yttrium (III) acetylacetonate, Y (acac) 3 , yttrium (III) hexafluoroacetylacetonate, Y (acacF 6 ) 3 , and yttrium (III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate), Y (tmhd) 3 , were used to stabilize the cubic phase in zirconia deposited at temperatures from 500 to 800 °C. Our results showed that at temperatures between 500 and 600 °C, Y (tmhd) 3 appeared to be the most efficient dopant as it introduced the highest concentration of yttria (1–2.7 mol%) with only 6.4–5.6 at.% carbon. However, at 700 and 800 °C, Y (acac) 3 introduced twice as much yttria (8–15 mol%) as Y (tmhd) 3 with almost the same amount of carbon (5.4–3 at.%). Conversely, Y (acacF6)3 was the least efficient as it maintained a low concentration of yttria of around 0.7–1.8 mol% with 3.6–8.2 at.% carbon for all the deposition temperatures. Among these precursors, only Y (acac) 3 surpassed 8 mol% yttria and achieved a fully stabilized cubic phase at 800 °C, with the remaining samples stabilizing only the tetragonal phase. The tetragonal phase was stabilized due to the formation of crystallites of around 10 nm. The observed difference in the efficiency of the three precursors was correlated to important differences in their decomposition behavior as observed by mass spectrometry and thermogravimetry/differential scanning calorimetry.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Treatment of exhaust fluorescent lamps to recover yttrium: Experimental and process analyses

Highlights: > Recovery of yttrium from spent fluorescent lamps by sulphuric acid leaching. > The use of sulphuric acid allows to reduce calcium dissolutions. > Main contaminant of fluorescent powder are Si, Pb, Ca and Ba. > Hydrated yttrium oxalate, recovered by selective precipitation, is quite pure (>90%). > We have studied the whole process for the treatment of dangerous waste (plant capability). - Abstract: The paper deals with recovery of yttrium from fluorescent powder coming from dismantling of spent fluorescent tubes. Metals are leached by using different acids (nitric, hydrochloric and sulphuric) and ammonia in different leaching tests. These tests show that ammonia is not suitable to recover yttrium, whereas HNO{sub 3} produces toxic vapours. A full factorial design is carried out with HCl and H{sub 2}SO{sub 4} to evaluate the influence of operating factors. HCl and H{sub 2}SO{sub 4} leaching systems give similar results in terms of yttrium extraction yield, but the last one allows to reduce calcium extraction with subsequent advantage during recovery of yttrium compounds in the downstream. The greatest extraction of yttrium is obtained by 20% w/v S/L ratio, 4 N H{sub 2}SO{sub 4} concentration and 90 deg. C. Yttrium and calcium yields are nearly 85% and 5%, respectively. The analysis of variance shows that acid concentration alone and interaction between acid and pulp density have a significant positive effect on yttrium solubilization for both HCl and H{sub 2}SO{sub 4} medium. Two models are empirically developed to estimate yttrium and calcium concentration during leaching. Precipitation tests demonstrate that at least the stoichiometric amount of oxalic acid is necessary to recover yttrium efficiently and a pure yttrium oxalate n-hydrate can be produced (99% grade). The process is economically feasible if other components of the fluorescent lamps (glass, ferrous and non-ferrous scraps) are recovered after the equipment dismantling and valorized, besides the cost that is usually paid to recycling companies for collection, treatment or final disposal of such fluorescent powders.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Synthesis and photoluminescence properties of the high-brightness Eu{sup 3+}-doped M{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} (M=Li, Na) red phosphors

A series of red-emitting phosphors Eu{sup 3+}-doped M{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} (M=Li, Na) have been successfully synthesized at 850 Degree-Sign C by solid state reaction. The excitation spectra of the two phosphors reveal two strong excitation bands at 396 nm and 466 nm, respectively, which match well with the two popular emissions from near-UV and blue light-emitting diode chips. The intensity of the emission from {sup 5}D{sub 0} to {sup 7}F{sub 2} of M{sub 2}(Gd{sub 1-x}Eu{sub x}){sub 4}(MoO{sub 4}){sub 7} phosphors with the optimal compositions of x=0.85 for Li or x=0.70 for Na is about five times higher than that of Y{sub 2}O{sub 3}:Eu{sup 3+}. The quantum efficiencies of the entitled phosphors excited under 396 nm and 466 nm are also investigated and compared with commercial phosphors Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} and Y{sub 3}A{sub 5}O{sub 12}:Ce{sup 3+}. The experimental results indicate that the Eu{sup 3+}-doped M{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} (M=Li, Na) phosphors are promising red-emitting phosphors pumped by near-UV and blue light. - Graphical Abstract: The intensity of the red emission of M{sub 2}(Gd{sub 1-x}Eu{sub x}){sub 4}(MoO{sub 4}){sub 7} (M=Li, Na) phosphors with the optimal compositions is about five times higher than that of Y{sub 2}O{sub 3}:Eu{sup 3+}. Highlights: Black-Right-Pointing-Pointer Two novel Eu{sup 3+}-doped red phosphors (Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 2}, Li{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7}) were synthesized. Black-Right-Pointing-Pointer Their emission intensities are about five times higher than that of Y{sub 2}O{sub 3}:Eu{sup 3+}. Black-Right-Pointing-Pointer Their quantum efficiencies are higher than that of commercial red phosphor Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

First-Principles Investigation of Half-Metallic Ferromagnetism of a New 1:1:1:1 Type Quaternary Heusler Compound YRhTiSi

First-principles theory was applied to study the electronic, magnetic, and half-metallic behaviors of a new Y-based equiatomic quaternary Heusler compound YRhTiSi. We will come to study the physical properties of this compound and find it has the half-metallic nature in the ferromagnetic (FM) state. The total magnetic moment of this compound YRhTiSi is 2 μ{sub B}, which follows the famous Slater-Pauling rule, Mt = Zt − 18, Mt is the total magnetic moment and Zt is the total number of valence electrons. Based on its equilibrium and strained lattice constants, the magnetic and half-metallic behaviors of this compound have been discussed in detail. And we find that the H–M gap and the band gap can be regulated through the effect of uniform strain and the tetragonal deformation. A large H–M gap of 0.48 eV has been found in our work, which is nearly larger than any previous study. Furthermore, the formation and cohesive energies have also been discussed in our work to examine the phase stability of YRhTiSi. This theoretical investigation provides further insight into the application of Y-based compounds as spintronic materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Phase identification and structure investigation of novel quaternary rare-earth substituted titanates

Novel quaternary lanthanide-substituted oxides of stoichiometry LnxY2-xTi2O7 (where Ln is lanthanum, neodymium, samarium, gadolinium, or ytterbium) were prepared by traditional high-temperature, solid-state techniques and characterized by X-ray powder diffraction. Samples with nominal values of x up to 1.0 were attempted. The well-studied ternary cubic pyrochlore compound yttrium titanium oxide (Y2Ti2O7, space group Fd-3m, Z = 8), served as a parent structural framework in which Ln3+ cations were substituted on the Y3+ site. Laboratory-grade X-ray powder diffraction data revealed pure quaternary pyrochlore phases for LnxY2-xTi2O7 with x ≤ 0.2. Pyrochlore phase purity was verified by Rietveld analysis using high-resolution synchrotron X-ray powder diffraction data when x ≤ 0.2, however, for La3+ substitution specifically, pure quaternary pyrochlore formed at x<0.1. Band gap energies on selected samples were determined using optical diffuse reflectance spectroscopy and showed that these materials can be classified as electrical insulators with indirect band gap energies around 3.7 eV.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Microstructural characterization of a new mechanically alloyed Ni-base ODS superalloy powder

The microstructure of a new Ni-base oxide dispersion strengthened superalloy powder was studied for high temperature gas turbine applications after the mechanical alloying process. In this study, an atomized powder with a composition similar to the CMSX-10 superalloy was mechanically alloyed with yttria and Hf powders. The mechanically alloyed powder included only the supersaturated solid solution γ phase without γ′ and yttria provided by severe plastic deformation, while after the 3-step aging, the γ′ phase was precipitated due to the partitioning of Al and Ta to the γ′ and Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γ′ to the new coherent γ–γ′ nanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γ′ lamellae aligned preferentially along the elastically soft [100] direction. Also, the precipitated oxide particles were refined in the γ phase by adding Hf from large incoherent YAlO{sub 3} to fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm. - Highlights: • A new Ni-base ODS superalloy powder was produced by mechanical alloying. • The nanoscale γ–γ′ lamellar structure was precipitated after the aging treatment. • Fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles were precipitated by addition of Hf.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Dispersoids and γ′ precipitates in an ultrafine grained René 88DT – 5vol.%Y2O3 alloy with outstanding thermal stability

Highlights: • Dispersoids and precipitates in UFG René 88DT was systematically studied. • TiN and Y4Al2O9 particles are thermally stable in UFG René 88DT. • High thermal stability of the UFG structure was achieved by dispersoids formation. - Abstract: We report on an ultrafine-grained (UFG) René 88DT-5vol.%Y{sub 2}O{sub 3} alloy with a high thermal stability fabricated through high energy mechanical milling and thermomechanical powder consolidation. The as-extruded sample consists of an ultrafine grained γ matrix with an average size of 122 nm with Y{sub 4}Al{sub 2}O{sub 9} nanoparticles (average size: 12.6 nm) and TiN particles (size about 150 nm) being dispersed in the matrix. The UFG microstructure of the alloy showed an outstanding thermal stability with the average grain size only increasing slightly from 122 to 145 nm after holding at 1120 °C (0.85T{sub m}, where T{sub m} is the solidus temperature of the alloy in Kelvin scale) for 2 h and subsequently holding at 760 °C for 16 h. Due to the consumption of γ′ forming elements, Ti and Al, by the formation of the Y{sub 4}Al{sub 2}O{sub 9} and TiN dispersoids, the content of γ′ precipitates in the microstructure of the heat treated sample is significantly reduced, as confirmed by experimentation and calculation using the JMatPro software. Additionally, the size of γ′ precipitates also sharply decreased to 20–30 nm in the heat treated UFG René 88DT-5vol.%Y{sub 2}O{sub 3} alloy, in contrast to a size of 100–150 nm in the Y{sub 2}O{sub 3}-free base alloy under the same heat treatment condition.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Fine grained fully lamellar structure acquisition and microstructure characteristics of Ti-44Al-4Nb-4V-0.3Mo-Y alloy

Highlights: • Cellular structure is the component of the microstructure of hot forging in α + β two-phase-field. • Inhomogeneous lamellar structure could be eliminated by hot forging in β+γ binary phase field. • After hot forging and annealing at β+γ two-phase-region, fine grained fully-lamellar microstructure is obtained. - Abstract: In this paper, the microstructure characteristic of a β solidifying TiAl alloy Ti-44Al-4Nb-4V-0.3Mo-Y (at. %) was investigated systematically. Cylindrical blanks were isothermal forged at 1250 °C within (α + β) two-phase-field and 1200 °C within (β + γ) two-phase-field under the strain rate of 0.02 s{sup −1} and 0.03 s{sup −1}, with a total reduction of 75%. The microstructure of the alloy forged in α + β two-phase-field consists of lamellar colonies (only represents α{sub 2}/γ lamellar colonies), mixture structure of β/B2 phase and γ phase as well as β/γ lamellae resulted from cellular reaction. However, a large amount of equiaxed γ grains appear with no β/γ lamellae available under forging in β + γ two-phase-field, and the average size of γ grain is about 10 μm. By further annealed at 900 °C for about 0.5 h, the structure of hot forging at 1250 °C is composed of β/B2 phase and equiaxed γ grains with the mean size about 5 μm. After heat treated at 1200 °C for 2 h, the microstructure of this annealed samples is characterized by fine grained fully lamellar (FFL) structure with size of 20 μm. A specially designed hot forging process is proposed, which prevents the existence of inhomogeneous lamellar structure.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of cooling rate on microstructure evolution of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y alloy during multi-step heat treatment

Highlights: • Novel ideas to control cooling rate during different phase transformation are proposed. • Cooling rates induced microstructure evolutions during the whole phase transformation are investigated. • Phase transformation texture and the characteristics of lamellar structures are related to cooling rate. - Abstract: Microstructure evolution of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y alloy (at.%) resulted from different cooling rates during the whole phase transformation process has been thoroughly investigated. The results show that the cooling rate during β → α transformation plays a crucial role in the modification of the crystallographic orientation relationship between the α grains and their parent β phase. The decrease of cooling rate can reduce the volume fraction of Burgers α grains and avoid the preferential distribution of lamellar interface traces. This could be attributed to the different nucleation and growth kinetics of α phase affected by the cooling rate. Moreover, the lamellar structure characteristics are closely related to the cooling rate during α → α{sub 2} + γ transformation and their responses to stabilization treatment shall vary accordingly. A fast cooling rate retains a high quantity of high temperature α/α{sub 2} phase. These α/α{sub 2} phase could decompose into ultrafine lamellar structure during subsequent stabilization treatment. While the average lamellar spacing of the slow cooled microstructure has a small increase by limited continuous growth of the pre-existing γ lamellae during stabilization treatment.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Converting Y(OH){sub 3} nanofiber bundles to YVO{sub 4} polyhedrons for photodegradation of dye contaminants

Highlights: • YVO{sub 4} polyhedrons were prepared from Y(OH){sub 3} nanofiber bundles through a hydrothermal conversion process. • In contrast to the bulk oxide, the photocatalytic performance of the polyhedrons was much improved. • The main active species involved in photocatalytic oxidative reaction were also investigated. - Abstract: This paper reports a hydrothermal conversion process of rare earth microstructures, Y(OH){sub 3} nanofiber bundles, into YVO{sub 4} polyhedrons, together with the investigation on the related photocatalytic properties. The as-synthesized samples were characterized by a variety of techniques, including XRD, SEM, TEM and UV–vis diffuse reflectance spectroscopy. The photocatalytic activities of YVO{sub 4} polyhedrons were comparatively evaluated by the photodegradation of Rhodamine B and methylene blue. In contrast to the bulk oxide, the photocatalytic performance of the polyhedrons was much improved. The mechanism and the main active species involved in photocatalytic oxidative reaction were also investigated through the carriers trapping experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2014

First-principles study of structural, electronic, vibrational, dielectric and elastic properties of tetragonal Ba₂YTaO₆

We report first-principles study of structural, electronic, vibrational, dielectric, and elastic properties of Ba₂YTaO₆, a pinning material in high temperature superconductors (HTS), by using density functional theory. By using different exchange-correlation potentials, the accuracy of the calculated lattice constants of Ba₂YTaO₆ has been achieved with GGA-RPBE, since many important physical quantities crucially depend on change in volume. We have calculated the electronic band structure dispersion, total and partial density of states to study the band gap origin and found that Ba₂YTaO₆ is an insulator with a direct band gap of 3.50 eV. From Mulliken population and charge density studies, we conclude that Ba₂YTaO₆ have a mixed ionic-covalent character. Moreover, the vibrational properties, born effective charges, and the dielectric permittivity tensor have been calculated using linear response method. Vibrational spectrum determined through our calculations agrees well with the observed Raman spectrum, and allows assignment of symmetry labels to modes. We perform a detailed analysis of the contribution of the various infrared-active modes to the static dielectric constant to explain its anisotropy, while electronic dielectric tensor of Ba₂YTaO₆ is nearly isotropic, and found that static dielectric constant is in good agreement with experimental value. The six independent elastic constants were calculated and found that tetragonal Ba₂YTaO₆ is mechanically stable. Other elastic properties, including bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and elastic anisotropy ratios are also investigated and found that Poisson's ratio and Young's modulus of Ba₂YTaO₆ are similar to that of other pinning materials in HTS.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Terahertz probes of magnetic field induced spin reorientation in YFeO{sub 3} single crystal

Using the terahertz time-domain spectroscopy, we demonstrate the spin reorientation of a canted antiferromagnetic YFeO{sub 3} single crystal, by evaluating the temperature and magnetic field dependence of resonant frequency and amplitude for the quasi-ferromagnetic (FM) and quasi-antiferromagnetic modes (AFM), a deeper insight into the dynamics of spin reorientation in rare-earth orthoferrites is established. Due to the absence of 4f-electrons in Y ion, the spin reorientation of Fe sublattices can only be induced by the applied magnetic field, rather than temperature. In agreement with the theoretical predication, the frequency of FM mode decreases with magnetic field. In addition, an obvious step of spin reorientation phase transition occurs with a relatively large applied magnetic field of 4 T. By comparison with the family members of RFeO{sub 3} (R = Y{sup 3+} or rare-earth ions), our results suggest that the chosen of R would tailor the dynamical rotation properties of Fe ions, leading to the designable spin switching in the orthoferrite antiferromagnetic systems.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Modified Heisenberg model for the zig-zag structure in multiferroic RMn{sub 2}O{sub 5}

The class of RMn{sub 2}O{sub 5} (R = Ho, Tb, Y, Eu) compounds offers multiferroic properties where the refined magnetic zig-zag order breaks the inversion symmetry. Varying the temperature, the system undergoes a magnetic and a subsequent ferroelectric phase transition where the ferroelectricity is magnetically induced. We propose a modified anisotropic Heisenberg model that can be used as a tractable analytical model studying the properties of those antiferromagnetic zig-zag spin chains. Based on a finite temperature Green's function method, it is shown that the polarization is induced solely by different exchange couplings of the two different Mn{sup 4+} and Mn{sup 3+} magnetic ions. We calculate the excitation energy of the spin system for finite temperatures, which for its part determines the temperature dependent magnetization and polarization. The ferroelectric phase transition is manifested as a kink in the excitation energy. The variation of the polarization by an external magnetic field depends strongly on the direction of that field. Whereas, the polarization in b-direction increases with an external magnetic field as well in b-direction it can be switched for strong fields in a-direction. The results based on that modified Heisenberg model are in qualitative agreement with experimental data.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

50 MeV, Li{sup 3+} - ion irradiation effect on magnetic ordering of Y{sup 3+} - substituted yttrium iron garnet

This communication presents the effect of non-magnetic Y{sup 3+} ions substitution for magnetic Fe{sup 3+} ions and 50 MeV, Li{sup 3+} ion irradiation (fluence: 5 × 10{sup 13} ions/cm{sup 2}) on magnetic ordering and Neel temperature of Y{sub 3+x}Fe{sub 5-x}O{sub 12} (x = 0.0, 0.2, 0.4 and 0.6) garnet system, studied by means of X-ray powder diffractometry and thermal variation of low field (0.5 Oe) ac susceptibility measurements. The un-irradiated compositions exhibit normal ferrimagnetic behavior with decrease in transition temperature (T{sub N}) on increasing Y{sup 3+}-concentration (x). The irradiated counterparts are characterized by tailing effect indicative of non-uniform effect of irradiation and lower value of T{sub N}. The results have been discussed based on the weakening of magnetic exchange interactions and cumulative effect of redistribution of cations and fractional creation of localized paramagnetic centers resulting from swift heavy ion irradiation. The Neel temperatures and exchange integrals have been calculated theoretically.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Evaluation of critical distances for energy transfer between Pr{sup 3+} and Ce{sup 3+} in yttrium aluminium garnet

A series of Pr{sup 3+}/Ce{sup 3+} doped yttrium aluminium garnet (Y{sub 3}Al{sub 5}O{sub 12} or simply YAG) phosphors were synthesized to investigate the energy transfer between Pr{sup 3+} and Ce{sup 3+} for their potential application in a white light-emitting diode and quantum information storage and processing. The excitation and emission spectra of YAG:Pr{sup 3+}/Ce{sup 3+} were measured and analyzed, and it revealed that the reabsorption between Pr{sup 3+} and Ce{sup 3+} was so weak that it can be ignored, and the energy transfer from Pr{sup 3+} (5d) to Ce{sup 3+} (5d) and Ce{sup 3+} (5d) to Pr{sup 3+} ({sup 1}D{sub 2}) did occur. By analyzing the excitation and the emission spectra, the energy transfer from Pr{sup 3+} (5d) to Ce{sup 3+} (5d) and Ce{sup 3+} (5d) to Pr{sup 3+} ({sup 1}D{sub 2}) was examined in detail with an original strategy deduced from fluorescence dynamics and the Dexter energy transfer theory, and the critical distances of energy transfer were derived to be 7.9 Å and 4.0 Å for Pr{sup 3+} (5d) to Ce{sup 3+} (5d) and Ce{sup 3+} (5d) to Pr{sup 3+} ({sup 1}D{sub 2}), respectively. The energy transfer rates of the two processes of various concentrations were discussed and evaluated. Furthermore, for the purpose of sensing a single Pr{sup 3+} state with a Ce{sup 3+} ion, the optimal distance of Ce{sup 3+} from Pr{sup 3+} was evaluated as 5.60 Å, where the probability of success reaches its maximum value of 78.66%, and meanwhile the probabilities were evaluated for a series of Y{sup 3+} sites in a YAG lattice. These results will be of valuable reference for achievement of the optimal energy transfer efficiency in Pr{sup 3+}/Ce{sup 3+} doped YAG and other similar systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Magnetic proximity effect at the interface between a cuprate superconductor and an oxide spin valve

A heterostructure that consists of the YBa{sub 2}Cu{sub 3}O{sub 7–δ} cuprate superconductor and the SrRuO{sub 3}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} ruthenate/manganite spin valve is investigated using SQUID magnetometry, ferromagnetic resonance, and neutron reflectometry. It is shown that a magnetic moment is induced due to the magnetic proximity effect in the superconducting part of the heterostructure, while the magnetic moment in the composite ferromagnetic interlayer is suppressed. The magnetization emerging in the superconductor coincides in order of magnitude with the results of calculations taking into account the induced magnetic moment of Cu atoms because of orbital reconstruction at the interface between the superconductor and the ferromagnet, as well as with the results of the model taking into account the variations in the density of states at a distance on the order of the coherence length in the superconductor. The experimentally obtained characteristic penetration depth of the magnetic moment in the superconductor considerably exceeds the coherence length of the cuprate superconductor, which indicates the predominance of the mechanism of induced magnetic moment of Cu atoms.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Parameters of Nuclear Quadrupole Interaction and Spatial Distribution of Electronic Defects in YBa{sub 2}Cu{sub 3}O{sub 7} and La{sub 2–x}Sr{sub x}CuO{sub 4} Lattices

The comparison of calculated and experimental parameters of nuclear quadrupole interaction in the sites of crystal lattice of YBa{sub 2}Cu{sub 3}O{sub 7} and La{sub 2–x}Sr{sub x}CuO{sub 4} superconducting copper metal oxides has shown that effective charges of all atoms of superconducting ceramic lattices correspond to standard rates of their oxidation, except the atoms of chain and planar oxygen in YBa{sub 2}Cu{sub 3}O{sub 7} lattice and atoms of planar oxygen in La{sub 2–x}Sr{sub x}CuO{sub 4} lattice, whose decreased charge is interpreted as a result of hole localization in the corresponding sublattices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Superconducting Heterostructures Interlayered with a Material with Strong Spin–Orbit Interaction

Abstract—Superconducting heterostructures interlayered with a material with strong spin–orbit interaction are studied. As materials with strong spin–orbit interaction, we choose strontium iridates featuring the Ruddlesden–Popper structure (Sr{sub n} {sub + 1}Ir{sub n}O{sub 3n} {sub + 1}; n = 1, 2, ∞): paramagnetic metal SrIrO{sub 3} and magnetic insulator Sr{sub 2}IrO{sub 4}. Using laser ablation, epitaxial films of these materials are obtained, as well as heterostructures based on epitaxial films of cuprate superconducting YBa{sub 2}Cu{sub 3}O{sub x}. For electrical measurements, mesa-structures of micrometer sizes with top electrodes made of Au/Nb bilayer are fabricated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗