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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Supporting Data for "Constraints on magnetism and correlations in RuO2 from lattice dynamics and Mössbauer spectroscopy"

Contents of this DOI are data for the research paper "Constraints on magnetism and correlations in RuO2 from lattice dynamics and Mossbauer spectroscopy" by the authors: George Yumnam, et. al. The dataset contains data from inelastic x-ray scattering measurements of RuO2 single crystals performed at the Advanced Photon Source in Argonne National Lab. This dataset also contains data from inelastic neutron scattering experiments of RuO2 powder performed at the ARCS spectrometer at Spallation Neutron Source at ORNL. Supporting theoretical calculations based on density functional theory with r2SCAN and DFT+U methods is also included in this dataset. Please see the README.txt files for more information of the dataset and file contents. For comments and questions, please contact: George Yumnam (yumnamg@ornl.gov) and/or Raphael P Hermann (hermannrp@ornl.gov)

density functional theory↗
DOE OSTI2025

Atomic Structure, Dynamics, Changes in Chemical Bonding and Semiconductor-Metal Transition in Sb 2 Se 3 : A Remarkable Material for Quantum Networks and Energy Applications

Antimony sesquiselenide has become an outstanding functional material for photovoltaics, energy storage and transformation, memory and photonic applications. Sb 2 Se 3 is one of the most successful emerging solar light absorbers and has also been identified as a highly promising ultralow-loss phase-change material (PCM) for next-generation coherent nanophotonic processors, photonic tensor cores, quantum and neuromorphic networks. Unlike benchmark telluride PCMs, Sb 2 Se 3 features a quasi-one-dimensional (1D) crystalline structure consisting of (Sb 4 Se 6 ) ∞ ribbons, lacks the typical PCM chemical bonding, and undergoes an extended semiconductor-metal transition above the melting point. Consequently, the origin of high optical contrast between crystalline (SET) and amorphous (RESET) logic states remains elusive and presents a significant challenge. Using high-energy X-ray diffraction and Raman spectroscopy over a wide temperature range, supported by first-principles simulations and complemented by thermal, optical and electrical measurements, as well as by 121 Sb-Mossbauer spectroscopy, the quasi-1D network of orthorhombic antimony sesquiselenide was found to undergo significant evolution in amorphous and supercooled Sb 2 Se 3 , leading to lower coordination, shorter interatomic distances and a higher p-electron density on antimony, indicating changes in chemical bonding. The observed novel Sb 2 Se 3 nanocrystalline polymorph, characterized by trigonal antimony coordination and more isolated Sb-Se ribbons, could help reduce multiple trapping defect states in the bandgap, which are typical of orthorhombic Sb 2 Se 3 , thereby enhancing the power-conversion efficiency of photovoltaic devices. Semimetallic and metallic liquid Sb 2 Se 3 exhibit a gradual transformation into a denser 2D and/or 3D network with higher antimony coordination. Localized electron states in the pseudogap are becoming extended, leading to an increase in electronic conductivity σ following the relationship σ ∝ N(E F ) 2 . Liquid Sb 2 Se 3 also appears to be strongly fragile, with a nonmonotonic change in viscosity and higher atomic mobility in the metallic liquid. Furthermore, these results explain extraordinary functionalities of Sb 2 Se 3 for photonic and energy applications.

antimony↗
NASA NTRS2005

Error Analysis of Remotely-Acquired Mossbauer Spectra

On the Mars Exploration Rovers, Mossbauer spectroscopy has recently been called upon to assist in the task of mineral identification, a job for which it is rarely used in terrestrial studies. For example, Mossbauer data were used to support the presence of olivine in Martian soil at Gusev and jarosite in the outcrop at Meridiani. The strength (and uniqueness) of these interpretations lies in the assumption that peak positions can be determined with high degrees of both accuracy and precision. We summarize here what we believe to be the major sources of error associated with peak positions in remotely-acquired spectra, and speculate on their magnitudes. Our discussion here is largely qualitative because necessary background information on MER calibration sources, geometries, etc., have not yet been released to the PDS; we anticipate that a more quantitative discussion can be presented by March 2005.

Schaefer, Martha W.↗
NASA NTRS1975

Moessbauer studies in zinc-manganese ferrites for use in measuring small velocities and accelerations with great precision

Mossbauer spectroscopy was used for a systematic study of the magnetic behavior of manganese and zinc in mixed ferrites. It was observed that Zn2+ has preference to substitute Mn2+ at interstitial sites where the metal ions are tetrahedrally coordinated with four oxygen neighbors. The internal magnetic hyperfine field at the tetrahedral iron site is larger than that at the octahedral site. The relaxation effects were observed to play an important role as the zinc contents were increased, while the spin-correlation time and the magnetic field were observed to decrease in strength. It is concluded that Mossbauer effect data on complex materials, when used in conjunction with other data, can provide useful insight into the origin of the microscopic properties of magnetic materials.

Escue, W. T.↗
NASA NTRS2003

Moessbauer Spectroscopy of Mineral Separates from SNC Meteorites

Numerous workers have recently focused attention on the issue of the oxygen fugacity (f(sub O2)) of martian samples. Estimates of fO2 based on Fe-Ti oxides and D(sub Eu)/D(sub Gd) and D(sub Eu)/D(sub Sm) ratios suggest a range of fO2 values for SNC meteorites from IW+2.5 - IW+3.5 for Shergotty to IW- 2.0 - IW+0.2 for QUE94201. Fe(3+)/Fe(2+) is also a function of f(sub O2), and synchrotron micro-XANES values for olivine, pyroxene, and feldspar Fe(3+) have been reported. However, the relationship between the reported Fe(3+) values and the other methods for estimating f(sub O2) is not clear, and further measurements of Fe(3+)/Fe(2+) by a more conventional technique have been needed. Accordingly, in this project, new Mossbauer spectroscopy data on mineral separates handpicked from 10 SNC meteorites are reported.

Dyar, M. D.↗
NASA NTRS1999

Spectroscopic Properties of Metamorphosed Mafic Rocks: Remote Sensing Applications on Mars

Reflectance spectroscopy in the visible and near-infrared wavelengths, between 420 mn to 2588 nm. was utilized on a suite of hydrothermally metamorphosed mafic rocks from the Smartville complex in the northern Sierra Nevada mountains in California. A detailed data base of 102 samples was compiled in order to distinguish differences in mineralogy, petrology, and degree of metamorphism for remote sensing applications. Study was limited to metaigneous and metasedimentary rocks in an attempt to spectrally characterize terrestrial rocks analogous to the possible surface of Mars, for a better understanding and possible detection of the geologic features on the remote surface. Diagnostic absorption bands of iron, water, and hydroxyl produced the majority of discernible features in this study. Mossbauer spectroscopy was performed in order to determine specific iron sites. The resulting spectral data base along with thin section mineral identification, metamorphic zone, rock type and location were recorded and available for future application and research. Continued exploration of Mars in the advancing years, will further advance our understanding of the geology of Mars. Spectroscopic techniques will undoubtedly be integral parts of these future missions. Work on terrestrial analogs to the Martian surface must continue, in order to produce extensive data bases and broaden our knowledge of spectral features.

Graff, Trevor G.↗
DOE OSTI2020

Magneto-structural and induction heating properties of MFe2O4 (M?=?Co, Mn, Zn) MNPs for magnetic particle hyperthermia application

The thermal decomposition approach was used for the synthesis of MFe2O4 magnetic nanoparticles (MNPs) by substituting M as Co, Mn, and Zn. The obtained MNPs were characterized for magneto-structural properties using X-Ray diffraction patterns, FTIR, Raman and Mossbauer spectroscopy techniques which confirm the formation of phase pure cubic spinel ferrite with space group Fd3m and five Raman active modes. The size, morphology, and compositional analysis was performed using HRTEM and EDX where the size of MNPs was found to be less than 10 nm that attains superparamagnetism. The magnetic hyperthermia performance of obtained MNPs was evaluated by induction heating experiments at magnetic field range 13.3 to 26.7 kAm-1. The specific absorption rate (SAR) and intrinsic loss power (ILP) values were determined at different magnetic fields within the human tolerable range and correlated with magneto-structural properties to evaluate its potential for possible magnetic particle hyperthermia therapy.

Magnetic nanoparticles, complex-decomposition, mag↗
NASA NTRS1971

Oxidation state of iron in plagioclase from lunar basalts.

Determination of the oxidation state of iron in the plagioclase from the coarse-grained basalts 10044 and 12021, using Mossbauer spectroscopy. The location of iron in the crystal structure was also investigated. The spectra show that iron is in the high-spin ferrous state, and they located at least two distinct positions with different coordination numbers. Some excess resonant absorption is probably due to Fe(3+), although the Fe(3+) doublet could not be positively resolved.

Hafner, S. S.↗
NASA NTRS1972

Hyperfine interactions of Fe/2+/ in ilmenite.

Hyperfine interactions at the Fe(2+) sites in ilmenite have been determined by Mossbauer spectroscopy. At 5 K, the internal magnetic field is -43 (plus or minus 3) kOe, and the quadrupole coupling constant is +1.44 (plus or minus 0.01) mm/sec. Theoretical interpretation of the internal magnetic field in terms of dipolar-, orbital-, and core-polarization contributions is shown to depend critically upon the still unknown lattice contribution to the quadrupole coupling constant.

Grant, R. W.↗
NASA NTRS1971

Moessbauer spectra of ferrite catalysts used in oxidative dehydrogenation

Room temperature Mossbauer spectroscopy was used to examine bulk changes which occur in low surface area CoFe2O4 and CuFe2O4 catalysts as a result of contact with various mixtures of trans-2-butene and O2 during oxidative dehydrogenation reactions at about 420 C. So long as there was at least some O2 in the gas phase, the CoFe2O4 spectrum was essentially unchanged. However, the spectrum changed from a random spinel in the oxidized state to an inverse spinel as it was reduced by oxide ion removal. The steady state catalyst lies very near the fully oxidized state. More dramatic solid state changes occurred as the CuFe2O4 underwent reduction. Under severe reduction, the ferrite was transformed into Cu and Fe3O4, but it could be reversibly recovered by oxidation. An intense doublet located near zero velocity persisted in all spectra of CuFe2O4 regardless of the state of reduction.

Cares, W. R.↗
NASA NTRS1973

High voltage electron microscopy of lunar samples

Lunar pyroxenes from Apollo 11, 12, 14, and 15 were investigated. The iron-rich and magnesium-rich pyroxene specimens were crushed to a grain size of ca. 50 microns and studied by a combination of X-ray and electron diffraction, electron microscopy, 57 Fe Mossbauer spectroscopy and X-ray crystallography techniques. Highly ordered, uniform electron-dense bands, corresponding to exsolution lamellae, with average widths of ca. 230A to 1000A dependent on the source specimen were observed. These were?qr separated by wider, less-dense interband spacings with average widths of ca. 330A to 3100A. In heating experiments, splitting of the dense bands into finer structures, leading finally to obliteration of the exsolution lamellae was recorded. The extensive exsolution is evidence for significantly slower cooling rates, or possibly annealing, at temperatures in the subsolidus range, adding evidence that annealing of rock from the surface of the moon took place at ca. 600 C. Correlation of the band structure with magnetic ordering at low temperatures and iron clustering within the bands was studied.

Fernandez-Moran, H.↗
NASA NTRS1974

Mossbauer spectroscopic study of Luna 16 lunar regolith

Samples of bulk fractions of lunar regolith from the surface layer A and the deep layer V were measured by Mossbauer spectroscopy with the FE57 nucleus. Metallic iron, ilmenite, olivine, pyroxene (mainly augite), and glasses were found. The iron distribution by mineral phases indicates that Luna 16 regolith differs from Apollo 11 regolith by a lower ilmenite content and a greater amount of olivine, and differs from Apollo 12 regolith by somewhat more olivine. No appreciable amount of iron was found in the trivalent state.

Malysheva, T. V.↗
NASA NTRS1974

Solar wind and micrometeorite alteration of the lunar regolith

Developments in the understanding of reduction processes which occur in the lunar regolith as a result of solar-wind bombardment and micrometeorite impacts are discussed. The mechanism is described by which water released during reduction is removed from the lunar surface, and the possible contribution of solar-wind sputtering to the reduction process is considered. It is shown that the overall reduction efficiency of incoming hydrogen ions may reach several per cent, which is sufficient to produce all the metallic iron observed in the regolith. Mossbauer spectroscopic data on the amount of metallic iron present as isolated atoms or small clusters in reduced grain surfaces are presented together with data on the metallic iron content of fines samples obtained by Mossbauer spectroscopy, ferromagnetic resonance, and scanning as well as transmission electron microscopy. A portable magnetic probe is described which has been designed for determining surface-exposure age profiles in intact lunar core and drive-tube samples.

Housley, R. M.↗
NASA NTRS1974

Electrical conductivity of lunar surface rocks - Laboratory measurements and implications for lunar interior temperatures

Results are reported for laboratory measurements of the dc and low-frequency ac electrical conductivity of three lunar rocks with ferrous iron contents of 5 to 26 wt %. The measurements were made at temperatures ranging from 20 to 1000 C, and Mossbauer spectroscopy was used to determine the dependence of electrical conductivity on furnace atmosphere. It is found that the magnitude of electrical conductivity generally increases with increasing iron content. A comparison of the data on these samples with data on terrestrial olivines and pyroxenes shows that the electrical conductivity of anhydrous silicate minerals is influenced primarily by the concentration, oxidation state, and distribution of iron, while the silicate crystal structure is only of secondary importance. Lunar interior temperatures are deduced from experimental lunar conductivity profiles, and the resulting temperature-depth profiles are found to be consistent with those calculated for two different lunar evolutionary models as well as with various experimental constraints.

Schwerer, F. C.↗
NASA NTRS1977

Investigation of the composition of the Luna 16 lunar sample

The concentrations of aluminum, manganese, sodium, chromium, iron, cobalt, and 12 rare earth elements were determined by neutron activation analysis using slow neutrons. Oxygen and silicon were determined using a fast neutron generator. Mossbauer spectroscopy was used to investigate iron compounds in Luna 16 regolith samples from the upper part of the core.

Bakos, L.↗
NASA NTRS1977

The analysis of various size, visually selected and density and magnetically separated fractions of Luna 16 and 20 samples

Samples of Luna 16 and 20 have been separated according to size, visual appearance, density, and magnetic susceptibility. Selected aliquots were examined in eight British laboratories. The studies included mineralogy and petrology, selenochronology, magnetic characteristics, Mossbauer spectroscopy, oxygen isotope ratio determinations, cosmic ray track and thermoluminescence investigations, and carbon chemistry measurements. Luna 16 and 20 are typically mare and highland soils, comparing well with their Apollo counterparts, Apollo 11 and 16, respectively. Both soils are very mature (high free iron, carbide, and methane and cosmogenic Ar), while Luna 16, but not Luna 20, is characterized by a high content of glassy materials. An aliquot of anorthosite fragments, handpicked from Luna 20, had a gas retention age of about 4.3 plus or minus 0.1 Gy.

Eglinton, G.↗