Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Crystal-field mediated electronic transitions of EuS up to 35 GPa.

ABSTRACT: An advanced experimental and theoretical model to explain the correlation between the electronic and local structure of Eu[Formula: see text] in two different environments within a same compound, EuS, is presented. EuX monochalcogenides (X: O, S, Se, Te) exhibit anomalies in all their properties around 14 GPa with a semiconductor to metal transition. Although it is known that these changes are related to the [Formula: see text] [Formula: see text] [Formula: see text] electronic transition, no consistent model of the pressure-induced modifications of the electronic structure currently exists. We show, by optical and x-ray absorption spectroscopy, and by ab initio calculations up to 35 GPa, that the pressure evolution of the crystal field plays a major role in triggering the observed electronic transitions from semiconductor to the half-metal and finally to the metallic state.

SUBMITTER: Monteseguro V

PROVIDER: S-EPMC8786971 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Crystal-field mediated electronic transitions of EuS up to 35 GPa.

Monteseguro Virginia V Barreda-Argüeso Jose A JA Ruiz-Fuertes Javier J Rosa Angelika D AD Meyerheim Holger L HL Irifune Tetsuo T Rodriguez Fernando F

Scientific reports 20220124 1

An advanced experimental and theoretical model to explain the correlation between the electronic and local structure of Eu[Formula: see text] in two different environments within a same compound, EuS, is presented. EuX monochalcogenides (X: O, S, Se, Te) exhibit anomalies in all their properties around 14 GPa with a semiconductor to metal transition. Although it is known that these changes are related to the [Formula: see text] [Formula: see text] [Formula: see text] electronic transition, no co ...[more]

PMID: 35075233

Similar Datasets

Crystal structure and thermoelastic properties of (Mg0.91Fe0.09)SiO3 postperovskite up to 135 GPa and 2,700 K.

Project description:Intriguing seismic observations have been made for the bottom 400 km of Earth's mantle (the D'' region) over the past few decades, yet the origin of these seismic structures has not been well understood. Recent theoretical calculations have predicted many unusual changes in physical properties across the postperovskite transition, perovskite (Pv) --> postperovskite (PPv), that may provide explanations for the seismic observations. Here, we report measurements of the crystal structure of (Mg(0.91)Fe(0.09))SiO(3)-PPv under quasi-hydrostatic conditions up to the pressure (P)-temperature (T) conditions expected for the core-mantle boundary (CMB). The measured crystal structure is in excellent agreement with the first-principles calculations. We found that bulk sound speed (V(Phi)) decreases by 2.4 +/- 1.4% across the PPv transition. Combined with the predicted shear-wave velocity (V(S)) increase, our measurements indicate that lateral variations in mineralogy between Pv and PPv may result in the anticorrelation between the V(Phi) and V(S) anomalies at the D'' region. Also, density increases by 1.6 +/- 0.4% and Grüneisen parameter decreases by 21 +/- 15% across the PPv transition, which will dynamically stabilize the PPv lenses observed in recent seismic studies.

| S-EPMC2396716 | biostudies-literature

Vibrational Dynamics and Phase Transitions of Hydrazine to 50 GPa.

Project description:The high pressure behavior of hydrazine, N2H4, has been investigated to 50 GPa at room temperature using infrared and Raman spectroscopy to explore pressure induced phase transitions and changes in hydrogen bonding. Three solid-solid phase transitions were detected at 11, 21, and 32 GPa on room temperature compression through dramatic changes in the lattice vibration and N-H stretching regions with increasing pressure in both measurement techniques. The transition to phase IV, which appears at 32 GPa, exhibits increased hydrogen bonding with significant hysteresis, persisting to 9 GPa on decompression. This work presents a detailed analysis of the pressure dependence of mode shifts and calculations of mode Grüneisen parameters as well as a determination of an approximate thermodynamic Grüneisen parameter. We compare these results to the behavior of other small molecular materials such as ammonia and water and explore the evolution of hydrogen bonding in hydrazine toward the symmetrically hydrogen bonded state, which has previously been suggested by theoretical computations.

| S-EPMC11886758 | biostudies-literature

Phase transitions beyond post-perovskite in NaMgF3 to 160 GPa.

Project description:Neighborite, NaMgF3, is used as a model system for understanding phase transitions in ABX3 systems (e.g., MgSiO3) at high pressures. Here we report diamond anvil cell experiments that identify the following phases in NaMgF3 with compression to 162 GPa: NaMgF3 (perovskite) → NaMgF3 (post-perovskite) → NaMgF3 (Sb2S3-type) → NaF (B2-type) + NaMg2F5 (P2 1 /c) → NaF (B2) + MgF2 (cotunnite-type). Our results demonstrate the existence of an Sb2S3-type post-post-perovskite ABX3 phase. We also experimentally demonstrate the formation of the P2 1 /c AB2X5 phase which has been proposed theoretically to be a common high-pressure phase in ABX3 systems. Our study provides an experimental observation of the full sequence of phase transitions from perovskite to post-perovskite to post-post-perovskite followed by 2-stage breakdown to binary compounds. Notably, a similar sequence of transitions is predicted to occur in MgSiO3 at ultrahigh pressures, where it has implications for the mineralogy and dynamics in the deep interior of large, rocky extrasolar planets.

| S-EPMC6765287 | biostudies-literature

Polymorphism of pyrene on compression to 35 GPa in a diamond anvil cell.

Project description:Structural studies of pyrene have been limited to below 2 GPa. Here, we report on investigations of pyrene up to ~35 GPa using in situ single-crystal synchrotron X-ray diffraction in diamond anvil cells and ab initio calculations. They reveal the phase transitions from pyrene-I to pyrene-II (0.7 GPa), and to the previously unreported pyrene-IV (2.7 GPa), and pyrene-V (7.3 GPa). The structure and bonding analysis shows that gradual compression results in continuous compaction of molecular packing, eventually leading to curvature of molecules, which has never been observed before. Large organic molecules exhibit unexpectedly high conformational flexibility preserving pyrene-V up to 35 GPa. Ab initio calculations suggest that the phases we found are thermodynamically metastable compared to pyrene-III previously reported at 0.3 and 0.5 GPa. Our study contributes to the fundamental understanding of the polymorphism of polycyclic aromatic hydrocarbons and calls for further theoretical exploration of their structure-property relationships.

| S-EPMC11405754 | biostudies-literature

Pressure-induced coupled structural-electronic transition in SnS<sub>2</sub> under different hydrostatic environments up to 39.7 GPa.

Project description:A series of in situ high-pressure Raman spectroscopy and electrical conductivity experiments have been performed to investigate the vibrational and electrical transport properties of SnS2 under non-hydrostatic and hydrostatic environments. Upon compression, an coupled structural-electronic transition in SnS2 occurred at 30.2 GPa under non-hydrostatic conditions, which was evidenced by the splitting of the Eg mode and the discontinuities in Raman shifts, Raman full width at half maximum (FWHM) and electrical conductivity. However, the coupled structural-electronic transition took place at a higher pressure of 33.4 GPa under hydrostatic conditions, which may be due to the influence of the pressure medium. Furthermore, our first-principles theoretical calculations results revealed that the bandgap energy of SnS2 decreased slowly with increasing pressure and it closed in the pressure range of 30-40 GPa, which agreed well with our Raman spectroscopy and electrical conductivity results. Upon decompression, the recoverable Raman peaks and electrical conductivity indicated that the coupled structural-electronic transition was reversible, which was further confirmed by our HRTEM observations.

| S-EPMC8979095 | biostudies-literature

Resolving the spin reorientation and crystal-field transitions in TmFeO3 with terahertz transient.

Project description:Rare earth orthoferrites (RFeO3) exhibit abundant physical properties such as, weak macroscopic magnetization, spin reorientation transition, and magneto-optical effect, especially the terahertz magnetic response, have received lots of attention in recent years. In this work, quasi-ferromagnetic (FM) and quasi-antiferromagnetic (AFM) modes arising from Fe sublattice of TmFeO3 single crystal are characterized in a temperature range from 40 to 300 K, by using terahertz time-domain spectroscopy (THz-TDS). The magnetic anisotropy constants in ac-plane are estimated according to the temperature-dependent resonant frequencies of both FM and AFM modes. Here, we further observe the broad-band absorptions centered ~0.52, ~0.61, and ~1.15 THz below 110 K, which are reasonably assigned to a series of crystal-field transitions (R modes) of ground multiplets ((6)H3) of Tm(3+) ions. Specially, our finding reveals that the spin reorientation transition at a temperature interval from 93 to 85 K is driven by magnetic anisotropy, however, which plays negligible role on the electronic transitions of Tm ions in the absence of applied magnetic fields.

| S-EPMC4806309 | biostudies-literature

Atomic Pathways of Crystal-to-Crystal Transitions and Electronic Origins of Resistive Switching in MnTe for Ultralow-Power Memory.

Project description:In conventional phase change memory (PCM) technology, the melting process required to create an amorphous state typically results in extremely high power consumption. Recently, a new type of PCM device based on a melting-free crystal-to-crystal phase transition in MnTe has been developed, offering a potential solution to the problem. However, the electronic and atomic mechanisms underlying this transition remain unclear. In this work, by first-principles calculations, the resistance contrast is attributed to the differences in hole effective mass and vacancy formation energy of the two phases. Moreover, two phase transition pathways of the α-MnTe-to-β-MnTe transition, namely, the 'slide-and-stand-up' transitions, are identified based on coherent atomic movements. The energy barriers for the two pathways are 0.17 eV per formula unit (f.u.) and 0.38 eV/f.u., respectively. Furthermore, the energy barriers can be reduced to 0.10 eV/f.u. and 0.26 eV/f.u. via c-axis tensile strains, which makes the phase transition easier. The current result provides new insights into the non-melting phase transition process in MnTe, facilitating the development of low-power PCM technology.

| S-EPMC11820569 | biostudies-literature

Raman measurements of phase transitions in dense solid hydrogen and deuterium to 325 GPa.

Project description:Raman spectroscopy of dense hydrogen and deuterium performed to 325 GPa at 300 K reveals previously unidentified transitions. Detailed analysis of the spectra from multiple experimental runs, together with comparison with previous infrared and Raman measurements, provides information on structural modifications of hydrogen as a function of density through the I-III-IV transition sequence, beginning near 200 GPa at 300 K. The data suggest that the transition sequence at these temperatures proceeds by formation of disordered stacking of molecular and distorted layers. Weaker spectral changes are observed at 250, 285, and 300 GPa, that are characterized by discontinuities in pressure shifts of Raman frequencies, and changes in intensities and linewidths. The results indicate changes in structure and bonding, molecular orientational order, and electronic structure of dense hydrogen at these conditions. The data suggest the existence of new phases, either variations of phase IV, or altogether new structures.

| S-EPMC3977230 | biostudies-literature

Observation of methane filled hexagonal ice stable up to 150 GPa.

Project description:Gas hydrates consist of hydrogen-bonded water frameworks enclosing guest gas molecules and have been the focus of intense research for almost 40 y, both for their fundamental role in the understanding of hydrophobic interactions and for gas storage and energy-related applications. The stable structure of methane hydrate above 2 GPa, where CH4 molecules are located within H2O or D2O channels, is referred to as methane hydrate III (MH-III). The stability limit of MH-III and the existence of a new high-pressure phase above 40 to 50 GPa, although recently conjectured, remain unsolved to date. We report evidence for a further high-pressure, room-temperature phase of the CH4-D2O hydrate, based on Raman spectroscopy in diamond anvil cell and ab initio molecular dynamics simulations including nuclear quantum effects. Our results reveal that a methane hydrate IV (MH-IV) structure, where the D2O network is isomorphic with ice Ih, forms at ∼40 GPa and remains stable up to 150 GPa at least. Our proposed MH-IV structure is fully consistent with previous unresolved X-ray diffraction patterns at 55 GPa [T. Tanaka et al., J. Chem. Phys. 139, 104701 (2013)]. The MH-III → MH-IV transition mechanism, as suggested by the simulations, is complex. The MH-IV structure, where methane molecules intercalate the tetrahedral network of hexagonal ice, represents the highest-pressure gas hydrate known up to now. Repulsive interactions between methane and water dominate at the very high pressure probed here and the tetrahedral topology outperforms other possible arrangements in terms of space filling.

| S-EPMC6697897 | biostudies-literature

Synthesis and crystal structure of silicon pernitride SiN<sub>2</sub> at 140 GPa.

Project description:Silicon pernitride, SiN2, was synthesized from the elements at 140 GPa in a laser-heated diamond anvil cell. Its crystal structure was solved and refined by means of synchrotron-based single-crystal X-ray diffraction data. The title compound crystallizes in the pyrite structure type (space group Pa , No. 205). The Si atom occupies a site with multiplicity 4 (Wyckoff letter b, site symmetry ..), while the N atom is located on a site with multiplicity 8 (Wyckoff letter c, site symmetry .3.). The crystal structure of SiN2 is comprised of slightly distorted [SiN6] octa-hedra inter-connected with each other by sharing vertices. Crystal chemical analysis of bond lengths suggests that Si has a formal oxidation state of +IV, while nitro-gen forms pernitride anions (N-N)4-.

| S-EPMC10561209 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data