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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

UV-Vis spectrophotometric determination of rare earth elements (REE) speciation at near-neutral to alkaline pH. Part I: m-cresol purple properties from 25-75 °C and Er hydrolysis

The speciation and mobility of rare earth elements (REE) strongly depends on pH which controls the formation of charged aqueous hydroxyl species. The latter potentially play an important role in controlling heavy REE adsorption on clay minerals in near-neutral to alkaline waters such as in regolith-hosted REE mineral deposits. However, accurate REE hydrolysis constants are needed for developing geochemical models that can predict the role of these charged species in natural systems. Here, we develop a robust experimental UV-Vis spectrophotometric method using m-cresol purple to determine in situ pH from 25 to 75 °C. This method is used to derive the average ligand number and hydrolysis constants of erbium (Er) at 25 °C in aqueous solutions with low ionic strength (≤ 0.001 mol/L) at pH from ~7 to 9.5 and in the presence of Er concentrations from 0 to 0.057 mM. The average ligand number ranges between 1 and 3 indicating that Er(OH) 2+ , Er(OH) 2 + and Er(OH) 3 0 control speciation in the experiments. The logarithm of the Er hydrolysis constants (log*β n ° , n= 1 to 3) derived at infinite dilution for the reaction Er 3+ + nH 2 O = Er(OH) n 3-n + nH + are: *β 1 ° = –7.22 ± 0.10, *β 2 ° = –14.52 ± 0.08, *β 3 ° = –23.24 ± 0.04. Implementation of these experimental data into a geochemical model indicates that the Er(OH) 2 + and Er(OH) 3 0 species are both stable in a much wider pH range than previously predicted. Consequently, the positively charged REE hydroxyl complexes can potentially control the fractionation of light vs. heavy REE via adsorption as observed in the formation of certain regolith-hosted REE deposits.

58 GEOSCIENCES↗
DOE OSTI2020

Materials Data on Er(VGa2)2 by Materials Project

Er(VGa2)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Er is bonded to twelve Ga atoms to form a mixture of distorted edge and face-sharing ErGa12 cuboctahedra. There are four shorter (2.83 Å) and eight longer (3.20 Å) Er–Ga bond lengths. V is bonded in a 10-coordinate geometry to two equivalent V and eight Ga atoms. Both V–V bond lengths are 2.62 Å. All V–Ga bond lengths are 2.72 Å. There are six inequivalent Ga sites. In the first Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent V, and four equivalent Ga atoms. There are two shorter (2.61 Å) and two longer (2.79 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent V, and four Ga atoms. There are two shorter (2.61 Å) and two longer (2.79 Å) Ga–Ga bond lengths. In the third Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent V, and four Ga atoms. There are two shorter (2.61 Å) and two longer (2.79 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent V, and four Ga atoms. There are two shorter (2.61 Å) and two longer (2.79 Å) Ga–Ga bond lengths. In the fifth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent V, and four Ga atoms. In the sixth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent V, and four Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(Al5Fe)2 by Materials Project

ErFe2Al10 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Er is bonded in a 10-coordinate geometry to four equivalent Fe and sixteen Al atoms. All Er–Fe bond lengths are 3.39 Å. There are a spread of Er–Al bond distances ranging from 3.09–3.64 Å. Fe is bonded in a 10-coordinate geometry to two equivalent Er and ten Al atoms. There are a spread of Fe–Al bond distances ranging from 2.50–2.70 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to one Er, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.55–2.98 Å. In the second Al site, Al is bonded in a 2-coordinate geometry to two equivalent Er, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.68–2.80 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Er, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.73–2.89 Å. In the fourth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Er, two equivalent Fe, and eight Al atoms. There are one shorter (2.58 Å) and one longer (2.80 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded to one Er, two equivalent Fe, and nine Al atoms to form a mixture of distorted face and corner-sharing AlErAl9Fe2 cuboctahedra. The Al–Al bond length is 2.68 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(MnAl)6 by Materials Project

Er(MnAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Er is bonded in a 8-coordinate geometry to twelve Mn and eight Al atoms. There are four shorter (3.18 Å) and eight longer (3.30 Å) Er–Mn bond lengths. There are a spread of Er–Al bond distances ranging from 2.89–3.05 Å. There are two inequivalent Mn sites. In the first Mn site, Mn is bonded in a 12-coordinate geometry to two equivalent Er, four Mn, and six Al atoms. There are two shorter (2.46 Å) and two longer (2.52 Å) Mn–Mn bond lengths. There are a spread of Mn–Al bond distances ranging from 2.52–2.63 Å. In the second Mn site, Mn is bonded to two equivalent Er, four equivalent Mn, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing MnEr2Mn4Al6 cuboctahedra. There are two shorter (2.61 Å) and four longer (2.64 Å) Mn–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Er, six Mn, and three Al atoms. There are one shorter (2.69 Å) and two longer (2.80 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Er, six Mn, and one Al atom. The Al–Al bond length is 2.78 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Er, six Mn, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(Al3Ni)3 by Materials Project

ErNi3Al9 crystallizes in the trigonal R32 space group. The structure is three-dimensional. Er is bonded in a 11-coordinate geometry to six equivalent Ni and eleven Al atoms. There are three shorter (3.27 Å) and three longer (3.28 Å) Er–Ni bond lengths. There are a spread of Er–Al bond distances ranging from 2.98–3.15 Å. Ni is bonded in a 8-coordinate geometry to two equivalent Er and eight Al atoms. There are a spread of Ni–Al bond distances ranging from 2.33–2.62 Å. There are six inequivalent Al sites. In the first Al site, Al is bonded in a 3-coordinate geometry to two equivalent Er, three equivalent Ni, and five Al atoms. There are a spread of Al–Al bond distances ranging from 2.71–2.79 Å. In the second Al site, Al is bonded in a distorted trigonal non-coplanar geometry to one Er, three equivalent Ni, and seven Al atoms. There are three shorter (2.81 Å) and one longer (2.84 Å) Al–Al bond lengths. In the third Al site, Al is bonded in a 2-coordinate geometry to two equivalent Er, two equivalent Ni, and six Al atoms. Both Al–Al bond lengths are 2.64 Å. In the fourth Al site, Al is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ni and seven Al atoms. There are three shorter (2.83 Å) and one longer (2.87 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a distorted trigonal non-coplanar geometry to one Er, three equivalent Ni, and seven Al atoms. All Al–Al bond lengths are 2.80 Å. In the sixth Al site, Al is bonded in a linear geometry to two equivalent Ni and six Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(Fe5Si)2 by Materials Project

ErFe10Si2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Er is bonded in a 12-coordinate geometry to sixteen Fe and four equivalent Si atoms. There are a spread of Er–Fe bond distances ranging from 2.93–3.17 Å. All Er–Si bond lengths are 3.07 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to one Er, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.32–2.90 Å. Both Fe–Si bond lengths are 2.60 Å. In the second Fe site, Fe is bonded in a 10-coordinate geometry to one Er, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.41–2.66 Å. Both Fe–Si bond lengths are 2.53 Å. In the third Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Er, eight Fe, and two equivalent Si atoms. All Fe–Fe bond lengths are 2.42 Å. Both Fe–Si bond lengths are 2.60 Å. In the fourth Fe site, Fe is bonded to two equivalent Er, eight Fe, and two equivalent Si atoms to form distorted FeEr2Fe8Si2 cuboctahedra that share corners with four equivalent SiEr2Fe10 cuboctahedra, corners with ten equivalent FeEr2Fe8Si2 cuboctahedra, edges with two equivalent SiEr2Fe10 cuboctahedra, edges with four equivalent FeEr2Fe8Si2 cuboctahedra, faces with four equivalent SiEr2Fe10 cuboctahedra, and faces with six equivalent FeEr2Fe8Si2 cuboctahedra. Both Fe–Fe bond lengths are 2.37 Å. Both Fe–Si bond lengths are 2.39 Å. Si is bonded to two equivalent Er and ten Fe atoms to form distorted SiEr2Fe10 cuboctahedra that share corners with six equivalent SiEr2Fe10 cuboctahedra, corners with eight equivalent FeEr2Fe8Si2 cuboctahedra, edges with three equivalent SiEr2Fe10 cuboctahedra, edges with four equivalent FeEr2Fe8Si2 cuboctahedra, a faceface with one SiEr2Fe10 cuboctahedra, and faces with eight equivalent FeEr2Fe8Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(AlFe)6 by Materials Project

ErFe6Al6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Er is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.22 Å) and eight longer (3.27 Å) Er–Fe bond lengths. There are a spread of Er–Al bond distances ranging from 2.85–2.99 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Er, four Fe, and six Al atoms. All Fe–Fe bond lengths are 2.49 Å. There are two shorter (2.51 Å) and four longer (2.59 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded to two equivalent Er, four equivalent Fe, and six Al atoms to form a mixture of distorted corner, edge, and face-sharing FeEr2Al6Fe4 cuboctahedra. There are two shorter (2.58 Å) and four longer (2.62 Å) Fe–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Er, six Fe, and three Al atoms. There are one shorter (2.66 Å) and two longer (2.82 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Er, six Fe, and one Al atom. The Al–Al bond length is 2.78 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Er, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Epitaxial strain tuning of Er 3+ in ferroelectric thin films

Er 3+ color centers are promising candidates for quantum science and technology due to their long electron and nuclear spin coherence times, as well as their desirable emission wavelength. By selecting host materials with suitable, controllable properties, we introduce new parameters that can be used to tailor the Er 3+ emission spectrum. PbTiO 3 is a well-studied ferroelectric material with known methods of engineering different domain configurations through epitaxial strain. By distorting the structure of Er 3+ -doped PbTiO 3 thin films, we can manipulate the crystal fields around the Er 3+ dopant. This is resolved through changes in the Er 3+ resonant fluorescence spectra, tying the optical properties of the defect directly to the domain configurations of the ferroelectic matrix. Additionally, we are able to resolve a second set of peaks for films with in-plane ferroelectric polarization. We hypothesize these results to be due to either the Er 3+ substituting different sites of the PbTiO 3 crystal, differences in charges between the Er 3+ dopant and the original substituent ion, or selection rules. Systematically studying the relationship between the Er 3+ emission and the epitaxial strain of the ferroelectric matrix lays the pathway for future optical studies of spin manipulation by altering ferroelectric order parameters.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Stability, electronic quantum states, and magnetic interactions of Er 3+ ions in Ga 2 ⁢O 3

Here, we report an ab initio study of phase stability, defect formation, electronic structure, and multiple magnetic, Dzyaloshinskii-Moriya, optical, hyperfine, and crystal field interactions in erbium (Er)-doped wide band gap 𝛼- and 𝛽-gallium oxides (Ga 2 ⁢O 3 ), critically important to make a foundation for both optoelectronic and quantum information applications. The chemical, structural, mechanical, and dynamical stabilities of the pristine phases are confirmed from respective negative formation energies, negative cohesive energies, favorable elastic constants, and positive phonon frequencies. The phonon dispersions indicate that the Ga-O bonds are uniform in the 𝛼-phase, while they vary in the 𝛽-phase due to the anisotropic polyhedral movement. The defect formation energy analysis confirms that both Er-doped 𝛼- and 𝛽−Ga 2 ⁢O 3 prefer Er 3+ (neutral) state. The underestimated band gaps of the pristine phases from standard density functional theory (DFT) calculations as compared to experimental values are corrected by employing the hybrid functional calculations, resulting in the indirect band gaps of 5.21 eV in 𝛼−Ga 2 ⁢O 3 and 4.94 eV in 𝛽−Ga 2 ⁢O 3 . The site preference energy analysis indicates partial occupation of Er in the octahedral site of Ga. The anisotropic nature of hyperfine tensor coefficients of Er is similar in both phases, which may be due to the occupation of Er in the same octahedral Ga site. On the other hand, the calculated magnetic exchange interaction between two Er dopants is negative for 𝛼 and positive for 𝛽, indicating an antiferromagnetic (AFM) ground state in the former and a ferromagnetic (FM) ground state in the latter. Large values of Dzyaloshinskii-Moriya interactions (DMIs) are obtained along the 𝑥 direction in the 𝛼 and along the 𝑦 direction in the 𝛽. The large DMI may support exotic magnetic textures, a promising direction for spintronic applications. The analysis of dielectric constants and refractive indices of both pristine and Er-doped phases shows a good agreement with available experimental values. The calculated optical anisotropy is slightly higher in 𝛽 than those in 𝛼, which is due to the involvement of lower symmetry in 𝛽. The crystal field coefficients (CFCs) calculated from DFT are used to analyze 4⁢𝑓 multiplets and 4⁢𝑓 −4⁢𝑓 transitions. Thus calculated lowest energy level of the first excited state to the lowest energy level of the ground state is about 1.53 µ⁢m, which is in a good agreement with available experiments, and it falls within the quantum telecommunication wavelength range.

3-dimensional systems↗
NASA NTRS1994

Computational modelling of Er(3+): Garnet laser materials

The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host for 1.5 micron laser operation, GSGG or YSAG as the best host for a 2.8 micron operation, and LuGG as the best host for an upconversion material.

Spangler, Lee H.↗
DOE OSTI2020

Materials Data on Er(SiNi5)2 by Materials Project

ErNi10Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Er is bonded in a 12-coordinate geometry to sixteen Ni and four equivalent Si atoms. There are a spread of Er–Ni bond distances ranging from 2.87–3.06 Å. All Er–Si bond lengths are 3.16 Å. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded to two equivalent Er, eight Ni, and two equivalent Si atoms to form NiEr2Si2Ni8 cuboctahedra that share corners with six equivalent SiEr2Ni10 cuboctahedra, corners with twelve NiEr2Si2Ni8 cuboctahedra, edges with four equivalent NiEr2Si2Ni8 cuboctahedra, edges with four equivalent SiEr2Ni10 cuboctahedra, faces with two equivalent SiEr2Ni10 cuboctahedra, and faces with twelve NiEr2Si2Ni8 cuboctahedra. There are four shorter (2.41 Å) and four longer (2.47 Å) Ni–Ni bond lengths. Both Ni–Si bond lengths are 2.33 Å. In the second Ni site, Ni is bonded to two equivalent Er, eight Ni, and two equivalent Si atoms to form distorted NiEr2Si2Ni8 cuboctahedra that share corners with four equivalent SiEr2Ni10 cuboctahedra, corners with fourteen NiEr2Si2Ni8 cuboctahedra, edges with two equivalent SiEr2Ni10 cuboctahedra, edges with five NiEr2Si2Ni8 cuboctahedra, faces with four equivalent SiEr2Ni10 cuboctahedra, and faces with eleven NiEr2Si2Ni8 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.52–2.60 Å. Both Ni–Si bond lengths are 2.31 Å. In the third Ni site, Ni is bonded in a 12-coordinate geometry to one Er, eleven Ni, and two equivalent Si atoms. There are a spread of Ni–Ni bond distances ranging from 2.40–2.97 Å. Both Ni–Si bond lengths are 2.51 Å. Si is bonded to two equivalent Er and ten Ni atoms to form distorted SiEr2Ni10 cuboctahedra that share corners with four equivalent SiEr2Ni10 cuboctahedra, corners with fourteen NiEr2Si2Ni8 cuboctahedra, edges with eight NiEr2Si2Ni8 cuboctahedra, faces with four equivalent SiEr2Ni10 cuboctahedra, and faces with ten NiEr2Si2Ni8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(Al2Mo)2 by Materials Project

Er(MoAl2)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Er is bonded in a 4-coordinate geometry to twelve Al atoms. There are four shorter (2.91 Å) and eight longer (3.25 Å) Er–Al bond lengths. Mo is bonded in a 10-coordinate geometry to two equivalent Mo and eight Al atoms. Both Mo–Mo bond lengths are 2.67 Å. All Mo–Al bond lengths are 2.78 Å. There are four inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Mo, and four Al atoms. There are two shorter (2.62 Å) and two longer (2.87 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Mo, and four Al atoms. Both Al–Al bond lengths are 2.62 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Mo, and four Al atoms. There are one shorter (2.62 Å) and two longer (2.87 Å) Al–Al bond lengths. In the fourth Al site, Al is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Mo, and four Al atoms. The Al–Al bond length is 2.62 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(ClO2)3 by Materials Project

Er(O2Cl)3 crystallizes in the monoclinic P2/c space group. The structure is two-dimensional and consists of one Er(O2Cl)3 sheet oriented in the (0, 1, 0) direction. Er is bonded in a distorted octahedral geometry to six O atoms. All Er–O bond lengths are 2.25 Å. There are three inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Er and one Cl atom. The O–Cl bond length is 1.57 Å. In the second O site, O is bonded in a bent 120 degrees geometry to one Er and one Cl atom. The O–Cl bond length is 1.58 Å. In the third O site, O is bonded in a bent 150 degrees geometry to one Er and one Cl atom. The O–Cl bond length is 1.57 Å. There are two inequivalent Cl sites. In the first Cl site, Cl is bonded in a bent 120 degrees geometry to two O atoms. In the second Cl site, Cl is bonded in a water-like geometry to two equivalent O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(SiPt)2 by Materials Project

ErPt2Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Er is bonded in a 12-coordinate geometry to eight Pt and eight Si atoms. There are four shorter (3.19 Å) and four longer (3.27 Å) Er–Pt bond lengths. There are four shorter (3.17 Å) and four longer (3.22 Å) Er–Si bond lengths. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded to four equivalent Er and four equivalent Si atoms to form distorted PtEr4Si4 tetrahedra that share corners with twelve equivalent SiEr4Pt4 tetrahedra, edges with two equivalent SiEr4Pt4 tetrahedra, edges with four equivalent PtEr4Si4 tetrahedra, and faces with four equivalent PtEr4Si4 tetrahedra. All Pt–Si bond lengths are 2.48 Å. In the second Pt site, Pt is bonded in a 9-coordinate geometry to four equivalent Er and five Si atoms. There are one shorter (2.37 Å) and four longer (2.43 Å) Pt–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Er and four equivalent Pt atoms to form distorted SiEr4Pt4 tetrahedra that share corners with twelve equivalent PtEr4Si4 tetrahedra, edges with two equivalent PtEr4Si4 tetrahedra, edges with four equivalent SiEr4Pt4 tetrahedra, and faces with four equivalent SiEr4Pt4 tetrahedra. In the second Si site, Si is bonded in a 9-coordinate geometry to four equivalent Er and five Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Er Al :Al 2 ⁢O 3 for telecom-band photonics: Electronic structure and optical properties

Er-doped Al 2 ⁢O 3 is a promising host for telecom-band integrated photonics. Here, in this study, we combine ab initio calculations with a symmetry-resolved analysis to elucidate substitutional Er on the Al site (Er Al ) in 𝛼−Al 2 ⁢O 3 . First-principles relaxations confirm the structural stability of Er Al . We then use the local trigonal crystal-field symmetry to classify the Er-derived impurity levels by irreducible representations and to derive polarization-resolved electric-dipole selection rules, explicitly identifying the symmetry-allowed 𝑓−𝑑 hybridization channels. Kubo-Greenwood absorption spectra computed from Kohn-Sham states quantitatively corroborate these symmetry predictions. Furthermore, we connect the calculated intra-4⁢𝑓 line strengths to Judd-Ofelt theory, clarifying the role of 4⁢𝑓−5⁢𝑑 admixture in enabling optical activity. Notably, we predict a characteristic absorption near 1.47 µ⁢m (telecom band), relevant for on-chip amplification and emission. To our knowledge, a symmetry-resolved first-principles treatment of Er:Al 2 ⁢O 3 with an explicit Judd-Ofelt interpretation has not been reported, providing a transferable framework for tailoring rare-earth dopants in wide-band-gap oxides for integrated photonics. Our results for the optical spectra are in good agreement with experimental data. The resulting symmetry-based selection rules translate directly to polarization-dependent coupling in Al 2 ⁢O 3 integrated photonic waveguides and resonators, enabling device-level design of TE/TM-mode interaction with Er emitters in the 1.5-µ⁢m telecom band.

Er-doped Al2O3↗
DOE OSTI2021

Revealing functional insights into ER proteostasis through proteomics and interactomics

The endoplasmic reticulum (ER), responsible for processing approximately one-third of the human proteome including most secreted and membrane proteins, plays a pivotal role in protein homeostasis (proteostasis). Dysregulation of ER proteostasis has been implicated in a number of disease states. As such, continued efforts are directed at elucidating mechanisms of ER protein quality control which are mediated by transient and dynamic protein-protein interactions with molecular chaperones, co-chaperones, protein folding and trafficking factors that take place in and around the ER. Technological advances in mass spectrometry have played a pivotal role in characterizing and understanding these protein-protein interactions that dictate protein quality control mechanisms. Here, we highlight the recent progress from mass spectrometry-based investigation of ER protein quality control in revealing the topological arrangement of the proteostasis network, stress response mechanisms that adjust the ER proteostasis capacity, and disease specific changes in proteostasis network engagement. We close by providing a brief outlook on underexplored areas of ER proteostasis where mass spectrometry is a tool uniquely primed to further expand our understanding of the regulation and coordination of protein quality control processes in diverse diseases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Advanced genomics identifies growth effectors for proteotoxic ER stress recovery in Arabidopsis thaliana

Abstract Adverse environmental and pathophysiological situations can overwhelm the biosynthetic capacity of the endoplasmic reticulum (ER), igniting a potentially lethal condition known as ER stress. ER stress hampers growth and triggers a conserved cytoprotective signaling cascade, the unfolded protein response (UPR) for ER homeostasis. As ER stress subsides, growth is resumed. Despite the pivotal role of the UPR in growth restoration, the underlying mechanisms for growth resumption are yet unknown. To discover these, we undertook a genomics approach in the model plant species Arabidopsis thaliana and mined the gene reprogramming roles of the UPR modulators, basic leucine zipper28 (bZIP28) and bZIP60, in ER stress resolution. Through a network modeling and experimental validation, we identified key genes downstream of the UPR bZIP-transcription factors (bZIP-TFs), and demonstrated their functional roles. Our analyses have set up a critical pipeline for functional gene discovery in ER stress resolution with broad applicability across multicellular eukaryotes.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1998

Structural Loading on the QCM/SAW Instrument Aboard the ER-2 Used for Atmospheric Testing

Several experiments have been proposed to capture and evaluate samples of the atmosphere where SST's travel. One means to achieve this is to utilize the quartz crystal microbalance (QCM) / surface acoustical wave (SAW) instrument installed aboard the ER-2, formerly the U-2 reconnaissance aircraft. The QCM is a cascade impactor designed to perform in-situ, real-time measurements of aerosols and chemical vapors at an altitude of 60,000-70,000 feet. The primary use of the ER-2 is by NASA for Earth resources to test new sensor systems before being placed aboard satellites. One of the main reasons the ER-2 is used for this flight experiment is its capability to fly approximately twelve miles above the sea level (can reach an altitude of 78,000 feet). Because the ER-2 operates at such a high altitude, it is of special interest to scientists interested in space exploration or supersonic aircraft. The purpose of some of the experiments is to extinct data from the atmosphere around the ER-2. For the current CSTEA flight experiment, the housing of the QCM is in a frame that connects to an outer pod that attaches to the fuselage of the ER-2. Due to the location of the QCM within the housing frame and the location of the pod on the ER-2, the pod and its contents are subject to structural loads. In addition to structural loads, structural vibrations are also of importance because the QCM output data is based on the determination of beat frequencies between a pair of oscillators (one coated, the second uncoated, according to the chemical reaction being monitored). A structural analysis of this system can indicate whether potential resonances may exist between the (higher) structural modal frequencies and the beat frequencies. In addition undesirable deformations may result due to maximum expected static or dynamic loads during typical flight conditions. If the deformations are excessive they may adversely affect the accuracy the instrumentation output.

Bainum, Peter M.↗