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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

ER-associated VAP27-1 and VAP27-3 proteins functionally link the lipid-binding ORP2A at the ER-chloroplast contact sites

Abstract The plant endoplasmic reticulum (ER) contacts heterotypic membranes at membrane contact sites (MCSs) through largely undefined mechanisms. For instance, despite the well-established and essential role of the plant ER-chloroplast interactions for lipid biosynthesis, and the reported existence of physical contacts between these organelles, almost nothing is known about the ER-chloroplast MCS identity. Here we show that the Arabidopsis ER membrane-associated VAP27 proteins and the lipid-binding protein ORP2A define a functional complex at the ER-chloroplast MCSs. Specifically, through in vivo and in vitro association assays, we found that VAP27 proteins interact with the outer envelope membrane (OEM) of chloroplasts, where they bind to ORP2A. Through lipidomic analyses, we established that VAP27 proteins and ORP2A directly interact with the chloroplast OEM monogalactosyldiacylglycerol (MGDG), and we demonstrated that the loss of the VAP27-ORP2A complex is accompanied by subtle changes in the acyl composition of MGDG and PG. We also found that ORP2A interacts with phytosterols and established that the loss of the VAP27-ORP2A complex alters sterol levels in chloroplasts. We propose that, by interacting directly with OEM lipids, the VAP27-ORP2A complex defines plant-unique MCSs that bridge ER and chloroplasts and are involved in chloroplast lipid homeostasis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Phonon-mediated temperature dependence of Er 3+ optical transitions in Er 2 O 3

Characterization of the atomic level processes that determine optical transitions in emerging materials is critical to the development of new platforms for classical and quantum networking. Such understanding often emerges from studies of the temperature dependence of the transitions. We report measurements of the temperature dependent Er 3+ photoluminescence in single crystal Er 2 O 3 thin films epitaxially grown on Si(111) focused on transitions that involve the closely spaced Stark-split levels. Radiative intensities are compared to a model that includes relevant Stark-split states, single phonon-assisted excitations, and the well-established level population redistribution due to thermalization. This approach, applied to the individual Stark-split states and employing Er 2 O 3 specific single-phonon-assisted excitations, gives good agreement with experiment. This model allows us to demonstrate the difference in the electron-phonon coupling of the 4 S 3/2 and 2 H 11/2 states of Er 3+ in E 2 O 3 and suggests that the temperature dependence of Er 3+ emission intensity may vary significantly with small shifts in the wavelength (~0.1 nm) of the excitation source.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Indistinguishable telecom band photons from a single Er ion in the solid state

Atomic defects in the solid state are a key component of quantum repeater networks for long-distance quantum communication1. Recently, there has been significant interest in rare earth ions, in particular Er 3+ for its telecom band optical transition that allows long-distance transmission in optical fibres. However, the development of repeater nodes based on rare earth ions has been hampered by optical spectral diffusion, precluding indistinguishable single-photon generation. Here, we implant Er 3+ into CaWO 4 , a material that combines a non-polar site symmetry, low decoherence from nuclear spins and is free of background rare earth ions, to realize significantly reduced optical spectral diffusion. For shallow implanted ions coupled to nanophotonic cavities with large Purcell factor, we observe single-scan optical linewidths of 150 kHz and long-term spectral diffusion of 63 kHz, both close to the Purcell-enhanced radiative linewidth of 21 kHz. This enables the observation of Hong–Ou–Mandel interference between successively emitted photons with a visibility of V = 80(4)%, measured after a 36 km delay line. We also observe spin relaxation times T 1,s = 3.7 s and T 2,s > 200 μs, with the latter limited by paramagnetic impurities in the crystal instead of nuclear spins. Furthermore, this represents a notable step towards the construction of telecom band quantum repeater networks with single Er 3+ ions.

42 ENGINEERING↗
DOE OSTI2023

Updated analysis of the Er 170 ( p , t ) Er 168 reaction data

More than 200 states up to 4.1 MeV excitation have been populated in 168 Er with the 170 Er ( p , t ) reaction at 25 MeV incident energy. About 80 of these states, with 0 + and 2 + assignments, were reported in a previous publication [D. Bucurescu et al., Phys. Rev. C 73, 064309 (2006)]. Here, the present work considerably enriches the knowledge of this nucleus. A multistep coupled-channels analysis of the angular distributions is now presented for all the states observed in this experiment. Spin and parity values between 0 + and 7 - are newly assigned for more than 100 states. For the states already reported in the ENSDF database with J π values there is a good agreement with our values. The 168 Er nucleus remains one of the best experimentally known nuclei for states with low and medium spins below 4 MeV excitation energy, representing a challenge for future microscopic structure model calculations aiming to disentangle the contributions of different excitation degrees of freedom.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Defect enhancement of Er emission in single crystal Er 2 O 3

We report observations of crystal defect induced modifications in the laser-excited Er 3+ photoluminescence spectra of single-crystal Er 2 O 3 thin films. These include marked enhancement of transition intensities known to be weak or nonexistent in as-grown samples. In this Letter, we examine the temperature and defect density dependence of the measurements and suggest photophysical processes that may account for these unexpected results.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er by Materials Project

Er is alpha Samarium structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are five inequivalent Er sites. In the first Er site, Er is bonded to twelve Er atoms to form a mixture of edge, face, and corner-sharing ErEr12 cuboctahedra. There are six shorter (3.50 Å) and six longer (3.54 Å) Er–Er bond lengths. In the second Er site, Er is bonded to twelve Er atoms to form a mixture of edge, face, and corner-sharing ErEr12 cuboctahedra. There are three shorter (3.49 Å) and six longer (3.54 Å) Er–Er bond lengths. In the third Er site, Er is bonded to twelve Er atoms to form a mixture of edge, face, and corner-sharing ErEr12 cuboctahedra. There are three shorter (3.49 Å) and six longer (3.54 Å) Er–Er bond lengths. In the fourth Er site, Er is bonded to twelve Er atoms to form a mixture of edge, face, and corner-sharing ErEr12 cuboctahedra. There are a spread of Er–Er bond distances ranging from 3.49–3.54 Å. In the fifth Er site, Er is bonded to twelve Er atoms to form a mixture of edge, face, and corner-sharing ErEr12 cuboctahedra. There are three shorter (3.50 Å) and six longer (3.54 Å) Er–Er bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2026

The solubility of ErPO 4 and Er speciation in hydrothermal fluids at varying pH and salinity between 350 and 450 °C

The rare earth elements (REE) are important for the green-energy transition and can be incorporated into the REE phosphates, such as xenotime-(Y), which also hosts heavy REE (Tb– Lu). Xenotime-(Y) is a common accessory mineral in metamorphic rocks and a range of mineral deposits where it controls the mobility of heavy REE, however, the impact of high temperature aqueous fluids on the behavior of heavy REE is largely unknown. Thermodynamic modeling can be utilized as a tool to predict the mobility of REE in hydrothermal aqueous fluids, but must be supported by accurate experimental data. Here, we measured the solubility of endmember synthetic xenotime-structured ErPO4 in NaCl-HCl-NaOH-bearing aqueous solutions at 350 °C and water vapor saturation pressure, at 400 and at 450 °C and 500 bar using batch-type Inconel reactors. Erbium speciation was investigated as a function of pH from 2.8 to 8, where Er chloride species are predominant at acidic conditions (pH <3) and Er hydroxyl complexes are predominant at near- neutral to alkaline conditions (pH >3). At pH 7–9, the measured ErPO 4 solubility (-9.8 to -7.5 log m Er ) is up to 2.5 orders of magnitude lower than thermodynamic predictions (-9.4 to -6.7 log m Er ) using existing thermodynamic databases. At pH 2–3, the predicted ErPO 4 solubility is ~0.5 orders of magnitude higher at 350 °C and ~1 order of magnitude lower at 450 °C compared to experimentally measured Er concentrations. The thermodynamic properties of aqueous Er species were therefore revised in this study. The partial molal Gibbs energy of formation (Δ f G 0 T,P ) for aqueous Er hydroxyl and chloride species are optimized using GEMSFITS and the logarithmic formation constants (logβ n ( Cl,OH) ) were derived at each experimental temperature and pressure. The updated thermodynamic properties for Er hydroxyl species (Er(OH) +2 , Er(OH) 2 + , and Er(OH) 3 0 ) show that their stability shifts to more acidic conditions at and below 400 °C. The Er chloride species (ErCl +2 and ErCl 2 + ) show increased stability compared to Er hydroxyl species at temperatures of 450 °C and 0.01 mol/kg NaCl. The updated thermodynamic properties are implemented into the GEM-Selektor modeling package to investigate the mobility of Er in saline hydrothermal fluids in equilibrium with alkaline rocks. Importantly, the updated properties for Er hydroxyl species result in low Er solubility at rock equilibrated pH conditions due to an expanded hydroxyl predominance zone, but lower aqueous complex stability overall, whereas previous models suggest greater stability for aqueous Er species. Furthermore, ErPO 4 solubility increases with decreasing temperature due to the deprotonation of HCl, which increases the acidity of hydrothermal fluids and the availability of Cl - to complex with the REE. These simulations highlight how fluid-rock reaction and temperature affect the mobility of REE in hydrothermal ore-forming systems.

58 GEOSCIENCES↗
DOE OSTI2020

Materials Data on Er by Materials Project

Er is alpha La structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Er sites. In the first Er site, Er is bonded to twelve Er atoms to form a mixture of face, edge, and corner-sharing ErEr12 cuboctahedra. There are six shorter (3.49 Å) and six longer (3.52 Å) Er–Er bond lengths. In the second Er site, Er is bonded to twelve Er atoms to form a mixture of face, edge, and corner-sharing ErEr12 cuboctahedra. All Er–Er bond lengths are 3.52 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(Mg4Al3)4 by Materials Project

Er(Mg4Al3)4 is gamma-brass-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are five inequivalent Mg sites. In the first Mg site, Mg is bonded in a 1-coordinate geometry to seven Mg, one Er, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.12–3.38 Å. The Mg–Er bond length is 3.11 Å. There are a spread of Mg–Al bond distances ranging from 2.82–3.14 Å. In the second Mg site, Mg is bonded in a 9-coordinate geometry to three equivalent Mg, one Er, and twelve Al atoms. All Mg–Mg bond lengths are 3.16 Å. The Mg–Er bond length is 3.30 Å. There are a spread of Mg–Al bond distances ranging from 3.16–3.24 Å. In the third Mg site, Mg is bonded in a 3-coordinate geometry to seven Mg, one Er, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.05–3.17 Å. The Mg–Er bond length is 3.59 Å. There are a spread of Mg–Al bond distances ranging from 2.87–3.21 Å. In the fourth Mg site, Mg is bonded in a 11-coordinate geometry to five Mg and six Al atoms. Both Mg–Mg bond lengths are 3.05 Å. There are a spread of Mg–Al bond distances ranging from 3.06–3.12 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. Both Mg–Mg bond lengths are 3.05 Å. There are a spread of Mg–Al bond distances ranging from 2.95–3.31 Å. Er is bonded in a 12-coordinate geometry to seven Mg and nine Al atoms. There are six shorter (3.21 Å) and three longer (3.22 Å) Er–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are one shorter (2.68 Å) and two longer (2.75 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 12-coordinate geometry to eight Mg, one Er, and three Al atoms. Both Al–Al bond lengths are 2.75 Å. In the third Al site, Al is bonded in a distorted q6 geometry to seven Mg, one Er, and three Al atoms. There are one shorter (2.71 Å) and one longer (2.78 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(TiGa2)2 by Materials Project

Er(TiGa2)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Er is bonded in a distorted square co-planar geometry to twelve Ga atoms. There are four shorter (2.87 Å) and eight longer (3.32 Å) Er–Ga bond lengths. Ti is bonded in a 10-coordinate geometry to two equivalent Ti and eight Ga atoms. Both Ti–Ti bond lengths are 2.73 Å. All Ti–Ga bond lengths are 2.79 Å. There are seven inequivalent Ga sites. In the first Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Ti, and four Ga atoms. There are two shorter (2.68 Å) and two longer (2.90 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Ti, and four Ga atoms. There are two shorter (2.68 Å) and two longer (2.90 Å) Ga–Ga bond lengths. In the third Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Ti, and four Ga atoms. Both Ga–Ga bond lengths are 2.90 Å. In the fourth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Ti, and four Ga atoms. Both Ga–Ga bond lengths are 2.68 Å. In the fifth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Ti, and four Ga atoms. Both Ga–Ga bond lengths are 2.68 Å. In the sixth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Ti, and four Ga atoms. Both Ga–Ga bond lengths are 2.90 Å. In the seventh Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Er, four equivalent Ti, and four Ga atoms.

36 MATERIALS SCIENCE↗
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(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↗