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DOE OSTI2020

Materials Data on CaHfMg6 by Materials Project

CaMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Ca is bonded to twelve Mg atoms to form CaMg12 cuboctahedra that share corners with four equivalent CaMg12 cuboctahedra, corners with eight equivalent HfMg12 cuboctahedra, edges with twenty-four MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with four equivalent HfMg12 cuboctahedra, and faces with twelve MgCa2Hf2Mg8 cuboctahedra. There are a spread of Ca–Mg bond distances ranging from 3.21–3.38 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.24–3.27 Å. There are one shorter (3.21 Å) and one longer (3.22 Å) Mg–Hf bond lengths. In the second Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. There are two shorter (3.03 Å) and two longer (3.40 Å) Mg–Mg bond lengths. Both Mg–Hf bond lengths are 3.16 Å. In the third Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. Both Mg–Hf bond lengths are 3.18 Å. In the fourth Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. Both Mg–Hf bond lengths are 3.17 Å. Hf is bonded to twelve Mg atoms to form HfMg12 cuboctahedra that share corners with four equivalent HfMg12 cuboctahedra, corners with eight equivalent CaMg12 cuboctahedra, edges with twenty-four MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, faces with four equivalent CaMg12 cuboctahedra, and faces with twelve MgCa2Hf2Mg8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaHfMg6 by Materials Project

BaMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Ba is bonded to twelve Mg atoms to form BaMg12 cuboctahedra that share corners with four equivalent BaMg12 cuboctahedra, corners with eight equivalent HfMg12 cuboctahedra, edges with eight equivalent MgBa2Hf2Mg8 cuboctahedra, faces with two equivalent BaMg12 cuboctahedra, faces with four equivalent MgBa2Hf2Mg8 cuboctahedra, and faces with four equivalent HfMg12 cuboctahedra. There are a spread of Ba–Mg bond distances ranging from 3.35–3.57 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Ba, eight Mg, and two equivalent Hf atoms to form distorted MgBa2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgBa2Hf2Mg8 cuboctahedra, edges with four equivalent BaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, faces with two equivalent BaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with six equivalent MgBa2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.34–3.39 Å. There are one shorter (3.34 Å) and one longer (3.36 Å) Mg–Hf bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent Ba, six Mg, and two equivalent Hf atoms. There are one shorter (2.97 Å) and one longer (2.98 Å) Mg–Mg bond lengths. Both Mg–Hf bond lengths are 3.16 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent Ba, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.19 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent Ba, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.20 Å. Hf is bonded to twelve Mg atoms to form HfMg12 cuboctahedra that share corners with four equivalent HfMg12 cuboctahedra, corners with eight equivalent BaMg12 cuboctahedra, edges with eight equivalent MgBa2Hf2Mg8 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, faces with four equivalent BaMg12 cuboctahedra, and faces with four equivalent MgBa2Hf2Mg8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb4HfS4O17 by Materials Project

Rb4HfS4O17 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. there are four inequivalent Rb sites. In the first Rb site, Rb is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Rb–O bond distances ranging from 2.98–3.47 Å. In the second Rb site, Rb is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Rb–O bond distances ranging from 2.88–3.09 Å. In the third Rb site, Rb is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Rb–O bond distances ranging from 2.89–3.52 Å. In the fourth Rb site, Rb is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Rb–O bond distances ranging from 2.83–3.22 Å. Hf is bonded to seven O atoms to form HfO7 pentagonal bipyramids that share corners with three SO4 tetrahedra and edges with two SO4 tetrahedra. There are a spread of Hf–O bond distances ranging from 2.03–2.20 Å. There are four inequivalent S sites. In the first S site, S is bonded to four O atoms to form SO4 tetrahedra that share corners with two equivalent HfO7 pentagonal bipyramids. There are a spread of S–O bond distances ranging from 1.45–1.53 Å. In the second S site, S is bonded to four O atoms to form SO4 tetrahedra that share an edgeedge with one HfO7 pentagonal bipyramid. There is two shorter (1.46 Å) and two longer (1.54 Å) S–O bond length. In the third S site, S is bonded to four O atoms to form SO4 tetrahedra that share an edgeedge with one HfO7 pentagonal bipyramid. There are a spread of S–O bond distances ranging from 1.45–1.55 Å. In the fourth S site, S is bonded to four O atoms to form SO4 tetrahedra that share a cornercorner with one HfO7 pentagonal bipyramid. There are a spread of S–O bond distances ranging from 1.46–1.56 Å. There are seventeen inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Hf and one S atom. In the second O site, O is bonded in a distorted linear geometry to one Rb, one Hf, and one S atom. In the third O site, O is bonded in a distorted single-bond geometry to two Rb and one S atom. In the fourth O site, O is bonded in a distorted single-bond geometry to three Rb and one S atom. In the fifth O site, O is bonded in a 2-coordinate geometry to two Rb, one Hf, and one S atom. In the sixth O site, O is bonded in a 2-coordinate geometry to two Rb, one Hf, and one S atom. In the seventh O site, O is bonded in a single-bond geometry to three Rb and one S atom. In the eighth O site, O is bonded in a distorted single-bond geometry to three Rb and one S atom. In the ninth O site, O is bonded in a 2-coordinate geometry to one Rb, one Hf, and one S atom. In the tenth O site, O is bonded in a 4-coordinate geometry to two Rb, one Hf, and one S atom. In the eleventh O site, O is bonded in a distorted single-bond geometry to three Rb and one S atom. In the twelfth O site, O is bonded in a distorted single-bond geometry to three Rb and one S atom. In the thirteenth O site, O is bonded in a bent 150 degrees geometry to one Hf and one S atom. In the fourteenth O site, O is bonded in a distorted single-bond geometry to two Rb and one S atom. In the fifteenth O site, O is bonded in a distorted single-bond geometry to two Rb and one S atom. In the sixteenth O site, O is bonded in a single-bond geometry to three Rb and one S atom. In the seventeenth O site, O is bonded in a water-like geometry to two Rb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaHfMg6 by Materials Project

NaMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Na is bonded to twelve Mg atoms to form NaMg12 cuboctahedra that share corners with four equivalent NaMg12 cuboctahedra, corners with eight equivalent HfMg12 cuboctahedra, edges with twenty-four MgNa2Hf2Mg8 cuboctahedra, faces with two equivalent NaMg12 cuboctahedra, faces with four equivalent HfMg12 cuboctahedra, and faces with twelve MgNa2Hf2Mg8 cuboctahedra. There are a spread of Na–Mg bond distances ranging from 3.19–3.50 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Na, eight Mg, and two equivalent Hf atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgNa2Hf2Mg8 cuboctahedra, edges with four equivalent NaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgNa2Hf2Mg8 cuboctahedra, faces with two equivalent NaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgNa2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.14–3.27 Å. There are one shorter (3.21 Å) and one longer (3.23 Å) Mg–Hf bond lengths. In the second Mg site, Mg is bonded to two equivalent Na, eight Mg, and two equivalent Hf atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgNa2Hf2Mg8 cuboctahedra, edges with four equivalent NaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgNa2Hf2Mg8 cuboctahedra, faces with two equivalent NaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgNa2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.04–3.40 Å. Both Mg–Hf bond lengths are 3.15 Å. In the third Mg site, Mg is bonded to two equivalent Na, eight Mg, and two equivalent Hf atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with twelve MgNa2Hf2Mg8 cuboctahedra, edges with four equivalent NaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgNa2Hf2Mg8 cuboctahedra, faces with two equivalent NaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgNa2Hf2Mg8 cuboctahedra. Both Mg–Hf bond lengths are 3.11 Å. In the fourth Mg site, Mg is bonded to two equivalent Na, eight Mg, and two equivalent Hf atoms to form MgNa2Hf2Mg8 cuboctahedra that share corners with twelve MgNa2Hf2Mg8 cuboctahedra, edges with four equivalent NaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgNa2Hf2Mg8 cuboctahedra, faces with two equivalent NaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgNa2Hf2Mg8 cuboctahedra. Both Mg–Hf bond lengths are 3.13 Å. Hf is bonded to twelve Mg atoms to form HfMg12 cuboctahedra that share corners with four equivalent HfMg12 cuboctahedra, corners with eight equivalent NaMg12 cuboctahedra, edges with twenty-four MgNa2Hf2Mg8 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, faces with four equivalent NaMg12 cuboctahedra, and faces with twelve MgNa2Hf2Mg8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHfMg6 by Materials Project

KMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent HfMg12 cuboctahedra, edges with eight equivalent MgK2Hf2Mg8 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Hf2Mg8 cuboctahedra, and faces with four equivalent HfMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.33–3.54 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Hf atoms to form distorted MgK2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgK2Hf2Mg8 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with six equivalent MgK2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.28–3.37 Å. There are one shorter (3.31 Å) and one longer (3.35 Å) Mg–Hf bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. There are one shorter (2.98 Å) and one longer (3.01 Å) Mg–Mg bond lengths. Both Mg–Hf bond lengths are 3.16 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.13 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.16 Å. Hf is bonded to twelve Mg atoms to form HfMg12 cuboctahedra that share corners with four equivalent HfMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Hf2Mg8 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Hf2Mg8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfMg6Ni by Materials Project

Mg6HfNi crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded to eight Mg, two equivalent Hf, and two equivalent Ni atoms to form distorted MgHf2Mg8Ni2 cuboctahedra that share corners with four equivalent HfMg10Ni2 cuboctahedra, corners with four equivalent NiHf2Mg10 cuboctahedra, corners with ten equivalent MgHf2Mg8Ni2 cuboctahedra, edges with two equivalent HfMg10Ni2 cuboctahedra, edges with two equivalent NiHf2Mg10 cuboctahedra, edges with six MgHf2Mg8Ni2 cuboctahedra, faces with two equivalent HfMg10Ni2 cuboctahedra, faces with two equivalent NiHf2Mg10 cuboctahedra, and faces with six MgHf2Mg8Ni2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 2.92–3.07 Å. There are one shorter (3.08 Å) and one longer (3.15 Å) Mg–Hf bond lengths. There are one shorter (3.05 Å) and one longer (3.17 Å) Mg–Ni bond lengths. In the second Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, two equivalent Hf, and two equivalent Ni atoms. There are one shorter (3.07 Å) and one longer (3.15 Å) Mg–Mg bond lengths. Both Mg–Hf bond lengths are 3.03 Å. Both Mg–Ni bond lengths are 2.96 Å. In the third Mg site, Mg is bonded in a 2-coordinate geometry to six Mg and two equivalent Ni atoms. Both Mg–Mg bond lengths are 2.97 Å. Both Mg–Ni bond lengths are 2.99 Å. In the fourth Mg site, Mg is bonded to ten Mg and two equivalent Hf atoms to form MgHf2Mg10 cuboctahedra that share corners with six equivalent MgHf2Mg10 cuboctahedra, edges with four equivalent HfMg10Ni2 cuboctahedra, edges with eight equivalent MgHf2Mg8Ni2 cuboctahedra, faces with two equivalent HfMg10Ni2 cuboctahedra, faces with six MgHf2Mg8Ni2 cuboctahedra, and faces with six equivalent NiHf2Mg10 cuboctahedra. Both Mg–Hf bond lengths are 3.00 Å. Hf is bonded to ten Mg and two equivalent Ni atoms to form distorted HfMg10Ni2 cuboctahedra that share corners with four equivalent NiHf2Mg10 cuboctahedra, corners with six equivalent HfMg10Ni2 cuboctahedra, corners with eight equivalent MgHf2Mg8Ni2 cuboctahedra, edges with two equivalent NiHf2Mg10 cuboctahedra, edges with eight MgHf2Mg8Ni2 cuboctahedra, faces with two equivalent HfMg10Ni2 cuboctahedra, faces with two equivalent NiHf2Mg10 cuboctahedra, and faces with six MgHf2Mg8Ni2 cuboctahedra. Both Hf–Ni bond lengths are 2.97 Å. Ni is bonded to ten Mg and two equivalent Hf atoms to form NiHf2Mg10 cuboctahedra that share corners with four equivalent HfMg10Ni2 cuboctahedra, corners with six equivalent NiHf2Mg10 cuboctahedra, corners with eight equivalent MgHf2Mg8Ni2 cuboctahedra, edges with two equivalent HfMg10Ni2 cuboctahedra, edges with four equivalent MgHf2Mg8Ni2 cuboctahedra, faces with two equivalent HfMg10Ni2 cuboctahedra, faces with two equivalent NiHf2Mg10 cuboctahedra, and faces with ten MgHf2Mg8Ni2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Novel gas exposure system for the controlled exposure of plants to gaseous hydrogen fluoride

Abstract Plants can serve as sensitive bioindicators of the presence of contaminant vapors in the atmosphere. This work describes a novel laboratory-based gas exposure system capable of calibrating plants as bioindicators for the detection and delineation of the atmospheric contaminant hydrogen fluoride (HF) as a preparatory step for monitoring release emissions. To evaluate changes in plant phenotype and stress-induced physiological effects attributed to HF alone, the gas exposure chamber must have additional controls to simulate otherwise optimal plant growth conditions including variables such as light intensity, photoperiod, temperature, and irrigation. The exposure system was designed to maintain constant growth conditions during a series of independent experiments that varied between optimal (control) and stressful (HF exposure) conditions. The system was also designed to ensure the safe handling and application of HF. An initial system calibration introduced HF gas into the exposure chamber and monitored HF concentrations by cavity ring-down spectroscopy for a 48-h period. Stable concentrations inside the exposure chamber were observed after approximately 15 h, and losses of HF to the system ranged from 88 to 91%. A model plant species ( Festuca arundinacea ) was then exposed to HF for 48 h. Visual phenotype stress-induced responses aligned with symptoms reported in the literature for fluoride exposure (tip dieback and discoloration along the dieback transition margin). Fluoride concentrations in exposed tissues compared to control tissues confirmed enhanced fluoride uptake due to HF exposure. The system described herein can be applied to other reactive atmospheric pollutants of interest in support of bioindicator research.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Trace Chemical Detection Using Intercalated MXenes as a Signal Enhancing Substrate in Optical Probes

MXenes are 2D materials composed of layered transition metal nitrides or carbides. These materials are synthesized by HF exfoliation from MAX phases (Ti{sub 3}AlC{sub 2}). The 2D nanomaterial was synthesized by the removal of the 'A' element, resulting in a Mxene product (Ti{sub 3}C{sub 2}). MXenes have the general formula M{sub n+1}X{sub n}T{sub x}, where M is an early transition metal, X is Carbon and/or Nitrogen, and T accounts for surface terminated functional groups such as Fluoride, hydroxyl, and oxygen. These materials have very unique properties, similar to graphene, that allows them to be applied in a variety of trace detection techniques including surface-enhanced Raman spectroscopy (SERS). MXenes have also been demonstrated to selectively uptake uranyl ion, UO{sub 2}{sup 2+}. If this property can be combined with SERS or fluorescence detection, it may be possible to use MXenes as the basis for an alternative method to kinetic phosphorescence analysis (KPA) for trace uranyl measurements. Objectives: To confirm that MXene Nano materials are suitable substrates for SERS and sensor development by enhancing Raman signaling. To determine if certain MXene preparation methods yield materials that are more suitable for trace sensing methods. To determine uranyl uptake properties of these MXene materials and test them for analytical signals. Sample Preparation: Preparation of Ti{sub 3}C{sub 2}MXene (at FSU). MXenes were prepared by etching Al from Ti{sub 3}AlC{sub 2} (MAX phase)material. Two etching techniques yield different MXene products: LiF/HCl: Milder reaction, larger MXene flakes. HF: Harsher reaction, smaller flakes, larger layer separation. Products washed to remove etchant, vacuum filtered, and dried. Dried MXene flakes are air-stable. Film preparation for sensor testing (at SRNL): Suspend powder in diH{sub 2}O, purge with Ar, sonicate for 30 min. Centrifuge and collect supernate with suspended particles. Observed LiF-etched Mxene yielded a higher density of particles and darker collected solution. Drop-cast (4 ml) supernate onto slides and dried with Ar. For Rhodamine B (RhB) testing, drop-cast 4 ml drops onto Mxene spots and dried with Ar. Scanning Electron Microscopy conditions: 10 kV Beam energy, high vacuum; Working distance of 8 mm; beam penetration depth appx. 4 microns, beam spot size appx. 2 nanometers. Results: Detection of aluminum correlates with bright spots on image. Presence of aluminum shows that LiF/HCl etching was less thorough than HF etching. Trace Cl detection in LiF images suggests incomplete rinsing. HF has smaller feature size, more layer structure, and increased homogeneity, consistent with expectations. Macroscopic Raman spectroscopy measurements: 532 nm excitation, ∼50 mW with a ∼100 micron spot size (InPhotonics RPB probe). Kaiser Optical Holospec f/1.8 spectrometer with cooled (-60 deg.C) Andor iDus OE420 CCD. LiF 1x supernate showed good signal for trace measurements of Rhodamine B. HF and 1/4x LiF supernates showed little Mxene or Rhodamine B signal. Low deposition densities led to excess background signal from glass slides. For LiF film, response is linear with Rhodamine B concentration over range tested. Will retest with Raman microscope (∼1 micron spot size) to characterize SERS of more dilute LiF and HF etched Mxenes. Conclusions: The LiF etched material was more suitable for macroscopic SERS measurements because it was more concentrated, resulting in a thicker film than the HF etched Mxene and diluted LiF sample. However, the other materials may give greater SERS enhancements, which we hope to determine from measurements with the Raman microscope. From characterization with SEM we concluded that the HF etched Mxene is more uniform/homogenous and has smaller particle size than the LiF etched Mxene. There is still aluminum present in both samples indicating that etching wasn't complete, but the removal of the aluminum was more efficient in the HF method. Path Forward: Observe SERS with Raman microscopy, to obtain better signals for the more diluted samples and be able to compare enhancement effects for the different MXenes. Characterize uranyl sorption into MXene films and test Raman and fluorescence signals. Revisit the etching conditions to improve removal of aluminum. FSU and SRNL will continue to collaborate to create and characterize different Mxene materials and test their usefulness for sensor applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Hf5Te4 by Materials Project

Hf5Te4 is Titanium telluride structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 5-coordinate geometry to five equivalent Te atoms. There are four shorter (2.92 Å) and one longer (2.93 Å) Hf–Te bond lengths. In the second Hf site, Hf is bonded in a distorted square co-planar geometry to four equivalent Te atoms. All Hf–Te bond lengths are 3.13 Å. Te is bonded in a 6-coordinate geometry to six Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf5Si3 by Materials Project

Hf5Si3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 5-coordinate geometry to five equivalent Si atoms. There are a spread of Hf–Si bond distances ranging from 2.71–2.96 Å. In the second Hf site, Hf is bonded in a 6-coordinate geometry to six equivalent Si atoms. All Hf–Si bond lengths are 2.80 Å. Si is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf5Ge3 by Materials Project

Hf5Ge3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 6-coordinate geometry to six equivalent Ge atoms. All Hf–Ge bond lengths are 2.84 Å. In the second Hf site, Hf is bonded in a 5-coordinate geometry to five equivalent Ge atoms. There are a spread of Hf–Ge bond distances ranging from 2.74–2.99 Å. Ge is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3Si2 by Materials Project

Hf3Si2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 6-coordinate geometry to six equivalent Si atoms. There are two shorter (2.73 Å) and four longer (2.80 Å) Hf–Si bond lengths. In the second Hf site, Hf is bonded in a square co-planar geometry to four equivalent Si atoms. All Hf–Si bond lengths are 2.78 Å. Si is bonded in a 9-coordinate geometry to eight Hf and one Si atom. The Si–Si bond length is 2.46 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf5Sn3 by Materials Project

Hf5Sn3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 5-coordinate geometry to five equivalent Sn atoms. There are a spread of Hf–Sn bond distances ranging from 2.91–3.13 Å. In the second Hf site, Hf is bonded in a 6-coordinate geometry to six equivalent Sn atoms. All Hf–Sn bond lengths are 2.97 Å. Sn is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf5Ga3 by Materials Project

Hf5Ga3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 6-coordinate geometry to six equivalent Ga atoms. All Hf–Ga bond lengths are 2.85 Å. In the second Hf site, Hf is bonded in a 5-coordinate geometry to five equivalent Ga atoms. There are a spread of Hf–Ga bond distances ranging from 2.74–3.09 Å. Ga is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2Fe by Materials Project

Hf2Fe crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 12-coordinate geometry to six equivalent Fe atoms. All Hf–Fe bond lengths are 2.65 Å. In the second Hf site, Hf is bonded in a 2-coordinate geometry to four equivalent Fe atoms. There are two shorter (2.73 Å) and two longer (3.06 Å) Hf–Fe bond lengths. Fe is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3Te2 by Materials Project

Hf3Te2 crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two Hf3Te2 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 4-coordinate geometry to four equivalent Te atoms. All Hf–Te bond lengths are 2.95 Å. In the second Hf site, Hf is bonded in a distorted linear geometry to two equivalent Te atoms. Both Hf–Te bond lengths are 3.04 Å. Te is bonded in a 5-coordinate geometry to five Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3(Bi5Cl9)2 by Materials Project

Hf3BiCl18(Bi)9 crystallizes in the hexagonal P6_3 space group. The structure is zero-dimensional and consists of two Bi clusters and two Hf3BiCl18 clusters. In each Bi cluster, there are three inequivalent Bi sites. In the first Bi site, Bi is bonded in a 4-coordinate geometry to four Bi atoms. There are a spread of Bi–Bi bond distances ranging from 3.12–3.24 Å. In the second Bi site, Bi is bonded in a 4-coordinate geometry to four Bi atoms. There are one shorter (3.13 Å) and one longer (3.18 Å) Bi–Bi bond lengths. In the third Bi site, Bi is bonded in a 6-coordinate geometry to two equivalent Bi atoms. In each Hf3BiCl18 cluster, Hf is bonded in an octahedral geometry to six Cl atoms. There are a spread of Hf–Cl bond distances ranging from 2.38–2.56 Å. Bi is bonded in a trigonal planar geometry to three equivalent Cl atoms. All Bi–Cl bond lengths are 2.75 Å. There are six inequivalent Cl sites. In the first Cl site, Cl is bonded in a single-bond geometry to one Hf atom. In the second Cl site, Cl is bonded in a single-bond geometry to one Hf atom. In the third Cl site, Cl is bonded in a bent 120 degrees geometry to one Hf and one Bi atom. In the fourth Cl site, Cl is bonded in a single-bond geometry to one Hf atom. In the fifth Cl site, Cl is bonded in a single-bond geometry to one Hf atom. In the sixth Cl site, Cl is bonded in a single-bond geometry to one Hf atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrHfO4 by Materials Project

PrHfO4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Pr4+ sites. In the first Pr4+ site, Pr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.34–2.69 Å. In the second Pr4+ site, Pr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.33–2.69 Å. In the third Pr4+ site, Pr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.33–2.72 Å. In the fourth Pr4+ site, Pr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.33–2.68 Å. In the fifth Pr4+ site, Pr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.33–2.70 Å. In the sixth Pr4+ site, Pr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.34–2.68 Å. In the seventh Pr4+ site, Pr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.34–2.69 Å. In the eighth Pr4+ site, Pr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Pr–O bond distances ranging from 2.34–2.66 Å. There are eight inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.12–2.50 Å. In the second Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.11–2.57 Å. In the third Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.12–2.56 Å. In the fourth Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.10–2.53 Å. In the fifth Hf4+ site, Hf4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.11–2.47 Å. In the sixth Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.11–2.55 Å. In the seventh Hf4+ site, Hf4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.12–2.48 Å. In the eighth Hf4+ site, Hf4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Hf–O bond distances ranging from 2.10–2.52 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the second O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with two OPr4 tetrahedra and edges with three OPr2Hf2 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the fourth O2- site, O2- is bonded to four Pr4+ atoms to form a mixture of corner and edge-sharing OPr4 tetrahedra. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to four Hf4+ atoms. In the sixth O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with two OPr4 tetrahedra and edges with three OPr2Hf2 tetrahedra. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the ninth O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with two OPr4 tetrahedra and edges with three OPr2Hf2 tetrahedra. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to four Hf4+ atoms. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the thirteenth O2- site, O2- is bonded to four Pr4+ atoms to form OPr4 tetrahedra that share corners with nine OPr4 tetrahedra and edges with two OPr2Hf2 tetrahedra. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the fifteenth O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with four OPr4 tetrahedra and edges with three OPr2Hf2 tetrahedra. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the seventeenth O2- site, O2- is bonded to four Pr4+ atoms to form a mixture of corner and edge-sharing OPr4 tetrahedra. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to four Hf4+ atoms. In the nineteenth O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with four OPr2Hf2 tetrahedra and edges with three OPr4 tetrahedra. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the twenty-first O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with ten OPr2Hf2 tetrahedra and an edgeedge with one OPr4 tetrahedra. In the twenty-second O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with four OPr2Hf2 tetrahedra and edges with three OPr4 tetrahedra. In the twenty-third O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the twenty-fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the twenty-fifth O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with four OPr4 tetrahedra and edges with three OPr2Hf2 tetrahedra. In the twenty-sixth O2- site, O2- is bonded in a 2-coordinate geometry to four Hf4+ atoms. In the twenty-seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the twenty-eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the twenty-ninth O2- site, O2- is bonded to four Pr4+ atoms to form OPr4 tetrahedra that share corners with nine OPr4 tetrahedra and edges with two OPr2Hf2 tetrahedra. In the thirtieth O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms. In the thirty-first O2- site, O2- is bonded to two Pr4+ and two Hf4+ atoms to form distorted OPr2Hf2 tetrahedra that share corners with two OPr4 tetrahedra and edges with three OPr2Hf2 tetrahedra. In the thirty-second O2- site, O2- is bonded in a 4-coordinate geometry to two Pr4+ and two Hf4+ atoms.

36 MATERIALS SCIENCE↗