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Evidence of molecular hydrogen trapped in two-dimensional layered titanium carbide-based MXene

Two-dimensional transition metal carbides and nitrides (MXenes) are one of the largest and fastest growing families of materials. The presence of molecular hydrogen at ambient conditions in a MXene (Ti 3 C 2 T x , where T x represents a surface terminating species, including O, OH, and F) material is revealed here by inelastic and elastic neutron scatterings. The inelastic neutron-scattering spectrum measured at 5 K shows a peak at 14.6 meV, presenting a clear indication of the presence of parahydrogen in the MXene synthesized using 48% hydrofluoric acid and annealed at 110°C in vacuum prior to the measurement. An increase in the measurement temperature gradually reduces the peak intensity and increases the peak width due to the mobility of the molecular hydrogen in confinement. The presence of molecular hydrogen is confirmed further from the observed elastic intensity drop in a fixed energy-window scan of elastic intensity measurements in the temperature range of 10–35 K. Using milder etching conditions, ion intercalation, or an increase in the annealing temperature all result in the absence of the trapped hydrogen molecules in MXene. Here, the results of this paper can guide the development of MXene materials with desired properties and improve our understanding of the behavior of MXenes in applications ranging from supercapacitors to hydrogen evolution reaction catalysis and hydrogen storage.

36 MATERIALS SCIENCE↗

A new method for measuring refractory corrosion of ceramics in glass

Abstract Nuclear waste glass vitrification furnaces are lined with refractory ceramic blocks to contain the molten glass. The refractory liner is susceptible to corrosion and has a finite service lifetime. For this reason, predicting the refractory corrosion in contact with molten glass is integral to estimating melter service lifetime. Standardized laboratory tests varying time and temperature are commonly performed to estimate refractory material loss as a function of glass composition. These data are time and resource‐intensive to collect and are susceptible to considerable measurement error. In order to accelerate glass formulation and design for nuclear waste vitrification, methods are needed to increase laboratory‐scale throughput while maintaining data quality. In this work, a method to remove the residual glass from a corroded coupon using hydrofluoric acid is presented that accelerates the throughput of sample analysis while simultaneously facilitating more accurate measurements.

Amoroso, Jake W. [Savannah River National Laborato↗

The challenge of acquiring a satisfactory EBSD result of CWSR Zircaloy-4 cladding tube

This article presents a methodology combining SEM, EDS, conventional EBSD, and transmission-EBSD to analyse a recrystallised Zircaloy-4 sheet and cold-worked stress-relieved (CWSR) Zircaloy-4 cladding in unprecedented detail. Second-phase precipitates (SPPs) in Zircaloy-4 specimens were revealed after chemical polishing using a solution containing hydrofluoric acid (HF). Pitting corrosion of Zircaloy-4 specimens was revealed after electropolishing using an electrolyte containing HClO4. A zirconium coupon without SPPs was used to confirm the chemical response of SPPs on surface morphology. Intrinsic features of cold-worked Zircaloy-4 such as relatively small grain sizes, high dislocation density, and complex microstructure make it significantly more difficult to collect excellent EBSD results compared to recrystallised Zircaloy-4. The fine hydride structure of as-hydrided CWSR Zircaloy-4 cladding further increases the level of challenge on EBSD analysis.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Determination of Main Components of Glass-Forming Cu–Zr Alloys

A rapid procedure is developed for determination of copper and zirconium in their binary alloys Cu{sub 100–x}Zr{sub x} in the content ranges corresponding to the region of bulk amorphization (x = 30–70) using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The spectrometer operating conditions are optimized, and the analytical spectral lines (Cu II 224.700 nm and Zr II 354.262 nm) are selected, as well as calibration method and sampling procedure: dissolution in the mixture of HNO{sub 3} and HF with addition of HCl, providing for the minimum standard deviation of the analytical signal. A procedure of oxygen determination by inert gas fusion technique and a procedure for determination of copper by spectrophotometry and zirconium by gravimetric analysis in a single sample together with quality control of ICP-AES are developed for the considered alloys. The results of analysis of Cu{sub 100–x}Zr{sub x} alloys according to the developed procedures agree well between themselves and accounting for adjustment of oxygen content agree within the error limits (not more than 0.5 wt %) with the added content of copper and zirconium upon synthesis.

36 MATERIALS SCIENCE↗

Electrochemical Polishing Applications and EIS of a Novel Choline Chloride-Based Ionic Liquid

Minimal surface roughness is a critical feature for high-field superconducting radio frequency (SRF) cavities used to engineer particle accelerators. Current methods for polishing Niobium cavities typically utilize solutions containing a mixture of concentrated sulfuric and hydrofluoric acid. Polishing processes such as these are effective, yet there are many hazards and costs associated with the use (and safe disposal) of the concentrated acid solutions. An alternative method for electrochemical polishing of the cavities was explored using a novel ionic liquid solution containing choline chloride. Potentiostatic electrochemical impedance spectroscopy (EIS) was used to analyze the ionic polishing solution. Final surface roughness of the Nb was found to be comparable to that of the acid-polishing method, as assessed by atomic force microscopy (AFM). This indicates that ionic liquid-based electrochemical polishing of Nb is a viable replacement for acid-based methods for preparation of SRF cavities.

36 MATERIALS SCIENCE↗

Electrochemical Polishing Applications and EIS of a Vitamin B{sub 4}-Based Ionic Liquid

Modern particle accelerators require minimal interior surface roughness for Niobium superconducting radio frequency (SRF) cavities. Polishing of the Nb is currently achieved via electrochemical polishing with concentrated mixtures of sulfuric and hydrofluoric acids. This acid-based approach is effective at reducing the surface roughness to acceptable levels for SRF use, but due to acid-related hazards and extra costs (including safe disposal of used polishing solutions), an acid-free method would be preferable. This study focuses on an alternative electrochemical polishing method for Nb, using a novel ionic liquid solution containing choline chloride, also known as Vitamin B{sub 4} (VB{sub 4}). Potentiostatic electrochemical impedance spectroscopy (EIS) was also performed on the VB4-based system. Nb polished using the VB4-based method was found to have a final surface roughness comparable to that achieved via the acid-based method, as assessed by atomic force microscopy (AFM). These findings indicate that acid-free VB{sub 4}-based electrochemical polishing of Nb represents a promising replacement for acid-based methods of SRF cavity preparation.

36 MATERIALS SCIENCE↗

TiO 2 Nanocoatings with Controllable Crystal Type and Nanoscale Topography on Zirconia Implants to Accelerate Bone Formation

In dentistry, zirconia implants have emerged as a promising alternative for replacing missing teeth due to their superior aesthetic performance and chemical stability. To improve the osseointegration of zirconia implants, modifying their surface with hierarchical micro/nanotopography and bioactive chemical composition are two effective ways. In this work, a microscale topography was prepared on a zirconia surface using hydrofluoric acid etching, and then a 50 nm TiO 2 nanocoating was deposited via atomic layer deposition (ALD). Subsequently, an annealing treatment was used to transform the TiO 2 from amorphous to anatase and simultaneously generate nanoscale topography. Various investigations into the coating surface morphology, topography, wettability, and chemical composition were carried out using scanning electron microscopy, white light interferometry, contact‐angle measurement, X‐ray diffraction, and X‐ray photoelectron spectroscopy. In addition, in vitro cytocompatibility and osteogenic potential performance of the coatings were evaluated by human bone marrow mesenchymal stem cells (hBMSCs), and in vivo osseointegration performance was assessed in a rat femoral condyle model. Moreover, the possible mechanism was also investigated. The deposition of TiO 2 film with/without annealing treatment did not alter the microscale roughness of the zirconia surface, whereas the nanotopography changed significantly after annealing. The in vitro studies revealed that the anatase TiO 2 coating with regular wavelike nanostructure could promote the adhesion and proliferation of osteoblasts and further improve the osteogenic potential in vitro and osseointegration in vivo. These positive effects may be caused by nanoscale topography via the canonical Wnt/ β ‐catenin pathway. The results suggest that using ALD in combination with annealing treatment to fabricate a nanotopographic TiO 2 coating is a promising way to improve the osteogenic properties of zirconia implants.

Li, Nan (ORCID:0000000255156737)↗

Materials Data on F2 by Materials Project

F2 crystallizes in the cubic Pm-3n space group. The structure is zero-dimensional and consists of eight hydrofluoric acid molecules. F is bonded in a 1-coordinate geometry to atoms.

36 MATERIALS SCIENCE↗

Materials Data on H4NF by Materials Project

NH4F is Iron carbide-derived structured and crystallizes in the hexagonal P6_3mc space group. The structure is zero-dimensional and consists of two ammonium molecules and two hydrofluoric acid molecules.

36 MATERIALS SCIENCE↗

Materials Data on Na3SO4F by Materials Project

Na3SO4F crystallizes in the trigonal R3m space group. The structure is three-dimensional and consists of three hydrofluoric acid molecules and one Na3SO4 framework. In the Na3SO4 framework, Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.37 Å. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.49 Å) and three longer (1.50 Å) S–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Na1+ and one S6+ atom to form a mixture of corner and edge-sharing ONa3S trigonal pyramids. In the second O2- site, O2- is bonded to three equivalent Na1+ and one S6+ atom to form a mixture of corner and edge-sharing ONa3S trigonal pyramids.

36 MATERIALS SCIENCE↗

Materials Data on H24OsC8(NF3)2 by Materials Project

FFOs((CH3)4NF)2F2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one difluoroosmium molecule, two hydrofluoric acid molecules, and two (CH3)4NF clusters. In each (CH3)4NF cluster, there are four inequivalent C+1.25- sites. In the first C+1.25- site, C+1.25- is bonded in a 1-coordinate geometry to four H1+ atoms. There are a spread of C–H bond distances ranging from 0.83–1.70 Å. In the second C+1.25- site, C+1.25- is bonded in a 4-coordinate geometry to four H1+ atoms. There are a spread of C–H bond distances ranging from 0.82–1.66 Å. In the third C+1.25- site, C+1.25- is bonded in a 4-coordinate geometry to one N3- and three H1+ atoms. The C–N bond length is 1.12 Å. There are a spread of C–H bond distances ranging from 1.12–1.72 Å. In the fourth C+1.25- site, C+1.25- is bonded in a distorted single-bond geometry to one N3- and three H1+ atoms. The C–N bond length is 1.55 Å. There are a spread of C–H bond distances ranging from 0.80–1.75 Å. N3- is bonded in a 2-coordinate geometry to two C+1.25- atoms. There are twelve inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the third H1+ site, H1+ is bonded in a bent 150 degrees geometry to one C+1.25- and one F1- atom. The H–F bond length is 1.44 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the fifth H1+ site, H1+ is bonded in a water-like geometry to two C+1.25- atoms. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C+1.25- atom. In the twelfth H1+ site, H1+ is bonded in a distorted L-shaped geometry to two C+1.25- atoms. F1- is bonded in a single-bond geometry to one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on SbH12C4NF4 by Materials Project

CH3C3NH8SbF3HF crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four antimony trifluoride molecules, four hydrofluoric acid molecules, four methane molecules, and four trimethylamine molecules.

36 MATERIALS SCIENCE↗

Materials Data on KCa4Si8H16O28F by Materials Project

(KCa4Si8(H4O7)4)2F2 crystallizes in the tetragonal P4/mnc space group. The structure is three-dimensional and consists of two hydrofluoric acid molecules and one KCa4Si8(H4O7)4 framework. In the KCa4Si8(H4O7)4 framework, K1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All K–O bond lengths are 2.64 Å. Ca2+ is bonded in a 8-coordinate geometry to two equivalent H1+ and six O2- atoms. Both Ca–H bond lengths are 2.36 Å. There are a spread of Ca–O bond distances ranging from 2.33–2.72 Å. Si4+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Si–O bond distances ranging from 1.64–2.01 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one Ca2+ and one H1+ atom. The H–H bond length is 0.77 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two equivalent Ca2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Ca2+, one Si4+, and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on MgH16C4S4N2(O4F3)4 by Materials Project

MgH4S4(NO4)2(CHF3)2(CF2)2(H2O)4(HF)2(O2)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four difluoromethane molecules, four fluoroform molecules, four hydrofluoric acid molecules, four hydrogen peroxide molecules, eight water molecules, and two MgH4S4(NO4)2 clusters. In each MgH4S4(NO4)2 cluster, Mg2+ is bonded in a distorted linear geometry to two equivalent O2- atoms. Both Mg–O bond lengths are 1.91 Å. N5+ is bonded in a distorted trigonal planar geometry to one H1+, one S, and one O2- atom. The N–H bond length is 1.09 Å. The N–S bond length is 1.69 Å. The N–O bond length is 1.24 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N5+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one S atom. The H–S bond length is 1.34 Å. There are two inequivalent S sites. In the first S site, S is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of S–O bond distances ranging from 1.49–1.57 Å. In the second S site, S is bonded in a 2-coordinate geometry to one N5+, one H1+, and one O2- atom. The S–O bond length is 2.41 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one S atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two S atoms. In the third O2- site, O2- is bonded in a single-bond geometry to one S atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one N5+ atom.

36 MATERIALS SCIENCE↗

Materials Data on HF by Materials Project

HF is alpha carbon monoxide-like structured and crystallizes in the orthorhombic Cmc2_1 space group. The structure is zero-dimensional and consists of four hydrofluoric acid molecules. H1+ is bonded in a single-bond geometry to one F1- atom. The H–F bond length is 0.95 Å. F1- is bonded in a single-bond geometry to one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on SbH7F11 by Materials Project

(SbH7F10)2SbH3F8Sb2H12F21(HF)6 crystallizes in the triclinic P1 space group. The structure is one-dimensional and consists of six hydrofluoric acid molecules; one SbH3F8 cluster; one SbH7F10 cluster; and one Sb2H12F21 ribbon oriented in the (1, 0, 0) direction. In the SbH3F8 cluster, Sb is bonded in a trigonal bipyramidal geometry to five F atoms. There are a spread of Sb–F bond distances ranging from 1.87–1.93 Å. There are three inequivalent H sites. In the first H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.49 Å) H–F bond length. In the second H site, H is bonded in a single-bond geometry to two F atoms. There is one shorter (0.97 Å) and one longer (1.65 Å) H–F bond length. In the third H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.50 Å) H–F bond length. There are eight inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one H atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a distorted bent 120 degrees geometry to two H atoms. In the sixth F site, F is bonded in a single-bond geometry to one Sb atom. In the seventh F site, F is bonded in a distorted bent 150 degrees geometry to one Sb and one H atom. In the eighth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the SbH7F10 cluster, there are two inequivalent Sb sites. In the first Sb site, Sb is bonded in a distorted rectangular see-saw-like geometry to four F atoms. There are a spread of Sb–F bond distances ranging from 1.98–2.44 Å. In the second Sb site, Sb is bonded in a 3-coordinate geometry to three F atoms. There are a spread of Sb–F bond distances ranging from 1.92–2.02 Å. There are fourteen inequivalent H sites. In the first H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.01 Å) and one longer (1.40 Å) H–F bond length. In the second H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.51 Å) H–F bond length. In the third H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.47 Å) H–F bond length. In the fourth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.00 Å) and one longer (1.39 Å) H–F bond length. In the fifth H site, H is bonded in a distorted linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.56 Å) H–F bond length. In the sixth H site, H is bonded in a distorted linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.49 Å) H–F bond length. In the seventh H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.02 Å) and one longer (1.36 Å) H–F bond length. In the eighth H site, H is bonded in a distorted linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.53 Å) H–F bond length. In the ninth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.03 Å) and one longer (1.34 Å) H–F bond length. In the tenth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.00 Å) and one longer (1.40 Å) H–F bond length. In the eleventh H site, H is bonded in a distorted linear geometry to two F atoms. There is one shorter (0.99 Å) and one longer (1.49 Å) H–F bond length. In the twelfth H site, H is bonded in a distorted linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.55 Å) H–F bond length. In the thirteenth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.99 Å) and one longer (1.47 Å) H–F bond length. In the fourteenth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.01 Å) and one longer (1.37 Å) H–F bond length. There are twenty inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb and one H atom. In the second F site, F is bonded in a single-bond geometry to one H atom. In the third F site, F is bonded in a bent 120 degrees geometry to one Sb and one H atom. In the fourth F site, F is bonded in a bent 150 degrees geometry to one Sb and one H atom. In the fifth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the sixth F site, F is bonded in a single-bond geometry to one H atom. In the seventh F site, F is bonded in a distorted bent 120 degrees geometry to one Sb and one H atom. In the eighth F site, F is bonded in a water-like geometry to two H atoms. In the ninth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the tenth F site, F is bonded in a distorted single-bond geometry to one Sb atom. In the eleventh F site, F is bonded in a distorted water-like geometry to two H atoms. In the twelfth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the thirteenth F site, F is bonded in a bent 150 degrees geometry to one Sb and one H atom. In the fourteenth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifteenth F site, F is bonded in a distorted bent 120 degrees geometry to two H atoms. In the sixteenth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the seventeenth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the eighteenth F site, F is bonded in a single-bond geometry to one H atom. In the nineteenth F site, F is bonded in a distorted L-shaped geometry to two H atoms. In the twentieth F site, F is bonded in a distorted bent 120 degrees geometry to two H atoms. In the Sb2H12F21 ribbon, there are two inequivalent Sb sites. In the first Sb site, Sb is bonded in an octahedral geometry to six F atoms. There are a spread of Sb–F bond distances ranging from 1.95–2.42 Å. In the second Sb site, Sb is bonded in a 7-coordinate geometry to seven F atoms. There are a spread of Sb–F bond distances ranging from 1.89–2.46 Å. There are twelve inequivalent H sites. In the first H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.47 Å) H–F bond length. In the second H site, H is bonded in a single-bond geometry to one F atom. The H–F bond length is 0.98 Å. In the third H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.99 Å) and one longer (1.45 Å) H–F bond length. In the fourth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.99 Å) and one longer (1.46 Å) H–F bond length. In the fifth H site, H is bonded in a distorted single-bond geometry to two F atoms. There is one shorter (0.97 Å) and one longer (1.59 Å) H–F bond length. In the sixth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.10 Å) and one longer (1.20 Å) H–F bond length. In the seventh H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.03 Å) and one longer (1.33 Å) H–F bond length. In the eighth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (0.99 Å) and one longer (1.50 Å) H–F bond length. In the ninth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.01 Å) and one longer (1.42 Å) H–F bond length. In the tenth H site, H is bonded in a distorted linear geometry to two F atoms. There is one shorter (0.98 Å) and one longer (1.49 Å) H–F bond length. In the eleventh H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.02 Å) and one longer (1.36 Å) H–F bond length. In the twelfth H site, H is bonded in a linear geometry to two F atoms. There is one shorter (1.11 Å) and one longer (1.20 Å) H–F bond length. There are twenty-one inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one H atom. In the third F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifth F site, F is bonded in a distorted bent 120 degrees geometry to two H atoms. In the sixth F site, F is bonded in a single-bond geometry to one Sb and one H atom. In the seventh F site, F is bonded in a distorted bent 120 degrees geometry to one Sb and one H atom. In the eighth F site, F is bonded in a bent 120 degrees geometry to one Sb and one H atom. In the ninth F site, F is bonded in a water-like geometry to two H atoms. In the tenth F site, F is bonded in a distorted bent 120 degrees geometry to one Sb and one H atom. In the eleventh F site, F is bonded in a single-bond geometry to one Sb and one H atom. In the twelfth F site, F is bonded in a bent 120 degrees geometry to one Sb and one H atom. In the thirteenth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the fourteenth F site, F is bonded in a single-bond geometry to one Sb atom. In the fifteenth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the sixteenth F site, F is bonded in a distorted single-bond geometry to one Sb and one H atom. In the seventeenth F site, F is bonded in a bent 120 degrees geometry to two H atoms. In the eighteenth F site, F is bonded in a single-bond geometry to one Sb atom. In the nineteenth F site, F is bonded in a distorted bent 120 degrees geometry to one Sb and one H atom. In the twentieth F site, F is bonded in a water-like geometry to two H atoms. In the twenty-first F site, F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗

Materials Data on K7Th6F31 by Materials Project

K7Th6F31 crystallizes in the trigonal R3 space group. The structure is three-dimensional and consists of three hydrofluoric acid molecules and one K7Th6F30 framework. In the K7Th6F30 framework, there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of K–F bond distances ranging from 2.70–2.83 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of K–F bond distances ranging from 2.71–2.83 Å. In the third K1+ site, K1+ is bonded in a 6-coordinate geometry to six F1- atoms. All K–F bond lengths are 2.79 Å. There are two inequivalent Th4+ sites. In the first Th4+ site, Th4+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Th–F bond distances ranging from 2.26–2.42 Å. In the second Th4+ site, Th4+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Th–F bond distances ranging from 2.27–2.45 Å. There are ten inequivalent F1- sites. In the first F1- site, F1- is bonded in a bent 150 degrees geometry to two Th4+ atoms. In the second F1- site, F1- is bonded to three K1+ and one Th4+ atom to form a mixture of distorted edge and corner-sharing FK3Th tetrahedra. In the third F1- site, F1- is bonded in a bent 150 degrees geometry to two Th4+ atoms. In the fourth F1- site, F1- is bonded to two equivalent K1+ and two Th4+ atoms to form a mixture of distorted edge and corner-sharing FK2Th2 tetrahedra. In the fifth F1- site, F1- is bonded to three K1+ and one Th4+ atom to form a mixture of distorted edge and corner-sharing FK3Th tetrahedra. In the sixth F1- site, F1- is bonded to two equivalent K1+ and two Th4+ atoms to form a mixture of distorted edge and corner-sharing FK2Th2 tetrahedra. In the seventh F1- site, F1- is bonded in a bent 150 degrees geometry to two equivalent Th4+ atoms. In the eighth F1- site, F1- is bonded to three K1+ and one Th4+ atom to form a mixture of distorted edge and corner-sharing FK3Th tetrahedra. In the ninth F1- site, F1- is bonded to three K1+ and one Th4+ atom to form distorted FK3Th tetrahedra that share corners with ten FK2Th2 tetrahedra and edges with five FK3Th tetrahedra. In the tenth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Th4+ atoms.

36 MATERIALS SCIENCE↗

Materials Data on RbAl6H20N5F24 by Materials Project

RbAl4H2F15Al2NH5F8(NH)2(NH4)2H2HF crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of two ammonia molecules; two ammonium molecules; one hydrofluoric acid molecule; one hydrogen molecule; one Al2NH5F8 sheet oriented in the (0, 0, 1) direction; and one RbAl4H2F15 sheet oriented in the (0, 0, 1) direction. In the Al2NH5F8 sheet, there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in an octahedral geometry to six F1- atoms. There are a spread of Al–F bond distances ranging from 1.70–1.97 Å. In the second Al3+ site, Al3+ is bonded in a 6-coordinate geometry to six F1- atoms. There are a spread of Al–F bond distances ranging from 1.70–2.03 Å. N3- is bonded in a tetrahedral geometry to four H1+ atoms. There are a spread of N–H bond distances ranging from 1.02–1.04 Å. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- and one F1- atom. The H–F bond length is 1.63 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a 2-coordinate geometry to two F1- atoms. There is one shorter (1.00 Å) and one longer (1.44 Å) H–F bond length. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. There are eight inequivalent F1- sites. In the first F1- site, F1- is bonded in a linear geometry to two Al3+ atoms. In the second F1- site, F1- is bonded in a linear geometry to two Al3+ atoms. In the third F1- site, F1- is bonded in a single-bond geometry to one Al3+ atom. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to one Al3+ and one H1+ atom. In the fifth F1- site, F1- is bonded in a distorted single-bond geometry to one Al3+ and one H1+ atom. In the sixth F1- site, F1- is bonded in a linear geometry to two Al3+ atoms. In the seventh F1- site, F1- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the eighth F1- site, F1- is bonded in a single-bond geometry to one Al3+ atom. In the RbAl4H2F15 sheet, Rb1+ is bonded in a 4-coordinate geometry to four F1- atoms. There are a spread of Rb–F bond distances ranging from 2.67–2.82 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six F1- atoms to form corner-sharing AlF6 octahedra. The corner-sharing octahedra tilt angles range from 2–19°. There are a spread of Al–F bond distances ranging from 1.70–1.98 Å. In the second Al3+ site, Al3+ is bonded in a distorted octahedral geometry to one H1+ and five F1- atoms. The Al–H bond length is 1.56 Å. There are a spread of Al–F bond distances ranging from 1.76–2.19 Å. In the third Al3+ site, Al3+ is bonded to six F1- atoms to form corner-sharing AlF6 octahedra. The corner-sharing octahedra tilt angles range from 2–19°. There are a spread of Al–F bond distances ranging from 1.71–1.94 Å. In the fourth Al3+ site, Al3+ is bonded in a 5-coordinate geometry to six F1- atoms. There are a spread of Al–F bond distances ranging from 1.67–2.38 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one Al3+ atom. In the second H1+ site, H1+ is bonded in a linear geometry to two F1- atoms. There is one shorter (1.11 Å) and one longer (1.16 Å) H–F bond length. There are fifteen inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Al3+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Al3+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Al3+ atom. In the fourth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two Al3+ atoms. In the fifth F1- site, F1- is bonded in a bent 150 degrees geometry to two Al3+ atoms. In the sixth F1- site, F1- is bonded in a distorted single-bond geometry to one Rb1+ and one Al3+ atom. In the seventh F1- site, F1- is bonded in a distorted single-bond geometry to one Rb1+ and one Al3+ atom. In the eighth F1- site, F1- is bonded in a distorted linear geometry to two Al3+ atoms. In the ninth F1- site, F1- is bonded in a linear geometry to two Al3+ atoms. In the tenth F1- site, F1- is bonded in a linear geometry to two Al3+ atoms. In the eleventh F1- site, F1- is bonded in a bent 150 degrees geometry to two Al3+ atoms. In the twelfth F1- site, F1- is bonded in a single-bond geometry to one Rb1+, one Al3+, and one H1+ atom. In the thirteenth F1- site, F1- is bonded in a 2-coordinate geometry to one Rb1+, one Al3+, and one H1+ atom. In the fourteenth F1- site, F1- is bonded in a bent 150 degrees geometry to two Al3+ atoms. In the fifteenth F1- site, F1- is bonded in a linear geometry to two Al3+ atoms.

36 MATERIALS SCIENCE↗