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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Leaving in the lead: Priorities for perovskite photovoltaics

The need for moving electricity generation to a sustainable model requires the development of low cost ubiquitous photovoltaics (PVs) to harvest the planet’s primary energy source, the Sun. Building upon the successes of Si-based and CdTe-based PV technologies, PVs with lower-embodied energy and requiring lower carbon dioxide equivalent to produce will be required to meet long-term sustainability goals. In particular, thin-film technologies, such as high-efficiency metal halide perovskite (MHP) PV modules, provide avenues to reduced embodied energy, lower energy payback times, and enabling energy-dense tandems [H. M. Wikoff et al., Joule 6(7), 1710–1725 (2022) and V. Fthenakis, Renewable Sustainable Energy Rev. 13(9), 2746–2750 (2009)]. The ability to improve efficiency and lower energy payback time of next generation thin-film PV modules is a critical foundation for green H2 and electrification more broadly. In this regard, Pb-based MHP-PVs have separated themselves as a result of the high-efficiencies that can be realized across a range of electronic gaps. Questions regarding Pb-based MHP-PVs that are often asked, as the challenges of efficiency and reliability are met, revolve around the “problem” of the Pb content. Specifically, “does Pb toxicity preclude MHP-PV modules from being deployed at the TW scale?” To provide this sense of scale, in 2021, the United States burned 10.5 quads of coal, with 90% of that used for electricity generation. Given the energy content of coal of 29 MJ/kg and a residual lead content in that coal of 30 mg/kg, electricity generation from coal resulted in more lead emitted into the atmosphere than what would be required to produce over 2 TW of MHP-PV name plate capacity (assuming a 20% module efficiency and an ∼700 nm active layer). This amounts to more PV power than has been deployed across all PV technologies and geographies to date. This only includes US coal consumption; the rest of the world would be much larger. This example illustrates the scale of the material usage relative to the energy production. Imagine a power-generation technology that offsets these Pb emissions from coal and essentially sequesters this Pb content between two sheets of impermeable glass. Why should we let Pb’s history of misuse prevent it from being included in next generation PV modules that can enable a sustainable energy future?

14 SOLAR ENERGY↗
DOE OSTI2023

Potassium jarosite seeding of soils decreases lead and arsenic bioaccessibility: A path toward concomitant remediation

Soils are common sources of metal(loid) contaminant exposure globally. Lead (Pb) and arsenic (As) are of paramount concern due to detrimental neurological and carcinogenic health effects, respectively. Pb and/or As contaminated soils require remediation, typically leading to excavation, a costly and environmentally damaging practice of removing soil to a central location (e.g., hazardous landfill) that may not be a viable option in low-income countries. Chemical remediation techniques may allow for in situ conversion of soil contaminants to phases that are not easily mobilized upon ingestion; however, effective chemical remediation options are limited. Here, we have successfully tested a soil remediation technology using potted soils that relies on converting soil Pb and As into jarosite-group minerals, such as plumbojarosite (PLJ) and beudantite, possessing exceptionally low bioaccessibility [i.e., solubility at gastric pH conditions (pH 1.5 to 3)]. Across all experiments conducted, all new treatment methods successfully promoted PLJ and/or beudantite conversion, resulting in a proportional decrease in Pb and As bioaccessibility. Increasing temperature resulted in increased conversion to jarosite-group minerals, but addition of potassium (K) jarosite was most critical to Pb and As bioaccessibility decreases. Our methods of K-jarosite treatment yielded <10% Pb and As bioaccessibility compared to unamended soil values of approximately 70% and 60%, respectively. In conclusion, the proposed treatment is a rare dual remediation option that effectively treats soil Pb and As such that potential exposure is considerably reduced. Research presented here lays the foundation for ongoing field application.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Metallothionein expression in Eastern mosquitofish ( Gambusia holbrooki ) exposed to 137 Cs and lead: implications for using metallothionein as a metal exposure biomarker

Given the range of threats facing aquatic ecosystems, it is critical we have monitoring tools to quickly and efficiently identify stressors within ecosystems. Metallothionein’s (MTs) are a group of proteins widely used as biomarkers of metal exposure; however, their suitability has been questioned due to their influenceable nature and ability to be induced by various stressors. Through our study, we sought to (1) evaluate induction of MT in eastern mosquitofish (Gambusia holbrooki) exposed to a radionuclide ( 137 Cs) and metal (Pb), (2) assess the influence of in situ 137 Cs pre-exposure on Pb-induced MT expression, and (3) quantify changes in MT concentrations during Pb depuration. We conducted our experiment in three phases using mosquitofish as a model species: Phase I—pre-exposure to 137 Cs in the field, Phase II—exposure to Pb in the lab immediately following 137 Cs exposure, and Phase III—depuration in the laboratory. We quantified MT concentrations over time and assessed differences among treatments. We did not find in situ exposure of mosquitofish to 137 Cs to induce MT, nor did pre-exposure to 137 Cs appear to influence induction of MT following Pb exposure. Metallothionein was rapidly induced in mosquitofish following Pb exposure; however, MT induction was also observed in control fish. Additionally, there was no apparent relationship between MT and Pb body burdens. During depuration, we found MT concentrations to be highly variable among fish demonstrating no clear response. Furthermore, our study demonstrates the high variability exhibited by MT, the need for further validation of MT as a metal exposure biomarker, and the value in additional research on these proteins under varying exposure scenarios, particularly environmentally realistic concentrations.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Heavy-ion physics at the LHC

Heavy-ion collisions have been part of the programme of the LHC since its conception. The main nucleus–nucleus system is 208 82 + Pb + 208 82 + Pb . During the Runs 1 and 2, the LHC provided Pb+Pb collisions with centre-of-mass energy per nucleon pair √ s NN = 2.76 and 5.02 TeV, Xe+Xe with √ s NN = 5.44 TeV, and p+Pb with √ s NN = 5.02 and 8.16 TeV. The LHC performance with heavy-ion beams is described in Ref. 1. The ALICE detector was conceived to be dedicated to the study of heavy-ion collisions. The ATLAS and CMS experiments participated in the programme since the very beginning, and the LHCb experiment participated since the end of Run 1. Figure 1 shows event displays of Pb+Pb collisions from the four experiments.

Audurier, Benjamin↗
DOE OSTI2020

Variation of lead isotopic composition and atomic weight in terrestrial materials (IUPAC Technical Report)

The isotopic composition and atomic weight of lead are variable in terrestrial materials because its three heaviest stable isotopes are stable end-products of the radioactive decay of uranium ( 238 U to 206 Pb; 235 U to 207 Pb) and thorium ( 232 Th to 208 Pb). The lightest stable isotope, 204 Pb, is primordial. These variations in isotope ratios and atomic weights provide useful information in many areas of science, including geochronology, archaeology, environmental studies, and forensic science. While elemental lead can serve as an abundant and homogeneous isotopic reference, deviations from the isotope ratios in other lead occurrences limit the accuracy with which a standard atomic weight can be given for lead. In a comprehensive review of several hundred publications and analyses of more than 8000 samples, published isotope data indicate that the lowest reported lead atomic weight of a normal terrestrial materials is 206.1462 ± 0.0028 (k = 2), determined for a growth of the phosphate mineral monazite around a garnet relic from an Archean high-grade metamorphic terrain in north-western Scotland, which contains mostly 206 Pb and almost no 204 Pb. The highest published lead atomic weight is 207.9351 ± 0.0005 (k = 2) for monazite from a micro-inclusion in a garnet relic, also from a high-grade metamorphic terrain in north-western Scotland, which contains almost pure radiogenic 208 Pb. When expressed as an interval, the lead atomic weight is [206.14, 207.94]. It is proposed that a value of 207.2 be adopted for the single lead atomic-weight value for education, commerce, and industry, corresponding to previously published conventional atomic-weight values.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on BaPb by Materials Project

BaPb1 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ba is bonded in a 7-coordinate geometry to seven equivalent Pb atoms. There are a spread of Ba–Pb bond distances ranging from 3.71–3.84 Å. Pb is bonded in a 9-coordinate geometry to seven equivalent Ba and two equivalent Pb atoms. Both Pb–Pb bond lengths are 3.18 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PdPb2 by Materials Project

Pb2Pd is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Pd is bonded in a 10-coordinate geometry to two equivalent Pd and eight equivalent Pb atoms. Both Pd–Pd bond lengths are 2.96 Å. All Pd–Pb bond lengths are 3.02 Å. Pb is bonded in a 7-coordinate geometry to four equivalent Pd and three equivalent Pb atoms. There are one shorter (3.25 Å) and two longer (3.43 Å) Pb–Pb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrPb by Materials Project

SrPb crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Sr is bonded in a 5-coordinate geometry to seven equivalent Pb atoms. There are a spread of Sr–Pb bond distances ranging from 3.50–3.74 Å. Pb is bonded in a 5-coordinate geometry to seven equivalent Sr and two equivalent Pb atoms. Both Pb–Pb bond lengths are 3.16 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PtPb2 by Materials Project

PtPb2 is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Pt is bonded in a distorted q6 geometry to two equivalent Pt and eight equivalent Pb atoms. Both Pt–Pt bond lengths are 2.91 Å. All Pt–Pb bond lengths are 3.04 Å. Pb is bonded in a 7-coordinate geometry to four equivalent Pt and three equivalent Pb atoms. There are one shorter (3.23 Å) and two longer (3.42 Å) Pb–Pb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pb2Au by Materials Project

AuPb2 is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Au is bonded in a 10-coordinate geometry to two equivalent Au and eight equivalent Pb atoms. Both Au–Au bond lengths are 2.97 Å. All Au–Pb bond lengths are 3.15 Å. Pb is bonded in a 7-coordinate geometry to four equivalent Au and three equivalent Pb atoms. There are one shorter (3.34 Å) and two longer (3.52 Å) Pb–Pb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pb4IF7 by Materials Project

Pb4IF7 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are four inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 4-coordinate geometry to four equivalent I1- and four equivalent F1- atoms. There are two shorter (3.59 Å) and two longer (3.63 Å) Pb–I bond lengths. All Pb–F bond lengths are 2.42 Å. In the second Pb2+ site, Pb2+ is bonded in a 11-coordinate geometry to eleven F1- atoms. There are a spread of Pb–F bond distances ranging from 2.56–3.07 Å. In the third Pb2+ site, Pb2+ is bonded in a distorted pentagonal planar geometry to four equivalent I1- and five F1- atoms. There are two shorter (3.92 Å) and two longer (3.96 Å) Pb–I bond lengths. There are one shorter (2.29 Å) and four longer (2.46 Å) Pb–F bond lengths. In the fourth Pb2+ site, Pb2+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are four shorter (2.55 Å) and four longer (2.69 Å) Pb–F bond lengths. I1- is bonded in a 4-coordinate geometry to eight Pb2+ and eight equivalent F1- atoms. There are four shorter (3.92 Å) and four longer (3.93 Å) I–F bond lengths. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to four Pb2+ and two equivalent I1- atoms. In the second F1- site, F1- is bonded to four Pb2+ atoms to form a mixture of edge and corner-sharing FPb4 tetrahedra. In the third F1- site, F1- is bonded in a distorted single-bond geometry to four Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on P2Pb8O13 by Materials Project

Pb8P2O13 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are six inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.24–2.98 Å. In the second Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.23–3.12 Å. In the third Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to three O2- atoms. There are two shorter (2.24 Å) and one longer (2.40 Å) Pb–O bond lengths. In the fourth Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.20–2.75 Å. In the fifth Pb2+ site, Pb2+ is bonded in a distorted pentagonal planar geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.35–2.76 Å. In the sixth Pb2+ site, Pb2+ is bonded in a distorted pentagonal planar geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.30–2.65 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.56 Å) and two longer (1.57 Å) P–O bond length. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.55–1.57 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two Pb2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to three Pb2+ and one P5+ atom. In the fifth O2- site, O2- is bonded to four Pb2+ atoms to form a mixture of distorted edge and corner-sharing OPb4 tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to four Pb2+ atoms. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two Pb2+ and one P5+ atom. In the eighth O2- site, O2- is bonded to four Pb2+ atoms to form a mixture of distorted edge and corner-sharing OPb4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on As2Pb8O13 by Materials Project

Pb8O5(AsO4)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are six inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.21–2.63 Å. In the second Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.24–3.02 Å. In the third Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.25–3.03 Å. In the fourth Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.30–2.68 Å. In the fifth Pb2+ site, Pb2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.25–2.97 Å. In the sixth Pb2+ site, Pb2+ is bonded in a distorted pentagonal planar geometry to five O2- atoms. There are a spread of Pb–O bond distances ranging from 2.34–2.70 Å. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.72 Å) and three longer (1.73 Å) As–O bond length. In the second As5+ site, As5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.73 Å) and two longer (1.74 Å) As–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Pb2+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one As5+ atom. In the fourth O2- site, O2- is bonded to four Pb2+ atoms to form a mixture of distorted corner and edge-sharing OPb4 tetrahedra. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one As5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to four Pb2+ atoms. In the eighth O2- site, O2- is bonded to four Pb2+ atoms to form a mixture of distorted corner and edge-sharing OPb4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RhPb2 by Materials Project

Pb2Rh is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Rh is bonded in a 10-coordinate geometry to two equivalent Rh and eight equivalent Pb atoms. Both Rh–Rh bond lengths are 2.97 Å. All Rh–Pb bond lengths are 2.94 Å. Pb is bonded in a 7-coordinate geometry to four equivalent Rh and one Pb atom. The Pb–Pb bond length is 3.22 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pb3(BrO)2 by Materials Project

Pb3O2Br2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 4-coordinate geometry to four equivalent O2- and three Br1- atoms. There are two shorter (2.39 Å) and two longer (2.49 Å) Pb–O bond lengths. There are two shorter (3.53 Å) and one longer (3.67 Å) Pb–Br bond lengths. In the second Pb2+ site, Pb2+ is bonded in a distorted L-shaped geometry to two equivalent O2- and four Br1- atoms. Both Pb–O bond lengths are 2.26 Å. There are a spread of Pb–Br bond distances ranging from 3.04–3.68 Å. In the third Pb2+ site, Pb2+ is bonded in a 2-coordinate geometry to two equivalent O2- and five Br1- atoms. Both Pb–O bond lengths are 2.31 Å. There are a spread of Pb–Br bond distances ranging from 3.16–3.81 Å. O2- is bonded to four Pb2+ atoms to form a mixture of distorted edge and corner-sharing OPb4 tetrahedra. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 1-coordinate geometry to five Pb2+ atoms. In the second Br1- site, Br1- is bonded in a 7-coordinate geometry to seven Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pb3(ClO)2 by Materials Project

Pb3O2Cl2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 7-coordinate geometry to four equivalent O2- and three Cl1- atoms. There are two shorter (2.38 Å) and two longer (2.49 Å) Pb–O bond lengths. There are one shorter (3.43 Å) and two longer (3.44 Å) Pb–Cl bond lengths. In the second Pb2+ site, Pb2+ is bonded in a 2-coordinate geometry to two equivalent O2- and four Cl1- atoms. Both Pb–O bond lengths are 2.25 Å. There are a spread of Pb–Cl bond distances ranging from 2.89–3.61 Å. In the third Pb2+ site, Pb2+ is bonded in a 2-coordinate geometry to two equivalent O2- and four Cl1- atoms. Both Pb–O bond lengths are 2.30 Å. There are a spread of Pb–Cl bond distances ranging from 2.98–3.32 Å. O2- is bonded to four Pb2+ atoms to form a mixture of distorted edge and corner-sharing OPb4 tetrahedra. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four Pb2+ atoms. In the second Cl1- site, Cl1- is bonded in a 7-coordinate geometry to seven Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Te2Pb3(ClO3)2 by Materials Project

Pb3Te2(O3Cl)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 9-coordinate geometry to eight O2- and one Cl1- atom. There are a spread of Pb–O bond distances ranging from 2.57–3.05 Å. The Pb–Cl bond length is 3.32 Å. In the second Pb2+ site, Pb2+ is bonded in a 4-coordinate geometry to four O2- and four Cl1- atoms. There are two shorter (2.46 Å) and two longer (2.61 Å) Pb–O bond lengths. There are a spread of Pb–Cl bond distances ranging from 3.23–3.30 Å. In the third Pb2+ site, Pb2+ is bonded in a 5-coordinate geometry to five O2- and three Cl1- atoms. There are a spread of Pb–O bond distances ranging from 2.44–2.70 Å. There are two shorter (3.32 Å) and one longer (3.33 Å) Pb–Cl bond lengths. There are two inequivalent Te4+ sites. In the first Te4+ site, Te4+ is bonded to four O2- atoms to form distorted edge-sharing TeO4 trigonal pyramids. There are two shorter (1.96 Å) and two longer (2.08 Å) Te–O bond lengths. In the second Te4+ site, Te4+ is bonded in a 3-coordinate geometry to three O2- and one Cl1- atom. There is one shorter (1.88 Å) and two longer (1.91 Å) Te–O bond length. The Te–Cl bond length is 3.31 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Pb2+ and two equivalent Te4+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three Pb2+ and one Te4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to three Pb2+ and one Te4+ atom. In the fourth O2- site, O2- is bonded to three Pb2+ and one Te4+ atom to form distorted edge-sharing OTePb3 tetrahedra. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four Pb2+ and one Te4+ atom. In the second Cl1- site, Cl1- is bonded in a 4-coordinate geometry to four Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ge3Pb5O11 by Materials Project

Pb5Ge3O11 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are six inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded to six O2- atoms to form distorted PbO6 pentagonal pyramids that share corners with four GeO4 tetrahedra and an edgeedge with one GeO4 tetrahedra. There are a spread of Pb–O bond distances ranging from 2.22–2.78 Å. In the second Pb2+ site, Pb2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Pb–O bond distances ranging from 2.47–3.12 Å. In the third Pb2+ site, Pb2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Pb–O bond distances ranging from 2.24–2.89 Å. In the fourth Pb2+ site, Pb2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.48 Å) and three longer (2.80 Å) Pb–O bond lengths. In the fifth Pb2+ site, Pb2+ is bonded to six equivalent O2- atoms to form distorted PbO6 pentagonal pyramids that share corners with six equivalent GeO4 tetrahedra. All Pb–O bond lengths are 2.50 Å. In the sixth Pb2+ site, Pb2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are six shorter (2.69 Å) and three longer (3.03 Å) Pb–O bond lengths. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two PbO6 pentagonal pyramids and a cornercorner with one GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.75–1.84 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent PbO6 pentagonal pyramids and an edgeedge with one PbO6 pentagonal pyramid. All Ge–O bond lengths are 1.78 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Pb2+ and two equivalent Ge4+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to three Pb2+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Pb2+ and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one Ge4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Pb2+ and one Ge4+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to three Pb2+ and one Ge4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to three Pb2+ and one Ge4+ atom.

36 MATERIALS SCIENCE↗