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All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

A Satellite Infrared Technique for Diurnal Rainfall Variability Studies

Reliable information on the distribution of precipitation at high temporal resolution (<l hour) is essential for understanding the characteristics of convection in a region. Cloud-top infrared (IR) brightness temperatures from geostationary platforms have a weak physical connection to precipitation, however, their high sampling frequency makes them attractive in studying the temporal evolution of cloudiness and convection. On the other hand, microwave-based (MW) observations from lower sampling-frequency polar-orbiting platforms can provide a better physical connection to precipitating hydrometeors. A recent invention in rainfall estimation from a combination of these two sensors involves adjustment of IR estimates using co-existing MW-based precipitation data on a monthly basis. These techniques use the MW data to remove systematic errors in IR rain estimates, while retaining the high sampling frequency of IR observations (approximately every 15-30 minutes). Perhaps of even greater importance to climate and hydrometeorological applications is the separation of mesoscale convective systems into a portion of rain associated with deep convection (hereafter called convective precipitation), and to precipitation falling from more widespread anvil clouds. This current work focuses on estimation of tropical convective and stratiform rainfall. We attempt to answer fundamental questions, such as : is estimation of convective and stratiform precipitation from IR feasible? If so, how accurate can this be? What is the scale dependence of the IR algorithm's performance? To address these questions, quantitative comparisons are performed between coincident IR- and MW-based instantaneous rainfall estimates at the MW 85 Ghz resolution (-12.5 km). Our data set spans a three-month period (January to March, 1996) of MW and IR observations over northern South America (15N-15S and 35W-80W), which includes the Amazon river basin.

Anagnostou, Emmanouil↗
NASA NTRS2008

Impaired Cytogenetic Damage Repair and Cell Cycle Regulation in Response to Ionizing Radiation in Human Fibroblast Cells with Individual Knock-down of 25 Genes

Changes of gene expression profile are one of the most important biological responses in living cells after ionizing radiation (IR) exposure. Although some studies have demonstrated that genes with upregulated expression induced by IR may play important roles in DNA damage sensing, cell cycle checkpoint and chromosomal repair, the relationship between the regulation of gene expression by IR and its impact on cytogenetic responses to ionizing radiation has not been systematically studied. In our present study, the expression of 25 genes selected based on their transcriptional changes in response to IR or from their known DNA repair roles were individually knocked down by siRNA transfection in human fibroblast cells. Chromosome aberrations (CA) and micronuclei (MN) formation were measured as the cytogenetic endpoints. Our results showed that the yield of MN and/or CA formation were significantly increased by suppressed expression of 5 genes that included Ku70 in the DSB repair pathway; XPA in the NER pathway; RPA1 in the MMR pathway; RAD17 and RBBP8 in cell cycle control. Knocked-down expression of 4 genes including MRE11A, RAD51 in the DSB pathway, and SESN1 and SUMO1 showed significant inhibition of cell cycle progression, possibly because of severe impairment of DNA damage repair. Furthermore, loss of XPA, p21 and MLH1 expression resulted in both enhanced cell cycle progression and significantly higher yield of cytogenetic damage, indicating the involvement of these gene products in both cell cycle control and DNA damage repair. Of these 11 genes that affected the cytogenetic response, 9 were up-regulated in the cells exposed to gamma radiation, suggesting that genes transcriptionally modulated by IR were critical to regulating the biological consequences after IR. Failure to express these IR-responsive genes, such as by gene mutation, could seriously change the outcome of the post IR scenario and lead to carcinogenesis.

Zhang, Ye↗
NASA NTRS2011

Image Quality Indicator for Infrared Inspections

The quality of images generated during an infrared thermal inspection depends on many system variables, settings, and parameters to include the focal length setting of the IR camera lens. If any relevant parameter is incorrect or sub-optimal, the resulting IR images will usually exhibit inherent unsharpness and lack of resolution. Traditional reference standards and image quality indicators (IQIs) are made of representative hardware samples and contain representative flaws of concern. These standards are used to verify that representative flaws can be detected with the current IR system settings. However, these traditional standards do not enable the operator to quantify the quality limitations of the resulting images, i.e. determine the inherent maximum image sensitivity and image resolution. As a result, the operator does not have the ability to optimize the IR inspection system prior to data acquisition. The innovative IQI described here eliminates this limitation and enables the operator to objectively quantify and optimize the relevant variables of the IR inspection system, resulting in enhanced image quality with consistency and repeatability in the inspection application. The IR IQI consists of various copper foil features of known sizes that are printed on a dielectric non-conductive board. The significant difference in thermal conductivity between the two materials ensures that each appears with a distinct grayscale or brightness in the resulting IR image. Therefore, the IR image of the IQI exhibits high contrast between the copper features and the underlying dielectric board, which is required to detect the edges of the various copper features. The copper features consist of individual elements of various shapes and sizes, or of element-pairs of known shapes and sizes and with known spacing between the elements creating the pair. For example, filled copper circles with various diameters can be used as individual elements to quantify the image sensitivity limit. Copper line-pairs of various sizes where the line width is equivalent to the spacing between the lines can be used as element-pairs to quantify the image resolution limit.

Burke, Eric↗
NASA NTRS2012

Large Binocular Telescope and Sptizer Spectroscopy of Star-forming Galaxies at 1 < z < 3: Extinction and Star Formation Rate Indicators

We present spectroscopic observations in the rest-frame optical and near- to mid-infrared wavelengths of four gravitationally lensed infrared (IR) luminous star-forming galaxies at redshift 1 < z < 3 from the LUCIFER instrument on the Large Binocular Telescope and the Infrared Spectrograph on Spitzer. The sample was selected to represent pure, actively star-forming systems, absent of active galactic nuclei. The large lensing magnifications result in high signal-to-noise spectra that can probe faint IR recombination lines, including Paα and Brα at high redshifts. The sample was augmented by three lensed galaxies with similar suites of unpublished data and observations from the literature, resulting in the final sample of seven galaxies. We use the IR recombination lines in conjunction with Hα observations to probe the extinction, Av, of these systems, as well as testing star formation rate (SFR) indicators against the SFR measured by fitting spectral energy distributions to far-IR photometry. Our galaxies occupy a range of Av from ∼0 to 5.9 mag, larger than previously known for a similar range of IR luminosities at these redshifts. Thus, estimates of SFR even at z ∼ 2 must take careful count of extinction in the most IR luminous galaxies.We also measure extinction by comparing SFR estimates from optical emission lines with those from far- IR measurements. The comparison of results from these two independent methods indicates a large variety of dust distribution scenarios at 1 < z < 3. Without correcting for dust extinction, the Hα SFR indicator underestimates the SFR; the size of the necessary correction depends on the IR luminosity and dust distribution scenario. Individual SFR estimates based on the 6.2μm polycyclic aromatic hydrocarbon emission line luminosity do not show a systematic discrepancy with extinction, although a considerable, ∼0.2 dex, scatter is observed.

Rujopakarn, W.↗
NASA NTRS2013

The Herschel* PEP-HERMES Luminosity Function- I. Probing the Evolution of PACS Selected Galaxies to z approx. equal to 4

We exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared (IR) luminosity functions (LFs) up to z ∼ 4.We detect very strong luminosity evolution for the total IR LF (LIR ∝ (1 + z)(sup 3.55 +/- 0.10) up to z ∼ 2, and ∝ (1 + z)(sup 1.62 +/- 0.51) at 2 less than z less than approximately 4) combined with a density evolution (∝ (1 + z)(sup −0.57 +/- 0.22) up to z ∼ 1 and ∝ (1 + z)(sup −3.92 +/- 0.34) at 1 less than z less than approximately 4). In agreement with previous findings, the IR luminosity density (ρIR) increases steeply to z ∼ 1, then flattens between z ∼ 1 and z ∼ 3 to decrease at z greater than approximately 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ρIR. Galaxies occupying the well-established SFR-stellar mass main sequence (MS) are found to dominate both the total IR LF and ρIR at all redshifts, with the contribution from off-MS sources (≥0.6 dex above MS) being nearly constant (∼20 per cent of the total ρIR) and showing no significant signs of increase with increasing z over the whole 0.8 < z <2.2 range. Sources with mass in the range 10 ≤ log(M/solar mass) ≤ 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z (greater than approximately 2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event), is followed by an AGN-dominated phase, then evolving towards a local elliptical. On the other hand, moderately star-forming galaxies containing a low-luminosity AGN have various properties suggesting they are good candidates for systems in a transition phase preceding the formation of steady spiral galaxies.

Herschel↗
NASA NTRS2017

Improved Reference Sampling and Subtraction: A Technique for Reducing the Read Noise of Near-Infrared Detector Systems

Near-infrared array detectors, like the James Webb Space Telescope (JWST) NIRSpec's Teledyne's H2RGs, often provide reference pixels and a reference output. These are used to remove correlated noise. Improved reference sampling and subtraction (IRS(exp 2)) is a statistical technique for using this reference information optimally in a leastsquares sense. Compared with the traditional H2RG readout, IRS(exp 2) uses a different clocking pattern to interleave many more reference pixels into the data than is otherwise possible. Compared with standard reference correction techniques, IRS(exp 2) subtracts the reference pixels and reference output using a statistically optimized set of frequency dependent weights. The benefits include somewhat lower noise variance and much less obvious correlated noise. NIRSpec's IRS(exp 2) images are cosmetically clean, with less 1/f banding than in traditional data from the same system. This article describes the IRS(exp 2) clocking pattern and presents the equations needed to use IRS(exp 2) in systems other than NIRSpec. For NIRSpec, applying these equations is already an option in the calibration pipeline. As an aid to instrument builders, we provide our prototype IRS(exp 2) calibration software and sample JWST NIRSpec data. The same techniques are applicable to other detector systems, including those based on Teledyne's H4RG arrays. The H4RG's interleaved reference pixel readout mode is effectively one IRS(exp 2) pattern.

Methods-statistical↗
NASA NTRSDate not supplied

MULTI-OMICS ANALYSIS OF THE IMPACT OF CHRONIC LOW-DOSE RADIATION AND HINDLIMB SUSPENSION ON MURINE BRAIN AND RETINA

The space environment includes hazards like radiation and microgravity which can adversely affect biological systems. We assessed multi-omics multi-tissue NASA GeneLab datasets where 6-month-old female mice were gamma irradiated (IR) and/or hindlimb unloaded (HLU) for 21 days. Whole transcriptome shotgun sequencing (RNA-Seq) and reduced representation bisulfite sequencing (RRBS) of brain and retina samples collected at 4 months post-exposure was performed to better characterize the retinal and neurological responses to spaceflight. We compared epigenomic and transcriptomic profiles within each exposure group for both tissue types to identify correlation (Pearson’s correlation test; p-value < 0.05) between gene expression and DNA methylation levels that may be related to transcriptional regulation. We then obtained genes with methylation-expression correlation that also showed differences in mean expression or dispersion between exposed and control groups (adjusted p-value < 0.25; relaxed to denote ‘hypothesis’) in the brain (37 genes in HLU, 4 in IR, and 156 in HLU+IR) or retina (92 genes in HLU, 1 in IR, and 55 in HLU+IR). Enriched Gene Ontology (GO) terms for these genes are listed in Table 1 for HLU and HLU+IR for both tissue types. No enriched terms and only a few genes were detected with IR-only exposure in the brain (Chmp1a, Limd1, Rab40b, Ubc) and retina (retinoblastoma binding protein Rbbp7). Cellular components related to synapse were enriched in both tissue types. Previous analysis of differentially expressed genes in the retina after 1 month of HLU+IR showed enrichment in the somatodendritic compartment of the neuron, which was also observed in the brain 4 months post-exposure. Interestingly, genes related to ubiquitination showed correlation between methylation and expression and were differentially expressed or dispersed in different exposure groups indicating that this pathway may play an important role in multi-stressor response (Figure 1). The current multi-omics and multi-tissue analysis interrogates the epigenomic and transcriptomic impacts of radiation and hindlimb unloading, in isolation and in combination, on the retina and the brain. The results provide insight into the adaptive response to individual spaceflight hazard analogs and their interplay, as well as hypotheses to be further tested for understanding spaceflight-induced neurological and vision effects.

Prachi Kothiyal↗
DOE OSTI2025

Can Large Language Models Understand Intermediate Representations?

Intermediate Representations (IRs) are essential in compiler design and program analysis, yet their comprehension by Large Language Models (LLMs) remains underexplored. This paper presents a pioneering empirical study to investigate the capabilities of LLMs, including GPT-4, GPT-3, Gemma 2, LLaMA 3.1, and Code Llama, in understanding IRs. We analyze their performance across four tasks: Control Flow Graph (CFG) reconstruction, decompilation, code summarization, and execution reasoning. Our results indicate that while LLMs demonstrate competence in parsing IR syntax and recognizing high-level structures, they struggle with control flow reasoning, execution semantics, and loop handling. Specifically, they often misinterpret branching instructions, omit critical IR operations, and rely on heuristic-based reasoning, leading to errors in CFG reconstruction, IR decompilation, and execution reasoning. The study underscores the necessity for IR-specific enhancements in LLMs, recommending fine-tuning on structured IR datasets and integration of explicit control flow models to augment their comprehension and handling of IR-related tasks.

Jiang, Hailong↗
DOE OSTI2023

Impact of Flow Configurations on Response Time and Data Quality in Real-Time, In-Line Fourier Transform Infrared (FTIR) Monitoring of Viscous Flows

The real-time, in-line monitoring of continuous flow concentrations is widely conducted via infrared (IR) spectrometry by using a flow cell connected to a reactive flow stream. For protective purposes, the IR sensor tip is typically offset from the flow. This offset can cause the formation of a stagnant boundary layer above the sensor, especially when dealing with high-viscosity fluids. As a result, the IR signal response time is often controlled by the slow diffusional exchange of fluid in the boundary layer, as confirmed via 2D computational fluid dynamics (CFD) simulations. We evaluated several flow configuration modifications in a typical IR flow cell in order to identify the changes to the flow dynamics that enable improved response times with minimal changes to the cell configuration: the use of (i) vertical flow, where the standard horizontal flow over the sensor is redirected to contact vertically with the sensor, (ii) a static mixer to create radial flow momentum above the IR sensor, and (iii) horizontal or vertical nozzles to direct the flow toward the IR sensor. The vertical flow configuration did not show any significant improvement over the standard horizontal flow configuration. However, the static mixer, horizontal nozzle, and vertical nozzle configurations all resulted in markedly improved response times and signal quality, albeit at the expense of a higher pressure drop across the flow cell. These results point toward straightforward, user-accessible modifications of in-line IR flow cells that result in significant improvements in signal stability and acquisition times.

42 ENGINEERING↗
DOE OSTI2020

Materials Data on Al9Ir2 by Materials Project

Al9Ir2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ir is bonded in a 9-coordinate geometry to nine Al atoms. There are a spread of Ir–Al bond distances ranging from 2.47–2.61 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded in a linear geometry to two equivalent Ir atoms. In the second Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ir atoms. In the third Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ir atoms. In the fourth Al site, Al is bonded in a distorted bent 120 degrees geometry to two equivalent Ir atoms. In the fifth Al site, Al is bonded in a distorted bent 150 degrees geometry to two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba3NaIr2O9 by Materials Project

Ba3NaIr2O9 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na is bonded to six O atoms to form NaO6 octahedra that share corners with six equivalent IrO6 octahedra and faces with six equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 9–13°. There are two shorter (2.25 Å) and four longer (2.28 Å) Na–O bond lengths. There are two inequivalent Ba sites. In the first Ba site, Ba is bonded to twelve O atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, corners with three equivalent IrO6 octahedra, faces with four equivalent BaO12 cuboctahedra, faces with three equivalent NaO6 octahedra, and faces with four equivalent IrO6 octahedra. The corner-sharing octahedra tilt angles range from 4–16°. There are a spread of Ba–O bond distances ranging from 2.82–3.31 Å. In the second Ba site, Ba is bonded in a 12-coordinate geometry to twelve O atoms. There are a spread of Ba–O bond distances ranging from 2.80–3.33 Å. Ir is bonded to six O atoms to form IrO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent NaO6 octahedra, faces with four equivalent BaO12 cuboctahedra, and a faceface with one IrO6 octahedra. The corner-sharing octahedra tilt angles range from 9–13°. There are a spread of Ir–O bond distances ranging from 1.91–2.07 Å. There are five inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to one Na, four Ba, and one Ir atom. In the second O site, O is bonded in a 2-coordinate geometry to four Ba and two equivalent Ir atoms. In the third O site, O is bonded to four Ba and two equivalent Ir atoms to form distorted corner-sharing OBa4Ir2 octahedra. The corner-sharing octahedral tilt angles are 8°. In the fourth O site, O is bonded in a 2-coordinate geometry to one Na, four Ba, and one Ir atom. In the fifth O site, O is bonded in a 2-coordinate geometry to one Na, four Ba, and one Ir atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaIn4Ir by Materials Project

CaIrIn4 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. Ca is bonded in a 1-coordinate geometry to one Ir and twelve In atoms. The Ca–Ir bond length is 3.06 Å. There are a spread of Ca–In bond distances ranging from 3.33–3.76 Å. Ir is bonded in a 9-coordinate geometry to one Ca and eight In atoms. There are a spread of Ir–In bond distances ranging from 2.65–2.93 Å. There are three inequivalent In sites. In the first In site, In is bonded in a linear geometry to two equivalent Ca and two equivalent Ir atoms. In the second In site, In is bonded in a 2-coordinate geometry to four equivalent Ca and two equivalent Ir atoms. In the third In site, In is bonded in a distorted square co-planar geometry to two equivalent Ca and two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrIn4Ir by Materials Project

SrIrIn4 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. Sr is bonded in a 1-coordinate geometry to one Ir and twelve In atoms. The Sr–Ir bond length is 3.23 Å. There are a spread of Sr–In bond distances ranging from 3.43–3.77 Å. Ir is bonded in a 9-coordinate geometry to one Sr and eight In atoms. There are a spread of Ir–In bond distances ranging from 2.63–2.92 Å. There are three inequivalent In sites. In the first In site, In is bonded in a 2-coordinate geometry to four equivalent Sr, two equivalent Ir, and six In atoms. There are a spread of In–In bond distances ranging from 3.20–3.40 Å. In the second In site, In is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr, two equivalent Ir, and four equivalent In atoms. In the third In site, In is bonded in a linear geometry to two equivalent Sr, two equivalent Ir, and four equivalent In atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3IrI3 by Materials Project

Y3IrI3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are three inequivalent Y sites. In the first Y site, Y is bonded to three equivalent Ir and three I atoms to form distorted edge-sharing YIr3I3 octahedra. There are two shorter (2.79 Å) and one longer (2.92 Å) Y–Ir bond lengths. There are one shorter (3.26 Å) and two longer (3.33 Å) Y–I bond lengths. In the second Y site, Y is bonded in a 6-coordinate geometry to one Ir and five I atoms. The Y–Ir bond length is 2.76 Å. There are a spread of Y–I bond distances ranging from 3.13–3.58 Å. In the third Y site, Y is bonded in a 6-coordinate geometry to two equivalent Ir and four I atoms. Both Y–Ir bond lengths are 2.79 Å. There are a spread of Y–I bond distances ranging from 3.30–3.59 Å. Ir is bonded in a 6-coordinate geometry to six Y atoms. There are three inequivalent I sites. In the first I site, I is bonded in a 5-coordinate geometry to five Y atoms. In the second I site, I is bonded in a distorted T-shaped geometry to three Y atoms. In the third I site, I is bonded in a 4-coordinate geometry to four Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y6IrI10 by Materials Project

Y6IrI10 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Y sites. In the first Y site, Y is bonded to one Ir and five I atoms to form a mixture of corner and edge-sharing YIrI5 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. The Y–Ir bond length is 2.75 Å. There are a spread of Y–I bond distances ranging from 3.12–3.33 Å. In the second Y site, Y is bonded to one Ir and five I atoms to form a mixture of distorted corner and edge-sharing YIrI5 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. The Y–Ir bond length is 2.67 Å. There are a spread of Y–I bond distances ranging from 3.06–3.38 Å. In the third Y site, Y is bonded to one Ir and five I atoms to form a mixture of corner and edge-sharing YIrI5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. The Y–Ir bond length is 2.77 Å. There are a spread of Y–I bond distances ranging from 3.02–3.31 Å. Ir is bonded in an octahedral geometry to six Y atoms. There are five inequivalent I sites. In the first I site, I is bonded in a distorted L-shaped geometry to two Y atoms. In the second I site, I is bonded in a distorted T-shaped geometry to three Y atoms. In the third I site, I is bonded in a distorted T-shaped geometry to three Y atoms. In the fourth I site, I is bonded in a distorted see-saw-like geometry to four Y atoms. In the fifth I site, I is bonded in a 3-coordinate geometry to three Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sn5(BIr3)2 by Materials Project

Sn5(Ir3B)2 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ir is bonded in a 7-coordinate geometry to two B and five Sn atoms. There are one shorter (2.19 Å) and one longer (2.22 Å) Ir–B bond lengths. There are a spread of Ir–Sn bond distances ranging from 2.72–2.91 Å. There are two inequivalent B sites. In the first B site, B is bonded in a distorted pentagonal pyramidal geometry to six equivalent Ir atoms. In the second B site, B is bonded in a 6-coordinate geometry to six equivalent Ir and three equivalent Sn atoms. All B–Sn bond lengths are 2.71 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 6-coordinate geometry to six equivalent Ir atoms. In the second Sn site, Sn is bonded in a 7-coordinate geometry to six equivalent Ir and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiIr3 by Materials Project

LiIr3 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. Li is bonded in a 12-coordinate geometry to ten Ir atoms. There are a spread of Li–Ir bond distances ranging from 2.61–2.78 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to three equivalent Li atoms. In the second Ir site, Ir is bonded in a 12-coordinate geometry to four equivalent Li atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr3Ir by Materials Project

Zr3Ir crystallizes in the tetragonal I-42m space group. The structure is three-dimensional. there are three inequivalent Zr sites. In the first Zr site, Zr is bonded in a water-like geometry to two equivalent Ir atoms. Both Zr–Ir bond lengths are 2.80 Å. In the second Zr site, Zr is bonded in a distorted water-like geometry to two equivalent Ir atoms. Both Zr–Ir bond lengths are 2.80 Å. In the third Zr site, Zr is bonded in a 4-coordinate geometry to four equivalent Ir atoms. There are two shorter (2.75 Å) and two longer (2.94 Å) Zr–Ir bond lengths. Ir is bonded in a 8-coordinate geometry to eight Zr atoms.

36 MATERIALS SCIENCE↗