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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

DESI Mg II Absorbers: Extinction Characteristics and Quasar Redshift Accuracy

In this paper, we study how absorption-line systems affect the spectra and redshifts of quasi-stellar objects (QSOs), using catalogs of Mg II absorbers from the early data release and first data release of the Dark Energy Spectroscopic Instrument. We determine the reddening effect of an absorption system by fitting an unreddened template spectrum to a sample of 50,674 QSO spectra that contain Mg II absorbers. We find that reddening caused by intervening absorbers (v off > 3500 km s −1 ) has an average color excess of $\overline{E(B-V)}$ = 0.04 mag. We find that the E(B − V) tends to be greater for absorbers at low redshifts, or those having Mg II absorption lines with higher equivalent widths, but shows no clear trend with v off for intervening systems. However, the $\overline{E(B-V)}$ of associated absorbers, those at v off < 3500 km s −1 , shows a strong trend with v off , increasing rapidly with decreasing v off and peaking (∼0.15 mag) around v off = 0 km s −1 . We demonstrate that Mg II absorbers impact redshift estimation for QSOs by investigating the distributions of v off for associated absorbers. We find that at z > 1.5, these distributions broaden and bifurcate in a nonphysical manner. In an effort to mitigate this effect, we mask pixels associated with the Mg II absorption lines and recalculate the QSO redshifts. We find that we can recover voff populations in better agreement with those for z < 1.5 absorbers and in doing so typically shift background QSO redshifts by Δz ≈ ± 0.005.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Tracing the Evolution of the Cool Gas in CGM and IGM Environments through Mg II Absorption from Redshift z = 0.75 to z = 1.65 Using DESI-Y1 Data

We present a measurement of the mean absorption of cool gas traced by Mg II (λλ2796, 2803) around emission line galaxies (ELGs), spanning spatial scales from 20 kpc to 10 Mpc. The measurement is based on crossmatching the positions ELGs at z = 0.75–1.65 and the metal absorption in the spectra of background quasars with data provided by the Year 1 sample of the Dark Energy Spectroscopic Instrument. The ELGs are divided into two redshift intervals: 0.75 < z < 1.0 and 1.0 < z < 1.65. We find that the composite quasar spectra constructed by stacking the ELG-QSO pairs evolve with redshift, with z > 1 having a systematically higher signal of Mg II absorption. Within 1 Mpc, the covering fraction of the cool gas at z > 1 is higher than that of z < 1. The enhancement becomes less apparent especially if the projected distance r p > 1 Mpc. ELGs with higher stellar mass and star formation rate (SFR) yield higher clustering of Mg ii absorbers at z < 1. For z > 1, the covering fractions with different SFRs show little difference. The higher Mg II absorption at higher redshift supports the observations of higher star formation at cosmic noon. Converting the Mg II absorbers to unsaturated Si II , our estimate indicates that the metal abundance of Si II ranges from 0.7 to 1.2 × 10 −6 from z = 0.9 to 1.3. The growth of low-ionization metal abundance strongly suggests a metal-enriched circumgalactic medium and an increased presence of cool gas in the intergalactic medium toward higher redshifts.

circumgalactic medium↗
DOE OSTI2025

The CAI Database: 26 Al– 26 Mg Isotope Systematics

We present a publicly available calcium–aluminum-rich inclusion (CAI) database that focuses on the initial 26 Al/ 27 Al 0 ratio in CAIs, designed in a way that researchers in cosmochemistry and astrophysics may find useful. To date, the database contains 497 CAIs from 75 peer-reviewed papers. The CAIs are from all chondrite groups and cover different CAI types, textures, and sizes. The database includes the paper; the host meteorite; the CAI name and type; the 26 Al/ 27 Al 0 , δ 26 Mg$^*_0$, and δ 25 Mg values and their uncertainties; the number of regression points; the maximum 27 Al/ 24 Mg; the mean-squared weighted deviation; the CAI size; and CAI descriptions. We grouped the CAIs in different ways to discuss 26 Al/ 27 Al 0 ratio distributions with implications for the CAI formation timeline. Overall, we agree with previous authors that CAIs have a bimodal 26 Al distribution: CAIs with robust isochrons (n = 151) have a median 26 Al/ 27 Al 0 = 4.8 × 10 −5 (with a 1σ standard error of 0.1), while those with isotopic anomalies (n = 87) have a median 26 Al/ 27 Al 0 = 0.3 × 10 −5 (with a 1σ standard error of 0.2). However, the large standard deviation of both groups (1.3 and 2.3, respectively) indicates that the 26 Al/ 27 Al 0 values scatter significantly within each population. CAI types and groups can have distinct 26 Al/ 27 Al 0 and δ 26 Mg$^*_0$, but the unmelted inclusions (n = 33) have the highest median 26 Al/ 27 Al 0 = 5.1 × 10 −5 and a low median δ 26 Mg$^*_0$ = −0.05‰. We find slightly different 26 Al/ 27 Al 0 distributions between CAI chondrite types, but no differences between petrographic types or sizes. These observations can help us to understand CAI formation in the context of astrophysical models.

Astronomy and AstroPhysics↗
NASA NTRS1976

The behavior of the Mg II doublet features near 2800 A observed in F, A, and B supergiants

The Mg II doublet features near 2800 A were recently observed in F-, A-, and B-type supergiants with a balloon-borne ultraviolet stellar spectrometer. The stars observed are Alpha UMi (F8 Ib), Alpha Per (F5 Ib), Eta Leo (A0 Ib), and Rho Leo (B1 Ib). The Mg II doublet features in Alpha UMi and Alpha Per show emission superposed on photospheric absorption. In the spectrum of Eta Leo, the Mg II lines are in absorption and show shortward-shifted components attributable to mass loss. In the spectrum of Rho Leo, the Mg II lines are primarily a composite of the photospheric and interstellar absorption features. The general behavior of the Mg II lines for supergiants of spectral types M through B are also discussed.

Kondo, Y.↗
NASA NTRS1986

Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

A study was conducted: (1) to develop rapid solidification processed (RSP) dispersoid-containing Al-3Cu-2Li-1Mg-0.2Zr alloys as substitutes for titanium alloys and commercial 2XXX aluminum alloys for service to at least 150 C; and (2) to develop RSP Al-4Li-Cu-Mg-Zr alloys as substitutes for high-strength commercial 7XXX alloys in ambient-temperature applications. RSP Al-3Cu-2Li-1Mg-0.2Zr alloys have density-normalized yield stresses at 150 C up to 52% larger than that of 2124-T851 and up to 30% larger than that of Ti-6Al-4V. Strength at 150 C in these alloys is provided by thermally stable delta' (Al3Li), T1 (Al2LiCu), and S' (Al2CuMg) precipitates. Density-normalized yield stresses of RSP Al-3Cu-2Li-1Mg-0.2Zr alloys are up to 100% larger than that of 2124-T851 and equivalent to that of Al-8Fe-4Ce at 260 C. Strength in the RSP alloys at 260 C is provided by incoherent dispersoids and subboundary constituent particles such as T1 and S. The RSP alloys are attractive substitutes in less than or = 100-h exposures for 2xxx and Al-4Fe-Ce alloys up to 260 C and for titanium alloys up to 150 C. RSP Al-4Li-Cu-Mg-Zr alloys have ambient-temperature yield and ultimate tensile stresses similar to that of 7050-T7651, and are 14% less dense. RSP Al-4Li-0.5Cu-1.5Mg-0.2Zr has a 20% higher specific yield stress, 40% higher specific elastic modulus, and superior corrosion resistance compared to the properties of 7050-T7651. Strength in the Al-4Li-Cu-Mg-Zr alloy class is primarily provided by the substructure and delta' precipitates and is independent of Cu:Mg ratio. Improvements in fracture toughness and transverse-orientation properties in both alloy classes depend on improved melt practices to eliminate oxide inclusions which are incorporated into the consolidated forms.

Meschter, P. J.↗
NASA NTRS1986

Detection of 12 micron Mg I and OH lines in stellar spectra

Infrared lines of Mg I and OH have been detected in stellar spectra near 12.3 microns. The Mg I 7i-6h transition was seen in Alpha Ori and Alpha Tau, and the R2e(23.5) and R1f(24.5) transitions of OH were seen in Alpha Ori. All lines appear in absorption, in contrast to the solar spectrum where the Mg I line shows a prominent emission core. The lack of emission in these low surface gravity stars is due to a greatly reduced volume recombination rate for the high-n states of Mg I, which is not fully compensated by the increased chromospheric scale height. The OH equivalent widths are sensitive to the temperature structure of the upper photosphere of Alpha Ori, and they indicate that the photosphere near tau 5000 of about 10 to the -5th is approximately 100 K hotter than is given by flux constant models. The OH measurements agree more closely with the 1981 semiemprical model of Basri, Linsky, and Eriksson (1981), which is based on Ca II and Mg II ultraviolet features.

Jennings, D. E.↗
NASA NTRS1989

Mechanical properties of particulate composites based on a body-centered-cubic Mg-Li alloy containing boron

The effect of substituting the Mg metal in Mg-B composites by a Mg-14 wt pct Li solid solution on the ductility of the resulting composite was investigated using elastic modulus measurements on the P/M composite material prepared with a dispersion of B particles (in a vol pct range of 0-30) in a matrix of Mg-14 wt pct Li-1.5 wt pct Al. It was found that the elastic modulus of the composites increased rapidly with increasing boron, with specific stiffness values reaching about two times that of most structural materials. The values of the compression and tensile strengths increased significantly with boron additions. Good tensile ductility was achieved at the level of 10 vol pct B. However, at 20 vol pct B, the Mg-Li composite exhibited only limited tensile ductility (about 2 percent total elongation).

Whalen, R. T.↗
NASA NTRS1993

Infrared imaging of MG 0414 + 0534 - The red gravitational lens systems as lensed radio galaxies

We present an IR image of the gravitational lens system MG 0414 + 0534, and IR photometry of PG 1115 + 080, H1413 + 117, and Q1429 - 008. The IR of MG 0414 + 0534 shows a morphology that is similar to the radio and optical morphologies. The object is bright (K-prime = 13.7) and extremely red (I-K-prime = 5.7). MG 0414 + 0534 thus becomes the second radio-selected lens system to have very red optical IR colors. When plotted on a color-magnitude diagram of objects from a radio survey, MG 0414 + 0534 and the other very red system, MG 1131 + 0456, lie near the locus of radio galaxies. We therefore suggest that these systems are lensed high-redshift radio galaxies. In general, lensed radio galaxies should be common among lens systems selected from radio surveys, since a high proportion of radio sources are radio galaxies.

Annis, James↗
NASA NTRS1993

Composite Mg II solar activity index for solar cycles 21 and 22

On the basis of version 1.0 of the composite MG II solar activity index data set, it is shown that the change in the 27-day running average of the Mg II index from solar maximum to solar minimum is about 8 percent for solar cycle 21 and about 9 percent for solar cycle 22 through January 1992. Scaling factors based on the short-term variations in the Mg II index and solar irradiance data sets are developed for each instrument to estimate solar variability at mid-UV and near-UV wavelengths. A set of composite scale factors are derived for use with the present composite MG index. Near 205 cm, where solar irradiance variations are important for stratospheric chemistry, the estimated change in irradiance during solar cycle 22 is about 10 +/- 1 percent using the composite Mg II index (version 1.0) and scale factors.

Deland, Matthew T.↗
NASA NTRS1994

Changes in photochemically significant solar UV spectral irradiance as estimated by the composite Mg II index and scale factors

Quantitative assessment of the impact of solar ultraviolet irradiance variations on stratospheric ozone abundances currently requires the use of proxy indicators. The Mg II core-to-wing index has been developed as an indicator of solar UV activity between 175-400 nm that is independent of most instrument artifacts, and measures solar variability on both rotational and solar cycle time scales. Linear regression fits have been used to merge the individual Mg II index data sets from the Nimbus-7, NOAA-9, and NOAA-11 instruments onto a single reference scale. The change in 27-dayrunning average of the composite Mg II index from solar maximum to solar minimum is approximately 8 percent for solar cycle 21, and approximately 9 percent for solar cycle 22 through January 1992. Scaling factors based on the short-term variations in the Mg II index and solar irradiance data sets have been developed to estimate solar variability at mid-UV and near-UV wavelengths. Near 205 nm, where solar irradiance variations are important for stratospheric photo-chemistry and dynamics, the estimated change in irradiance during solar cycle 22 is approximately 10 percent using the composite Mg II index and scale factors.

Deland, Matthew T.↗
NASA NTRS1994

Mg II absorption in a sample of 56 steep-spectrum quasars

We present an analysis of the statistical properties of Mg II absorbers found in the spectra of 56 intrinsically faint, steep-spectrum radio quasars. We observe for the first time a significant excess of associated Mg II absorbers over the number expected from cosmologically distributed absorbers. This result is in contrast to previous Mg II surveys in which the QSOs were optically selected. This distinction is similar to the result for associated C IV absorbers, in which intrinsically faint, steep-spectrum quasars show excess associated absorption and intrinsically bright QSOs (both radio-loud and radio-quiet) do not show an excess. From our spectra a statistically complete list of absorption lines is derived, and we find 29 Mg II absorbers, 18 of which have not been previously reported. We also determine several characteristics of the quasar emission lines in our spectra. The Mg II absorber distribution as a function of redshift and equivalent width is calculated both for our sample alone and from our sample combined with spectra from other surveys. For the redshift distribution n(z) = n(1 + z)(exp gamma), we obtain, using the combined sample, the values gamma = 1.11 +/- 0.46 for W(min) = 0.6 A and gamma = 2.47 +/- 0.68 for W(min) = 1.0 A. We find that the distribution fo strong absorbers is inconsistent with no evolution at a confindence level between 2.2 and 2.9 sigma, depending on the deceleration parameter q(sub 0). The deviation from no evolution is similar to what had been previously reported.

Aldcroft, Thomas L.↗
NASA NTRS1994

Cosmic-ray isotopic composition of C, N, O, Ne, Mg, Si nuclei in the energy range 50-200 MeV per nucleon measured by the Voyager spacecraft during the solar minimum period

The isotopic composition of C, N, O, Ne, Mg, Si cosmic ray nuclei has been measured in the energy range 50-200 MeV per nucleon using data collected by the High-Energy Telescope of the cosmic-ray subsystem experiment on the Voyager 1 and 2 spacecraft. These data were collected during the period of minimum solar activity in 1986-1988 at an average distance of 27 AU with an effective solar modulation that was much less than at the Earth. The isotope analysis, based on the energy loss - total energy method, has a mass resolution of 0.2 amu for carbon and 0.4 amu at silicon. We find a (C-13)/(C-12) ratio slightly lower and a (O-18)/(O-16) ratio slightly enhanced over their solar system value. We also observe the previously reported enhancement of the (Ne-22)/(Ne-20) ratio relative to solar at the cosmic-ray source but only a weak, if any, enhancement of the (Mg-25)/(Mg-24), (Mg-26)/(Mg 24), and (Si-30)/(Si-28) ratios.

Lukasiak, A.↗
NASA NTRS2001

Expression of extracellular calcium-sensing receptor in human osteoblastic MG-63 cell line

We have previously shown the expression of the extracellular calcium (Ca2+o)-sensing receptor (CaR) in osteoblast-like cell lines, and others have documented its expression in sections of murine, bovine, and rat bone. The existence of the CaR in osteoblasts remains controversial, however, since some studies have failed to document its expression in the same osteoblast-like cell lines. The goals of the present study were twofold. 1) We sought to determine whether the CaR is expressed in the human osteoblast-like cell line, MG-63, which has recently been reported by others not to express this receptor. 2) We investigated whether the CaR, if present in MG-63 cells, is functionally active, since most previous studies have not proven the role of the CaR in mediating known actions of Ca2+o on osteoblast-like cells. We used immunocytochemistry and Western blotting with the specific, affinity-purified anti-CaR antiserum 4637 as well as Northern blot analysis and RT-PCR using a riboprobe and PCR primers specific for the human CaR, respectively, to show readily detectable CaR protein and mRNA expression in MG-63 cells. Finally, we employed the patch-clamp technique to show that an elevation in Ca2+o as well as the specific, allosteric CaR activator NPS R-467 (0.5 microM), but not its less active stereoisomer NPS S-467 (0.5 microM), activate an outward K+ channel in MG-63 cells, strongly suggesting that the CaR in MG-63 cells is not only expressed but is functionally active.

NASA Discipline Regulatory Physiology↗
DOE OSTI2020

Materials Data on Mg(ScGa)2 by Materials Project

Mg(ScGa)2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Mg is bonded in a square co-planar geometry to four equivalent Ga atoms. All Mg–Ga bond lengths are 2.82 Å. Sc is bonded in a 6-coordinate geometry to six equivalent Ga atoms. There are two shorter (2.84 Å) and four longer (2.92 Å) Sc–Ga bond lengths. Ga is bonded in a 9-coordinate geometry to two equivalent Mg, six equivalent Sc, and one Ga atom. The Ga–Ga bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(HO)2 by Materials Project

Mg(OH)2 crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one Mg(OH)2 sheet oriented in the (0, 0, 1) direction. Mg2+ is bonded in a distorted q6 geometry to three equivalent H1+ and six O2- atoms. All Mg–H bond lengths are 1.97 Å. There are three shorter (2.11 Å) and three longer (2.23 Å) Mg–O bond lengths. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to three equivalent Mg2+ and one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to three equivalent Mg2+ and one H1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to three equivalent Mg2+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(InSe2)2 by Materials Project

Mg(InSe2)2 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Mg(InSe2)2 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share a cornercorner with one MgSe4 tetrahedra, corners with five InSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and edges with four equivalent InSe6 octahedra. There are a spread of Mg–Se bond distances ranging from 2.74–2.79 Å. In the second Mg2+ site, Mg2+ is bonded to four Se2- atoms to form MgSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent InSe6 octahedra, and corners with six InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–59°. There are a spread of Mg–Se bond distances ranging from 2.58–2.62 Å. There are four inequivalent In3+ sites. In the first In3+ site, In3+ is bonded to six Se2- atoms to form InSe6 octahedra that share corners with two equivalent MgSe4 tetrahedra, corners with four InSe4 tetrahedra, edges with two equivalent InSe6 octahedra, and edges with four equivalent MgSe6 octahedra. There are a spread of In–Se bond distances ranging from 2.75–2.83 Å. In the second In3+ site, In3+ is bonded to four Se2- atoms to form InSe4 tetrahedra that share a cornercorner with one InSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of In–Se bond distances ranging from 2.60–2.68 Å. In the third In3+ site, In3+ is bonded to four Se2- atoms to form InSe4 tetrahedra that share a cornercorner with one InSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of In–Se bond distances ranging from 2.61–2.68 Å. In the fourth In3+ site, In3+ is bonded to four Se2- atoms to form InSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent InSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four InSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of In–Se bond distances ranging from 2.62–2.67 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three In3+ atoms. In the second Se2- site, Se2- is bonded to two Mg2+ and two equivalent In3+ atoms to form distorted SeMg2In2 trigonal pyramids that share corners with seven SeMg2In2 tetrahedra, corners with two equivalent SeMg2In2 trigonal pyramids, an edgeedge with one SeMgIn3 tetrahedra, and edges with two SeMg2In2 trigonal pyramids. In the third Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two In3+ atoms. In the fourth Se2- site, Se2- is bonded to two equivalent Mg2+ and two In3+ atoms to form a mixture of distorted edge and corner-sharing SeMg2In2 trigonal pyramids. In the fifth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two In3+ atoms. In the sixth Se2- site, Se2- is bonded to two equivalent Mg2+ and two In3+ atoms to form distorted SeMg2In2 tetrahedra that share corners with two equivalent SeMgIn3 tetrahedra, corners with seven SeMg2In2 trigonal pyramids, edges with two SeMg2In2 tetrahedra, and an edgeedge with one SeMg2In2 trigonal pyramid. In the seventh Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two In3+ atoms. In the eighth Se2- site, Se2- is bonded to one Mg2+ and three In3+ atoms to form a mixture of distorted edge and corner-sharing SeMgIn3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)4 by Materials Project

Mg(FeO2)4 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Mg is bonded to six equivalent O atoms to form MgO6 octahedra that share corners with six equivalent FeO6 octahedra and edges with six equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Mg–O bond lengths are 2.15 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share edges with two equivalent MgO6 octahedra and edges with six FeO6 octahedra. There is four shorter (1.95 Å) and two longer (1.96 Å) Fe–O bond length. In the second Fe site, Fe is bonded to six equivalent O atoms to form FeO6 octahedra that share corners with six equivalent MgO6 octahedra and edges with six equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Fe–O bond lengths are 2.06 Å. There are two inequivalent O sites. In the first O site, O is bonded in a rectangular see-saw-like geometry to one Mg and three Fe atoms. In the second O site, O is bonded in a distorted T-shaped geometry to three equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(CuO2)2 by Materials Project

MgCu2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.38 Å. In the second Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.18–2.42 Å. In the third Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.43 Å. In the fourth Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.20–2.40 Å. There are eight inequivalent Cu3+ sites. In the first Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the second Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Cu–O bond distances ranging from 1.94–2.05 Å. In the third Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the fourth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Cu–O bond distances ranging from 1.94–2.06 Å. In the fifth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.89–2.07 Å. In the sixth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Cu–O bond distances ranging from 1.89–2.06 Å. In the seventh Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Cu–O bond distances ranging from 1.89–2.06 Å. In the eighth Cu3+ site, Cu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Cu–O bond distances ranging from 1.90–2.07 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the third O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the sixth O2- site, O2- is bonded to two Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 trigonal bipyramids. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Cu3+ atoms. In the ninth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the tenth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the eleventh O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the twelfth O2- site, O2- is bonded to two equivalent Mg2+ and three Cu3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Cu3 square pyramids. In the thirteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the fourteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the fifteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms. In the sixteenth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Cu3+ atoms.

36 MATERIALS SCIENCE↗