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At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Microstructure-derived macroscopic residual resistance of brominated graphite fibers

The microscopic bromine distribution in pitch-based brominated graphite fibers has been measured with a scanning transmission electron microscope by monitoring the Br K alpha1 X-ray intensity. An imhomogeneous distribution of Br along the fiber is found with two distinct cross-sectional distributions, namely, a uniform distribution in Br-rich regions and a Gaussian-like distribution in Br-poor regions. A model based on these Br distribution measurements is proposed to understand the relation between the Br microstructure and the macroscopic residual resistance of the fiber. This model yields semiquantitative agreement with experimental results.

Qian, X. W.↗
NASA NTRS1988

Airborne measurements of tropospheric ozone destruction and particulate bromide formation in the Arctic

Aircraft profiles of O3 concentrations over the Arctic ice pack in spring exhibit a depletion of O3 beneath the surface temperature inversion. One such profile from the NOAA WP-3D Arctic Gas and Aerosol Sampling Program (AGASP) flights in April, 1986 north of Alert, NWT (YLT, 82.5 N) is shown. The gradient of O3 across the temperature inversion, which is essentially a step function from tropospheric values (35 to 40 ppbv) to 0, is somewhat masked by a 1-min running mean applied to the data. Evidence is presented that O3 destruction beneath the Arctic temperature inversion is the result of a photochemical reaction between gaseous Br compounds and O3 to produce particulate Br aerosol. It is noted that in springtime, O3 at the Alert Baseline Station regularly decreases from 30 to 40 ppbv to near 0 over the period of a few hours to a day. At the same time, there is a production of particulate Br with a near 1.0 anti-correlation to O3 concentration. Surface concentrations of bromoform in the Arctic exhibit a rapid decrease following polar sunrise. AGASP aircraft measurements of filterable bromine particulates in the Arctic (March-April, 1983 and 1986) are shown. The greatest concentrations of Br aerosol (shown as enrichment factors relative to to Na in seawater, EFBR (Na)) were observed in samples collected beneath the surface temperature inversion over ice. Samples collected at the same altitude over open ocean (off Spitzbergen) labeled Marine did not exhibit similar Br enrichments. A second region of particulate Br enrichment was observed in the lower stratosphere, which regularly descends to below 500 mb (5.5 km) in the high Arctic. The NOAA WP-3D flew in the stratosphere on all AGASP flights and occasionally measured O3 concentrations in excess of 300 ppbv.

Schnell, Russell C.↗
NASA NTRS1990

Canopy bidirectional reflectance dependence on leaf orientation

The dependence of the bidirectional reflectance (BR) on the inclination and azimuthal orientation of a leaf is analyzed, with the primary assumption that, in terms of both obscuration and shadowing, the entire canopy consists of the same leaves. The BR patterns of a dense canopy are examined as a function of canopy architecture. It is assumed that the leaves are opaque Lambertian reflectors, having identical orientation and relfecting properties throughout the canopy, and distributed randomly with respect to the the irradiation field and the viewing direction. Analytical expressions are presented and analyzed for the BR factor. It is noted that maximal BR occurs at large viewing zenith angles. A complex and often steep dependence of the BR on azimuthal location is reported, noting that the BR thus depends on the leaf azimuth as well as the zenith angle. It is concluded that the question of azimuthal distribution has to be addressed when conducting model inversions to infer canopy characteristics and architecture.

Brakke, Thomas W.↗
NASA NTRS1995

Effect of heat acclimation on sitting orthostatic tolerance in the heat after 48 and 96 hour bed rest in men

The purpose of this pilot study was to investigate sitting orthostatic tolerance and determine potentially adverse signs and symptoms that would incapacitate subjects in a hot environment (Gemini reentry cabin temperature profile) after 48 hr and 96 hr of horizontal bed rest (BR), which simulated microgravity deconditioning. Six college men (23-29 yr) were allocated into two groups: heat acclimated (three subjects: No. 1- control, No. 2- 48 hr BR, and No. 3- 96 hr BR) and nonheat acclimated (three subjects: No. 4- control, No. 5- 48 hr BR, and No. 6- 96 hr BR). After BR they sat in an ambient temperature of 57 C (135 F) for 30 min which then was decreased to 49 C (120 F) for up to 480 min. Tolerance time in the heat with seated orthostatic stress was 480 min (subject No. 1) and 180 min (subject No. 4) in the two ambulatory men, but was reduced to 22-150 min in the four bed-rested men irrespective of their heat acclimation status. Although heat acclimation appeared to enhance tolerance and attenuate accompanying physiological responses, as well as ameliorate the frequency and intensity of adverse signs and symptoms at termination of exposure, tolerance was reduced in the bed-rest deconditioned subjects regardless of their acclimation level. Thus, these few collective findings do not indicate an unequivocal positive effect of acute heat acclimation on sitting orthostatic tolerance in acute bed-rest deconditioned subjects.

Greenleaf, J. E.↗
NASA NTRS1999

Multiplexed Holographic Data Storage in Bacteriorhodopsin

Biochrome photosensitive films in particular Bacteriorhodopsin exhibit features which make these materials an attractive recording medium for optical data storage and processing. Bacteriorhodopsin films find numerous applications in a wide range of optical data processing applications; however the short-term memory characteristics of BR limits their applications for holographic data storage. The life-time of the BR can be extended using cryogenic temperatures [1], although this method makes the system overly complicated and unstable. Longer life-times can be provided in one modification of BR - the "blue" membrane BR [2], however currently available films are characterized by both low diffraction efficiency and difficulties in providing photoreversible recording. In addition, as a dynamic recording material, the BR requires different wavelengths for recording and reconstructing of optical data in order to prevent the information erasure during its readout. This fact also put constraints on a BR-based Optical Memory, due to information loss in holographic memory systems employing the two-lambda technique for reading-writing thick multiplexed holograms.

Mehrl, David J.↗
NASA NTRS1998

Interstellar Extinction in the Vicinity of the Galactic Center

We present J (1.2 microns) H (1-6 microns) K' (2.11 microns) and Br(gamma) (2.166 microns) images from four large regions within the central 40 pc of the Galaxy. Localized variations in the extinction, as determined by observations of the stellar population, are examined using the median H-K' color as a function of position within each region. As the value of the derived extinction from the stars is dependent upon the intrinsic magnitude of the assumed stellar type, the J-H vs. H-K' diagrams are first used to investigate the distribution of stellar types in the four regions. We find that there is a distinct OB population, contrary to earlier assumptions, with the ratio of K and M giants and supergiants to OB stars approximately twice that of the solar neighborhood. Although the on the scale of approx. 1 min. fluctuations in the extinction are on the order of A(sub V) approx. greater than 2, throughout the entire region the extinction varies from A(sub V) approx. greater than 25 to A(sub V) approx. less than 40. We also examine whether there is any variation in the extinction and stellar number density relative to the unusual radio features in these regions and do not find a significant correlation. Spectral imaging in Br(gamma) 2.166 microns emission shows a strong morphological correspondence between the 6 cm radio images and the diffuse Br(gamma) emission. By comparing the theoretical Br(gamma) flux derived from the radio flux using recombination theory, with our measured Br(gamma) flux, we obtain a second, independent, estimate of the extinction. We compare the two data sets and find that the extinction as derived from the stars is consistently greater, sometimes by a factor of two, than the value of the extinction derived from the Br(gamma) images. The derived extinction in various regions, however, is insufficient for any of these regions to be located behind the molecular clouds as previously observed in the Galactic Center, consistent with the theory that the observed radio emission is produced on the foreground surface of these clouds.

Cotera, Angela S.↗
NASA NTRS2000

Interstellar Extinction in the Vicinity of the Galactic Center

We present J (1.2 microns), H (1-6 microns), K' (2.11 microns) and Br(gamma) (2.166 microns) images from four large regions within the central 40 pc of the Galaxy. Localized variations in the extinction, as determined by observations of the stellar population, are examined using the median H-K' color as a function of position within each region. As the value of the derived extinction from the stars is dependent upon the intrinsic magnitude of the assumed stellar type, the J-H vs. H-K' diagrams are first used to investigate the distribution of stellar types in the four regions. We find that there is a distinct OB population, contrary to earlier assumptions, with the ratio of K and M giants and supergiants to OB stars approximately twice that of the solar neighborhood. Although the on the scale of approx. l' fluctuations in the extinction are on the order of A(sub V) approx. 2, throughout the entire region the extinction varies from A(sub V) approx. greater than 25 to A(sub V) approx. less than 40. We also examine whether there is any variation in the extinction and stellar number density relative to the usual radio features in these regions and do not find a significant correlation. Spectral imaging in Br(gamma) 2.166 microns emission shows a strong morphological correspondence between the 6 cm radio images and the diffuse Br(gamma) emission. By comparing the theoretical Br(gamma) flux derived from the radio flux using recombination theory, with our measured Br(gamma) flux, we obtain a second, independent, estimate of the extinction. We compare the two data sets and find that the extinction as derived from the stars is consistently greater, sometimes by a factor of two, than the value of the extinction derived from the Br(gamma) images. The derived extinction in various regions, however, is insufficient for any of these regions-to be located behind the molecular clouds as previously observed in the Galactic Center, consistent with the theory that the observed radio emission is produced on the foreground surface of these clouds.

Cotera, Angela S.↗
NASA NTRS2001

Effects of Three-Day Bed Rest on Physiological Responses to Graded Exercise in Endurance Athletes, Body Builders and Sedentary Men

To test the hypotheses that short-term bed rest (BR) deconditioning influences metabolic, cardiorespiratory and neurohormonal responses to exercise and that these effects depend on the subjects' training status 12 sedentary men, and 10 endurance- and 10 strength-trained athletes were submitted to three-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and HR were recorded continuously and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate [LA], adrenaline [A], noradrenaline, [NA], renting activity (PRA), growth hormone [hGH], testosterone and cortisol determination. Reduction of peak oxygen uptake (VO2peak) after BR was greater in the endurance athletes (than in the remaining groups (17 % vs. 100%). Decrements in VO2peak correlated positively with the initial values (r = 0.73, p less than 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased the in endurance athletes from 71 to 60 %VO2 peak (p less than 0.001); they also had an earlier increase in [NA], and an attenuated increase in [hGH), and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion: reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

Smorawinski, J.↗
NASA NTRS2001

Effects of Three-Day Bed Rest on Physiological Responses to Graded Exercise in Endurance Athletes, Body Builders and Sedentary Men

To test the hypotheses that short-term bed rest (BR) deconditioning influences metabolic, cardiorespiratory and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men, and 10 endurance- and 10 strength-trained athletes were submitted to three-day BR. Before and after BR they performed incremental exercise tests until volitional exhaustion. Respiratory gas exchange and HR were recorded continuously and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate [LA], adrenaline [A], noradrenaline [NA], renin activity (PRA), growth hormone [hGH], testosterone and cortisol determination. Reduction of peak oxygen uptake (V02peak) after BR was greater in the endurance athletes than in the remaining groups (17 % vs. 10%). Decrements in VO2peak correlated positively with the initial values (r = 0.73, p is less than 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased the in endurance athletes from 71 to 60% V02 peak (p is less than0.001), they also had an earlier increase in [NA], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion: reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

Smorawinski, J.↗
NASA NTRS2003

Effect of dietary sodium on fluid/electrolyte regulation during bed rest

BACKGROUND: A negative fluid balance during bed rest (BR) is accompanied by decreased plasma volume (PV) which contributes to cardiovascular deconditioning. HYPOTHESIS: We hypothesized that increasing dietary sodium while controlling fluid intake would increase plasma osmolality (POSM), stimulate fluid conserving hormones, and reduce fluid/electrolyte (F/E) losses during BR; conversely, decreasing dietary sodium would decrease POSM, suppress fluid conserving hormones, and increase F/E losses. METHODS: We controlled fluid intake (30 ml x kg(-1) x d(-1)) in 17 men who consumed either a 4.0 +/- 0.06 g x d(-1) (174 mmol x d(-1)) (CONT; n = 6), 1.0 +/- 0.02 g x d(-1) (43 mmol x d(-1)) (LS; n = 6), or 10.0 +/- 0.04 g x d(-1) (430 mmol x d(-1)) (HS; n = 5) sodium diet before, during, and after 21 d of 6 degrees head-down BR. PV, total body water, urine volume and osmolality, POSM, and F/E controlling hormone concentrations were measured. RESULTS: In HS subjects, plasma renin activity (-92%), plasma/urinary aldosterone (-59%; -64%), and PV (-15.0%; 6.0 ml x kg(-1); p < 0.05) decreased while plasma atrial natriuretic peptide (+34%) and urine antidiuretic hormone (+24%) increased during BR (p < 0.05) compared with CONT. In LS, plasma renin activity (+166%), plasma aldosterone (+167%), plasma antidiuretic hormone (+19%), and urinary aldosterone (+335%) increased with no change in PV compared with CONT (p < 0.05). Total body water did not change in any of the subjects. CONCLUSIONS: Contrary to our hypothesis, increasing dietary sodium while controlling fluid intake during BR resulted in a greater loss of PV compared with the CONT subjects. Reducing dietary sodium while controlling fluid intake did not alter the PV response during BR compared with CONT subjects.

Clinical Trial↗
NASA NTRS2001

Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men

To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

NASA Center ARC↗
NASA NTRS2005

Intensive exercise training suppresses testosterone during bed rest

Spaceflight and prolonged bed rest (BR) alter plasma hormone levels inconsistently. This may be due, in part, to prescription of heavy exercise as a countermeasure for ameliorating the adverse effects of disuse. The initial project was to assess exercise programs to maintain aerobic performance and leg strength during BR. The present study evaluates the effect of BR and the performance of the prescribed exercise countermeasures on plasma steroid levels. In a 30-day BR study of male subjects, the efficacy of isotonic (ITE, n = 7) or isokinetic exercise (IKE, n = 7) training was evaluated in contrast to no exercise (n = 5). These exercise countermeasures protected aerobic performance and leg strength successfully. BR alone (no-exercise group) did not change steroidogenesis, as assessed by the plasma concentrations of cortisol, progesterone, aldosterone, and free (FT) and total testosterone (TT). In the exercise groups, both FT and TT were decreased (P < 0.05): FT during IKE from 24 +/- 1.7 to 18 +/- 2.0 pg/ml and during ITE from 21 +/- 1.5 to 18 +/- 1 pg/ml, and TT during IKE from 748 +/- 68 to 534 +/- 46 ng/dl and during ITE from 565 +/- 36 to 496 +/- 38 ng/dl. The effect of intensive exercise countermeasures on plasma testosterone was not associated with indexes of overtraining. The reduction in plasma testosterone associated with both the IKE and ITE countermeasures during BR supports our hypothesis that intensive exercise countermeasures may, in part, contribute to changes in plasma steroid concentrations during spaceflight.

Clinical Trial↗
NASA NTRS2012

Lower Limb Venous Compliance is Different Between Men and Women Following 60 Days of Head-Down Bedrest but Is Not Associated with Venoconstriction Dysfunction

Space flight-induced orthostatic intolerance (OI) is more prevalent in female (F) than male (M) astronauts. The mechanisms explaining the higher incidence of OI in F are unclear. We tested the hypothesis that venous compliance would be higher in F more than M following 6 deg head-down bed rest (BR) and would be associated with constrictor dysfunction. Using 2-D ultrasound, dorsal hand (DHV) and dorsal foot (DFV) vein compliances were determined in 24 subjects (10 F, 14 M; 35 +/- 1 yr) by measuring mean diameter response to increasing congestion pressure (0, 20, 30, and 40 mmHg) before and after 60 d of BR. Constrictor function was assessed by intravenous infusions of Ketorolac (KE; 1.5 ig/min) Phenylephrine (PE; 3160 ng/min), and L-NMMA (50 ig/min). The effects of BR between F vs. M and hand vs. foot were determined using mixed-effects linear regression. DFV but not DHV compliance changed in response to BR (p=0.012). Mean DFV increased significantly (0.903 mm to 1.191mm) in F but decreased in M (1.353 mm to 1.154 mm). DFV constrictor response was not different between sexes in response to BR (KE; p=0.647, PE; p=0.717, and L-NMMA; p=0.825). These BR data suggest that the higher incidence of OI in F astronauts may be related to increased lower limb venous compliance, contributing to blood pooling upon standing. Notably, changes to DFV compliance was not accompanied by impaired constrictor function.

Westby, Christian M.↗
NASA NTRS2014

Bunburra Rockhole: Exploring the Geology of a New Differentiated Basaltic Asteroid

Bunburra Rockhole (BR) is the first recovered meteorite of the Desert Fireball Network. It was initially classified as a basaltic eucrite, based on texture, mineralogy, and mineral chemistry but subsequent O isotopic analyses showed that BR's composition lies significantly far away from the HED group of meteorites. This suggested that BR was not a piece of the HED parent body (4 Vesta), but other explanations could also account for the observed oxygen signatures. Possible scenarios include contamination by components from other bodies (chondrites or other achondrites) or that 4 Vesta may not be as equilibrated as hypothesized. After examining multiple pieces with different instruments (CT scans and x-ray maps), no obvious evidence of contamination was found. If BR is not from Vesta, a conundrum exists as no unusual features were found in mineral and bulk trace element chemistry as exist for other anomalous basaltic achondrites such as Ibitira or Asuka 881394. These meteorites have distinct petrological and geochemical characteristics, in addition to their anomalous O isotope compositions, that set them apart from eucrites. Thus, early results provided a somewhat ambiguous picture of BR's petrogenesis and parentage. To clarify the nature of the relationship, if any, between BR and eucrites, we have performed a correlated stable isotope and bulk chemical study of several lithologic fragments.

Benedix, G.K.↗
DOE OSTI2020

Materials Data on BrF3 by Materials Project

BrF3 crystallizes in the orthorhombic Cmc2_1 space group. The structure is one-dimensional and consists of two BrF3 ribbons oriented in the (0, 0, 1) direction. Br is bonded in a rectangular see-saw-like geometry to four F atoms. There are a spread of Br–F bond distances ranging from 1.80–2.20 Å. There are three inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Br atom. In the second F site, F is bonded in a bent 150 degrees geometry to two equivalent Br atoms. In the third F site, F is bonded in a single-bond geometry to one Br atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb3BiBr6 by Materials Project

Rb3BiBr6 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Rb–Br bond distances ranging from 3.38–4.08 Å. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Rb–Br bond distances ranging from 3.54–3.99 Å. In the third Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Rb–Br bond distances ranging from 3.53–3.84 Å. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in an octahedral geometry to six Br1- atoms. There are a spread of Bi–Br bond distances ranging from 2.87–2.92 Å. In the second Bi3+ site, Bi3+ is bonded in an octahedral geometry to six Br1- atoms. There are a spread of Bi–Br bond distances ranging from 2.87–2.93 Å. There are seven inequivalent Br1- sites. In the first Br1- site, Br1- is bonded to four Rb1+ and one Bi3+ atom to form a mixture of distorted edge, face, and corner-sharing BrRb4Bi trigonal bipyramids. In the second Br1- site, Br1- is bonded in a 5-coordinate geometry to four Rb1+ and one Bi3+ atom. In the third Br1- site, Br1- is bonded in a 6-coordinate geometry to five Rb1+ and one Bi3+ atom. In the fourth Br1- site, Br1- is bonded to four Rb1+ and one Bi3+ atom to form a mixture of distorted face and corner-sharing BrRb4Bi square pyramids. In the fifth Br1- site, Br1- is bonded to four Rb1+ and one Bi3+ atom to form a mixture of distorted edge and corner-sharing BrRb4Bi trigonal bipyramids. In the sixth Br1- site, Br1- is bonded to four Rb1+ and one Bi3+ atom to form a mixture of distorted edge and corner-sharing BrRb4Bi trigonal bipyramids. In the seventh Br1- site, Br1- is bonded in a 4-coordinate geometry to three Rb1+ and one Bi3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsI2Br by Materials Project

CsI2Br crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Cs is bonded in a 10-coordinate geometry to six I and four equivalent Br atoms. There are a spread of Cs–I bond distances ranging from 4.06–4.27 Å. There are a spread of Cs–Br bond distances ranging from 3.74–3.91 Å. There are two inequivalent I sites. In the first I site, I is bonded to four equivalent Cs and one I atom to form a mixture of edge and corner-sharing ICs4I trigonal bipyramids. The I–I bond length is 2.86 Å. In the second I site, I is bonded in a 1-coordinate geometry to two equivalent Cs, one I, and one Br atom. The I–Br bond length is 2.86 Å. Br is bonded in a 5-coordinate geometry to four equivalent Cs and one I atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb3Ge2Br7 by Materials Project

Rb3Ge2Br7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine Br1- atoms. There are a spread of Rb–Br bond distances ranging from 3.57–3.75 Å. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Rb–Br bond distances ranging from 3.45–3.81 Å. In the third Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Rb–Br bond distances ranging from 3.46–3.88 Å. There are two inequivalent Ge2+ sites. In the first Ge2+ site, Ge2+ is bonded in a 5-coordinate geometry to five Br1- atoms. There are a spread of Ge–Br bond distances ranging from 2.56–3.34 Å. In the second Ge2+ site, Ge2+ is bonded in a distorted rectangular see-saw-like geometry to four Br1- atoms. There are a spread of Ge–Br bond distances ranging from 2.56–3.28 Å. There are seven inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a distorted rectangular see-saw-like geometry to three Rb1+ and one Ge2+ atom. In the second Br1- site, Br1- is bonded in a 1-coordinate geometry to four Rb1+ and two equivalent Ge2+ atoms. In the third Br1- site, Br1- is bonded in a 1-coordinate geometry to three Rb1+ and one Ge2+ atom. In the fourth Br1- site, Br1- is bonded in a 1-coordinate geometry to three Rb1+ and one Ge2+ atom. In the fifth Br1- site, Br1- is bonded to four Rb1+ and two Ge2+ atoms to form BrRb4Ge2 octahedra that share corners with two equivalent BrRb4Ge2 octahedra, corners with three equivalent BrRb4Ge square pyramids, and a faceface with one BrRb4Ge square pyramid. The corner-sharing octahedral tilt angles are 28°. In the sixth Br1- site, Br1- is bonded in a 5-coordinate geometry to four Rb1+ and one Ge2+ atom. In the seventh Br1- site, Br1- is bonded to four Rb1+ and one Ge2+ atom to form distorted BrRb4Ge square pyramids that share corners with three equivalent BrRb4Ge2 octahedra, an edgeedge with one BrRb4Ge square pyramid, and a faceface with one BrRb4Ge2 octahedra. The corner-sharing octahedra tilt angles range from 40–50°.

36 MATERIALS SCIENCE↗