共查询到20条相似文献，搜索用时 734 毫秒
1.
2.
The Influence of Redox Reactions on the Uptake of Dissolved Ce by Suspended Fe and Mn Oxide Particles 总被引：1，自引：0，他引：1
Laboratory experiments were conducted to evaluate the partitioning ofrare earth elements (REE) between solution and suspended
particles. Becauseof their strong tendency to complex, the REE can be used to study a varietyof marine processes and in particular
particle scavenging. In this study, anemphasis was placed on examining abiotic redox processes that influence theuptake of
dissolved Ce by particles. Batch sorption experiments wereconducted with REE and synthetic mineral phases over the range of
pH4–9. The solutions varied in ionic strength between 0 and 0.7 M andconsisted of individual solutes (NaNO3, NaCl, andNa2SO4), ionic mixtures that duplicate theseawater composition, and natural seawater. The uptake of REE from solutionwas also studied
at a Pt electrode coated with
using cyclic voltametry.
Experimental results are consistent with uptake of dissolved Ce onto
occurring by a combination of oxidativescavenging and surface complexation. The contribution of oxidativescavenging to the
removal of Ce from solution is most pronounced at acidicpH, where the strictly trivalent REE exhibit little propensity for
sorptiononto
. Sorption of dissolved Ce onto FeOOH occursin a manner analogous to that of the other strictly trivalent REE and nocontribution
from oxidative scavenging is observed on this mineral phase atlow pH. Our work also substantiates the hypothesis that anions
in solution,particularly
and Cl-, aswell as those adsorbed on the surface of the particles, influence the extentof Ce uptake by
.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Most altered clay minerals in uranium ore deposits in granites in the selected provinces of South China haveδ
18O
m
values ranging from 6.22 to 7.24,δDm from −60 to −70,δ
18O
from +3.05 to −3.07, and
from −20.2 to −37.5‰. Relative enrichment of32S in the uranium ore deposits and greater variations in Pb isotopic composition of galenas from them show that uranium ores
in the granites were formed in such a way that uranium in shallow-source granites had been mobilized by heated meteoric waters
and then migrated to local favourable locations along great faults to form uranium ore deposits.
Zhang Shaoli, Yang Wenjin, Tang Chunjing and Xu Wenxin did part of this work. 相似文献
4.
Dr P. Keller Prof. Dr. H. Hess Dr. P. Süsse Dr. G. Schnorrer P. J. Dunn 《Mineralogy and Petrology》1979,26(1-2):51-58
Zusammenfassung Das neue Mineral Koritnigit ist ein wasserhaltiges Zinkhydrogenarsenat der Formel Zn[H2O|HOAsO3]. Die chemische Analyse (Elektronenmikrosonde und T.G.A.) ergab: As2O5 51,75%, ZnO 35,97% und H2O 12,3%, Summe 100,0%. Die HOAsO3-Ionen wurden IR-spektroskopisch nachgewiesen. Koritnigit ist löslich in kalter, verdünnter HCl und HNO3.Die Gitterkonstanten sind:a
0=7,948(2),b
0=15,829(5),c
0=6,668(2) Å, =90,86(2), =96,56(2), =90,05(2)o,V=833,2(4)Å3,V=8. Die Raumgruppe ist
. Die stärksten Linien des Pulverdiagramms sind: 7,90(10) (020,100), 3,83(7) (
), 3,16(9) (
) 2,926(4) (150), 2,679(4) (
), 2,461(6) (
), 2,186(5) (
), 1,969(4) (400), 1,649(3) (004).Koritnigit ist wasserklar bis durchscheinend weiß. Idiomorphe Kristalle sind nicht bekannt. Die Spaltbarkeit nach {010} ist ausgezeichnet und auf {010} sind Spaltspuren nach [001] und nach [100] erkennbar. Härte 2.G=3,54 g·cm–3,D
x
=3,56 g·cm–3. Koritnigit ist optisch zweiachsig positiv, 2V70(5)o. Die Werte der Lichtbrechung sind:n
=1,632(5),n
=1,652(3) undn
=1,693(3).Koritnigit wurde auf der 31. Sohle der Tsumeb-Mine, Südwestafrika gefunden. Er kommt als Sekundärmineral in Paragenese mit Cu-Adamin, Stranskiit und drei weiteren, vorerst nicht identifizierten mineralen in Zersetzungshohlräumen von Tennantit vor.
Mit 2 Abbildungen
Herrn Univ. Prof. Dr.H. Meixner zum 70. Geburtstag gewidmet. 相似文献
Koritnigite, Zn[H2O|HOAsO3], a new mineral from Tsumeb, South West Africa
Summary The new mineral koritnigite is a hydrated zinc hydrogen arsenate with the formula Zn[H2O|HOAsO3]. Chemical analysis (electron microprobe and t.g.a.) gave: As2O5 51.75%, ZnO 35.97%, and H2O 12.3%, total 100.0%. The HOAsO3 ions were determined by IR spectroscopy. Koritnigite is soluble in cold diluted HCl and HNO3. The unit cell dimensions are:a 0=7.948(2),b 0=15.829(5),c 0=6.668(2)Å, =90.86(2), =96.56(2), =90.05(2)o,V=833.2(4) Å3,Z=8. The space group is . The strongest lines of the powder pattern are: 7.90(10) (020, 100), 3.83(7) ( ), 3.16(9) ( ), 2.926(4) (150), 2.679(4) ( ), 2.461(6) ( ), 2.186(5) ( ), 1.969(4)(400), 1.649(3) (004).
Mit 2 Abbildungen
Herrn Univ. Prof. Dr.H. Meixner zum 70. Geburtstag gewidmet. 相似文献
5.
6.
Zusammenfassung Die chemische Analyse des neuen Minerals Johillerit mit der Elektronenmikrosonde ergab: Na2O 5,4, MgO 18,3, ZnO 5,4, CuO 15,8 und As2O5 55,8, Summe 100.7%. Aus diesem Ergebnis wurde die idealisierte Formel Na(Mg, Zn)3 Cu(AsO4)3 abgeleitet. Johillerit ist monoklin mit der RaumgruppeC2/c. Die Gitterkonstanten sind:a=11,870 (3),b=12,755 (3),c=6,770 (2) , =113,42 (2)°,Z=4. Die stärksten Linien des Pulverdiagramms sind: 4,06 (5) (22
), 3,50 (4) (310), 3,25 (8) (11
), 2,75 (10) (330, 240), 2,64 (5) (311, 13
, 40
), 1,952 (4) (13
, 35
), 1,682 (4) (20
, 460), 1,660 (5) (40
, 71
, 550, 64
), 1,522 (4) (442, 153, 13
). Es bestehen enge strukturelle Beziehungen zwischen Johillerit und O'Danielit, Na(Zn, Mg)3H2(AsO4)3, sowie einigen synthetischen. Verbindungen.Johillerit ist violett durchscheinend. Die Spaltbarkeit nach {010} ist ausgezeichnet und nach {100} und {001} gut.H (Mohs)3.D=4,15 undD
X
=4,21 g·cm–3. Das Mineral ist optisch zweiachsig positiv, 2V80 (5)°. Die Werte der Lichtbrechung sindn
=1,715 (4),n
=1,743 (4) undn
=1,783 (4). Die Auslöschung istn
b und auf (010)n
c16°. Johillerit ist stark pleochroitisch mit den AchsenfarbenX=violett-rot,Y = blauviolett undZ = grünblau. Das neue Mineral kommt in radialstrahligen Massen gemeinsam mit kupferhaltigem Adamin und Konichalcit in zersetzem Kupfererz von Tsumeb, Namibia, vor. Die Benennung erfolgte nach Prof. Dr.J.-E. Hiller (1911–1972).
Mit 1 Abbildung 相似文献
Johillerite, Na(Mg, Zn) 3 Cu(AsO 4 ) 3 , a new mineral from Tsumeb, Namibia
Summary Electron microprobe analysis of the new mineral johillerite gave Na2O 5.4, MgO 18.3, ZnO 5.4, CuO 15.8, and As2O5 55.8, total 100.7%. From this result, the ideal formula is given as Na(Mg, Zn)3 Cu(AsO4)3. Johillerite crystallizes monoclinic,C2/c. The unit cell dimensions are:a=11.870(3),b=12.755 (3),c=6.770 (2) , =113.42 (2)°,Z=4. The strongest lines on the X-ray powder diffraction pattern are: 4,06 (5) (22 ), 3,50 (4) (310), 3,25 (8) (11 ), 2,75 (10) (330, 240), 2,64 (5) (311, 13 , 40 ), 1,952 (4) (13 , 35 ), 1,682 (4) (20 , 460), 1,660 (5) (40 , 71 , 550, 64 ), 1,522 (4) (442, 153, 13 ). There is a close relationship between johillerite, o'danielite, Na(Zn, Mg)3H2(AsO4)3, and some synthetic compounds. Johillerite is violet in colour, transparent. Cleavage is {010} perfect, {100} and {001} good.H (Mohs)3.D=4.15 andD X =4.21 g·cm–3. The mineral is optically biaxial positive, 2V80 (5)°. The refractive indices are:n =1.715 (4),n =1.743 (4),n =1.783 (4). The extinction isn b and on (010)n c16°. Strongly pleochroic with axial coloursX=violet-red,Y=bluish violet andZ=greenish blue. The new mineral was found in radiated masses together with cuprian adamite and conichalcite in an oxidized copper ore from Tsumeb, Namibia. It is named in honour of Prof. Dr.J.-E. Hiller (1911–1972).
Mit 1 Abbildung 相似文献
7.
The oxygen fugacity (
) of a C-O-H fluid in equilibrium with graphite has been determined in the range 10–30 kbar by equilibrating solid
-buffer assemblages in graphite capsules containing C-O-H fluid. By using different buffers (FexO-Fe3O4, Ni-NiO, Co-CoO, Mo-MoO2), the
of the graphite-saturated fluid is bracketed within a narrow range. This technique produces a calibration for the
imposed on a sample contained within a graphite capsule. To achieve a thermodynamically-invariant system at fixed P and T,
the
was imposed on the system with an external buffer and the double-capsule technique. The experiments were performed in solid-media,
high pressure apparatus with 19 mm tale-pyrex assemblies. A series of experiments at 10, 15, 20, 25, and 30 kbar, 800–1600°
C, with
imposed by the Fe2O3-Fe3O4-H2O equilibrium were conducted. The experimental results have been fitted to the following equation:
|
相似文献
8.
9.
The massive Zn-(Pb) sulfide ore body at Rampura-Agucha in Bhilwara district, Rajasthan, occurs within graphitic metapelites
surrounded by garnet-biotite-sillimanite gneiss containing concordant bodies of amphibolite. These rocks and the sulfide ores
have been studied to estimate the pressure, temperature and fluid composition associated with upper amphibolite facies metamorphism.
Geothermobarometric calculations involving garnet-biotite and garnet-hornblende pairs, as well as sphalerite-hexagonal pyrrhotite-pyrite
and garnet-plagioclase-sillimanite-quartz assemblages indicate that the most pervasive P-T condition during peak of regional
metamorphism was 650°C and 6 kb, and was attained between the first and second deformations in the region. Some temperature-pressure
estimates also cluster around 500°C–5.1 kb which probably represent retrograde cooling during unloading.
Consideration of devolatilization equilibria in the C-O-H-S system at the pervasive metamorphic conditions mentioned above
shows that the metamorphic fluid was H2O-rich (
) but also had a substantial component of
.
and
were the other important phases in the fluid. CO (XCO = 0.002) and
were the minor phases in the fluid. It is probable that a part of this aqueous fluid was consumed by re-/neocrystallization
of hydrous silicate phases like chlorite during the retrogressive metamorphic path, so that fluid entrapped in quartz below
450°C was rendered CO2-rich (Holleret al 1996). 相似文献
10.
The dynamic character of the
phase transition in anorthite from Monte Somma has been studied by high-temperature hard mode infrared spectroscopy. The
mean local order parameter, as revealed by the temperature evolution of the frequencies of absorption bands between 540 and
620 cm-1, follows classical second-order Landau behaviour with a critical exponent β = 1.. There is no observable first-order step.
Anomalous line broadening of the 582 cm-1 band indicates that dynamic fluctuations with a relaxation time τ ≈ 10−10 s exist over a limited temperature interval of approximately 150 K about Tc, and decay rapidly as T becomes greater than Tc. Previous order-disorder models of the high-temperature
phase are not supported by these results. The Ca-flip motions, which we link to the line broadening, stabilize the driving
soft mode of the transition. These flip motion fluctuations do not give rise to departures from the classical Landau theory
because of the essential co-elastic nature of the phase transition. In the light of these results the
structural instability can be described as an essentially displacive transition. 相似文献
11.
In gravel-bedded streams where bed material of a tributary differs distinctly in lithology from that of the main stream, rock-type percentages can be used to estimate bed-load contributions of the two streams. The rock type that shows the greatest difference in abundance between the two streams is selected as the indicator lithology. Percentages of this lithology are estimated in both the main stream and tributary stream above their junction, and also in the main stream at a distance sufficiently downstream from the junction to allow complete mixing. The fraction of bed load contributed by the main stream, p,is estimated by
,where
is an estimate of the proportion of indicator rock fragments in the bed of the main stream above the junction,
is an estimate of the proportion in the bed of the tributary above the junction, and
is an estimate of the proportion in the bed of the main stream below the junction. The variance of
is obtained as var (
)= [p1q1(pr – p2)2/n(p1 – p2)4] + [p2q2(pr – p1)2/n(p1 – p2)4] + [prqr/n(p1 – p2)2].Although no estimate of actual quantity of bed load is provided, the indicator rock technique supplies data that can serve as a check on data obtained by means of empirical formulas or actual transport measurements. 相似文献
12.
13.
N. V. Chukanov O. V. Yakubovich I. V. Pekov D. I. Belakovsky W. Massa 《Geology of Ore Deposits》2008,50(8):713-719
Britvinite, a new mineral species, has been found in manganese ore at the Långban deposit, Bergslagen ore district, Filipstad, Värmland County, Sweden. Calcite, barytocalcite, brucite, cerussite, and hausmannite are associated minerals. Britvinite occurs as pale yellow to colorless transparent plates with a white streak up to 0.2 × 0.5 × 0.5 mm in size, which are flat parallel to {001}; the luster is adamantine. Thin lamellae are flexible, whereas thick ones are brittle; the Mohs hardness is 3. The cleavage is eminent parallel to {001}. The calculated density is 5.51 g/cm3. In the infrared spectrum of the new mineral, the bands of (OH)?, (CO3)2?, and (BO3)3? are recorded, whereas those corresponding to water molecules are absent. Britvinite is optically biaxial and negative, α = 1.896(2), β = 1.903(2), γ = 1.903(2), 2Vmeas = 20(10), Z≈c. Dispersion is strong, r<v. The chemical composition (electron microprobe; H2O determined with the Alimarin method, CO2, with selective sorption) is (wt %) 7.95 MgO, 71.92 PbO, 0.41 Al2O3, 12.77 SiO2, 2.2 H2O, 2.1 CO2, 2.67 B2O3 (calculated on the basis of structural data); total 100.02. The empirical formula calculated on the basis of 59 anions (O + OH) (Z = 1) is as follows: Pb14.75Mg9.03Si9.73Al0.37O30.76(BO3)3.51(CO3)2.18(OH)11.7. The simplified formula (Z = 2) is Pb7 + x Mg4.5(Si5O14)(BO3)2(CO3)(OH,O)7 (x < 0.5). The crystal structure of britvinite has been studied on a single crystal at 173 K; R = 0.0547. The new mineral is triclinic, space group P $ \bar 1
14.
Summary The unit cell of Ca7Mg9(Ca,Mg)2(PO4)12 isa=22.841(3) Å,b=9.994(1) Å,c=17.088(5) Å and =99.63(3)° at 24° C. The space-group is C2/c with four formula weights per cell. The crystal structure has been determined from 6330 X-ray reflections measured from a single crystal by a counter method and has been refined toR
w
=0.044,R=0.046 (based on 4227 observed reflections and 322 of the unobserved reflections). One cation site may be occupied by Ca or Mg and gives rise to variability in composition as is reflected in the formula give above. In the sample studied, Ca and Mg occupy the site approximately equally. The
direction in the unit cell is pseudo-hexagonal. The structure of Ca7Mg9(Ca,Mg)2(PO4)12 is related to that of K3Na(SO4)2 in that along
it has columns of cations and columns of cations and anions. These columns are arranged in a K3Na(SO4)2-type pseudo-cell. In the cation-anion columns, every other cation site in K3Na(SO4)2 is vacant in Ca7Mg9(Ca,Mg)2(PO4)12.
Die Kristallstruktur von Ca7Mg9(Ca,Mg)2(PO4)12 Zusammenfassung Die Gitterkonstanten von Ca7Mg9(Ca,Mg)2(PO4)12 sind (bei 24° C)a=22,841(3) Å,b=9,994(1) Å,c=17,088(5) Å und =99,63(3)°; Raumgruppe: C2/c;Z=4. Die Kristallstruktur wurde aus 6330 Röntgendiffraktometer-Einkristalldaten bestimmt und (auf der Basis von 4227 beobachteten und 322 nicht-beobachteten Reflexen) aufR w =0,044 undR=0,046 verfeinert. Eine Kationenlage kann von Ca oder Mg besetzt werden, was eine Variabilität der Zusammensetzung ergibt, wie sie obige Formel ausdrückt. In der untersuchten Probe besetzen Ca und Mg diese Punktlage etwa zu gleichen Teilen. Die -Richtung der Elementarzelle ist pseudo-hexagonal. Die Struktur von Ca7Mg9(Ca,Mg)2(PO4)12 ist zu der von K3Na(SO4)2 darin verwandt, daß sie längs Säulen von Kationen und Säulen von Anionen hat. Diese Säulen sind in einer Pseudozelle vom K3Na(SO4)2-Typ angeordnet. In den Kation-Anion-Säulen ist jede zweite Kationen-Lage des K3Na(SO4)2 in Ca7Mg9(Ca,Mg)2(PO4)12 unbesetzt. With 6 Figures 相似文献 15.
Fractionation of yttrium (Y) and the rare earth elements (REEs) begins in riverine systems and continues in estuaries and the ocean. Models of yttrium and rare earth (YREE) distributions in seawater must therefore consider the fractionation of these elements in both marine and riverine systems. In this work we develop a coupled riverine/marine fractionation model for dissolved rare earths and yttrium, and apply this model to calculations of marine YREE fractionation for a simple two-box (riverine/marine) geochemical system. Shale-normalized YREE concentrations in seawater can be expressed in terms of fractionation factors (
ij
) appropriate to riverine environments (
) and seawater (
):
16.
Near-liquidus phase relationships of a spinel lherzolite-bearing olivine melilitite from Tasmania were investigated over a P, T range with varying
,
, and
. At 30 kb under MH-buffered conditions, systematic changes of liquidus phases occur with increasing
(
= CO2/CO2 +H2O+olivine melilitite). Olivine is the liquidus phase in the presence of H2O alone and is joined by clinopyroxene at low
. Increasing
eliminates olivine and clinopyroxene becomes the only liquidus phase. Further addition of CO2 brings garnet+orthopyroxene onto the liquidus together with clinopyroxene, which disappears with even higher CO2. The same systematic changes appear to hold at higher and lower pressures also, only that the phase boundaries are shifted to different
. The field with olivine- +clinopyroxene becomes stable to higher
with lower pressure and approaches most closely the field with garnet+orthopyroxene+clinopyroxene at about 27 kb, 1160 °C,
0.08 and
0.2 (i.e., 6–7% CO2+ 7–8% H2O). Olivine does not coexist with garnet+orthopyroxene+clinopyroxene under these MH-buffered conditions. Lower oxygen fugacities do not increase the stability of olivine to higher
and do not change the phase relationships and liquidus temperatures drastically. Thus, it is inferred that olivine melilitite 2927 originates as a 5% melt (inferred from K2
O and P2O5 content) from a pyrolite source at about 27kb, 1160 dg with about 6–7% CO2 and 7–8% H2O dissolved in the melt. The highly undersaturated character of the melt and the inability to find olivine together with garnet and orthopyroxene on the liquidus (in spite of the close approach of the respective liquidus fields) can be explained by reaction relationships of olivine and clinopyroxene with orthopyroxene, garnet and melt in the presence of CO2. 相似文献
17.
Otto Zedlitz 《Mineralogy and Petrology》1965,10(1-4):130-139
Zusammenfassung Die von Dr.Baumann, Heidelberg, synthetisierten Quarze zeichnen sich nicht nur durch eine außerordentliche Klarheit, sondern auch durch eine auffallende Morphologie aus. Es werden drei grundsätzlich verschiedene Typen beschrieben. Typ I ist pseudorhombisch; eine der a-Achsen verleiht ihm stark polare Gestalt. Als größte Fläche ist das re. trig. Prisma II. St.
, entwickelt. Das Trapezoeder
erscheint an zwei Stellen vizinal. Typ II ist nach einer der Winkelhalbierenden der a-Achsen gestreckt. In dieser Richtung betrachtet erscheint der Kristall tetragonal, da auf diese Weise die unter rechtem Winkel stehenden Flächen
, (0001),
und
das Quadrat begrenzen. Dies sind zugleich die größtentwickelten Flächen. Typ III ist isometrisch; sämtliche Flächen (Prismen, beide Rhomboeder sowie das Basisendflächenpaar) sind etwa gleich stark entwickelt. In Richtung auf das pos. Rhomboeder betrachtet, erweckt dieser Typ den Eindruck eines kubischen Kristalles. Hier fehlen trig. Prisma und das Trapezoeder.
Summary Quarz crystals, grown by Dr.Baumann, Heidelberg, are remarkable not only for their extraordinary transparency but also for a conspicuous morphology. Three completely different types are described. Type I is pseudo-orthorhombic; one of the a-axes causes a strongly polar appearance. Largest face is the right trig. prism II. position . The trapezohedron appears in two positions as vicinals. Type II is alongated parallel to one of the bisectrices of the a-axes. Viewed in this direction the crystal seems to be tetragonal, as the faces , (0001), and , which are at right angles to each other, form a square; these faces are at the same time the largest ones. Typ III is isometric; all the faces (prisms, both rhombohedrons, and the pinacoid) are of approximately the same size. Viewed in the direction upon the pos. rhombohedron this type appears to be cubic. The trig. prism and the trapezohedron are here missing. Mit 4 Figuren und 3 Textabbildungen Herrn Professor Dr.F. Machatschki zum 70. Geburtstag gewidmet. 相似文献 18.
Field and laboratory data are presented that show a soluble FeS species(FeSaq) exists in sulfidic seawater solutions, and is observedwhen the IAP exceeds the Ksp of amorphous FeS. TheFeSaq yields a discrete signal (double peak) using square-wavevoltammetry and two one-electron waves in sampled DC polarographyexperiments at the Hg electrode. The aqueous FeS species reacts irreversiblyat the electrode as a single FeS subunit and not as a polymeric entity. Thepeak potential of FeSaq occurs at -1.1 V whereas the peakpotential of Fe
occurs at-1.45 V; the positive shift for Fe2+ reduction inFeSaq indicates a change in geometry for Fe2+from octahedral to tetrahedral. The kinetics of electron transfer at theelectrode are determined to be similar for both Fe2+ andFeSaq. Molecular orbital energy diagrams, further indicatethat Fe(II) does change from octahedral to tetrahedral geometry in solution.First, Fe(II) exists as octahedralFe
in solution whichundergoes a substitution reaction of bisulfide for water. The resultingcomplex, Fe(H2O)5(HS)+, thentransforms to a tetrahedral complex on further addition of sulfide. Thisgeometry change is consistent with the formation of amorphous FeS thatconverts to mackinawite which has tetrahedral Fe(II). The process is entropydriven because of the water loss that occurs. The overall sequence can berepresented as:
Soluble FeS species are important asreactants in the formation of iron-sulfide minerals including pyrite. 相似文献
19.
Dr. K. Mereiter 《Mineralogy and Petrology》1976,23(4):317-327
Zusammenfassung Die Kristallstruktur des Ferrinatrits, Na3Fe[SO4]3·3H2O, Raumgruppe
,a
o=15,560 Å,c
o=8,666 Å,Z=6, wurde mittels der mit einem Zweikreis-Diffrak tometer gemessenen Röntgen-Intensitäten bestimmt und für 1591 symmetrieunabhängigeF
obs
aufR=0,047 verfeinert. In Ferrinatrit sind FeO6-Oktaeder und Sulfattetraeder über gemeinsame Ecken zu Ketten
verknüpft. Diese Ketten verlaufen parallelz und sind untereinander über Natriumionen und Wassermoleküle verbunden. Die Mittelwerte der wichtigsten Bindun gslängen betrgen: Fe–O=1,997 Å, S–O=1,474 Å, Na–(4×O+2×Ow)=2,49 Å.
The crystal structure of ferrinatrite, Na3Fe[SO4]3 · 3H2O Summary The crystal structure of ferrinatrite, Na3Fe[SO4]3·3H2O, space group ,a 0=15.560 Å,c 0=8.666 Å,Z=6, was determined from X-ray intensities measured on a 2-circle diffractometer and was refined using 1591 independentF obs toR=0.047. FeO6 Octahedra and sulfate tetrahedra share common corners to from infinite chains which run parallel toz and are linked by sodium ions and water molecules. Important average bond lengths are: Fe–O=1.997 Å, S–O=1.474Å, Na-(4×0+2×Ow)=2.49 Å. Mit 2 Abbildungen Herrn Prof. DDr.H. Wieseneder zum 70. Geburtstag gewidmet. 相似文献 20.
Sytle M. Antao Ishmael Hassan Willem H. Mulder Peter L. Lee Brian H. Toby 《Physics and Chemistry of Minerals》2009,36(3):159-169
The temperature dependences of the crystal structure and intensities of the (113) and (211) reflections in calcite, CaCO3, were studied using Rietveld structure refinements based on synchrotron powder X-ray diffraction data. Calcite transforms
from to at about T
c = 1,240 K. A CO3 group occupies, statistically, two positions with equal frequency in the disordered phase, but with unequal frequency in the partially ordered phase. One position for the CO3 group is rotated by 180° with respect to the other. The unequal occupancy of the two orientations in the partially ordered
phase is obtained directly from the occupancy factor, x, for the O1 site and gives rise to the order parameter, S = 2x − 1. The a cell parameter shows a negative thermal expansion at low T, followed by a plateau region at higher T, then a steeper contraction towards T
c, where the CO3 groups disorder in a rapid process. Using a modified Bragg–Williams model, fits were obtained for the order parameter S, and for the intensities of the (113) and (211) reflections.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
|