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1.
Emil Makovicky Sven Karup-Møller Milota Makovicky Jhon Rose-Hansen 《Mineralogy and Petrology》1990,42(1-4):307-319
Summary In the present paper current results of experimental investigation of the phase system Pd-Fe-Ni-S at 900°C, 725°C, 550°C and 400°C as well as of the phase system Pt-Fe-As-S at 850°C and 470°C are summarized. A preliminary note on the system Pt-Pd-As-S is added. Individual phase assemblages are presented, data on solubility of PGE in base metal sulphides/arsenides or alloys are given and solid solution ranges of important minerals are described as a function of temperature and phase assemblage. The extent and role of sulphide/arsenide melts in these systems are presented together with hints for, and examples of the application of the current experimental results for the explanation of ore-geological processes.
With 6 Figures 相似文献
Bisherige Ergebnisse experimenteller Untersuchungen in den Systemen Fe-Ni-Pd-S und Fe-Pt-Pd-As-S und ihre Bedeutung für Lagerstätten der Platin-Gruppen-Elemente
Zusammenfassung In der vorliegenden Arbeit werden bisherige Ergebnisse experimenteller Untersuchungen in den Phasensystemen Pd-Fe-Ni-S bei 900°C, 725°C, 550°C sowie 400°C, bzw. Pt-Fe-As-S bei 850°C und 470°C zusammengefasst. Vorläufige Anmerkungen zum System Pt-Pd-As-S werden gegeben. Die Phasenbeziehungen und die Löslichkeitsdaten von PGE's in Buntmetall-Sulfiden/Arseniden sowie deren Verbindungen werden präsentiert. Die Mischungsbereiche der wichtigsten Minerale werden als Funktion von Temperatur und Phasenvergesellschaftung diskutiert. Die Rolle von Sulfid/Arsenid Schmelzen in diesen Systemen und Beispiele für die Anwendung dieser experimentellen Ergebnisse zur Erklärung lagerstättenkundlicher Prozesse werden beschrieben.
With 6 Figures 相似文献
2.
Emil Makovicky 《Mineralogy and Petrology》2012,106(1-2):19-24
3.
Jens Wenzel Andreasen Emil Makovicky Bente Lebech Sven Karup Møller 《Physics and Chemistry of Minerals》2008,35(8):447-454
Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu12?xFexSb4S13) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu12?xFexAs4S13) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I $ \ifmmode\expandafter\bar\else\expandafter\=\fi{4} Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu12−xFexSb4S13) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu12−xFexAs4S13) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I 3 m). The refinement results also confirm that M2 is a split (24g), flat-pyramidal site situated statistically on both sides of the S1−S1–S2 triangle. In tetrahedrite, this split is about
0.6 ?, in tennantite about 0.7 ?. Trends in bond lengths and magnitude of the M2 split were evaluated by means of linear regression
with Fe concentration as the independent variable. 相似文献
4.
L. F.?LundegaardEmail author R.?Miletich T.?Balic-Zunic E.?Makovicky 《Physics and Chemistry of Minerals》2003,30(8):463-468
High-precision unit-cell volume data of stibnite, collected in the pressure range of 0–10 GPa, was used for fitting a third-order Birch–Murnaghan equation of state. The zero-pressure volume, bulk modulus and its pressure derivative were found to be 487.73(6) Å3, 26.91(14) GPa and 7.9(1), respectively. A series of X-ray intensity data was collected in the same pressure range using a CCD-equipped Bruker diffractometer. The high-pressure structures were all refined to R1(|F0|>4) values of approximately 0.03. Crystal-chemical parameters as polyhedron volume, centroid and eccentricity were calculated for the seven coordinated cation positions using the software IVTON. The cation eccentricity appears to be a very useful tool for quantification of the lone electron pair activity. U2S3, Dy2S3 and Nd2Te3 are all isostructural with stibnite, but the cations in these materials have no lone electron pair. Their eccentricity is much smaller than that of Sb, and close to zero. This confirms that the stibnite structure type alone does not force eccentricity upon the cations involved and it is the lone electron pairs of Sb that generate the eccentricity of cation positions in the structures of stibnite. At increasing pressure the eccentricity of Sb is decreasing. It is therefore reasonable to conclude that the lone electron pair activity is decreasing with increasing pressure. 相似文献
5.
Summary Tetrahedrites with the composition between Cu12Sb4S13 and Cu10Fe2Sb4S13 were synthesized at 457 °C and 500 °C from the elements and carefully studied by Mössbauer spectroscopy of57Fe. Between Cu12Sb4S13 and Cu11Fe1Sb4S13 iron is predominantly ferric. Between Cu11Fe1Sb4S13 and Cu10Fe2Sb4S13 iron is predominantly ferrous and occupies the tetrahedral M1-sites.
Zusammenfassung Die Rolle von Fe2+ und Fe3+ in synthetischen Tetraedriten mit Fe-Substitution Tetraedrite mit einer Zusammensetzung zwischen Cu12Sb4S13 and Cu10Fe2Sb4S13 wurden bei 457 °C und 500 °C aus den Elementen synthetisiert und sorgfdltig mit Mössbauer-Spektroskopie von57Fe untersucht. Zwischen Cu12Sb4S13 and Cu11Fe1Sb4S13 ist Eisen überwiegend dreiwertig. Zwischen Cu11Fe1Sb4S13 and Cu11Fe2Sb4S13 ist Eisen überwiegend zweiwertig und besetzt die tetraedrisch koordinierten M1-Plätze.相似文献
6.
Lars A. Olsen Tonci Balic-Zunic Emil Makovicky Angela Ullrich Ronald Miletich 《Physics and Chemistry of Minerals》2007,34(7):467-475
A single-crystal sample of galenobismutite was subjected to hydrostatic pressures in the range of 0.0001 and 9 GPa at room temperature using the diamond-anvil cell technique. A series of X-ray diffraction intensities were collected at ten distinct pressures using a CCD equipped 4-circle diffractometer. The crystal structure was refined to R1(|F0| > 4σ) values of approximately 0.05 at all pressures. By fitting a third-order Birch-Murnaghan equation of state to the unit-cell volumes V 0 = 700.6(2) Å3, K 0 = 43.9(7) GPa and dK/dP = 6.9(3) could be determined for the lattice compression. Both types of cations in galenobismutite have stereochemically active lone electron pairs, which distort the cation polyhedra at room pressure. The cation eccentricities decrease at higher pressure but are still pronounced at 9 GPa. Galenobismutite is isotypic with CaFe2O4 (CF) but moves away from the idealised CF-type structure during compression. Instead of the two octahedral cation sites and one bi-capped trigonal-prismatic site, PbBi2S4 attains a new high-pressure structure characterised by one octahedral site and two mono-capped trigonal-prismatic sites. Analyses of the crystal structure at high pressure confirm the preference of Bi for the octahedral site and the smaller one of the two trigonal-prismatic sites. 相似文献
7.
L. A. Olsen K. Friese E. Makovicky T. Balić-Žunić W. Morgenroth A. Grzechnik 《Physics and Chemistry of Minerals》2011,38(1):1-10
The crystal structure of Pb6Bi2S9 is investigated at pressures between 0 and 5.6 GPa with X-ray diffraction on single-crystals. The pressure is applied using diamond anvil cells. Heyrovskyite (Bbmm, a = 13.719(4) Å, b = 31.393(9) Å, c = 4.1319(10) Å, Z = 4) is the stable phase of Pb6Bi2S9 at ambient conditions and is built from distorted moduli of PbS-archetype structure with a low stereochemical activity of the Pb2+ and Bi3+ lone electron pairs. Heyrovskyite is stable until at least 3.9 GPa and a first-order phase transition occurs between 3.9 and 4.8 GPa. A single-crystal is retained after the reversible phase transition despite an anisotropic contraction of the unit cell and a volume decrease of 4.2%. The crystal structure of the high pressure phase, β-Pb6Bi2S9, is solved in Pna2 1 (a = 25.302(7) Å, b = 30.819(9) Å, c = 4.0640(13) Å, Z = 8) from synchrotron data at 5.06 GPa. This structure consists of two types of moduli with SnS/TlI-archetype structure in which the Pb and Bi lone pairs are strongly expressed. The mechanism of the phase transition is described in detail and the results are compared to the closely related phase transition in Pb3Bi2S6 (lillianite). 相似文献
8.
L. F. Lundegaard E. Makovicky T. Boffa-Ballaran T. Balic-Zunic 《Physics and Chemistry of Minerals》2005,32(8-9):578-584
Crystal structure of Bi2S3 was refined at eight distinct hydrostatic pressures in the range 0–10 GPa using a CCD equipped 4-circle diffractometer and a diamond-anvil cell. Coefficients of the BM3 equation of state are as follows: zero-pressure volume 498.4(7) Å3, bulk modulus K 0 36.6(15) GPa and its pressure derivative 6.4(5). The bulk of compression takes place in the structural space between Bi4S6 ribbons, where lone-electron pairs are accommodated. Eccentricity of Bi in its coordination polyhedra decreases in the process, with long Bi–S distances decreasing, whereas the opposing short Bi–S distances stay constant or even increase in length. All these phenomena are compatible with the movement of lone-electron pairs of Bi closer to the parent atom at increasing pressure. 相似文献
9.
Karen Friese Andrzej Grzechnik Emil Makovicky Tonči Balić-Žunić Sven Karup-Møller 《Physics and Chemistry of Minerals》2008,35(8):455-465
Rietveld refinement of X-ray synchrotron data was performed for two synthetic tetrahedrite samples, with 0.61 and 1.83 Fe atoms, and two synthetic tennantite samples with 0.10 and 1.23 Fe atoms p.f.u. M12(Sb,As)4S13. Measurements were performed at 25 and 250°C. For both the phases, increased Fe substitution is reflected in the increased tetrahedral ‘Cu1’–S distance (‘Cu1’ is a site of Fe substitution) and Cu2–S distances. Cu2 was refined as a split position; the Cu2–Cu2 split about the plane of the S12S2 triangle is about 0.56 and 0.65 Å for tetrahedrite and tennantite, respectively. Cu2–Cu2 distances in the structure cavity are 2.8–2.9 Å. Between 25 and 250°C, the lattice parameter a increased by 0.02–0.04 Å and the interatomic distances by 0.01 Å on an average. Thermal expansion coefficients of little-substituted samples are similar to those of unsubstituted samples, whereas thermal expansion appears to decrease with increasing substitution by Fe. The Cu2–Cu2 split increases at 250°C by about 0.1 Å for tetrahedrite and by more than 0.15 Å for tennantite but the cage expansion is minimal so that the Cu2–Cu2 distances in the cavity decrease with temperature. Difference Fourier maps indicate that there is little residual electron density left between the two Cu2 half-sites in tetrahedrite but this inter-site density is substantially higher in tennantite. It increases with temperature, especially in the little-substituted tennantite sample. 相似文献
10.
Mineralogy and Petrology - Monohydrocalcite, CaCO3·H2O, forms a P31 structure composed of composite rods in which a spiral arrangement of Ca ions is accompanied by spiral arrangements of CO3... 相似文献