scholarly journals Ultrahigh-Temperature Sphalerite from Zn-Cd-Se-Rich Combustion Metamorphic Marbles, Daba Complex, Central Jordan: Paragenesis, Chemistry, and Structure

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 822 ◽  
Author(s):  
Ella V. Sokol ◽  
Svetlana N. Kokh ◽  
Yurii V. Seryotkin ◽  
Anna S. Deviatiiarova ◽  
Sergey V. Goryainov ◽  
...  
Keyword(s):  
Solid Solution ◽  
Trace Element ◽  
Unit Cell ◽  
Homogeneous Solid Solution ◽  
Central Jordan ◽  
Carbonate Fluorapatite ◽  
Ultrahigh Temperature

Minerals of the Zn-Cd-S-Se system that formed by moderately reduced ~800–850 °C combustion metamorphic (CM) alteration of marly sediments were found in marbles from central Jordan. Their precursor sediments contain Se- and Ni-enriched authigenic pyrite and ZnS modifications with high Cd enrichment (up to ~10 wt%) and elevated concentrations of Cu, Sb, Ag, Mo, and Pb. The marbles are composed of calcite, carbonate-fluorapatite, spurrite, and brownmillerite and characterized by high P, Zn, Cd, U, and elevated Se, Ni, V, and Mo contents. Main accessories are either Zn-bearing oxides or sphalerite, greenockite, and Ca-Fe-Ni-Cu-O-S-Se oxychalcogenides. CM alteration lead to compositional homogenization of metamorphic sphalerite, for which trace-element suites become less diverse than in the authigenic ZnS. The CM sphalerites contain up to ~14 wt% Cd and ~6.7 wt% Se but are poor in Fe (means 1.4–2.2 wt%), and bear 100–250 ppm Co, Ni, and Hg. Sphalerite (Zn,Cd,Fe)(S,O,Se)cub is a homogeneous solid solution with a unit cell smaller than in ZnScub as a result of S2− → O2− substitution (a = 5.40852(12) Å, V = 158.211(6) Å3). The amount of lattice-bound oxygen in the CM sphalerite is within the range for synthetic ZnS1−xOx crystals (0 < x ≤ 0.05) growing at 900 °C.

The solid solution TbNiIn1−x Ga x

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Myroslava Horiacha ◽  
Galyna Nychyporuk ◽  
Rainer Pöttgen ◽  
Vasyl Zaremba
Keyword(s):  
Solid Solution ◽  
Unit Cell ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Structure Space ◽  
Arc Melting

Abstract Phase formation in the solid solution TbNiIn1−x Ga x at 873 K was investigated in the full concentration range by means of powder X-ray diffraction and EDX analysis. The samples were synthesized by arc-melting of the pure metals with subsequent annealing at 873 K for one month. The influence of the substitution of indium by gallium on the type of structure and solubility was studied. The solubility ranges have been determined and changes of the unit cell parameters were calculated on the basis of powder X-ray diffraction data: TbNiIn1–0.4Ga0–0.6 (ZrNiAl-type structure, space group P 6 ‾ 2 m $P&#x203e;{6}2m$ , a = 0.74461(8)–0.72711(17) and c = 0.37976(5)–0.37469(8) nm); TbNiIn0.2–0Ga0.8–1.0 (TiNiSi-type structure, space group Pnma, а = 0.68950(11)–0.68830(12), b = 0.43053(9)–0.42974(6), с = 0.74186(10)–0.73486(13) nm). The crystal structures of TbNiGa (TiNiSi type, Pnma, a = 0.69140(5), b = 0.43047(7), c = 0.73553(8) nm, wR2=0.0414, 525 F 2 values, 21 variables), TbNiIn0.83(1)Ga0.17(1) (ZrNiAl type, P 6 ‾ 2 m $P&#x203e;{6}2m$ , a = 0.74043(6), c = 0.37789(3) nm, wR2 = 0.0293, 322 F 2 values, 16 variables) and TbNiIn0.12(2)Ga0.88(2) (TiNiSi type, Pnma, a = 0.69124(6), b = 0.43134(9), c = 0.74232(11) nm, wR2 = 0.0495, 516 F 2 values, 21 variables) have been determined. The characteristics of the solid solutions and the variations of the unit cell parameters are briefly discussed.

The role of mineral nanoparticles at a fluid-magnetite interface: Implications for trace-element uptake in hydrothermal systems

2019 ◽  
Vol 104 (8) ◽  
pp. 1180-1188 ◽  
Author(s):  
Shuo Yin ◽  
Richard Wirth ◽  
Changqian Ma ◽  
Jiannan Xu
Keyword(s):  
Solid Solution ◽  
Crystal Lattice ◽  
Trace Element ◽  
Hydrothermal Systems ◽  
Oscillatory Zoning ◽  
Bulk Fluid ◽  
Continuous Increase ◽  
Interfacial Fluid ◽  
Spinel Nanoparticles

Abstract The migrating fluid-mineral interface provides an opportunity for the uptake of trace elements as solid solutions in the newly formed crystal lattice during the non-equilibrium growth of the crystal. However, mineral nanoparticles could precipitate directly from the interfacial fluid when it evolves to a supersaturated situation. To better understand the role of mineral nanoparticles in this scenario, this study focuses on a well-documented magnetite with oscillatory zoning from a skarn deposit by using high-resolution transmission electron microscopy (TEM). Our results show that the Al concentration in magnetite measured on a micrometer-scale is caused by three different effects: Al solid solution, Al-rich nanometer-sized lamellae, and zinc spinel nanoparticles in the host magnetite. Here, we propose a genetic relationship among the three different phases mentioned above. At first, a continuous increase of the Al concentration in the interfacial fluid can be incorporated into the crystal lattice of magnetite forming a solid solution. During cooling in a later stage, aluminum in magnetite is oversaturated and exsolution of hercynite (Al-rich lamellae) occurs from the host magnetite. If the Al concentration at the fluid-magnetite interface still increases during further growth of magnetite, the substitution of Fe by Al has gradually reached saturation so that aluminum cannot be incorporated in the magnetite crystal structure any longer. Using the magnetite lattice as a template, nucleation of abundant zinc spinel nanoparticles occurs. This will, in turn, lead to a gradual depletion of Al concentration in the interfacial fluid until the available ions for zinc spinel nucleation and growth have been used up. As a result, the migrating fluid-magnetite interface will enrich the Al concentration in the interfacial fluid until the available ion concentration is sufficient for nucleation of zinc spinel phase again. The fluid-mineral interface in this mechanism has been repeatedly utilized during crystal growth, providing an efficient way for the uptake of trace element from a related undersaturated bulk fluid.

scholarly journals Enhanced catalytic activity of inhomogeneous Rh-based solid-solution alloy nanoparticles

RSC Advances ◽  
2019 ◽  
Vol 9 (66) ◽  
pp. 38882-38890 ◽  
Author(s):  
Md Samiul Islam Sarker ◽  
Takahiro Nakamura ◽  
Satoshi Kameoka ◽  
Yuichiro Hayasaka ◽  
Shu Yin ◽  
...  
Keyword(s):  
Solid Solution ◽  
Catalytic Activity ◽  
Solid Solution Alloy ◽  
Alloy Nanoparticles ◽  
Solution Structures ◽  
Homogeneous Solid Solution

Catalytic Rh-based alloy nanoparticles (NPs) with inhomogeneous solid-solution structures were prepared from homogeneous solid-solution alloy NPs.

scholarly journals Nepheline solid solution compositions: stoichiometry revisited, reviewed, clarified and rationalised

2020 ◽  
pp. 1-26 ◽  
Author(s):  
C. Michael B. Henderson
Keyword(s):  
Solid Solution ◽  
Unit Cell ◽  
Alkaline Complex ◽  
High Quality ◽  
Diagnostic Parameters ◽  
Rock Types ◽  
Charge Parameter ◽  
Cation Charge ◽  
Excel File

Abstract Molecular formulae used to recalculate nepheline analyses generally have different numbers of oxygens (e.g. NaAlSiO4 (Ne), KAlSiO4, (Ks), CaAl2Si2O8 (An) and SiO2 (Q)). A 32 oxygen cell has 16 T cations and 8 cavity sites, but ideal nepheline stoichiometry is not necessarily followed. Ca end-member □CaCaAl2Si2O4 (CaNe) and excess silica end-member □SiSi2O4 (Q’) calculation requires inclusion of both vacancy species as cavity cation values. Q’ parameter calculations can involve different assumptions and four parameters are described: Qxs; QSi; Q(Si–Al); and Qcavity; these should have closely similar values for high-quality, stoichiometric analyses. Representative published compositions are recalculated to assess whether authors followed ideal nepheline stoichiometry. Phenocrysts from peralkaline rocks and nephelinites typically exhibit Al deficiencies reflected in negative Δ(Al – cavity cation) parameters (ΔAlcc), negative ‘normative’ corundum (Al2O3, Cn), and anomalously low or negative Qxs parameters; for such rock types Q(Si–Al) provides a better estimate of excess silica contents. A ΔT-site (cation charge) parameter (ΔTcharge), is closely coupled to ΔAlcc and end-member NaAlSiO4 has a ΔAlcc/ΔTcharge ratio of 1.4296; the derivation of this value is controlled by strict stuffed-tridymite, unit-cell constraints. Natural nephelines all contain excess silica with a mean ΔAlcc/ΔTcharge of ~1.134 reflecting their Si/Al ratio being > 1. Nepheline analyses with relatively low Al and Si and high Na (also Ca) contents are common; this might reflect the presence of small amounts (up to ~5%) of cancrinite as an alteration phase or perhaps even in solid solution. The compositions of alteration lamellae of Ca-rich cancrinite in altered nepheline phenocrysts in phonolites from the Marangudzi alkaline complex, Zimbabwe, are used to define diagnostic parameters for recognising such non-stoichiometry. These alteration lamellae formed hydrothermally from Ca-rich and K-poor fluids. An EXCEL file is provided to help researchers to standardise calculation of nepheline end-member molecular proportions.

Neutron Powder Diffraction Investigation of Pd2.7Ni0.3P0.94

2004 ◽  
Vol 443-444 ◽  
pp. 353-356
Author(s):  
M. Vennström ◽  
Y. Andersson
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Neutron Powder Diffraction ◽  
Unit Cell ◽  
Type Structure ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Method Show

Pd3P, which crystallises in the cementite, Fe3C-type structure, forms a solid solution with nickel. The crystal structure contains two crystallographically different palladium sites (8d and 4c). Refinements of neutron powder diffraction intensities using the Rietveld method show that all nickel atoms occupy the eight-fold position. The unit cell parameters were refined to a=5.7812(4) Å, b=7.4756(6) Å and c=5.1376(4) Å, for Pd2.7Ni0.3P0.94.

The crystal structure of ammoniojarosite, (NH4)Fe3(SO4)W(OH)6 and the crystal chemistry of the ammoniojarosite–hydronium jarosite solid-solution series

2007 ◽  
Vol 71 (4) ◽  
pp. 427-441 ◽  
Author(s):  
L. C. Basciano ◽  
R. C. Peterson
Keyword(s):  
Solid Solution ◽  
Short Wave ◽  
Unit Cell ◽  
Solid Solution Series ◽  
Hydrogen Atoms ◽  
Solution Series ◽  
Hydronium Jarosite ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
End Members

AbstractThe atomic structure of ammoniojarosite,[(NH4)Fe3(SO4)2(OH)6], a = 7.3177(3) Å, c = 17.534(1) Å, space group Rm, Z = 3, has been solved using single-crystal X-ray diffraction (XRD) to wR 3.64% and R 1.4%. The atomic coordinates of the hydrogen atoms of the NH4 group were located and it was found that the ammonium group has two different orientations with equal probability. Hydronium commonly substitutes into jarosite group mineral structures and samples in the ammoniojarosite–hydronium jarosite solid-solution series were synthesized and analysed using powder XRD and Rietveld refinement. Changes in unit-cell dimensions and bond lengths are noted across the solidsolution series. The end-member ammoniojarosite synthesized in this study has no hydronium substitution in the A site and the unit-cell dimensions determined have a smaller a dimension and larger c dimension than previous studies. Two natural ammoniojarosite samples were analysed and shown to have similar unit-cell dimensions to the synthetic samples. Short-wave infrared and Fourier transform infrared spectra were collected for samples from the NH4–H3O jarosite solid-solution series and the differences between the end-members were significant. Both are useful tools for determining NH4 content in jarosite group minerals.

Defect fluorite structures containing Bi 2 O 3 : the system Bi 2 O 3 -Nb 2 O 5

1986 ◽  
Vol 406 (1831) ◽  
pp. 173-182 ◽  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Electron Diffraction ◽  
Pyrochlore Structure ◽  
High Resolution Electron Microscopy ◽  
Unit Cell ◽  
Compositional Range ◽  
Resolution Electron ◽  
Structural Principles

A previously described solid solution in the system Bi 2 O 3 -Nb 2 O 5 based on the δ-Bi 2 O 3 structure has been reinvestigated by electron diffraction and high resolution electron microscopy. Four distinct phases have been found, all of which are based upon defect fluorite structures, and the structural principles of the phase with the greatest compositional range have been elucidated. This involves an adaption of elements of the pyrochlore structure with an ordering of niobium-oxygen octahedra into groups lying on the {111} planes of an enlarged cubic unit cell, separated by a matrix of δ-Bi 2 O 3 structure.

scholarly journals Synthesis of α-cristobalite-type CO2-SiO2under extreme conditions

2014 ◽  
Vol 70 (a1) ◽  
pp. C753-C753
Author(s):  
Julien Haines ◽  
Mario Santoro ◽  
Federico Gorelli ◽  
Roberto Bini ◽  
Olivier Cambon ◽  
...  
Keyword(s):  
Solid Solution ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Metastable Phase ◽  
Ambient Pressure ◽  
Small Variation ◽  
Unit Cell ◽  
Extreme Conditions ◽  
Oxygen Sublattice ◽  
Compact Structure

Extreme conditions change the behavior and reactivity of elements and compounds and permit the synthesis of novel materials. In the case of group IV oxides, molecular CO2and a network solid silica, which were considered to be incompatible, are found to react under HP-HT conditions. A crystalline CO2-SiO2solid solution was synthesized from molecular CO2and microporous silicalite SiO2at 16-22 GPa and temperatures above 4000 K in a laser heated diamond anvil cell [1]. Synchrotron X-ray diffraction data show that the crystal adopts a densely packed α-cristobalite structure (space group P41212) with carbon and silicon in 4-fold coordination. This occurs at pressures at which SiO2normally adopts a 6-fold coordinated rutile-type stishovite structure. The P-T conditions used in this study represent a compromise between the respective stabilities of 3- and 4-fold coordination in CO2and 4- and 6-fold coordination in SiO2. This solid solution can be recovered at ambient pressure at which the unit cell volume is 26% lower than that of α-cristobalite SiO2. This is due to the incorporation of much smaller carbon atoms, resulting in the collapse of the oxygen sublattice. The unit cell volume and the different C and Si sites identified in Raman spectroscopy are consistent with a C:Si ratio of 6(1):4(1). The tetragonal c/a ratio increases from 1.283 at 16 GPa to 1.303 at ambient pressure and is lower than that of SiO2due to the more compact structure of the new material and essentially corresponds to that of the dense rutile-type oxygen sublattice. This can explain the small variation in volume observed for this phase corresponding to a bulk modulus of about 240 GPa. Due to the incorporation of silicon atoms, this hard solid based on CO4tetrahedra can be retained as a metastable phase. This strongly modifies standard oxide chemistry and shows that carbon can enter silica giving rise to a new class of hard, light, carbon-rich oxide materials with novel physical properties.

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