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.

Silicon nitride: Enthalpy of formation of the α- and β-polymorphs and the effect of C and O impurities

1999 ◽  
Vol 14 (5) ◽  
pp. 1959-1968 ◽  
Author(s):  
Jian-jie Liang ◽  
Letitia Topor ◽  
Alexandra Navrotsky ◽  
Mamoru Mitomo
Keyword(s):  
Solid Solution ◽  
Enthalpy Of Formation ◽  
Solution Calorimetry ◽  
Molar Enthalpy ◽  
Solid Solution Series ◽  
Solution Series ◽  
Α Phase ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
The Enthalpy Of Formation

High-temperature oxidative drop solution calorimetry was used to measure the enthalpy of formation of α− and β−Si3N4. Two different solvents, molten alkali borate (48 wt% LiBO2 · 52 wt% NaBO2) at 1043 and 1073 K and potassium vanadate (K2O · 3V2O5) at 973 K, were used, giving the same results. Pure α− and β−Si3N4 polymorphs have the same molar enthalpy of formation at 298 K of −850.9 ± 22.4 and −852.0 ± 8.7 kJ/mol, respectively. The unit cell dimensions of impure α−Si3N4 samples depend linearly on the O and C impurity contents, and so does the molar enthalpy of formation. The energetic stability of the α−Si3N4phase decreases when the sample contains O and C impurities. The experimental evidence strongly suggests that the impurities dissolve into the α−Si3N4 structure to form a (limited) isostructural solid solution series but that this solid solution series is energetically less stable than a mechanical mixture of pure (α or β) Si3N4, SiO2, and SiC. Thus, the α-phase is not stabilized by impurities and is probably always metastable.

Monazite end members and solid solutions: synthesis, unit-cell characteristics, and utilization as microprobe standards

1989 ◽  
Vol 53 (369) ◽  
pp. 120-123 ◽  
Author(s):  
J. M. Montel ◽  
F. Lhote ◽  
J. M. Claude
Keyword(s):  
Solid Solution ◽  
Experimental Study ◽  
Solid Solutions ◽  
Unit Cell ◽  
Solid Solution Series ◽  
Solution Series ◽  
End Members ◽  
Characteristics And Utilization

The synthesis of monazite was first reported by Radominsky (1875). Since then various methods have been used to synthesize various end members of the monazite solid solution series, mainly CePO4 and LaPO4 (e.g. Anthony, 1957, 1965). As part of an experimental study dealing with the solubility of monazite in granitic melts (Montel, 1986, 1987, and in prep.), the synthesis of some of the end members, as well as solid solutions, was achieved.

The chemical stability of mimetite and distribution coefficients for pyromorphite–mimetite solid-solutions

1989 ◽  
Vol 53 (371) ◽  
pp. 363-371 ◽  
Author(s):  
Adedayo I. Inegbenebor ◽  
John H. Thomas ◽  
Peter A. Williams
Keyword(s):  
Solid Solution ◽  
Aqueous Solution ◽  
Solid Phase ◽  
Distribution Coefficients ◽  
Solid Solution Series ◽  
Solution Series ◽  
Ph Values ◽  
Naturally Occurring ◽  
Phosphate Species ◽  
End Members

AbstractThe equilibrium solubility of mimetite has been determined in aqueous solution at 298.2K. For the reaction Pb5(ASO4)3Cl(s,mimetite)+6H+(aq)⇌5Pb2+(aq)+3H2AsO4−(aq)+Cl−(aq) at this temperature log KH+, extrapolated to zero ionic strength, is equal to −27.9(4). This value is equal, within experimental error, to that corresponding to pyromorphite, Pb5(PO4)3Cl, derived from the literature, and redetermined here under analogous conditions. Distribution coefficients in terms of both HXO42− and H2XO4−(aq) ions (X = P,As) have also been determined for solid phases of the pyromorphite-mimetite solid solution series containing from 5 to 95 mol. % mimetite. Although the two end-members are isostructural without being strictly isomorphous, the solid solution series behaves ideally over the whole compositional range; that is, the composition of the solid phase reflects the ratio of arsenate to phosphate species in aqueous solution at pH values corresponding to naturally-occurring aqueous solutions generally associated with the oxidized zones of base metal orebodies. Some relationships between mimetite and other secondary lead(II) and copper(II) arsenate minerals have been explored.

True and brittle micas: composition and solid-solution series

2007 ◽  
Vol 71 (3) ◽  
pp. 285-320 ◽  
Author(s):  
G. Tischendorf ◽  
H.-J. Förster ◽  
B. Gottesmann ◽  
M. Rieder
Keyword(s):  
Solid Solution ◽  
Crystal Structures ◽  
Solid Solutions ◽  
Solid Solution Series ◽  
Octahedral Sheet ◽  
Tetrahedral Sheet ◽  
Solution Series ◽  
The Common ◽  
End Members ◽  
Graphical Presentation

AbstractMicas incorporate a wide variety of elements in their crystal structures. Elements occurring in significant concentrations in micas include: Si, IVAl, IVFe3+, B and Be in the tetrahedral sheet; Ti, VIAl, VIFe3+, Mn3+, Cr, V, Fe2+, Mn2+, Mg and Li in the octahedral sheet; K, Na, Rb, Cs, NH4, Ca and Ba in the interlayer; and O, OH, F, Cl and S as anions. Extensive substitutions within these groups of elements form compositionally varied micas as members of different solid-solution series. The most common true K micas (94% of almost 6750 mica analyses) belong to three dominant solid-solution series (phlogopite–annite, siderophyllite–polylithionite and muscovite–celadonite). Theirclassification parameters include: Mg/(Mg+Fetot) [=Mg#] formicas with VIR >2.5 a.p.f.u. and VIAl <0.5 a.p.f.u.; Fetot/(Fetot+Li) [=Fe#] formicas with VIR >2.5 a.p.f.u. and VIAl >0.5 a.p.f.u.; and VIAl/(VIAl+Fetot+Mg) [=Al#] formicas with VIR <2.5 a.p.f.u. The common true K micas plot predominantly within and between these series and have Mg6Li <0.3 a.p.f.u. Tainiolite is a mica with Mg6Li >0.7 a.p.f.u., or, fortr ansitional stages, 0.3–0.7 a.p.f.u. Some true K mica end-members, especially phlogopite, annite and muscovite, form binary solid solutions with non-K true micas and with brittle micas (6% of the micas studied). Graphical presentation of true K micas using the coordinates Mg minus Li (= mgli) and VIFetot+Mn+Ti minus VIAl (= feal) depends on theirclassification according to VIR and VIAl, complemented with the 50/50 rule.

Crandallite group minerals in the Helikian Athabasca Group in Alberta, Canada

1985 ◽  
Vol 22 (4) ◽  
pp. 637-641 ◽  
Author(s):  
John A. Wilson
Keyword(s):  
Solid Solution ◽  
Metamorphic Rock ◽  
Rock Fragment ◽  
Solid Solution Series ◽  
Depositional History ◽  
Solution Series ◽  
History Of ◽  
End Members ◽  
Petrographic Study ◽  
Detrital Component

Members of the crandallite group of aluminous hydroxy phosphates are present in trace amounts in every formation of the Athabasca Group in Alberta. The minerals of the group present in Alberta form a solid-solution series with end members goyazite (SrAl3(PO4)OH5), crandallite (CaAl3(PO4)OH5), and gorceixite (BaAl3(PO4)OH5). These minerals are present as cubes and subhedral grains, 2–20 μm across, in isolation or in clusters interstitially in the Athabasca Group sandstones, siltstones, and tuffs. Petrographic study indicates an authigenic origin for the crandallite-group minerals in the Athabasca Group. Their presence, locally, beneath quartz overgrowths and early diagenetic fluorapatite suggests formation very early in the post-depositional history of the rock. The presence of the crandallites within the regolith beneath the Athabasca Group and within a metamorphic rock fragment incorporated into the sandstone suggests more than one origin for the minerals and possibly a detrital component.

The CdO–CdCl2 reaction studied by thermal analysis and X-ray diffraction: X-ray diffractogram and infrared spectrum of CdCl2•2CdO

1969 ◽  
Vol 47 (6) ◽  
pp. 1045-1050 ◽  
Author(s):  
P. Ramamurthy ◽  
E. A. Secco
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Infrared Spectrum ◽  
Band Structure ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Orthorhombic System ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

CdO and molten CdCl2 react to form CdCl2•2CdO according to the equation:[Formula: see text]The compound CdCl2•2CdO dissociates to the oxide and chloride at 680 °C. CdO and CdCl2 form a solid solution of partial miscibility of 15% by weight of CdO.The X-ray diffractogram of CdCl2•2CdO was indexed to the orthorhombic system. The unit cell dimensions are calculated to be a = 4.38 Å, b = 11.47 Å, c = 9.93 Å with 4 molecules in the unit cell. The infrared spectrum shows a band structure of two doublets and a well-defined band in the region 370–550 cm−1.

Geikielite–ecandrewsite solid solutions: synthesis and crystal structures of the Mg1−x Zn x TiO3 (0 ≤ x ≤ 0.8) series

2004 ◽  
Vol 60 (5) ◽  
pp. 496-501 ◽  
Author(s):  
Ruslan P. Liferovich ◽  
Roger H. Mitchell
Keyword(s):  
Solid Solution ◽  
Crystal Structures ◽  
Solid Solutions ◽  
Ambient Pressure ◽  
Unit Cell ◽  
Solid Solution Series ◽  
Coordination Polyhedra ◽  
Cell Parameters ◽  
Solution Series ◽  
Zn Content

The crystal structures of members of the geikielite–ecandrewsite solid solution series, Mg1 − x Zn x TiO3 (0 ≤ x ≤ 0.8 a.p.f.u. Zn; a.p.f.u. = atoms per formula unit), synthesized by ceramic methods in air at ambient pressure, have been characterized by Rietveld analysis of X-ray powder diffraction patterns. These synthetic titanates adopt an ordered R\overline 3 structure similar to that of ilmenite. The maximum solubility of Zn in MgTiO3 is considered to be ∼ 0.8 a.p.f.u. Zn, as compounds with greater Zn content could not be synthesized at ambient conditions. Data are given for the cell dimensions and atomic coordinates, together with bond lengths, volumes and distortion indices for all the coordination polyhedra. Within the solid-solution series unit-cell parameters and unit-cell volumes increase with Zn content. All compounds consist of distorted (Mg,Zn)O6 and TiO6 polyhedra and, in common with geikielite and ilmenite (sensu lato), TiO6 polyhedra are distorted to a greater extent than (Mg,Zn)O6. The displacements of (Mg,Zn) and Ti from the centers of their coordination polyhedra vary insignificantly with increasing Zn content. The interlayer distance across the vacant octahedral site in the TiO6 layer decreases slightly with the entry of the larger Zn2+ cation into the vi A site. The empirically obtained upper limit of the Goldschmidt tolerance factor (t) for A 2+ BO3 compounds adopting an ordered R\overline 3 structure is 0.755. The absence of natural solid solutions between geikielite and ecandrewsite seems to be due to the contrasting geochemistry of Mg and Zn rather than for crystallochemical reasons.

A re-examination of herzenbergite–teallite solid solution at temperatures between 300 and 700°C

2001 ◽  
Vol 65 (5) ◽  
pp. 645-651 ◽  
Author(s):  
K. Hayashi ◽  
A. Kitakaze ◽  
A. Sugaki
Keyword(s):  
Solid Solution ◽  
Linear Relationship ◽  
Silica Glass ◽  
Glass Tube ◽  
Solid Solution Series ◽  
Solution Series ◽  
Cell Dimensions ◽  
Silica Glass Tube

AbstractIn order to investigate the range of the solid solution series in herzenbergite-teallite minerals, samples of different composition were synthesized. Herzenbergite-teallite minerals were synthesized by an evacuated silica glass tube method at 700°C. A linear relationship between cell dimensions, a, b and c and composition is established. Extension of solid solution to the Pb-rich portion of the system PbS-SnS is limited; the solid solution area is between Pb1.060Sn0.940S2 and SnS at 700°C. Teallite coexisting with galena was also synthesized by hydrothermal recrystallization at 300, 400 and 450°C. The compositions of teallite are Pb1.140Sn0.860S2 at 300°C, Pb1.114Sn0.886S2 at 400°C, and Pb1.124Sn0.876S2 at 450°C, respectively. Their compositions shift towards the PbS end-member from stoichiometric teallite. The cell dimensions of teallite, which was synthesized hydrothermally, follow the linear relationship between cell dimensions and composition established at 700°C.

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