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.

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.

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.

scholarly journals Structural systematics of SFCA-I type solid-solutions in the system CaO–Fe2O3–FeO–Al2O3

2021 ◽  
Vol 48 (7) ◽  
Author(s):  
Volker Kahlenberg ◽  
Hannes Krüger ◽  
Martina Tribus
Keyword(s):  
Solid Solution ◽  
Strain Tensor ◽  
Crystallographic Analysis ◽  
Solid Solution Series ◽  
Coordination Polyhedra ◽  
Cell Parameters ◽  
Al Content ◽  
Solution Series ◽  
Two Samples ◽  
The Impact

AbstractEffects of Fe ↔ Al substitution on triclinic SFCA-I-type compounds with general formula A40O56 (A: Ca, Al, Fe3+, Fe2+) have been studied using single-crystal X-ray diffraction. Crystals of sufficient quality and size were synthesized in the temperature range between 1200 and 1300 °C. Six samples with Al/FeTot ratios of 0.127, 0.173, 0.216, 0.310, 0.349 and 0.459 have been structurally characterized. SFCA-I can be described with a modular approach involving the stacking sequence < PSS > of “P” and “S” modules that can be imagined as being cut from the well-known pyroxene (P) and spinel (S) structure types. Furthermore, SFCA-I is related to the sapphirine supergroup of minerals. Within the present solid-solution series, the contents in calcium show only minor variations (≈ 6.7 a.p.f.u.). The twenty crystallographically independent tetrahedrally (T) and octahedrally (M) coordinated cation sites exhibit considerable differences concerning the Al uptake. Indeed, Al is preferentially incorporated into the tetrahedra belonging to the single-chains located in the pyroxene modules. Ferrous iron, on the other hand, is restricted to one of the T-positions within the spinel blocks. Most structural aspects from unit-cell parameters and cell volumes to site occupancies, tetrahedral chain kinking as well as polyhedral distortions are defined by linear or nearly linear trends when plotted against the Al/FeTot ratio. Analysis of the < T–O > and < M–O > distances showed a complex interplay between the different coordination polyhedra resulting in a contrasting behavior of these values with positive or negative change rates as a function of composition. Evaluation of the average chemical strain tensor derived from the sets of lattice parameters for the two samples of the abovementioned series showing the highest and lowest Al/FeTot ratios indicated, that the major contraction with increasing Al content is perpendicular to the pyroxene- and spinel modules. Furthermore, the pyroxene module seems to be more affected when compared with the spinel block. There is evidence that the SFCA-I-type solid-solution series is limited on both the Al- and Fe-rich sides. The present investigation provides—for the first time—a detailed crystallographic analysis on the impact of chemical variations on a compound that is of relevance to the field of applied mineralogy related to the technologically important process of iron-ore sintering.

The crystal chemistry of the solid solution series between chalcostibite (CuSbS2) and emplectite (CuBiS2)

1997 ◽  
Vol 61 (404) ◽  
pp. 79-88 ◽  
Author(s):  
M. F. Razmara ◽  
C. M. B. Henderson ◽  
R. A. D. Pattrick ◽  
A. M. T. Bell ◽  
J. M. Charnock
Keyword(s):  
Solid Solution ◽  
Cell Parameter ◽  
Decomposition Temperature ◽  
Waller Factor ◽  
Solid Solution Series ◽  
Orthorhombic Space Group ◽  
Cell Parameters ◽  
Solution Series ◽  
Debye Waller Factor ◽  
Complete Solid Solution

AbstractSulphosalts in the system CuSbS2-CuBiS2 (chalcostibite-emplectite) form a complete solid solution series. Seven compositions with the general formula Cu(SbxBi1–x)S2 have been synthesized using dry methods at 310°C. All members of the series are orthorhombic (space group Pnma) and show smoothly increasing a and b cell parameters with substitution of Bi for Sb; the c cell parameter increases up to 50% CuBiS2 substitution and then becomes constant. DSC experiments on CuBiS2 show an endothermic heat effect (2.45 kJ/mol.) at 472°C due to the breakdown reaction to Cu3BiS3 (wittichenite) plus Bi2S3 (bismuthinite). With the addition of 10% CuSbS2 to CuBiS2, the decomposition temperature increases and the endothermic peak is broadened but the energy remains essentially the same (2.53 kJ/mol.). No evidence of this decomposition was observed when the amount of the CuSbS2 component was >30%. The local structure and co-ordination of Cu in the samples were studied by EXAFS analysis of the Cu-K edge but no significant variation occurs in the local Cu environment. The Debye-Waller factor for the first shell of S atoms surrounding Cu in end member CuSbS2 tends to be slightly smaller than for the intermediate solid solutions, suggesting that the tetrahedral Cu environments in the intermediate composition samples is somewhat more disordered than in the end-member. The low expansion characteristics along c appear to be controlled by the linkages between the (CuS3 + BiS2) sheets perpendicular to c being relatively inflexible.

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.

scholarly journals The solid solutions of rebulite and jankovićite in the phase system Tl2S-As2S3-Sb2S3

2015 ◽  
Vol 34 (1) ◽  
pp. 125
Author(s):  
Tonci Balic-Zunic ◽  
Yves Moëlo ◽  
Ljiljana Karanović ◽  
Peter Berlepsch
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Solid Solutions ◽  
Unit Cell ◽  
Phase System ◽  
Structural Topology ◽  
Coordination Polyhedra ◽  
Ideal Composition ◽  
End Members ◽  
Compositional Line

Syntheses along the Tl<sub>5</sub>(As,Sb)<sub>13</sub>S<sub>22</sub> compositional line in the Tl<sub>2</sub>S-As<sub>2</sub>S<sub>3</sub>-Sb<sub>2</sub>S<sub>3</sub> phase system showed that the compositional range of rebulite extends from  Tl<sub>5</sub>As<sub>9.5</sub>Sb<sub>3.5</sub>S<sub>22</sub> to Tl<sub>5</sub>As<sub>7.75</sub>Sb<sub>5.25</sub>S<sub>22</sub>. The Sb-rich end-member is in equilibrium with jankovićite of ideal composition Tl<sub>5</sub>Sb<sub>7.5</sub>As<sub>5.5</sub>S<sub>22</sub>. It is considered to be the As-rich end-member of the jankovićite solid solution. The crystal structure analyses of crystals from the As and Sb end-members of rebulite show that the Sb/As substitution is present in Sb3, Sb4, Sb5, As1 and As2 structural sites. Of them, Sb3 is always Sb dominated whereas other four vary from As- to Sb-dominated over the range of the solid solution. The change of the structural topology from jankovićite to rebulite, the closely related but not identical structures, is explained through necessity to accommodate the smaller volumes of the As coordination polyhedra and is accomplished through unit-cell twinning over the periodic (001)<sub>reb</sub> twin boundaries. The As end-member of the rebulite solid solution is in equilibrium with the phase of Tl<sub>2.4</sub>Sb<sub>0.68</sub>As<sub>7.18</sub>S<sub>13</sub> ideal composition, interpreted as imhofite.

A Review of the XRD Data of the Phases Present in the CaO-SrO-CuO System

1992 ◽  
Vol 7 (3) ◽  
pp. 142-148 ◽  
Author(s):  
Brian J. Reardon ◽  
Camden R. Hubbard
Keyword(s):  
Solid Solution ◽  
Ternary System ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Solid Solution Series ◽  
Powder Diffraction File ◽  
Reference Pattern ◽  
X Ray ◽  
Solution Series ◽  
Xrd Patterns

AbstractX-ray powder patterns for the phases in the CaO-SrO-CuO ternary system, along with the corresponding crystal structures, were obtained from the literature and from the Powder Diffraction File. Available XRD patterns were compared with each other and with a calculated pattern for each phase, yielding a recommended reference pattern. The simulated powder patterns presented here deal with the phases found within the (Ca,Sr)O, (Ca,Sr)2CuO3, (Ca,Sr)14Cu24O41, (Ca,Sr)CuO2, (Ca,Sr)Cu2O3, and (Ca,Sr)Cu2O2 solid solution series and are recommended for the Powder Diffraction File (PDF).

Investigation of (Sr4−δCaδ)PtO6 using X-ray Rietveld refinement

1999 ◽  
Vol 14 (3) ◽  
pp. 181-189 ◽  
Author(s):  
W. Wong-Ng ◽  
J. A. Kaduk ◽  
R. A. Young ◽  
F. Jiang ◽  
L. J. Swartzendruber ◽  
...  
Keyword(s):  
Solid Solution ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Solid Solution Series ◽  
X Ray ◽  
Cell Parameters ◽  
Solution Series ◽  
Complete Solid Solution ◽  
Ca Ions ◽  
Diffraction Patterns

The structures of the solid solution series (Sr4−δCaδ)PtO6, with δ=0, 0.85(1), 2, and 3, have been investigated using the Rietveld refinement technique with laboratory X-ray powder diffraction data. A complete solid solution between Sr and Ca was confirmed to exist. These compounds crystallize in the rhombohedral space group R3¯c. The cell parameters of the series range from a of 9.4780(3) to 9.7477(1) Å, and c from 11.3301(4) to 11.8791(1) Å for δ from 3 to 0, respectively. The structure consists of chains of alternating trigonal prismatic (Sr, Ca)O6 and octahedral PtO6 units running parallel to the c axis. These chains are connected to each other via a second type of (Sr, Ca) ions, which are surrounded by eight oxygens, in a distorted square antiprismatic geometry. As Ca replaced Sr in Sr4PtO6, it was found to substitute preferentially in the smaller octahedral (Sr, Ca)1 site (6a) rather than at the eight-coordinate (Sr, Ca)2 site (18e). There appears to be an anomaly of cell parameters a and c at the compound Sr3.15Ca0.85PtO6. Their dependence on Ca content changes at δ≈1.00, where the Ca has fully replaced Sr in the 6a site. The substitution of Sr by Ca reduced the average (Sr, Ca)1–O length from 2.411 to 2.311 Å and (Sr, Ca)2–O from 2.659 to 2.570 Å as the composition varied from Sr4PtO6 to SrCa3PtO6. Reference X-ray powder diffraction patterns were prepared from the Rietveld refinement results for these members of the solid solution series. Magnetic susceptibility measurements of three of the samples (δ=0, 0.85, 2) show electronic transitions at low temperatures.

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