Carbonates of the magnesite–siderite series from four carbonatite complexes

1990 ◽  
Vol 54 (376) ◽  
pp. 413-418 ◽  
Author(s):  
H. A. Buckley ◽  
A. R. Woolley
Keyword(s):  
Solid Solution ◽  
Partial Melting ◽  
Solid Solution Series ◽  
Two Phase ◽  
X Ray ◽  
Liquidus Phase ◽  
Solution Series ◽  
The Past ◽  
Complete Solid Solution ◽  
Textural Evidence

AbstractCarbonates of the magnesite-siderite series have been found and analysed in carbonatites from the Lueshe, Newania, Kangankunde, and Chipman Lake complexes. This series has been represented until now only by a few X-ray identifications of magnesite and three published analyses of siderite and breunnerite (magnesian siderite). Most of the siderite identified in carbonatites in the past has proved to be ankerite, but the new data define the complete solid-solution series from magnesite to siderite. They occur together with dolomite and ankerite and in one rock with calcite. The magnesites, ferroan magnesites and some magnesian siderites may be metasomatic/hydrothermal in origin but magnesian siderite from Chipman Lake appears to have crystallized in the two-phase calcite + siderite field in the subsolidus CaCO3-MgCO3-FeCO3 system. Textural evidence in Newania carbonatites indicates that ferroan magnesite, which co-exists with ankerite, is a primary liquidus phase and it is proposed that the Newania carbonatite evolved directly from a Ca-poor, Mg-rich carbonatitic liquid generated by partial melting of phlogopite-carbonate peridotite in the mantle at pressures >32 kbar.

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.

Rietveld refinement of the solid-solution series: (Cu,Mg)SO4·H2O

1995 ◽  
Vol 10 (3) ◽  
pp. 189-194 ◽  
Author(s):  
C. L. Lengauer ◽  
G. Giester
Keyword(s):  
Solid Solution ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Solid Solution Series ◽  
Cation Site ◽  
Tg Analysis ◽  
X Ray ◽  
Solution Series

The kieserite-type solid-solution series of synthetic (Cu,Mg)SO4·H2O was investigated by TG-analysis and X-ray powder diffraction using the Rietveld method. Representatives with Cu≥20 mol% are triclinic distorted () analogous to the poitevinite (Cu,Fe)SO4·H2O compounds. Cation site ordering with preference of Cu for the more distorted M1 site was additionally proven by the structure refinement.

scholarly journals Rinkite–nacareniobsite-(Ce) solid solution series and hainite from the Ilímaussaq alkaline complex: occurrence and compositional variation

2014 ◽  
Vol 62 ◽  
pp. 1-15
Author(s):  
Jørn G. Rønsbo ◽  
Henning Sørensen ◽  
Encarnacion Roda-Robles ◽  
François Fontan ◽  
Pierre Monchoux
Keyword(s):  
Solid Solution ◽  
Electron Microprobe ◽  
Compositional Variation ◽  
Solid Solution Series ◽  
Alkaline Complex ◽  
Full Extension ◽  
X Ray ◽  
Solution Series ◽  
Compositional Variations ◽  
A Minor

In the Ilímaussaq alkaline complex, minerals from the rinkite–nacareniobsite-(Ce) solid solution series have been found in pulaskite pegmatite, sodalite foyaite, naujaite and naujaite pegmatite from the roof sequence, and in marginal pegmatite, kakortokite and lujavrite from the floor sequence. The electron microprobe analyses embrace almost the full extension of the solid solution series and confirm its continuity. The solid solution series shows similar compositional variations in the roof and floor sequences: Rinkite members of the series are found in the less evolved rocks in the two sequences, whereas nacareniobsite-Ce members occur in the most evolved rocks and pegmatites in the two sequences. The REE (+Y) content varies from 0.83 atoms per formula unit (apfu) in rinkite from pulaskite pegmatite to 1.31 apfu in nacareniobsite-(Ce) from naujaite pegmatite. The main substitution mechanisms in the solid solution series investigated in this work are 2Ca2+ = Na+ + REE3+ and Ti4+ + Ca2+ = Nb5+ + Na+. The increased contents of Nb5+ and REE3+ are only to a minor degree compensated through the F1– = O2– substitution. The chondrite normalised REE patterns of the minerals develop in a similar way in the two sequences, showing relative La-enrichment and Y-depletion from the less to the most evolved rocks. Hainite has not previously been found in the Ilímaussaq complex. It was here identified in a pulaskite pegmatite sample by a combination of X-ray diffraction giving the unit cell dimensions a = 9.5923(7) Å, b = 7.3505(5) Å, c = 5.7023(4) Å, α = 89.958(2)°, β = 100.260(1)°, γ = 101.100(2)°, and X-ray powder pattern and electron microprobe data giving the empirical formula (Ca1.62 Zr0.16Y 0.22) (Na0.87Ca1.11) (Ca 1.65 REE0.35)Na(Ti0.81Nb0.09Fe0.08 Zr0.02)(Si2O7)2O0.99F2.96. Based on published and the present data it is documented that minerals from the hainite-götzenite solid solution series show a compositional variation between the ideal end members (Y,REE,Zr)Na2Ca4Ti(Si2O7)2OF3 and NaCa6Ti(Si2O7)2OF3.

Crystal chemistry of lamprophyllite-group minerals from the Murun alkaline complex (Russia) and pegmatites of Rocky Boy and Gordon Butte (USA): single crystal X-ray diffraction and Raman spectroscopy study

2021 ◽  
Vol 77 (2) ◽  
Author(s):  
Sergey M. Aksenov ◽  
Anastasia D. Ryanskaya ◽  
Yuliya V. Shchapova ◽  
Nikita V. Chukanov ◽  
Nikolay V. Vladykin ◽  
...  
Keyword(s):  
Solid Solution ◽  
Single Crystal ◽  
Raman Spectra ◽  
Crystal Chemistry ◽  
Solid Solution Series ◽  
X Ray Diffraction ◽  
Alkaline Complex ◽  
Oh Groups ◽  
X Ray ◽  
Solution Series

Specific features of the crystal chemistry of lamprophyllite-group minerals (LGMs) are discussed using the available literature data and the results of the single-crystal X-ray diffraction and a Raman spectroscopic studies of several samples taken from the Murun alkaline complex (Russia), and Rocky Boy and Gordon Butte pegmatites (USA) presented here. The studied samples are unique in their chemical features and the distribution of cations over structural sites. In particular, the sample from the Gordon Butte pegmatite is a member of the barytolamprophyllite–emmerichite solid solution series, whereas the samples from the Murun alkaline complex and from the Rocky Boy pegmatite are intermediate members of the solid solution series formed by lamprophyllite and a hypothetical Sr analogue of emmerichite. The predominance of O2− over OH− and F− at the X site is a specific feature of sample Cha-192 from the Murun alkaline complex. New data on the Raman spectra of LGMs obtained in this work show that the wavenumbers of the O—H stretching vibrations depend on the occupancies of the M2 and M3 sites coordinating with (OH)− groups. Cations other than Na+ and Ti4+ (mainly, Mg and Fe3+) can play a significant role in the coordination of the X site occupied by (OH)−. Data on polarized Raman spectra of an oriented sample indicate that the OH groups having different local coordinations have similar orientations with respect to the crystal. The calculated measures of similarity (Δ) for lamprophyllite and ericssonite are identical (0.157 and 0.077 for the 2M- and 2O-polytypes, respectively), which indicates that these minerals are crystal-chemically isotypic and probably should be considered within the same mineral group by analogy to the other mineralogical groups which combine isotypic minerals.

scholarly journals Disorder in Ho2Ti2−xZrxO7: pyrochlore to defect fluorite solid solution series

RSC Advances ◽  
2020 ◽  
Vol 10 (57) ◽  
pp. 34632-34650
Author(s):  
Devon L. Drey ◽  
Eric C. O'Quinn ◽  
Tamilarasan Subramani ◽  
Kristina Lilova ◽  
Gianguido Baldinozzi ◽  
...  
Keyword(s):  
Solid Solution ◽  
Solid Solution Series ◽  
Length Scales ◽  
Total Scattering ◽  
Disorder Transition ◽  
X Ray ◽  
Chemical Substitution ◽  
Solution Series ◽  
Calorimetric Measurements ◽  
Fluorite Solid Solution

Combined neutron and X-ray total scattering with calorimetric measurements of the solid solution series Ho2Ti2−xZrxO7 reveals a complex order–disorder transition across short, intermediate, and long length scales induced by chemical substitution.

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.

scholarly journals Synthesis and characterisation of (La,Pr) monazite solid solution series

2014 ◽  
Vol 70 (a1) ◽  
pp. C1106-C1106
Author(s):  
Antje Hirsch ◽  
Andreas Neumann ◽  
Anja Wätjen ◽  
Julia Heuser ◽  
Anja Thust ◽  
...  
Keyword(s):  
Solid Solution ◽  
Nuclear Waste ◽  
Linear Increase ◽  
Nominal Composition ◽  
Gravimetric Analysis ◽  
Solid Solution Series ◽  
Scanning Calorimetry ◽  
Average Deviation ◽  
X Ray ◽  
Solution Series

Monazite type ceramics are considered as potential ceramic storage materials for high level nuclear waste. Natural monazite is a host for radioactive elements like U and Th without becoming metamict due to radiation damage. Monazites are also known for their chemical flexibility and thermal stability. In this context, a solid solution series of (La,Pr)PO4 was synthesised as powders and single crystals and characterised by PXRD (Powder X-Ray Diffraction analysis), EMPA (Electron Microprobe Analysis), TGA (Thermal Gravimetric Analysis) and DSC (Differential Scanning Calorimetry). La and Pr were used as inactive surrogates for the minor actinides Am, Cm and Np, which represent major challenges in nuclear waste management due to their long half-life and high radiotoxicity. The powder samples were prepared following the protocol of [1]. Ln2O3 were mixed with NH4H2PO4 in excess. Powders were ground, pressed, and heated for one day at 12500C in air. X-Ray laboratory and synchrotron data showed that all samples were single phase. A decrease in the lattice parameters and volume with increasing Pr content was observed as expected due to the smaller radius of Pr3+ with respect to La3+ in nine fold coordination. The monoclinic angle β showed a linear increase. Using EMPA, the composition of all samples was determined. The average deviation from the nominal composition was calculated to be about 4 mol% which covers both, sample inhomogeneity and, more importantly, experimental challenges due to grain shape and porosity. In TGA and DSC curves, similar behaviour for all samples was observed, except for the Pr end member. This unsolved issue is currently under investigation. Complementary IR and Raman spectroscopic data showed the expected linear trends [2]. This behaviour was also reported for LnPO4 (Ln = La-Gd) [3]. The author gratefully thanks the BMBF (02 NUK 021E) for financial funding.

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