Crystal structure determination of kosnarite, KZr2(PO4)3, from the Mario Pinto Mine, Jenipapo district, Itinga, Brazil

2020 ◽  
Vol 58 (5) ◽  
pp. 637-652
Author(s):  
Paula C. Piilonen ◽  
Henrik Friis ◽  
Ralph Rowe ◽  
Glenn Poirier
Keyword(s):  
Crystal Structure ◽  
Synthetic Analogue ◽  
Chemical Formula ◽  
Synthetic Compounds ◽  
Physiochemical Properties ◽  
Radioactive Nuclides ◽  
3D Network ◽  
First Time ◽  
Average Bond

ABSTRACT The crystal structure of a natural kosnarite, KZr2(PO4)3 from the Mario Pinto Mine, Jenipapo district, Brazil, has been determined for the first time. Kosnarite and its related synthetic compounds (NZP) are open-framework orthophosphates of the type ([6]M′[8]M′′)L2(TO4)3 (where M = Li, Na, K, Rb, Cs; L = Ti, Zr, Hf; and T = P, Si). These compounds have been proposed as potential radioactive waste hosts as a result of their physiochemical properties and because their crystal structure allows for extreme isomorphism and incorporation of all 42 radioactive nuclides present in nuclear waste. Kosnarite from the Mario Pinto mine is hexagonal, Rc, with a = 8.7205(1), c = 23.9436(3) Å, and V = 1576.89(4) Å3. The average chemical formula (n = 75) is (K0.96Na0.02)Σ0.98(Zr1.93Hf0.08)Σ1.01(P2.99Si0.01)Σ3.00O12. The structure contains one six-coordinated Zr site (L), one four-coordinated P site (T), and a six-coordinated K site (M′); in kosnarite, the M″ site is vacant. The average bond lengths in the ZrO6 octahedra (2.0646 Å) and PO4 tetrahedra (1.5278 Å) are slightly larger than those observed in the synthetic analogue (<Zr–O> = 2.063 Å, <P–O> = 1.522 Å). The ZrO6 octahedra and PO4 tetrahedra share corners to form ribbons of [Zr2(PO4)3]– units parallel to the c axis, which are further joined by PO4 tetrahedra perpendicular to c to form a 3D network. Kosnarite is one of only five natural alkali zircono-orthophosphates, all of which are late-stage hydrothermal minerals. Although synthetic Na-dominant endmember analogues of kosnarite exist, the distortions in the structure with respect to the M and L octahedra, along with experimental evidence at hydrothermal temperatures, suggest that only K (or Li) endmembers are possible in nature.

Structural, chemical and spectroscopic re-examination of type uklonskovite leads to its redefinition

2017 ◽  
Vol 81 (6) ◽  
pp. 1397-1404 ◽  
Author(s):  
S. Menchetti ◽  
L. Bindi ◽  
D. Belakovskiy ◽  
F. Zaccarini
Keyword(s):  
Crystal Structure ◽  
Scientific Literature ◽  
Careful Analysis ◽  
Chemical Formula ◽  
International Mineralogical Association ◽  
Mineralogical Association ◽  
Structural Details ◽  
First Time ◽  
Shed Light

AbstractThe crystal structure and the chemical composition of uklonskovite from the holotype material was reinvestigated to shed light on its correct chemical formula. On the basis of information gained from this characterization, we revised the formula from NaMg(SO4)OH·2H2O to NaMg(SO4)F·2H2O (F instead of OH). A careful analysis of the structural details together with a critical review of all the chemical data listed in the scientific literature for uklonskovite support our redefinition. We also present Raman data for the mineral for the first time. Our proposal was approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (voting proposal 16-J).

Synthesis of 2', 6'-Dihydroxychalcones by Using Tetrahydropyran-2-yl and Trialkylsilyl Protective Groups; the Crystal Structure Determination of 2',6'-Dihydroxy-2,4,6-trimethoxychalcone

1989 ◽  
Vol 42 (7) ◽  
pp. 1103 ◽  
Author(s):  
CO Miles ◽  
L Main ◽  
BK Nicholson
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Silyl Ether ◽  
X Ray ◽  
Protective Groups ◽  
Intramolecular Hydrogen ◽  
First Time ◽  
Mild Acid

Two improved general routes to 2′,6′-dihydroxychalcones are described in which the final step is protective-group removal from O 2′ under mild acid conditions. The first involves base-catalysed condensation of benzaldehydes with 2′-hydroxy-6′-tetrahydropyran-2-yloxyacetophenone, the second ring-opening of 5-hydroxyflavanones with 1,8-diazabicyclo[5.4.0]undec-7-ene in the presence of a trialkylchlorosilane to trap out the chalcone as a bis silyl ether. Chalcones prepared by the first route are 2',6'-dihydroxychalcone (1), and its 4-methoxy (2), 3,4-dimethoxy (3), 3,4,5-trimethoxy (4), and 2,4,6-trimethoxy (5) derivatives. The 4-chloro derivative (6) and the chalcone from hesperetin are prepared by the second method. .The X-ray crystal structure of 2',6'-dihydroxy-2,4,6-trimethoxychalcone (5), the first for a 2',6′-dihydroxychalcone, is reported, the hydrogen involved in intramolecular hydrogen-bonding between the carbonyl and phenolic oxygens being located for the first time for any 2'-hydroxychalcone derivative. The O 6' involved in the intramolecular hydrogen-bonding is also hydrogen-bonded intermolecularly to the hydrogen of the other (2'-)hydroxy group of a neighbouring molecule in the lattice. 13C n.m.r. data are the first reported for a series of 2',6'-dihydroxychalcones.

Structure determination of Mg3(OH)5Cl·4H2O (F5 phase) from laboratory powder diffraction data and its impact on the analysis of problematic magnesia floors

2007 ◽  
Vol 63 (6) ◽  
pp. 805-811 ◽  
Author(s):  
Kunihisa Sugimoto ◽  
Robert E. Dinnebier ◽  
Thomas Schlecht
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Real Life ◽  
Quantitative Phase Analysis ◽  
Binder Phase ◽  
Powder Diffraction Data ◽  
First Time

The crystal structure with the idealized formula Mg3(OH)5Cl·4H2O, the so-called F5 phase according to 5Mg(OH)2·MgCl2·8H2O in the system MgCl2–MgO–H2O, has been solved ab initio from high-quality laboratory powder diffraction data at room temperature. The F5 phase is structurally related to 3Mg(OH)2·MgCl2·8H2O (F3 form). The F5 phase consists of infinite triple chains with one Mg(OH)6 and two Mg(OH)4(OH2)2 octahedra as building units intercalated by chlorides, which are partly substituted by disordered hydroxides in the real structure. The F5 phase is of technological importance as the most important binder phase in Sorel cements. Knowledge of the crystal structure enables the full quantitative phase analysis of magnesia cements for the first time, which turns out to be very helpful in the search for possible causes of broken or bleached magnesia floors. Two real-life examples are given.

scholarly journals Raman Spectroscopy and Single-Crystal High-Temperature Investigations of Bentorite, Ca6Cr2(SO4)3(OH)12·26H2O

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 38
Author(s):  
Rafał Juroszek ◽  
Biljana Krüger ◽  
Irina Galuskina ◽  
Hannes Krüger ◽  
Martina Tribus ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Single Crystal ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Single Crystal Diffraction ◽  
Bending Vibrations ◽  
X Ray ◽  
First Time

The crystal structure of bentorite, ideally Ca6Cr2(SO4)3(OH)12·26H2O, a Cr3+ analogue of ettringite, is for the first time investigated using X-ray single crystal diffraction. Bentorite crystals of suitable quality were found in the Arad Stone Quarry within the pyrometamorphic rock of the Hatrurim Complex (Mottled Zone). The preliminary semi-quantitative data on the bentorite composition obtained by SEM-EDS show that the average Cr/(Cr + Al) ratio of this sample is >0.8. Bentorite crystallizes in space group P31c, with a = b = 11.1927(5) Å, c =21.7121(10) Å, V = 2355.60(18) Å3, and Z = 2. The crystal structure is refined, including the hydrogen atom positions, to an agreement index R1 = 3.88%. The bentorite crystal chemical formula is Ca6(Cr1.613Al0.387)Σ2[(SO4)2.750(CO3)0.499]Σ3.249(OH)11.502·~25.75H2O. The Raman spectra of bentorite from two different localities exhibit the presence of the main stretching and bending vibrations related to the sulfate group at 983 cm−1 (ν1), 1109 cm−1 (ν3), 442 cm−1 (ν2), and 601 cm−1 (ν4). Moreover, the presence of bands assigned to the symmetric Cr(OH)63− stretching mode and hydroxyl deformation vibrations of Cr–OH units at ~540 cm−1 and ~757 cm−1, respectively, may be used to distinguish between ettringite and bentorite. In situ high temperature single crystal XRD experiments show that the decomposition of bentorite starts at ca. 45 °C and that a dehydroxylation product similar to metaettringite is formed.

Mehrkernkomplexe aus PH3- und RPH2-Komplexen mit Co2(CO)8 / Polynuclear Complexes from PH3 and RPH2 Complexes with Co2(CO)8

1985 ◽  
Vol 40 (10) ◽  
pp. 1250-1257 ◽  
Author(s):  
Rajib Lal De ◽  
Heinrich Vahrenkamp
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Polynuclear Complexes ◽  
Phosphine Complexes ◽  
Trinuclear Complexes ◽  
Dinuclear Compounds ◽  
First Time ◽  
And Tungsten

The phosphine complexes M-PH3 (1), M-PH2Me (2). M-PH2Ph (3). and M-PH2/Bu (4) with M = Cr(CO)5. Mo(CO)5, W(CO)5, MnCp(CO)2. of which 2 and 4 were prepared for the first time, were reacted with Co2(CO)8. All four PH3 complexes yielded the clusters M-PCo3(CO)9 (5) with external M units as confirmed by a crystal structure determination of (CO)5W-PCo3(CO)9. Of the RPH2 complexes 2 and 3 the chromium and tungsten compounds gave open trinuclear complexes of the type M-PRCo2(CO)7 (6, R = Me: 7, R = Ph). The manganese containing complexes 2 and 3 and Co2(CO)8 formed the dinuclear compounds Cp(CO)2Mn(μ-PRH)Co(CO)3 (8d, R = Me; 9d, R = Ph). The molybdenum containing complexes 2 and 3 yielded unstable compounds of higher nuclearity with Co2(CO)8. The tBuPH2 complexes 4 did not react.

Weissite from Gambatesa mine, Val Graveglia, Liguria, Italy: occurrence, composition and determination of the crystal structure

2013 ◽  
Vol 77 (4) ◽  
pp. 475-483 ◽  
Author(s):  
L. Bindi ◽  
C. Carbone ◽  
D. Belmonte ◽  
R. Cabella ◽  
R. Bracco
Keyword(s):  
Crystal Structure ◽  
Vickers Hardness ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Black Streak ◽  
Pure Metals ◽  
Complex Crystal

AbstractWeissite, Cu2–xTe (x ≈ 0.21), a very rare copper telluride, occurs in a sample from the Gambatesa mine, Val Graveglia, Liguria, Italy, where it occurs as purplish black anhedral grains up to 0.1 mm in length and shows a black streak. No cleavage is observed and the Vickers hardness (VHN100) is 142 kg/mm2. Weissite is dark bluish black, weakly pleochroic, and moderately anisotropic in bluish tints. Reflectance percentages in air for Rmin and Rmax are 37.0, 38.4 (471.1 nm), 33.2, 34.2 (548.3 nm), 31.2, 32.1 (586.6 nm), and 28.6, 31.0 (652.3 nm), respectively.Weissite is trigonal and belongs to the space group P3m1 with the following unit-cell parameters: a = 8.3124(7) Å, c = 21.546(1) Å, V = 1289.3(2) Å3, and Z = 24. Electron microprobe analyses gave the chemical formula (Cu1.62Ag0.04Au0.04Fe0.04Sb0.04)Σ=1.78(Te0.96S0.02Se0.02). The crystal structure has been solved and refined to R = 1.95%. It consists of Cu and Te polyhedra forming complex crystal-chemical environments as is typical of many intermetallic compounds. The exceedingly short bond distances observed among the metals are discussed in relation to other copper tellurides and pure metals.

Crystal structure determination of K2Zn(PO3)4

2009 ◽  
Vol 24 (1) ◽  
pp. 4-7 ◽  
Author(s):  
L. N. Ji ◽  
Y. Q. Chen ◽  
J. B. Li ◽  
J. Luo ◽  
J. K. Liang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Rietveld Method ◽  
Unit Cell ◽  
Formula Unit ◽  
Chemical Formula ◽  
Monoclinic System ◽  
Calculated Density ◽  
Space Group

The crystal structure of K2Zn(PO3)4 was determined and refined using the Rietveld method based on the isostructure model of K2Cu(PO3)4. This compound belongs to the monoclinic system with space group Cc and lattice parameters of a=11.0941(2) Å, b=12.5215(3) Å, c=7.6597(2) Å, and β=102.47(2)°. The chemical formula unit per unit cell is Z=4 and the calculated density is 2.938(3) g∕cm3. Zigzag [PO3]∞ chains formed along the a axis, and their period contains eight PO4 tetrahedrons.

Metavivianite, Fe2+Fe3+2(PO4)2(OH)2·6H2O: new data and formula revision

2012 ◽  
Vol 76 (3) ◽  
pp. 725-741 ◽  
Author(s):  
N. V. Chukanov ◽  
R. Scholz ◽  
S. M. Aksenov ◽  
R. K. Rastsvetaeva ◽  
I. V. Pekov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Gas Chromatography ◽  
Optical Properties ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Homogeneous Sample ◽  
X Ray ◽  
Composition Structure ◽  
First Time

AbstractThe composition, structure, X-ray powder diffraction pattern, optical properties, density, infrared, Raman and Mössbauer spectra, and thermal properties of a homogeneous sample of metavivianite from the Boa Vista pegmatite, near Galiléia, Minas Gerais, Brazil are reported for the first time. Metavivianite is biaxial (+) with α = 1.600(3), β = 1.640(3), γ = 1.685(3) and 2Vmeas= 85(5)°. The measured and calculated densities are Dmeas= 2.56(2) and Dcalc= 2.579 g cm–3. The chemical composition, based on electronmicroprobe analyses, Mössbauer spectroscopy (to determine the Fe2+:Fe3+ratio) and gas chromatography (to determine H2O) is MgO 0.70, MnO 0.92, FeO 17.98, Fe2O326.60, P2O528.62, H2O 26.5; total 101.32 wt.%. The empirical formula is (Fe3+1.64Fe2+1.23Mg0.085Mn0.06)Σ3.015(PO4)1.98(OH)1.72·6.36H2O. Metavivianite is triclinic, P1̄, a = 7.989(1), b = 9.321(2), c = 4.629(1) Å, α = 97.34(1), β = 95.96(1), γ = 108.59(2)°, V = 320.18(11) Å3and Z = 1. The crystal structure was solved using a single-crystal techniques to an agreement index R = 6.0%. The dominant cations in the independent sites are Fe2+and Fe3+, with multiplicities of 1 and 2, respectively. The simplified crystal-chemical formula for metavivianite is Fe2+(Fe3+, Fe2+)2(PO4)2(OH,H2O)2·6H2O; the endmember formula is Fe2+Fe3+2(PO4)2(OH)2·6H2O, which is dimorphous with ferrostrunzite.

Darstellung und Kristallstrukturanalyse von K3BiO3 und Rb3BiO3 / Synthesis and Crystal Structure Determination of K3BiO3 and Rb3BiO3

1997 ◽  
Vol 52 (9) ◽  
pp. 1031-1036 ◽  
Author(s):  
Nicola Zoche ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystal ◽  
Structure Determination ◽  
Solid State Reactions ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Binary Compounds ◽  
First Time

K3BiO3 and Rb3BiO3 have been synthesized for the first time by solid state reactions of the respective binary compounds. K3BiO3 was obtained from Bi2O3 and K2O at 550 °C, Rb3BiO3 from Bi2O3 and Rb2O at 650 °C. The compounds were structurally examined by single-crystal X -ray investigations (K3BiO3: I 4̅ 3 m, a = 1070.15(2) pm, Z = 8; Rb3BiO3: P 21 3, a = 875.48(2) pm, Z = 4). The structures reveal “isolated” BiO33- groups. While K3BiO3 is isostructural to Na3BiO3, Rb3BiO3 has the same crystal structure as Cs3BiO3.

Die Kristallstruktur von Bis-[methylammonium]-hexafluorosilikat, (MeNH3)2SiF6 / The Crystal Structure of Bis-[methylammonium]-hexafluorosilicate, (MeNH3)2SiF6

2002 ◽  
Vol 57 (9) ◽  
pp. 1003-1007 ◽  
Author(s):  
Jens Graulich ◽  
Dietrich Babel
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Bond Length ◽  
Structure Determination ◽  
Average Bond Length ◽  
Space Group ◽  
X Ray ◽  
Average Bond

The results of a single crystal X-ray structure determination of monoclinic (MeNH3)2SiF6 are reported: a = 962.3(5), b = 964.4(1), c = 966.4(5) pm, " = 100.03(3)°; V = 883.2(7) Å3, Z = 4, space group C2/c; wR2 = 0.0999 based on F02 of 1291 independent reflections (including H refinement without restrictions). The structure is related to that of (NH4)2SiF6, but contains the dumb-bells of the cations well oriented along the greater cell diagonals and fixed by one nearly linear and two bi-furcated hydrogen bonds (N...F: 281 and 293 - 305 pm, resp.). The [SiF6]2- octahedron is nearly undistorted with average bond length Si-F: 167.7 pm (169.9 pm corrected for thermal motion)

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