VLASOVITE, Na2 Zr (Si4O11), FROM THE KIPAWA ALKALINE COMPLEX, QUEBEC, CANADA: CRYSTAL-STRUCTURE REFINEMENT AND INFRARED SPECTROSCOPY

2006 ◽  
Vol 44 (6) ◽  
pp. 1349-1356 ◽  
Author(s):  
E. Sokolova ◽  
F. C. Hawthorne ◽  
N. A. Ball ◽  
R. H. Mitchell ◽  
G. Della Ventura
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Structure Refinement ◽  
Crystal Structure Refinement ◽  
Alkaline Complex

Gem amphiboles from Mogok, Myanmar: crystal-structure refinement, infrared spectroscopy and short-range order–disorder in gem pargasite and fluoro-pargasite

2018 ◽  
Vol 83 (03) ◽  
pp. 361-371 ◽  
Author(s):  
Maxwell C. Day ◽  
Frank C. Hawthorne ◽  
Umberto Susta ◽  
Giancarlo Della Ventura ◽  
George E. Harlow
Keyword(s):  
Crystal Structure ◽  
Fine Structure ◽  
Infrared Spectroscopy ◽  
Infrared Spectra ◽  
Short Range ◽  
Short Range Order ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
Crystal Structure Refinement

AbstractThe crystal structures of six gem-quality pargasites and fluoro-pargasites from Mogok, Myanmar, space group C2/m, Z = 2, have been refined to R1 indices of 2.20–2.90% using MoKα X-radiation. The unit formulae were calculated from the results of electron-microprobe analysis, and were used with the refined site-scattering values and the observed mean bond lengths to assign site populations. TAl occurs at both the T(1) and T(2) sites but is strongly ordered at T(1). [6]Al is partly disordered over the M(2) and M(3) sites but does not occur at the M(1) site. ANa is split between the A(2) and A(m) sites and K occurs at the A(m) site. The infrared spectra in the principal OH-stretching region were measured and the fine structure was fit to component bands. The component bands were assigned to short-range ion arrangements over the configuration symbol M(1)M(1)M(3)–O(3)–A–O(3):T(1)T(1) using the refined site-populations and the expected frequencies from previously assigned spectra in more simple amphibole compositions, and correspond to the local arrangements: (1) MgMgMg–OH–Na–OH:SiAl; (2) MgMgMg–OH–Na–F:SiAl; (3) MgMgAl–OH–Na–OH:SiAl and (4) MgMgAl–OH–Na–F:SiAl.

Synthesis, crystal-structure refinement and properties of bastnaesite-type PrF[CO3], SmF[CO3] and EuF[CO3]

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Constantin Buyer ◽  
Samira A. Schumacher ◽  
Thomas Schleid
Keyword(s):  
Crystal Structure ◽  
Thermal Stability ◽  
Aqueous Solution ◽  
Infrared Spectroscopy ◽  
Ultraviolet Radiation ◽  
Structure Refinement ◽  
Bulk Sample ◽  
Crystal Structure Refinement ◽  
Europium Compound ◽  
Red Luminescence

Abstract By adding a hot aqueous solution containing KF and K2[CO3] to another hot aquatic brine of Pr[NO3]3 ⋅ 5 H2O, Sm[NO3]3 ⋅ 5 H2O or Eu[NO3]3 ⋅ 5 H2O with a 1.3 times excess of the anion-providing solution, amorphous water-insoluble powders of PrF[CO3], SmF[CO3] and EuF[CO3] can be obtained. Through hydrothermal treatment at 210 °C for five days crystalline powders could be synthesized and their crystal structure was refined with Rietveld methods based on PXRD data. The named compounds crystallize in the bastnaesite-type structure with a = 710.912(12) pm, c = 976.811(6) pm for the praseodymium, a = 704.77(2) pm, c = 971.83(4) pm for the samarium and a = 700.734(6) pm, c = 969.066(8) pm for the europium compound, all hexagonal with Z = 6. Upon heating them, the compounds lose CO2 and fluoride oxides REFO emerge. Thermogravimetric experiments with crystalline samples show thermal stability up to 420 °C for PrF[CO3], 400 °C for SmF[CO3] and 340 °C for EuF[CO3], but decomposition below 200 °C for the amorphous ones. Infrared spectroscopy confirms only marginal portions of [OH]− instead of F− anions in all cases. The RE 3+ cations are coordinated by 9 + 2 anions at distances between 236 and 254 pm plus 326 pm to F− anions and oxygen atoms bonded to carbon as oxocarbonate anions [CO3]2−. Triggered by ultraviolet radiation, the bulk sample of EuF[CO3] shows a poor red luminescence.

Short-Range Order-Disorder in Gem Richterite and Pargasite from Afghanistan: Crystal-Structure Refinement and Infrared Spectroscopy

2018 ◽  
Vol 56 (6) ◽  
pp. 939-950
Author(s):  
Maxwell C. Day ◽  
Frank C. Hawthorne ◽  
Umberto Susta ◽  
Giancarlo Della Ventura ◽  
George E. Harlow
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Structure Refinement ◽  
Range Order ◽  
Crystal Structure Refinement

Iron in kornerupine; a57Fe Moessbauer spectroscopic study and comparison with single-crystal structure refinement

1999 ◽  
Vol 84 (4) ◽  
pp. 536-549 ◽  
Author(s):  
Edward S. Grew ◽  
Guenther J. Redhammer ◽  
Georg Amthauer ◽  
Mark A. Cooper ◽  
Frank C. Hawthorne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Spectroscopic Study ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement
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