Zaoyang chondrite cooling history from Fe2+-Mg intracrystalline ordering in pyroxenes

1994 ◽  
Vol 58 (390) ◽  
pp. 143-150 ◽  
Author(s):  
Gian Mario Molin ◽  
Mario Tribaudino ◽  
Elisabetta Brizi
Keyword(s):  
Cooling Rate ◽  
Exchange Reaction ◽  
Crystal Chemistry ◽  
Microprobe Analysis ◽  
Structure Refinement ◽  
Cooling History ◽  
Cooling Rates ◽  
X Ray ◽  
Fast Cooling ◽  
Polyhedral Volumes

AbstractThe crystal chemistry of clinopyroxene, orthopyroxene and olivine from a crushed fragment of the H5 Zaoyang chondrite has been investigated by X-ray structure refinement and detailed microprobe analysis. The meteoritic pyroxenes have cell and polyhedral volumes which compare well with such data from terrestrial pyroxenes that typically crystallize at low-pressure. Fe2+ and Mg are rather disordered in M1 and M2 sites of clino- and orthopyroxenes; the closure temperatures of the exchange reaction are 600 and 512°C respectively, which is consistent with a reasonably fast cooling rate, estimated to be of the order of 1°C/day.The closure temperature for the intercrystalline Ca-Mg exchange reaction for clino- and orthopyroxenes is 900°C as calculated from clino- and orthopyroxene intergrowth.The cooling rates obtained from Fe2+-Mg intracrystalline partitioning suggest a cooling of the order of degrees per day at temperatures of 600–500°C due to a strong loss of heat by irradiation.

Effect of Cooling Rate on Glass Formation for Some Oxynitride Glasses

2007 ◽  
Vol 554 ◽  
pp. 25-30 ◽  
Author(s):  
Wynette Redington ◽  
Murt Redington ◽  
Stuart Hampshire
Keyword(s):  
Cooling Rate ◽  
Glass Formation ◽  
Resistance Furnace ◽  
Slow Cooling ◽  
Cooling Rates ◽  
X Ray ◽  
Glass Forming ◽  
Wide Range ◽  
Fast Cooling ◽  
Nd Systems

Rapid cooling rates and quenching have traditionally been associated with glass formation. Hampshire et al. [1] investigated oxynitride glasses cooled in a tungsten resistance furnace at approximately 200oC/min and found that fast cooling rates were only important near the limits of the glass-forming region. In the current work on various M-Si-Al-O-N (M=Y, La, Yb, Nd) systems, it was found that even at a relatively slow cooling rate glass formation was still possible for a wide range of compositions. Different cooling rates were investigated to determine the minimum cooling rate at which a glass will form. Quantitative X-ray analysis of melted compositions indicated the relative amounts of amorphous phase and crystalline phase.

Potassic-jeanlouisite from Leucite Hill, Wyoming, USA, ideally K(NaCa)(Mg4Ti)Si8O22O2: the first species of oxo amphibole in the sodium–calcium subgroup

2019 ◽  
Vol 83 (4) ◽  
pp. 587-593
Author(s):  
Roberta Oberti ◽  
Massimo Boiocchi ◽  
Frank C. Hawthorne ◽  
Giancarlo Della Ventura ◽  
Gunnar Färber
Keyword(s):  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
Crystal Structure Refinement ◽  
Unit Cell Parameters ◽  
X Ray ◽  
International Mineralogical Association ◽  
Cell Parameters ◽  
Mineralogical Association ◽  
Sodium Calcium

AbstractPotassic-jeanlouisite, ideally K(NaCa)(Mg4Ti)Si8O22O2, is the first characterised species of oxo amphibole related to the sodium–calcium group, and derives from potassic richterite via the coupled exchange CMg–1W${\rm OH}_{{\rm \ndash 2}}^{\ndash}{} ^{\rm C}{\rm Ti}_1^{{\rm 4 +}} {} ^{\rm W}\!{\rm O}_2^{2\ndash} $. The mineral and the mineral name were approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification, IMA2018-050. Potassic-jeanlouisite was found in a specimen of leucite which is found in the lava layers, collected in the active gravel quarry on Zirkle Mesa, Leucite Hills, Wyoming, USA. It occurs as pale yellow to colourless acicular crystals in small vugs. The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is: A(K0.84Na0.16)Σ1.00B(Ca0.93Na1.02Mg0.04${\rm Mn}_{{\rm 0}{\rm. 01}}^{2 +} $)Σ2.00C(Mg3.85${\rm Fe}_{{\rm 0}{\rm. 16}}^{2 +} $Ni0.01${\rm Fe}_{{\rm 0}{\rm. 33}}^{3 +} {\rm V}_{{\rm 0}{\rm. 01}}^{3 +} $Ti0.65)Σ5.01T(Si7.76Al0.09Ti0.15)Σ8.00O22W[O1.53F0.47]Σ2.00. The holotype crystal is biaxial (–), with α = 1.674(2), β = 1.688(2), γ = 1.698(2), 2Vmeas. = 79(1)° and 2Vcalc. = 79.8°. The unit-cell parameters are a = 9.9372(10), b = 18.010(2), c = 5.2808(5) Å, β = 104.955(2)°, V = 913.1(2) Å3, Z = 2 and space group C2/m. The strongest eight reflections in the powder X-ray pattern [d values (in Å) (I) (hkl)] are: 2.703 (100) (151); 3.380 (87) (131); 2.541 (80) ($\bar 2$02); 3.151 (70) (310); 3.284 (68) (240); 8.472 (59) (110); 2.587 (52) (061); 2.945 (50) (221,$\bar 1$51).

Structure refinement and crystal chemistry of tokkoite and tinaksite from the Murun massif (Russia)

2017 ◽  
Vol 81 (2) ◽  
pp. 251-272 ◽  
Author(s):  
M. Lacalamita ◽  
E. Mesto ◽  
E. Kaneva ◽  
F. Scordari ◽  
G. Pedrazzi ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Local Stress ◽  
Geometrical Parameters ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Mössbauer Analysis

AbstractThe structures of tokkoite, K2Ca4[Si7O18OH](OH,F) and tinaksite, K2Ca2NaTi[Si7O18OH]O from the Murun massif (Russia) were refined from single-crystal X-ray diffraction data in the triclinic space group P1̄. Average crystallographic data are a ≈ 10.423, b ≈ 12.477, c ≈ 7.112 Å, α ≈ 89.92°, β ≈ 99.68°, γ ≈ 92.97°, V ≈ 910.5 Å3 for tokkoite; a ≈ 10.373, b ≈ 12.176, c ≈ 7.057 Å, α ≈ 90.82°, β ≈ 99.22°, γ ≈ 92.80°, V ≈ 878.5 Å3 for tinaksite. The substantial similarities between the geometrical parameters of the tokkoite and tinaksite structures led us to conclude that the two minerals are isostructural. However, major differences of tokkoite with respect to tinaksite are larger lattice constants, especially concerning the b parameter, longer <M–O> distances, especially <M1–O>; larger values of the M1–M3 and O20–O2 bond lengths, and a stronger distortion of the M1 polyhedron. Mössbauer analysis showed that significant trivalent iron is present, VIFe3+ 40.0(7)% in tokkoite and 12.8(3)% in tinaksite. It is confirmed that 2Ca(M1+M2)2+ + (F,OH)(O20)–↔ Ti(M1)4+ + Na(M2)+ + O(O20)– is the exchange reaction that describes the relation between tokkoite and tinaksite. In addition, this exchange reaction causes local stress involving mainly the M1 site and its interaction with the M2 and M3 sites.

The crystal chemistry of rhodizite: a re-examination

1986 ◽  
Vol 50 (355) ◽  
pp. 163-172 ◽  
Author(s):  
A. Pring ◽  
V. K. Din ◽  
D. A. Jefferson ◽  
J. M. Thomas
Keyword(s):  
Single Crystal ◽  
Crystal Chemistry ◽  
Structure Refinement ◽  
High Resolution Electron Microscopy ◽  
Basic Structure ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Alkali Cations ◽  
X Ray ◽  
Using Data

AbstractThe crystal chemistry of rhodizite was re-examined using data from high-resolution electron microscopy (HREM), magic angle spinning nuclear magnetic resonance (MASNMR), a single crystal X-ray structure refinement, and a new chemical analysis. The analysis calculates to the formula: (K0.46Cs0.36Rb0.06 Na0.02)Σ0.90Al3.99Be4(B11·35Be0.55Li0.02)O28· The distribution of alkali cations was shown to be truly random by HREM images and computer image simulations. The distribution of boron and beryllium was monitored by MASNMR, the spectra for both elements gave only single resonances indicating that all beryllium and boron atoms are located in chemically equivalent sites. The structure of rhodizite was refined by single crystal X-ray diffraction techniques. The mineral is cubic a = 7.318(1) Å, space group P3. A full matrix least-squares refinement using 152 unique observed reflections [F > 3σ(F)] converged to R = 0.0344. The refinement confirmed the basic structure as determined by Taxer and Buerger (1967), 4 beryllium atoms of the unit cell were found to occupy a 4e special position, the remaining 0.5 being randomly distributed with the 11.35 boron atoms over the 12h sites.

Clino-suenoite, a newly approved magnesium-iron-manganese amphibole from Valmalenco, Sondrio, Italy

2018 ◽  
Vol 82 (1) ◽  
pp. 189-198
Author(s):  
Roberta Oberti ◽  
Massimo Boiocchi ◽  
Frank C. Hawthorne ◽  
Marco E. Ciriotti ◽  
Olav Revheim ◽  
...  
Keyword(s):  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
Type Specimen ◽  
Crystal Structure Refinement ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Iron Manganese

ABSTRACTClino-suenoite, ideally □${\rm Mn}_{2}^{2 +} $Mg5Si8O22(OH)2 is a new amphibole of the magnesium-iron-manganese subgroup of the amphibole supergroup. The type specimen was found at the Lower Scerscen Glacier, Valmalenco, Sondrio, Italy, where it occurs in Mn-rich quartzite erratics containing braunite, rhodonite, spessartine, carbonates and various accessory minerals. The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is: ANa0.04B(${\rm Mn}_{1.58}^{2 +} $Ca0.26Na0.16)Σ2.00C(Mg4.21${\rm Mn}_{0. 61}^{2 +} {\rm Fe}_{0.04}^{2 +} $Zn0.01Ni0.01${\rm Fe}_{0.08}^{3 +} $Al0.04)Σ5.00TSi8.00O22W[(OH1.94F0.06)]Σ=2.00. Clino-suenoite is biaxial (+), with α = 1.632(2), β = 1.644(2), γ = 1.664(2) and 2Vmeas. = 78(2)° and 2Vcalc. = 76.3°. The unit-cell parameters in the C2/m space group are a = 9.6128(11), b = 18.073(2), c = 5.3073(6) Å, β = 102.825(2)° and V = 899.1(2) Å3 with Z = 2. The strongest ten reflections in the powder X-ray diffraction pattern [d (in Å), I, (hkl)] are: 2.728, 100, (151); 2.513, 77, ($\bar 2$02); 3.079, 62, (310); 8.321, 60, (110); 3.421, 54, (131); 2.603, 42, (061); 2.175, 42, (261); 3.253, 41, (240); 2.969, 40, (221); 9.036, 40, (020).

Magnesio-riebeckite from the Varenche mine (Aosta Valley, Italy): crystal-chemical characterization of a grandfathered end-member

2017 ◽  
Vol 81 (6) ◽  
pp. 1431-1437 ◽  
Author(s):  
Roberta Oberti ◽  
Massimo Boiocchi ◽  
Frank C. Hawthorne ◽  
Marco E. Ciriotti
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
Chemical Characterization ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
D Values

AbstractMagnesio-riebeckite from the dumps of the abandoned mine of Varenche (45°47’22’’ N, 7°29’17’’ E), Saint-Barthélemy, Nus, Aosta Valley (Italy), was studied to provide the complete mineral description (including crystal structure) and insights into the crystal-chemistry of riebeckite. The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is A(Na0.09K0.01)Σ=0.10B(Na1.77Ca0.11Mg0.08Mn2+ 0:04)Σ=2.00C(Mg2.93Mn2+0:13Fe2+0:07Zn0.01Ni0.12Fe3+1:25Al0.48Ti0.01)Σ=5.00T(Si7.92Al0.08)Σ=8.00 O22W(OH1.88F0.12)Σ=2.00. Magnesio-riebeckite is biaxial (+), with α = 1.678(2), β = 1.682(2), γ = 1.688(2) and 2V (meas.) = 80.2(1.7)°, 2V (calc.) = 78.7°. The unit-cell parameters are a = 9.6481(14), b = 17.873(3), c = 5.3013(7) Å, β = 103.630(2)°, V = 888.4 (2)Å3, Z = 2, space group C2/m. The strongest ten reflections in the powder X-ray pattern [d values (in Å), I, (hkl)] are: 2.701, 100, (151); 8.303, 83, (110); 3.079, 62, (310); 3.391, 53, (131); 4.467, 50, (040,021); 2.522, 50, (̅202); 2.578, 35, (061); 2.155, 30, (261), 4.855, 30, (̅111), 2.300, 29, (̅351).

A Mössbauer spectroscopic study of the cooling history of hypersthene from selected members of the Taupo Pumice formation, New Zealand

1979 ◽  
Vol 43 (326) ◽  
pp. 279-285 ◽  
Author(s):  
J. H. Johnston ◽  
K. E. Knedler
Keyword(s):  
New Zealand ◽  
Spectroscopic Study ◽  
Cooling Rate ◽  
Analytical Data ◽  
Equilibrium Isotherms ◽  
Cooling History ◽  
X Ray ◽  
Deposit Thickness ◽  
History Of ◽  
Cation Sites

Summary57Fe Mössbauer spectroscopy has been used to determine the Mg2+-Fe2+ distribution between the two crystallographically inequivalent cation sites in hypersthenes from a stratigraphic tephra sequence of the Taupo Pumice formation, North Island, New Zealand. From these distributions and X-ray fluorescence analytical data, cooling histories were constructed using previously determined Mg2+-Fe2+ equilibrium isotherms for orthopyroxenes. The results showed that this cooling history geothermometer could be used to enable airfall and airflow tephra to be distinguished. In addition, they showed that the cooling rate of the above deposits correlated better with the deposit thickness, than with the distance of the deposit from the source.

Site occupancy in richterite-winchite from Libby, Montana, USA, by FTIR spectroscopy

2007 ◽  
Vol 71 (1) ◽  
pp. 93-104 ◽  
Author(s):  
G. Iezzi ◽  
G. Della Ventura ◽  
F. Bellatreccia ◽  
S. Lo Mastro ◽  
B. R. Bandli ◽  
...  
Keyword(s):  
Microprobe Analysis ◽  
Structure Refinement ◽  
Site Occupancy ◽  
Rietveld Analysis ◽  
Published Data ◽  
X Ray Diffraction ◽  
Cation Site ◽  
X Ray ◽  
Powder Samples ◽  
Frequency Components

AbstractThree natural amphibole samples collected from the former vermiculite mine near Libby, Montana. USA, have been analysed by Rietveld X-ray powder diffraction (XRPD) refinement and Fourier transform infrared spectroscopy (FTIR) in the OH-stretching region. The same materials have been analysed previously by electron microprobe analysis (EMPA), Mössbauer spectroscopy and structure refinement (SREF) single crystal X-ray diffraction (SC-XRD), which revealed that these amphiboles have a crystal chemical formula very close to an intermediate composition between winchite and richterite, i.e. AA0.5BNaCaCMg4.5M3+T0.5Si8O22(OH)2 (A = Na and/or K; M3+ = Fe3+ and/or Al). The Rietveld analysis showed the powder samples used for the experiments here to be composed only of amphibole. This in turn allowed us to use FTIR OH-stretching data to derive cation ordering on these powder samples. The three FTIR spectra are quite similar and up to four components can be fitted to the patterns. The two lower-frequency components (labelled A and B) can be attributed to a local O(3)-H dipole surrounded by M(1)M(3)Mg3 and M(1)M(3)Mg2Fe2+; (respectively), an empty A site and rSi8 environments; on the contrary, the higher-frequency C and D bands indicate the presence of an occupied A site. The FTIR OH-stretching data alone allow us to calculate the site occupancy of the A, M(1)–M(3) and T sites with confidence, as compared with previously published data. By contrast M(4)- and M(2)-site occupancies are more difficult to evaluate. This study takes advantage of the large database of well characterized synthetic amphiboles, built over the last two decades. The comparison of vibrational spectroscopy data with micro-chemical and crystallographic data reported in this study demonstrate that the FTIR OH-stretching method alone is a valuable and rapid method to derive or at least sensibly constrain site occupancy for natural amphiboles. A much more detailed cation site occupancy can be obtained by combining micro-chemical and FTIR OH-stretching data.

Effect of Ultra-Fast Cooling Rate on the Microstructure and Mechanical Properties of High Strength Cold-Rolled Sheet under Continuous Annealing

2018 ◽  
Vol 913 ◽  
pp. 311-316
Author(s):  
Kai Zhang ◽  
Ren Bo Song ◽  
Feng Gao ◽  
Wen Jie Niu ◽  
Chi Chen
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Cooling Rate ◽  
High Strength ◽  
Rolled Sheet ◽  
Cooling Rates ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size ◽  
Cold Rolled ◽  
Fast Cooling

The effect of different fast cooling rates on the microstructure and mechanical properties of the V and Ti microalloyed high strength cold-rolled sheet was studied under laboratory conditions. Five different fast cooling rates were set up as 20°C/s, 50°C/s, 200°C/s, 500°C/s and 1000°C/s, respectively. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microstructure, and the mechanical properties were also tested. The results showed that with the increase of fast cooling rate from 20°C/s to 1000°C/s, the grains of martensite and ferrite were finer, and the average grain size of both martensite and ferrite decreased from 7.7μm to 3.9μm. The proportion of ferrite in the two phases decreased while that of the martensite increased from 25.7% to 62.1%. The morphology of martensite tended to be lath, and the density of dislocation in the ferrite grains nearby the martensite gradually increased. With cooling rate rising from 20°C/s to 1000°C/s, the yield strength of the experimental steel increased from 381MPa to 1074MPa, and the tensile strength increased from 887MPa to 1199MPa. And the elongation decreased from 14.2% to 7.2%, and the product of strength and elongation decreased from 12.6GPa·% to 8.6GPa·%.

Sign in / Sign up

Export Citation Format

Share Document