| 1. |
- Dubrovinsky, LS, et al.
(författare)
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Stability of ferropericlase in the lower mantle
- 2000
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Ingår i: SCIENCE. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075. ; 289:5478, s. 430-432
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Tidskriftsartikel (refereegranskat)abstract
- We have heated ferropericlases (Mg0.60Fe0.40)O and (Mg0.50Fe0.50)O to temperatures of 1000 kelvin at pressures of 86 gigapascals, simulating the stability of the solid solution at physical conditions relevant to Earth's lower mantle. The in situ x-ray stu
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| 2. |
- Dubrovinsky, L, et al.
(författare)
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Stability of (Mg0.5Fe0.5)O and (Mg0.8Fe0.2)O magnesiowustites in the lower mantle
- 2001
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Ingår i: EUROPEAN JOURNAL OF MINERALOGY. - : E SCHWEIZERBARTSCHE VERLAGS. - 0935-1221. ; 13:5, s. 857-861
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Tidskriftsartikel (refereegranskat)abstract
- We have heated magnesiowtistites (Mg0.5Fe0.5)O and (Mg0.8Fe0.2)O to temperatures of over 1000 K at pressures of over 80 GPa simulating the stability of the solid solution at physical conditions relevant to the Earth's lower mantle. The X-ray study of the
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| 3. |
- Nadutov, V. M., et al.
(författare)
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Anti-Invar properties and magnetic order in fcc Fe-Ni-C alloy
- 2011
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 323:22, s. 2786-2791
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Tidskriftsartikel (refereegranskat)abstract
- Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy, which demonstrates high values of thermal expansion coefficient (TEC) (15-21) x 10(-6) K(-1) accompanied by almost temperature-insensitive behavior in temperature range of 122-525 K. Alloying with carbon considerably expanded the low temperature range of anti-Invar behavior in fcc Fe-Ni-based alloy. The Curie temperature of the alloy T(C) = 195 K was determined on measurements of temperature dependences of magnetic susceptibility and saturation magnetization. The Mossbauer and small-angle neutron scattering (SANS) experiments on the fcc Fe-25.3%Ni-(0.73-0.78)%C alloys with the varying temperatures below and above the Curie point and in external magnetic field of 1.5-5 T were conducted. Low value of the Debye temperature Theta(D) = 180 K was estimated using the temperature dependence of the integral intensity of Mossbauer spectra for specified temperature range. The inequality B(eff) = (0.7-0.9)B(ext) was obtained in external field Mossbauer measurement that points to antiferromagnetically coupled Fe atoms, which have a tendency to align their spins perpendicular to B(ext). Nano length scale magnetic in homogeneities nearby and far above T(C) were revealed, which assumed that it is caused by mixed antiferromagnetically and ferromagnetically coupled Fe atom spins. The anti-Invar behavior of Fe-Ni-C alloy is explained in terms of evolution of magnetic order with changing temperature resulting from thermally varied interspin interaction and decreasing stiffness of interatomic bond.
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| 4. |
- Abdu, Y. A., et al.
(författare)
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High-temperature cation ordering in olivine : an in situ Mossbauer study of synthetic (Mg0.55Fe0.45)(2) SiO4
- 2008
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Ingår i: Hyperfine Interactions. - : Springer Science and Business Media LLC. - 0304-3843 .- 1572-9540. ; 186:1-3, s. 99-103
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Tidskriftsartikel (refereegranskat)abstract
- High- temperature in situ Mossbauer spectroscopy measurements ( 300 950. C) were done on synthetic olivine of composition ( Mg0.55Fe0.45) 2 SiO4 (= Fa45) in order to study the distribution of Fe2+ over the M1 and M2 octahedral sites. The spectra are fit with two doublets, which are assigned to Fe2+ at the M1 ( smaller splitting) and M2 sites. The Fe2+ site- occupancies at M1 and M2, obtained from the Mossbauer relative areas, suggest that Fe2+ has a slight preference for the M1 site at temperatures below similar to 500. C, with a tendency of disordering around this temperature. At higher temperatures, Fe2+ again prefers to occupy the M1 site, where it shows a considerable order at this site up to 750C. At still higher temperatures, the spectra indicated partial reduction of the Fa- component into metallic iron and the resolution of the doublets was severely deteriorated.
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| 7. |
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| 8. |
- Eden, M, et al.
(författare)
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Pulse-assisted homonuclear dipolar recoupling of half-integer quadrupolar spins in magic-angle spinning NMR
- 2005
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 410:1-3, s. 24-30
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate numerically and experimentally that zero-quantum homonuclear dipolar recoupling techniques employing rotor-synchronized 180 degrees pulses, previously introduced for spin-1/2 applications, are useful also for magnetization transfers between half-integer quadrupolar nuclei in rotating solids. The recoupling sequences are incorporated as mixing periods in two-dimensional experimental protocols, that correlate either single-quantum coherences of coupled spins, or triple-quantum with single-quantum coherences for improving spectral resolution. We present Na-23 and Al-27 NMR experiments on powders of sodium sulphite [Na2SO3], YAG [Y3Al5O12] and a synthetic chlorite mineral [Mg4.5Al3Si2.5O10(OH)(8)].
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