![]() The interatomic distances in the two structures indicate that in pentlandite Fe 2+ and Ni 2+ are high spin and in violarite Fe 2+ is low spin with Ni 3+ with an inverted spinel structural type. The structures of RuddlesdenPopper n 2 member phases Sr 3x Y x Fe 1.25 Ni 0.75 O 7 with 0 x 0. Violarite did not exhibit any evidence of magnetic ordering upon cooling to −173 ☌. In situ neutron diffraction heating experiments in which pentlandite and violarite were heated up to 300 ☌ for 12 hours did not alter the Ni/Fe distribution between tetrahedral and octahedral sites. ![]() Steady development of instrumentation and data analysis techniques. Diffraction experiments on single crystals provide the most precise data, but sufficiently large specimens (>0.10.5 mm 3) are often not available. Synthetic violarite, FeNi 2S 4, prepared at 300 ☌, exhibits ordering of Ni onto the tetrahedral site, with Fe and the remaining Ni sharing the octahedral site. For many classes of materials, neutron diffraction is the best way to obtain detailed atomic-level structural information. For an unpolarized incident beam, the usual case in neutron powder diffraction, it is a useful consequence of the triple vector product that the magnetic scattering depends on the sine of the angle that the scattering vector makes with the magnetic moment on the scattering atom (see Section 2.3.4 and Chapter 7 in Kisi & Howard, 2008). After annealing for a further 2 months at 150 ☌ the Ni/Fe distribution is still disordered with 53(2)% Ni in the octahedral site and 48(2)% Ni in the tetrahedral site and the cell parameter increased by 0.21% possibly due to slight readjustment of the Fe/Ni ratio. The Polaris instrument at ISIS is a high intensity, medium resolution powder diffractometer. ![]() Pentlandite of composition Fe 4.8Ni 4.2S 8, annealed at 150° C for 1 month has a disordered Ni/Fe distribution with Ni occupying 57(2)% of the octahedral site and 46(1)% of the tetrahedral site with a unit cell repeat of 10.1075(1) Å. It combined the first-principles calculations, neutron powder-diffraction measurements and temperature tunable aberration-corrected scanning transmission. His paper shows that a user of the current version of PDF4+ (ICDD, proprietor of this journal) has access to new capabilities via the embedded software to simulate neutron TOF patterns (those obtained at. Cation ordering in two important iron nickel sulfide minerals, pentlandite and violarite, was studied by neutron powder diffraction using samples prepared with isotopically enriched 60Ni. John Faber describes another advance that will support users who are considering neutron powder diffraction. ![]()
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