Crystallography relevant to Mars and Galilean icy moons: Crystal behavior of kieserite-type sulfates

database, nuove specie, discrediti,
ridefinizioni, classificazioni, ecc.
Avatar utente
Marco E. Ciriotti
Messaggi: 28841
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy

Crystallography relevant to Mars and Galilean icy moons: Crystal behavior of kieserite-type sulfates

Messaggio da Marco E. Ciriotti » ven 14 gen, 2022 21:18

▪ Wildner, M., Zakharov, B.A., Bogdanov, N.E., Talla, D., Boldyreva, E., Miletich, R. (2022): Crystallography relevant to Mars and Galilean icy moons: crystal behavior of kieserite-type monohydrate sulfates at extraterrestrial conditions down to 15 K. IUCrJ, 9, DOI link:

Monohydrate sulfate kieserites ( M ²⁺ SO 4 ·H 2 O) and their solid solutions are essential constituents on the surface of Mars and most likely also on Galilean icy moons in our solar system. Phase stabilities of end-member representatives ( M ²⁺ = Mg, Fe, Co, Ni) have been examined crystallographically using single-crystal X-ray diffraction at 1 bar and temperatures down to 15 K, by means of applying open He cryojet techniques at in-house laboratory instrumentation. All four representative phases show a comparable, highly anisotropic thermal expansion behavior with a remarkable negative thermal expansion along the monoclinic b axis and a pronounced anisotropic expansion perpendicular to it. The lattice changes down to 15 K correspond to an `inverse thermal pressure' of approximately 0.7 GPa, which is far below the critical pressures of transition under hydrostatic compression ( P c ≥ 2.40 GPa). Consequently, no equivalent structural phase transition was observed for any compound, and neither dehydration nor rearrangements of the hydrogen bonding schemes have been observed. The M ²⁺ SO 4 ·H 2 O ( M ²⁺ = Mg, Fe, Co, Ni) end-member phases preserve the kieserite-type C 2/ c symmetry; hydrogen bonds and other structural details were found to vary smoothly down to the lowest experimental temperature. These findings serve as an important basis for the assignment of sulfate-related signals in remote-sensing data obtained from orbiters at celestial bodies, as well as for thermodynamic considerations and modeling of properties of kieserite-type sulfate monohydrates relevant to extraterrestrial sulfate associations at very low temperatures.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»


Chi c’è in linea

Visitano il forum: Nessuno e 3 ospiti