“Pressure-Induced Hydration and Formation of Bilayer Ice in Nacrite, a Kaolin-Group Clay”
H. Hwang, J. Choi, Z. Liu, D.-Y. Kim, Y. He, A.J. Celestian, T. Vogt, Y. Lee*
ACS Earth and Space Chemistry
Vol.4, pp.183-188, 2020.02
Pressure-induced hydration of the clay mineral nacrite, Al2Si2O5(OH)4 is, in contrast to its polymorph kaolinite, partially irreversible. At ambient conditions after pressure release, a majority phase with composition Al2Si2O5(OH)4·2H2O with an intense (002) diffraction peak near d ∼ 8.4 Å has been found. Both in situ X-ray diffraction and simulations based on the density functional theory point to intercalation of molecules in nominally nonswelling clays and specific geophysical and geochemical conditions.