@article{fdi:010055654,
  title = {{I}nsights into the high-pressure behavior of kaolinite from infrared spectroscopy and quantum-mechanical calculations},
  author = {{W}elch, {M}. {D}. and {M}ontgomery, {W}. and {B}alan, {E}tienne and {L}erch, {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he high-pressure behavior of {K}eokuk kaolinite has been studied to 9.5 {GP}a by infrared spectroscopy using synchrotron radiation. {T}he kaolinite-{I} -> kaolinite-{II} and kaolinite-{II} -> kaolinite-{III} transformations have clear spectroscopic expression, with discontinuities coinciding with the transformation pressures bracketed by {X}-ray diffraction ({W}elch and {C}richton in {A}m {M}ineral 95: 651654, 2010). {T}he experimental spectra have been interpreted from band assignments derived from density functional theory for the structures of kaolinite-{II} and kaolinite-{III}, using as starting models the ab initio structures reported by {M}ercier and {L}e {P}age ({A}cta {C}rystallogr {A} {B}64:131-143, 2008, {M}ater {S}ci {T}echnol 25:437-442, 2009) and unit-cell parameters from {W}elch and {C}richton ({A}m {M}ineral 95: 651654, 2010). {T}he relaxed theoretical structures are very similar to those reported by {M}ercier and {L}e {P}age ({A}cta {C}rystallogr {A} {B}64: 131-143, 2008, {M}ater {S}ci {T}echnol 25: 437-442, 2009) in their theoretical investigation of kaolinite polytypes at high pressure. {T}he vibrational spectra calculated from the quantum-mechanical analysis allow band assignments of the {IR} spectra to be made and provide insights into the behavior of different {OH} environments in the two high-pressure polytypes. {T}he single perpendicular-interlayer {OH} group of kaolinite-{III} has a distinctive spectroscopic signature that is diagnostic of this polytype (v = 3,595 cm(-1) at 9.5 {GP}a) and is sensitive to the compression/expansion of the interlayer space. {T}his {OH} group also has a distinctive signature in the calculated spectra. {T}he spectra collected on decompression are those of kaolinite-{III} and persist largely unchanged to 4.6 {GP}a, except for a continuous blue shift of the 3,595 cm(-1) band to 3,613 cm(-1). {F}inally, kaolinite-{I} is recovered at 0.6 {GP}a, confirming the kaolinite-{III} -> kaolinite-{I} transformation previously observed by {X}-ray diffraction, and the irreversibility of the kaolinite-{II} -> kaolinite-{III} transformation. {T}he ambient spectra collected at the start and finish of the experiment are those of kaolinite-{I}, and start/finish band frequencies agree to within 6 cm(-1).},
  keywords = {{K}aolinite ; {P}olytypism ; {I}n situ high-{P} ; {S}ynchrotron {IR} ; {P}hase transformations ; {F}irst-principles calculations},
  booktitle = {},
  journal = {{P}hysics and {C}hemistry of {M}inerals},
  volume = {39},
  numero = {2},
  pages = {143--151},
  ISSN = {0342-1791},
  year = {2012},
  DOI = {10.1007/s00269-011-0469-5},
  URL = {https://www.documentation.ird.fr/hor/fdi:010055654},
}