@article{fdi:010061759,
  title = {{C}ontribution of interstitial {OH} groups to the incorporation of water in forsterite},
  author = {{B}alan, {E}tienne and {B}lanchard, {M}. and {L}azzeri, {M}. and {I}ngrin, {J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{W}ater incorporation in forsterite samples synthesized under low to medium silica-activity conditions mostly occurs via a substitutional mechanism in which a {S}i vacancy is compensated by four protons. {C}orresponding {IR} absorption spectra display a cluster of narrow and weakly anharmonic {OH}-stretching bands at wavenumbers above 3,500 cm(-1). {H}owever, this diagnostic spectrum is often superimposed to one broader absorption band, rarely two, displaying pronounced temperature-dependent properties and tentatively assigned to {H} atoms in interstitial position ({I}ngrin et al. in {P}hys {C}hem {M}iner 40:499-510, 2013). {H}ere, we investigate the structural and vibrational properties of selected interstitial {H}-bearing defects in forsterite using a first-principles modeling approach. {W}e show that the broad bands discussed by {I}ngrin et al. ({P}hys {C}hem {M}iner 40:499-510, 2013) are most likely related to interstitial {OH} groups in the vacant octahedral sites alternating with the {M}2 sites along the c axis of the forsterite structure. {T}he corresponding {OH} defects lead to the formation of fivefold coordinated {S}i species. {T}heir peculiar thermal properties stem from the vibrational phase relaxation due to the anharmonic coupling of the high-energy local {OH}-stretching mode with a low-energy vibrational mode. {T}his "exchange mode" corresponds to the hindered longitudinal translation of the {OH} group. {T}hese results suggest that at high pressure, hydrogen incorporation in forsterite is dominated by coexisting interstitial {OH} groups and (4{H})({S}i) defects.},
  keywords = {{F}orsterite ; {OH} defects ; {IR} spectroscopy ; {A}b initio calculations ; {V}ibrational phase relaxation},
  booktitle = {},
  journal = {{P}hysics and {C}hemistry of {M}inerals},
  volume = {41},
  numero = {2},
  pages = {105--114},
  ISSN = {0342-1791},
  year = {2014},
  DOI = {10.1007/s00269-013-0628-y},
  URL = {https://www.documentation.ird.fr/hor/fdi:010061759},
}