Ingrin J., Kovacs I., Deloule E., Balan Etienne, Blanchard M., Kohn S. C., Hermann J. (2014). Identification of hydrogen defects linked to boron substitution in synthetic forsterite and natural olivine. American Mineralogist, 99 (10), p. 2138-2141. ISSN 0003-004X.
Titre du document
Identification of hydrogen defects linked to boron substitution in synthetic forsterite and natural olivine
Ingrin J., Kovacs I., Deloule E., Balan Etienne, Blanchard M., Kohn S. C., Hermann J.
Source
American Mineralogist, 2014,
99 (10), p. 2138-2141 ISSN 0003-004X
Experimental and theoretical evidence for the coupled substitution of B and H in synthetic forsterite and a natural olivine is presented. The intensities of OH bands at 3704 cm(-1) (//z), 3598 cm(-1) (//x,y), and 3525 cm(-1) (//x) in a heterogeneous B-doped synthetic forsterite crystal matches the zoning of B concentration measured by ion probe. The two anti-symmetric stretching vibrations of BO3 groups occur at 1301 cm(-1) (//x) and 1207 cm(-1) (//z) for the B-10 and at 1256 and 1168 cm(-1) for the B-11 isotope. A microscopic model of the mixed (B,H) defect that accounts for experimental observations is obtained from quantum mechanical calculations. The BO3 group lies on the (O3-O1-O3) face of the vacant Si site and the H atom is bonded to the O2 atom at the remaining apex. The occurrence of the same OH bands associated with v(3) BO3 vibrations in a natural olivine sample from Pakistan confirms the occurrence of this defect in nature. The three diagnostic OH bands can be used as a signature of H associated with boron substitution in olivine and forsterite, leading to a quantitative analysis of their contribution to H-defects.
