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Title: Single-crystal neutron diffraction and Raman spectroscopic study of hydroxylherderite, CaBePO4(OH, F)
Authors: Gatta, GD
Jacobsen, SD
Vignola, P
McIntyre, GJ
Guastella, G
Abate, LF
Keywords: Raman spectroscopy
Neutron diffraction
X-ray sources
Issue Date: 1-Jun-2014
Publisher: Mineralogical Society
Citation: Gatta, G. D., Jacobsen, S. D., Vignola, P., McIntyre, G. J., Guastella, G., & Abate, L. F. (2014). Single-crystal neutron diffraction and Raman spectroscopic study of hydroxylherderite, CaBePO<sub>4</sub>(OH, F). Mineralogical Magazine, 78(3), 723-737. doi:10.1180/minmag.2014.078.3.18
Abstract: The crystal structure, H bonding and chemical composition of hydroxylherderite from the Bennett pegmatite, Buckfield, Oxford County, Maine, USA were investigated by single-crystal X-ray diffraction and neutron Laue diffraction, electron microprobe analysis in wavelength-dispersive mode, inductively coupled plasma-atomic emission spectrometry and polarized Raman spectroscopy [ Ca (Na0.01Ca1.01)Σ1.02 Be (Be0.98Li0.01)Σ0.99 P (Si0.03P0.98)Σ1.01O4(OH0.67F0.33)Σ1, Z = 4, a = 9.7856(5), b = 7.6607(5), c = 4.8025(3) Å, b = 90.02(3)°, V= 360.02(4) Å3, space group P21/a]. The neutron-structure refinement converged with fully anisotropic displacement parameters to give a final agreement index R 1 = 0.0363 for 85 refined parameters and 1614 unique reflections with F o >4σ(F o). The structure refinement was used to determine the H position and geometry of H bonding in the structure. One H site was found on the O5 anion with an O–H interatomic distance, corrected for “riding motion”, of 0.996(2) Å. The H bond of hydroxylherderite is bifurcated with O2 and O4 acceptors forming H bonds with O5···O2 = 3.163(1) Å, H···O2 = 2.544(2) Å and O5–H···O2 = 121.8(1)°; O5···O4 = 3.081(1) Å, H···O4 = 2.428(2) Å and O5–H···O4 = 124.4(1)°. The highly non-linear O–H···O hydrogen bonds in hydroxylherderite and in the isotypic datolite [ideally CaBSiO4(OH)] are constrained by the tetrahedral network topology. Two main O–H stretching modes were observed in the Raman spectra at 3565 and 3620 cm–1, which are attributed to the bifurcated H bond. Two additional weak bands at 3575 and 3610 cm–1 are attributed to Si–P disorder in the tetrahedral sites. Results of this study will contribute to the correlation of H-bonding geometry and O–H stretching frequencies of highly non-linear H bonds.© The Mineralogical Society of Great Britain & Ireland.
Gov't Doc #: 6943
ISSN: 1471-8022
Appears in Collections:Journal Articles

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