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Single-crystal neutron diffraction and Raman spectroscopic study of hydroxylherderite, CaBePO (sub 4) (OH,F)

G. D. Gatta, S. D. Jacobsen, P. Vignola, G. J. McIntyre, G. Guastella and L. F. Abate
Single-crystal neutron diffraction and Raman spectroscopic study of hydroxylherderite, CaBePO (sub 4) (OH,F)
Mineralogical Magazine (June 2014) 78 (3): 723-737


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 [ (super Ca) (Na (sub 0.01) Ca (sub 1.01) ) (sub Sigma 1.02) (super Be) (Be (sub 0.98) Li (sub 0.01) ) (sub Sigma 0.99) (Si (sub 0.03) P (sub 0.98) ) (sub Sigma 1.01) O (sub 4) (OH (sub 0.67) F (sub 0.33) ) (sub Sigma 1) , Z = 4, a = 9.7856(5), b = 7.6607(5), c = 4.8025(3) Aa, beta = 90.02(3) degrees , V= 360.02(4) Aa (super 3) , space group P2 (sub 1) /a]. The neutron-structure refinement converged with fully anisotropic displacement parameters to give a final agreement index R (sub 1) = 0.0363 for 85 refined parameters and 1614 unique reflections with F (sub o) >4sigma (F (sub 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) Aa. The H bond of hydroxylherderite is bifurcated with O2 and O4 acceptors forming H bonds with O5...O2 = 3.163(1) Aa, H...O2 = 2.544(2) Aa and O5-H...O2 = 121.8(1) degrees ; O5...O4 = 3.081(1) Aa, H...O4 = 2.428(2) Aa and O5-H...O4 = 124.4(1) degrees . The highly non-linear O-H...O hydrogen bonds in hydroxylherderite and in the isotypic datolite [ideally CaBSiO (sub 4) (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 (super -1) , which are attributed to the bifurcated H bond. Two additional weak bands at 3575 and 3610 cm (super -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.

ISSN: 0026-461X
EISSN: 1471-8022
Serial Title: Mineralogical Magazine
Serial Volume: 78
Serial Issue: 3
Title: Single-crystal neutron diffraction and Raman spectroscopic study of hydroxylherderite, CaBePO (sub 4) (OH,F)
Affiliation: Universita degli Studi di Milano, Dipartimento di Scienze della Terra, Milan, Italy
Pages: 723-737
Published: 201406
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 40
Accession Number: 2014-096935
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N43°46'60" - N45°21'00", W71°05'60" - W70°16'00"
Secondary Affiliation: Northwestern University, USA, United StatesAustralian Nuclear Science and Technology Organisation, AUS, AustraliaAgenzia delle Dogane e dei Monopoli, ITA, Italy
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201449
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