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@ARTICLE{Gatta:859490,
author = {Gatta, G. Diego and Vignola, Pietro and Rotiroti, Nicola
and Meven, Martin},
title = {{H}-bonding in lazulite: a single-crystal neutron
diffraction study at 298 and 3 {K}},
journal = {Physics and chemistry of minerals},
volume = {46},
number = {5},
issn = {1432-2021},
address = {Heidelberg},
publisher = {Springer},
reportid = {FZJ-2019-00343},
pages = {449-458},
year = {2019},
abstract = {The crystal structure and crystal chemistry of a lazulite
from Crosscut Creek (Kulan Camp area, Dawson mining
district, Yukon, Canada) was investigated by electron
microprobe analysis in wavelength-dispersive mode (EMPA) and
single-crystal neutron diffraction at 298 and 3 K. Its
empirical formula, based on EMPA data, is:
(Mg0.871Fe0.127)Σ0.998Al2.030(P1.985Ti0.008Si0.007O4)2(OH)2.
The neutron diffraction experiments at room and low T proved
that the H-free structural model of lazulite previously
reported, on the basis of X-ray structure refinement, is
correct: the building unit of the lazulite structure
consists of a group of three face-sharing (Al-octahedron) +
(Mg,Fe-octahedron) + (Al-octahedron), connected to the
adjacent one via a corner-shared OH-group and two
corner-shared oxygen sites of the P-tetrahedron, to form a
dense 3D-edifice. Only one crystallographically independent
H site occurs in the structure of lazulite, forming a
hydroxyl group with the O5 oxygen, with O5–H = 0.9997 Å
at room temperature (corrected for riding motion effect).
The H-bonding scheme in the structure of lazulite is now
well defined: a bifurcated bonding scheme occurs with the O4
and O2 oxygen sites as acceptors. The two H-bonds are
energetically different, as shown by their bonding geometry:
the H-bond with the O2 site as acceptor is energetically
more favorable, being O5–H···O2 = 152.67(9)°,
O5···O2 = 3.014(1) Å and H···O2 = 2.114(1) Å,
whereas that with O4 as acceptor is energetically more
costly, being O5–H···O4 = 135.73(8)°, O5···O4 =
3.156(1) Å and H···O4 = 2.383(1) Å, at room
temperature. No T-induced phase transition occurs within the
T-range investigated. At low temperature, the O5–H···O2
bond is virtually identical to the room-T one, whereas the
effects of T on O5–H···O4 are more pronounced, with
significant differences of the Odonor···Oacceptor and
H···Oacceptor distances. The experimental findings of
this study do not support the occurrence of HPO4 or H2PO4
units into the structure of lazulite, recently reported on
the basis of infrared and Raman spectra.},
cin = {JCNS-FRM-II / JCNS-2 / MLZ},
ddc = {530},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)JCNS-2-20110106 / I:(DE-588b)4597118-3},
pnm = {6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623)
/ 6G15 - FRM II / MLZ (POF3-6G15)},
pid = {G:(DE-HGF)POF3-6G4 / G:(DE-HGF)POF3-6G15},
experiment = {EXP:(DE-MLZ)HEIDI-20140101},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000466218200002},
doi = {10.1007/s00269-018-1015-5},
url = {https://juser.fz-juelich.de/record/859490},
}