Data di Pubblicazione:
2014
Citazione:
Elastic behavior and pressure-induced structure evolution of topaz up to 45 GPa / G.D. Gatta, W. Morgenroth, P. Dera, S. Petitgirard, H. Liermann. - In: PHYSICS AND CHEMISTRY OF MINERALS. - ISSN 0342-1791. - 41:8(2014), pp. 569-577.
Abstract:
The behavior of a natural topaz,
Al2.00Si1.05O4.00(OH0.26F1.75), has been investigated by
means of in situ single-crystal synchrotron X-ray diffraction
up to 45 GPa. No phase transition or change in the compressional
regime has been observed within the pressure-range
investigated. The compressional behavior was described
with a third-order Birch–Murnaghan equation of state (IIIBM-
EoS). The III-BM-EoS parameters, simultaneously
refined using the data weighted by the uncertainties in P
and V, are as follows: KV = 158(4) GPa and KV′ = 3.3(3).
The confidence ellipse at 68.3 % (Δχ2 = 2.30, 1σ) was calculated
starting from the variance–covariance matrix of KV
and K′ obtained from the III-BM-EoS least-square procedure.
The ellipse is elongated with a negative slope, indicating
a negative correlation of the parameters KV and KV′,
with KV = 158 ± 6 GPa and KV′ = 3.3 ± 4. A linearized
III-BM-EoS was used to obtain the axial-EoS parameters
(at room-P), yielding: K(a) = 146(5) GPa [βa = 1/
(3K(a)) = 0.00228(6) GPa−1] and K′(a) = 4.6(3) for the a-axis; K(b) = 220(4) G Pa [βb = 0.00152(4) G Pa−1]
and K′(b) = 2.6(3) for the b-axis; K(c) = 132(4) GPa
[βc = 0.00252(7) GPa−1] and K′(c) = 3.3(3) for the
c-axis. The elastic anisotropy of topaz at room-P can
be expressed as: K(a):K(b):K(c) = 1.10:1.67:1.00
(βa:βb:βc = 1.50:1.00:1.66). A series of structure refinements
have been performed based on the intensity data collected
at high pressure, showing that the P-induced structure
evolution at the atomic scale is mainly represented
by polyhedral compression along with inter-polyhedral
tilting. A comparative analysis of the elastic behavior and
P/T-stability of topaz polymorphs and “phase egg” (i.e.,
AlSiO3OH) is carried out.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
G.D. Gatta, W. Morgenroth, P. Dera, S. Petitgirard, H. Liermann
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