Data di Pubblicazione:
2013
Citazione:
High-pressure behavior and phase stability of Al5BO9, a mullite-type ceramic material / G.D. Gatta, P. Lotti, M. Merlini, H.P. Liermann, M. Fisch. - In: JOURNAL OF THE AMERICAN CERAMIC SOCIETY. - ISSN 0002-7820. - 96:8(2013), pp. 2583-2592. [10.1111/jace.12411]
Abstract:
Phase stability, elastic behavior, and pressure-induced structural
evolution of synthetic boron-mullite Al5BO9 (a = 5.6780(7),
b = 15.035(6), and c =7.698(3) A, space group Cmc21, Z = 4)
were investigated up to 25.6(1) GPa by in situ single-crystal
synchrotron X-ray diffraction with a diamond anvil cell (DAC)
under hydrostatic conditions. No evidence of phase transition
was observed up to 21.7(1) GPa. At 25.6(1) GPa, the refined
unit-cell parameters deviated significantly from the compressional
trend, and the diffraction peaks appeared broader than
at lower pressure. At 26.7(1) GPa, the diffraction pattern was
not indexable, suggesting amorphization of the material or a
phase transition to an high-pressure polymorph. Fitting the
P–V data up to 21.7(1) GPa with a second-order Birch–
Murnaghan Equation-of-State, we obtained a bulk modulus
KT0 = 164(1) GPa. The axial compressibilities, here described
as linearized bulk moduli, are as follows: KT0(a) = 244(9), KT0
(b) = 120(4), and KT0(c) = 166(11) GPa (KT0(a):KT0(b):KT0
(c) = 2.03:1:1.38). The structure refinements allowed a description
of the main deformation mechanisms in response to the
applied pressure. The stiffer crystallographic direction appears
to be controlled by the infinite chains of edge-sharing octahedra
running along [100], making the structure less compressible
along the a-axis than along the b- and c-axis.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
G.D. Gatta, P. Lotti, M. Merlini, H.P. Liermann, M. Fisch
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