Phase transition and high-pressure behavior of ulexite, a potential aggregate in radiation-shielding concretes
Articolo
Data di Pubblicazione:
2021
Citazione:
Phase transition and high-pressure behavior of ulexite, a potential aggregate in radiation-shielding concretes / D. Comboni, F. Pagliaro, G.D. Gatta, P. Lotti, T. Battiston, M. Merlini, M. Hanfland. - In: CONSTRUCTION AND BUILDING MATERIALS. - ISSN 0950-0618. - 291(2021 Jul), pp. 123188.1-123188.12.
Abstract:
The high-pressure behavior of ulexite [ideally NaCaB5O6(OH)6x5(H2O)], a B-bearing raw material (with
B2O3 ca. 43 wt%) and a potential B-rich aggregate, has been studied by in-situ single-crystal synchrotron
X-ray diffraction up to 9.5 GPa, in order to explore its stability field at high pressure, the anisotropy of
its compressional behavior and the deformation mechanisms at the atomic scale. Ulexite undergoes a
first-order iso-symmetric phase transition, reconstructive in character, between 6.44 and 7.13 GPa (to
the ulexite-II polymorph); the crystal structure of ulexite-II was successfully solved and refined. For
the low-P polymorph of ulexite (stable in all the working conditions as aggregate in concretes), the
isothermal bulk modulus here obtained is KV0 = 36.9(5) GPa, with a strongly anisotropic compressional
pattern (finite-Eulerian principal components of the unit-strain ellipsoid: e1:e2:e3 =7:3:1). Ulexite-II also
shows a marked anisotropic compressional pattern and with a resulting bulk softening (KV0 = 26(4) GPa).
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Ulexite; Crystal structure; Elastic moduli; Stability; Phase transition
Elenco autori:
D. Comboni, F. Pagliaro, G.D. Gatta, P. Lotti, T. Battiston, M. Merlini, M. Hanfland
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