TY - JOUR
T1 - Elastic properties and stability of coexisting 3T and 2M1 phengite polytypes
AU - Curetti, Nadia
AU - Levy, Davide
AU - Paverse, Alessandro
AU - Ivaldi, Gabriella
PY - 2006/1
Y1 - 2006/1
N2 - The elastic properties of coexisting natural 3T and 2M1 phengite samples (Cima Pal, Sesia Zone; Val Savenca; Western Alps, Italy) with similar chemical compositions have been studied by room temperature-high pressure powder diffraction, using synchrotron radiation on the ID9A beam-line at ESRF (Grenoble, France). The P-V curves have been modelled by the Birch-Murnaghan model; a third-order expansion fitted to the experimental data yields for 3T and 2M1 K0 = 60.4(± 0.7) GPa, K′ = 5.79(± 0.11) at V0 = 703.8851 Å3, and K′ = 57.3(± 1.0) GPa, K′ = 6.97(± 0.24) at V0 = 938.8815 Å3, respectively. The relative stability of 3T vs. 2M1 has been explored as a function of pressure and temperature in terms of configuration and deformation contributions to the Gibbs energy, using the elastic properties determined here and other thermodynamic parameters from earlier investigations. The results presented agree with the hypothesis of stability of the 3T polytype in the high pressure regime.
AB - The elastic properties of coexisting natural 3T and 2M1 phengite samples (Cima Pal, Sesia Zone; Val Savenca; Western Alps, Italy) with similar chemical compositions have been studied by room temperature-high pressure powder diffraction, using synchrotron radiation on the ID9A beam-line at ESRF (Grenoble, France). The P-V curves have been modelled by the Birch-Murnaghan model; a third-order expansion fitted to the experimental data yields for 3T and 2M1 K0 = 60.4(± 0.7) GPa, K′ = 5.79(± 0.11) at V0 = 703.8851 Å3, and K′ = 57.3(± 1.0) GPa, K′ = 6.97(± 0.24) at V0 = 938.8815 Å3, respectively. The relative stability of 3T vs. 2M1 has been explored as a function of pressure and temperature in terms of configuration and deformation contributions to the Gibbs energy, using the elastic properties determined here and other thermodynamic parameters from earlier investigations. The results presented agree with the hypothesis of stability of the 3T polytype in the high pressure regime.
KW - 2M-3T phengites
KW - P-V EoS
KW - Relativestability
UR - http://www.scopus.com/inward/record.url?scp=31144469737&partnerID=8YFLogxK
U2 - 10.1007/s00269-005-0044-z
DO - 10.1007/s00269-005-0044-z
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AN - SCOPUS:31144469737
SN - 0342-1791
VL - 32
SP - 670
EP - 678
JO - Physics and Chemistry of Minerals
JF - Physics and Chemistry of Minerals
IS - 10
ER -