The nonlinear anomalous lattice elasticity associated with the high-pressure phase transition in spodumene: a high-precision static compression study

Autor(en)

Angela Ullrich, Wilfried Schranz, Ronald Miletich

Abstrakt

The high-pressure behavior of the lattice elasticity of spodumene, LiAlSi2O6, was studied by static compression in a diamond-anvil cell up to 9.3 GPa. Investigations by means of single-crystal XRD and Raman spectroscopy within the hydrostatic limits of the pressure medium focus on the pressure ranges around ~3.2 and ~7.7 GPa, which have been reported previously to comprise two independent structural phase transitions. While our measurements confirm the well-established first-order C2/c–P21/c transformation at 3.19 GPa (with 1.2% volume discontinuity and a hysteresis between 0.02 and 0.06 GPa), both unit-cell dimensions and the spectral changes observed in high-pressure Raman spectra give no evidence for structural changes related to a second phase transition. Monoclinic lattice parameters and unit-cell volumes at in total 59 different pressure points have been used to re-calculate the lattice-related properties of spontaneous strain, volume strain, and the bulk moduli as a function of pressure across the transition. A modified Landau free energy expansion in terms of a one component order parameter has been developed and tested against these experimentally determined data. The Landau solution provides a much better reproduction of the observed anomalies than any equation-of-state fit to data sets truncated below and above P tr, thus giving Landau parameters of K 0 = 138.3(2) GPa, K′ = 7.46(5), λ V = 33.6(2) GPa, a = 0.486(3), b = −29.4(6) GPa and c = 551(11) GPa.

Organisation(en)

Physik Funktioneller Materialien

Externe Organisation(en)

Universität Heidelberg

Journal

Physics and Chemistry of Minerals

Band

36

Seiten

545-555

Anzahl der Seiten

2

ISSN

0342-1791

DOI

https://doi.org/10.1007/s00269-009-0300-8

Publikationsdatum

2009

Peer-reviewed

Ja

ÖFOS 2012

105113 Kristallographie, 1030 Physik, Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/1125bb99-fdd9-4786-a5f6-7c27b241a45f