The nonlinear anomalous lattice elasticity associated with the high-pressure phase transition in spodumene: a high-precision static compression study
- Author(s)
- Angela Ullrich, Wilfried Schranz, Ronald Miletich
- Abstract
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(s)
- Physics of Functional Materials
- External organisation(s)
- Scientific Software Center
- Journal
- Physics and Chemistry of Minerals
- Volume
- 36
- Pages
- 545-555
- No. of pages
- 2
- ISSN
- 0342-1791
- DOI
- https://doi.org/10.1007/s00269-009-0300-8
- Publication date
- 2009
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105113 Crystallography, 1030 Physics, Astronomy
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/the-nonlinear-anomalous-lattice-elasticity-associated-with-the-highpressure-phase-transition-in-spodumene-a-highprecision-static-compression-study(1125bb99-fdd9-4786-a5f6-7c27b241a45f).html