Anelasticity and transient creep in NaMgF3 perovskite at high pressure

Li, Li; Weidner, Donald J.

doi:10.1016/j.pepi.2012.01.009

Cited by 12 publications

(2 citation statements)

References 33 publications

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“…For the volumetrically dominant Mg‐silicate perovskite phase, the low‐strain viscoelastic behavior is currently experimentally accessible only indirectly, notwithstanding pioneering forced‐oscillation studies at high pressures in the D‐DIA solid‐medium apparatus [ Li and Weidner , ]. Structural analogues for the silicate perovskites, which are stable at lower pressures, have accordingly received attention [e.g., Webb et al ., ; Harrison et al ., ; Carpenter and Zhang , ; Li and Weidner , ]. For the purest and microstructurally simplest of the Ca‐ and Sr‐titanate polycrystals studied by Webb et al .…”

Section: Discussionmentioning

confidence: 99%

Grain size‐sensitive viscoelastic relaxation and seismic properties of polycrystalline MgO

et al. 2016

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Torsional forced‐oscillation experiments on a suite of synthetic MgO polycrystals, of high‐purity and average grain sizes of 1–100 µm, reveal strongly viscoelastic behavior at temperatures of 800–1300°C and periods between 1 and 1000 s. The measured shear modulus and associated strain energy dissipation both display monotonic variations with oscillation period, temperature, and grain size. The data for the specimens of intermediate grain size have been fitted to a generalized Burgers creep function model that is also broadly consistent with the results for the most coarse‐grained specimen. The mild grain size sensitivity for the relaxation time τL, defining the lower end of the anelastic absorption band, is consistent with the onset of elastically accommodated grain boundary sliding. The upper end of the anelastic absorption band, evident in the highest‐temperature data for one specimen only, is associated with the Maxwell relaxation time τM marking the transition toward viscous behavior, conventionally ascribed a stronger grain size sensitivity. Similarly pronounced viscoelastic behavior was observed in complementary torsional microcreep tests, which confirm that the nonelastic strains are mainly recoverable, i.e., anelastic. With an estimated activation volume for the viscoelastic relaxation, the experimentally constrained Burgers model has been extrapolated to the conditions of pressure and temperature prevailing in the Earth's uppermost lower mantle. For a plausible grain size of 10 mm, the predicted dissipation Q−1 ranges from ~10−3 to ~10−2 for periods of 3–3000 s. Broad consistency with seismological observations suggests that the lower mantle ferropericlase phase might account for much of its observed attenuation.

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Section: Discussionmentioning

confidence: 99%

Grain size‐sensitive viscoelastic relaxation and seismic properties of polycrystalline MgO

et al. 2016

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“…For MgSiO 3 perovskite (bridgmanite), the mineral neighborite (NaMgF 3 ) provides an obvious and attractive analogue (e.g. Umemoto et al 2006b; Hustoft et al 2008; Li and Weidner 2012), although other ABF 3 compounds such as KCaF 3 (Watson et al 1995) and KZnF 3 (Poirier et al 1983) have also been used for this purpose. NaMgF 3 may be readily synthesised at atmospheric pressure and is stable at atmospheric pressure and room temperature.…”

Section: Introductionmentioning

confidence: 99%

The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

et al. 2017

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stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF 3 , the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF 3 phases follows the sequence: perovskite → CaIrO 3 structure → Sb 2 S 3 structure → P6 3 /mmc structure. However, only the perovskite and CaIrO 3 structures are stable with respect to dissociation into NaF and MgF 2 .

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