Investigation of the structure and properties of quartz in the α-β transition range by neutron diffraction and mechanical spectroscopy

Nikitin, A. N.; Маркова, Г. В.; Балагуров, А.М.; Vasin, R. N.; Алексеева, О. В.

doi:10.1134/s1063774507030145

Cited by 22 publications

(13 citation statements)

References 13 publications

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“…RUS data at ∼1 MHz from a polycrystalline sample show that Q −1 has a small peak in the vicinity of the transition point (McKnight et al . 2008), and a similar peak is seen also at ∼1 kHz (Nikitin et al . 2007).…”

Section: Phase Transitions Which Might Contribute To Anelastic Losssupporting

confidence: 56%

Anelasticity maps for acoustic dissipation associated with phase transitions in minerals

Carpenter¹,

Zhang²

2011

Geophysical Journal International

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S U M M A R YAcoustic dissipation due to structural phase transitions in minerals could give rise to large seismic attenuation effects superimposed on the high temperature background contribution from dislocations and grain boundaries in the Earth. In addition to the possibility of a sharp peak actually at a transition point for both compressional and shear waves, significant attenuation might arise over wider temperature intervals due to the mobility of transformation twins or other defects associated with the transition. Attenuation due to structural phase transitions in quartz, pyroxenes, perovskites, stishovite and hollandite, or to spin state transitions of Fe 2+ in magnesiowüstite and perovskite and the hcp/bcc transition in iron-nickel (Fe-Ni) alloy, are reviewed from this perspective. To these can be added possible loss behaviour associated with reconstructive transitions which might occur by a ledge mechanism on topotactic interfaces (orthopyroxene/clinopyroxene, olivine/spinel and perovskite/postperovskite), with impurities (Snoek effect) or with mobility of protons. There are experimental difficulties associated with measuring dissipation effects in situ at simultaneous high pressures and temperatures, so reliance is currently placed on investigation of analogue phases such as LaCoO 3 for spinstate behaviour and LaAlO 3 for the dynamics of ferroelastic twin walls. Similarly, it is not possible to measure loss dynamics simultaneously at the low stresses and low frequencies that pertain in seismic waves, so reliance must be placed on combining different techniques, such as dynamic mechanical analysis (low frequency, relatively high stress) and resonant ultrasound spectroscopy (high frequency, low stress), to extrapolate acoustic loss behaviour over wide frequency, temperature and stress intervals. In this context 'anelasticity maps' provide a convenient means of representing different loss mechanisms. Contouring of the inverse mechanical quality factor, Q −1 , can be achieved if the appropriate constitutive laws are known. The overall approach is illustrated using the examples of spin-state transitions of Co 3+ in LaCoO 3 and twin mobility in single crystals of the rhombohedral phase of LaAlO 3 . Anelasticity maps of this type should give seismologists a clearer view of the characteristic patterns of seismic velocity and attenuation that could be used to detect (or rule out) the presence of particular phase transitions or loss behaviour in the core and mantle.

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Section: Phase Transitions Which Might Contribute To Anelastic Losssupporting

confidence: 56%

Anelasticity maps for acoustic dissipation associated with phase transitions in minerals

Carpenter¹,

Zhang²

2011

Geophysical Journal International

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“…An increase in plasticity is therefore expected near the phase transition and transformation‐induced superplasticity can occur in discrete zones of high microplasticity, surrounded by an elastically deformed medium. The phase transition can also facilitate failure of quartz rich rocks, which would be expected to promote the formation of shear zones or regions of high deformation [ Nikitin et al ., ]. Kern [] conducted a series of experiments with different samples containing various percentages of quartz crystals and found that the amount of softening near the α‐β phase transition seems to be independent of content of the constituent quartz crystals, although softening occurs over a narrower temperature range in quartzite (100 vol.% quartz) than granite and granulite (21.6 vol.% and 28.2 vol.% quartz, respectively).…”

Section: Geophysical Implications Of the α‐β Quartz Transitionmentioning

confidence: 99%

“…[] and Nikitin et al . [, ] identify weakening and seismic velocity reductions in areas of Tibet which influence the dynamic tectonics of the region. A high abundance of quartz‐rich rocks in the lower crust has been proposed as a major triggering factor for initiating deformation, but the role of the phase transition on increasing the potential importance of quartz in controlling such deformation has not been directly investigated.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of quartz at the α‐β phase transition: Implications for tectonic and seismic anomalies

Peng

Redfern

2013

Geochem Geophys Geosyst

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[1] The anelastic response of single-crystal and polycrystalline quartz and quartz-rich sandstones to applied stress at low frequencies has been investigated by dynamic mechanical analysis and force torsion pendulum measurements. The dynamic modulus was measured on heating and cooling through the a-b phase transition under shear and bending stress applied at low frequency (~1 Hz). Single crystal quartz shows highly anisotropic properties in both the real and imaginary part of the modulus. Polycrystalline novaculite quartz displays the a-b phase transition temperatures (T c ) around 8 C higher than seen in single crystal quartz, due to the pinning stress effect of grain boundaries. The properties of the sandstone vary with heating and cooling cycles as the cementation and microfracturing of the grain structure changes at high temperature. The phase transition in quartz is ferrobielastic, and as such energy differences between domains in the transformation microstructure arise under conditions of applied shear stress. Pre-transition softening and an increase in anelastic loss above T c are attributed to ferrobielastic switching of incipient domain microstructures that arise in the silica microstructure. The influence of temperature on this microstructure is to induce increased switching of domains as a response to thermal stress inherent in the anisotropic thermal expansion of the polycrystalline structure. These results indicate that ferrobielastic switching in quartz is an important mechanism in controlling changes in mechanical properties. As such, we anticipate that it will induce measurable anomalies in seismic signatures of quartz-rich portions of the Earth's crust in regions of high thermal flux. The transition may also be responsible for observed seismic velocity reductions and tectonic weakening in western North America and in certain parts of Tibetan plateau.

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“…'s at face value (Table 5, line 18). Among the powder diffraction refinements the largest difference is 0.0144(14) A observed by Nikitin, Markova, Balagurov, Vasin, and Alekseeva (2007), Table 6, line 58. The value of the "best" structure of low quartz at 291 K in Table 8 is close to the average of these two determinations.…”

Section: Amentioning

confidence: 89%

In search of the crystal structure of low quartz

Baur¹

2009

Zeitschrift Für Kristallographie

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A comparison of numerous determinations of unit cell dimensions and of crystal structure refinements of low quartz, SiO2, shows that there exists no study at a defined temperature and at ambient pressure of a chemically well characterized sample, for which we have precise unit cell lengths and at the same time positional coordinates of high precision for the silicon and oxygen atoms. An analysis of the available data from 18 carefully selected measurements of cell lengths and 25 determinations of positional coordinates results in an averaged structure at 291 K in space group P3121 with unit cell dimensions: a = 4.9130(1) Å, c = 5.4047(1) Å; and standardized coordinates: x(Si) = 0.5301(2), x(O) = 0.4139(5), y(O) = 0.1466(4) and z(O) = 0.1188(3); the silicon atom is in Wyckoff position 3a (x, 0, 1/3) and the oxygen atoms are in Wyckoff position 6c (x, y, z). Error estimates for cell dimensions and coordinates are taken as the mean of the observed e.s.d.‘s in the various original structure refinements. The bond lengths within one coordination tetrahedron are, twice each, Si–O,a 1.604(2) Å and Si–O,b 1.613(2) Å; the angles around the silicon atom are O,a–Si–O,a 109.0(1)°, O,b–Si–O,b 109.5(1)°, and twice each O,a–Si–O,b 110.4(1)° and O,b–Si–O,a 108.8(1)°; the Si–O–Si angle between two tetrahedra is 143.7(1)°. For the time being this is the best currently available estimate of the geometry of the crystal structure of low quartz.

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Investigation of the structure and properties of quartz in the α-β transition range by neutron diffraction and mechanical spectroscopy

Cited by 22 publications

References 13 publications

Anelasticity maps for acoustic dissipation associated with phase transitions in minerals

Anelasticity maps for acoustic dissipation associated with phase transitions in minerals

Mechanical properties of quartz at the α‐β phase transition: Implications for tectonic and seismic anomalies

In search of the crystal structure of low quartz

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