Acoustic attenuation due to transformation twins in CaCl2: Analogue behaviour for stishovite

Zhang, Zhiying; Schranz, W.; Carpenter, Michael A.

doi:10.1016/j.pepi.2012.07.004

Cited by 4 publications

(3 citation statements)

References 106 publications

(145 reference statements)

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“…In CaCl 2 and CaBr 2 this gives rise to a tetragonal (P4 2 /mnm) ↔ orthorhombic (Pnnm) transition as a function of temperature [28][29][30][31][32], while the same transition occurs in MgF 2 as a function of pressure [33]. The transition in CaCl 2 has changes in elastic properties which match those expected for a pseudoproper ferroelastic transition [34], such as have been investigated more extensively for the equivalent transition in stishovite, SiO 2 [35][36][37][38][39][40][41]. As shown below, however, there does not seem to be any overt evidence for the influence of this transition on the evolution of elastic properties through T N in CoF 2 .…”

Section: Introductionmentioning

confidence: 69%

CoF₂: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions

Thomson

Chatterji

Carpenter

2014

J. Phys.: Condens. Matter

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Resonant ultrasound spectroscopy has been used to monitor variations in the elastic and anelastic behaviour of polycrystalline CoF2 through the temperature interval 10-290 K and in the frequency range ∼0.4-2 MHz. Marked softening, particularly of the shear modulus, and a peak in attenuation occur as the Néel point (TN=39 K) is approached from both high and low temperatures. Although the effective thermodynamic behaviour can be represented semiquantitatively with a Bragg-Williams model for a system with spin 1/2, the magnetoelastic coupling follows a pattern which is closely analogous to that of a Landau tricritical transition which is co-elastic in character. Analysis of lattice parameter data from the literature confirms that linear spontaneous strains scale with the square of the magnetic order parameter and combine to give effective shear and volume strains on the order of 1‰. Softening of the shear modulus at T>TN is attributed to coupling of acoustic modes with dynamical local ordering of spins and can be represented by a Vogel-Fulcher expression. At T

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Section: Introductionmentioning

confidence: 69%

CoF₂: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions

Thomson

Chatterji

Carpenter

2014

J. Phys.: Condens. Matter

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“…Its application to twins in minerals is far too extensive to be reviewed; here, the reader is referred to the excellent review by Carpenter and Zhang [93], which covers several minerals. Specific examples were discussed [94][95][96][97][98][99]. The underlying mechanisms of these dynamic phenomena of twins were computer simulated [100][101][102] and they show a multitude of mechanisms like the progression and retraction of needles, wall arching and shifts of wall defects [100][101][102][103].…”

Section: Topological Changes Of Twin Walls: Kinks and Surface Intersectionsmentioning

confidence: 99%

Ferroelastic Twinning in Minerals: A Source of Trace Elements, Conductivity, and Unexpected Piezoelectricity

Salje

2021

Minerals

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Ferroelastic twinning in minerals is a very common phenomenon. The twin laws follow simple symmetry rules and they are observed in minerals, like feldspar, palmierite, leucite, perovskite, and so forth. The major discovery over the last two decades was that the thin areas between the twins yield characteristic physical and chemical properties, but not the twins themselves. Research greatly focusses on these twin walls (or ‘twin boundaries’); therefore, because they possess different crystal structures and generate a large variety of ‘emerging’ properties. Research on wall properties has largely overshadowed research on twin domains. Some wall properties are discussed in this short review, such as their ability for chemical storage, and their structural deformations that generate polarity and piezoelectricity inside the walls, while none of these effects exist in the adjacent domains. Walls contain topological defects, like kinks, and they are strong enough to deform surface regions. These effects have triggered major research initiatives that go well beyond the realm of mineralogy and crystallography. Future work is expected to discover other twin configurations, such as co-elastic twins in quartz and growth twins in other minerals.

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Section: Topological Changes Of Twin Walls: Kinks and Surface Interse...mentioning

confidence: 99%

Modularity and Twinning in Mineral Crystal Structures

2021

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In 2004, the book Crystallography of Modular Materials (IUCr/Oxford University Press) by G.Ferraris, E. Makovicky and S. Merlino (2nd edition 2008) systematically reviewed theory and examples of mineral crystal structures that can be described as built up by periodic repetition at the atomic scale of either one (planar) module (polytypes) or more modules-m1, m2, . . . mn-with different compositions (polysomes). Whereas a series of polytypes, being based on the same module, essentially show a constant chemical composition, the members of a polysomatic series have different chemical compositions that depend on the m1/m2. . . /mn ratio. In a polysomatic series, the physical properties are a function of the chemistry of the modules and of their piling; thus, tailoring of the properties is possible. A special class of polytypes is rationalized by the so-called OD (Order/Disorder) theory. Twinning, i.e., the oriented association of two or more individuals of the same crystalline compound, is considered a modular structure at the macroscopic scale. The members of a series of polytypes or of polysomes usually have in common a supercell that, according to the reticular theory of twinning, favours the formation of twins.

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Acoustic attenuation due to transformation twins in CaCl2: Analogue behaviour for stishovite

Cited by 4 publications

References 106 publications

CoF₂: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions

CoF₂: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions

Ferroelastic Twinning in Minerals: A Source of Trace Elements, Conductivity, and Unexpected Piezoelectricity

Modularity and Twinning in Mineral Crystal Structures

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Acoustic attenuation due to transformation twins in CaCl2: Analogue behaviour for stishovite

Cited by 4 publications

References 106 publications

CoF2: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions

CoF2: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions

Ferroelastic Twinning in Minerals: A Source of Trace Elements, Conductivity, and Unexpected Piezoelectricity

Modularity and Twinning in Mineral Crystal Structures

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Product

Resources

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CoF₂: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions

CoF₂: a model system for magnetoelastic coupling and elastic softening mechanisms associated with paramagnetic ↔ antiferromagnetic phase transitions