Neutron Studies of Pretransitional Fluctuations Above Structural Transitions in Metals

Moss, S. C.

doi:10.1051/jphyscol:1977787

Cited by 5 publications

(2 citation statements)

References 15 publications

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“…Static adaptive states are known to be stable only over a narrow temperature range near the transformation temperature. It should be noted, however, that a strain or quadrupolar glass condition consisting of nanoregions of martensite has been reported to remain frozen to much lower temperatures for some of these alloys with high concentrations of defects [100][101][102], as originally conjectured by Sethna and Krumhansl [108]. In fact, they may be rather common, as there seems to be some development of shape anisotropy in the nanoregion morphology, suggesting the onset of tweed-like characteristics [110,169].…”

Section: How Might the Twin Wall Energy Be Significantly Decreased?mentioning

confidence: 96%

“…Early structural investigations of martensitic phase transformations have revealed a pretransitory phenomenon sandwiched between the high-temperature austenite and low-temperature martensite phase regions over a narrow temperature range near the transition temperature [100][101][102][103]. Electron microscopy indicated the presence of elastic tweed precursors, as illustrated in Figure 18 [102].…”

Section: Tweed Structure and Strain/orientational Glass-like Systemsmentioning

confidence: 99%

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Domain boundary-dominated systems: adaptive structures and functional twin boundaries

Viehland

Salje

2014

Advances in Physics

111

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Domain boundaries typically constitute only a minute fraction of the total volume of a crystal. However, a special (but not unusual) situation can occur in which the domain boundary energy becomes very small. Specifically, the domain size is miniaturized to near-atomic scales and the domain boundary density becomes extremely high. In such cases, the properties of the crystal become dominated by a combination of both the domains and the domain boundaries. This phenomenon differs from most ferromagnetic or ferroelectric materials wherein the motion of the domain boundaries dominates the response. As reported herein, novel emergent phenomena that differ from the properties of either the domains or the domain boundaries may be expected. In this article, we focus on one specific state found in ferroic materials -namely, the adaptive ferroic state. This state can be found, for example, in tweed-like structures in morphotropic phase boundary piezoelectric crystals, ferromagnetic shape memory alloys, and pre-martensitic states. In these materials, the properties of the twin boundaries represent the principal contributors to the functionality of a given system. In fact, further investigations of domain boundary-dominated phenomena could result in novel potential for tailoring functional properties for a desired outcome. It should also be noted that new properties can be designed into twin boundaries that are not the properties of the domains. In this paper, adaptive structures and functional twin boundaries are reviewed, and examples of various observed functionalities (e.g. superconductivity, polarity, and ferroelectricity) and corresponding twin boundary structures are provided. In addition, this review confirms that various theoretically predicted, structurally bridging low-symmetry phases do, in fact, exist. Moreover, the values of the lattice constants of the adaptive state are adjustable parameters that are determined by combinations of cubic, rhombohedral/tetragonal phases, and geometrical invariant conditions. Finally, we show that, in such cases, macroscopic properties are controlled by the unique functionality of the twin walls. Looking forward, domain boundary-dominated phenomena offer an important approach for enhancing the properties of the bulk, and to unique local properties where the "twin is the device". We encourage the community to rethink their approaches to materials by design that have treated the structure as homogeneous and to consider the alternative paradigm where the local structure is different from the apparent average symmetry. PACS: 77 Dielectrics piezoelectrics and ferroelectrics; 64 Equations of state, phase equilibria, and phase transitions; 73 Electronic structure and electrical properties of surfaces, interfaces, thin films, and lowdimensional structures

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Section: How Might the Twin Wall Energy Be Significantly Decreased?mentioning

confidence: 96%

Section: Tweed Structure and Strain/orientational Glass-like Systemsmentioning

confidence: 99%

Domain boundary-dominated systems: adaptive structures and functional twin boundaries

Viehland

Salje

2014

Advances in Physics

111

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High damping of inhomogeneous ferroics

Wuttig

2003

Journal of Alloys and Compounds

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Effects of quenched disorder on La-modified lead zirconate titanate: Long- and short-range ordered structurally incommensurate phases, and glassy polar clusters

Viehland

Dai

et al. 1998

Journal of Applied Physics

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Structure–property relationship studies have been performed in the La-modified lead zirconate titanate (PLZT) solution as a function of quenched La impurity content and Zr/Ti ratio by transmission electron microscopy, lattice imaging, and dielectric spectroscopy. Investigations were performed for 65/35⩽Zr/Ti⩽90/10. These investigations have demonstrated a general trend in domain structure and polar order with increasing quenched impurity concentration. For Zr/Ti ratios of 90/10 and 85/15, a structurally incommensurate antiferroelectric (AFEin) state was found to be stabilized with increasing La. Temperature dependent investigations demonstrated that the incommensurate structure becomes pinned into long-time metastable states, rather than transforming to a commensurate phase. Also, the modulation wavelength (λ) was found to increase significantly with increasing Ti. When λ increased to ∼40 Å, polar clusters began to condense from the AFEin order. For Zr/Ti ratios of 80/20 and 65/35, increasing quenched disorder was found to result in the evolution of polar order through a common sequence of domainlike states including polar clusters, tweedlike structures, and normal micron-sized polydomain structures. These results, in conjunction with dielectric spectroscopy, demonstrate a crossover between a long-period incommensurately modulated state and a relaxor ferroelectric state with increasing quenched disorder. Clearly, both quenched disorder (i.e., random fields) and competing polar orderings (i.e., frustration) underlay the unique behaviors of PLZT.

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Neutron Studies of Pretransitional Fluctuations Above Structural Transitions in Metals

Cited by 5 publications

References 15 publications

Domain boundary-dominated systems: adaptive structures and functional twin boundaries

Domain boundary-dominated systems: adaptive structures and functional twin boundaries

High damping of inhomogeneous ferroics

Effects of quenched disorder on La-modified lead zirconate titanate: Long- and short-range ordered structurally incommensurate phases, and glassy polar clusters

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