Disorder and Strain-Induced Complexity in Functional Materials
This book brings together an emerging consensus on our understanding of the complex functional materials including ferroics, perovskites, multiferroics, CMR and high-temperature superconductors. The common theme is the existence of many competing ground s
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Strain Glass and Strain Glass Transition Xiaobing Ren
Abstract Strain glass is a frozen disordered ferroelastic state with short-range strain order only. It is a conjugate state to the long-range ordered ferroelastic state or martensite. In this chapter, recent progress in strain glass and strain glass transition is reviewed. It is shown that a strain glass bears all the features of a glass, being parallel to other types of glasses such as relaxor ferroelectrics and cluster-spin glasses. Novel properties of strain glass are demonstrated. The origin of strain glass is discussed in terms of its relation to point defects. Finally, it is shown that the insight gained from strain glass may be able to solve a number of long-standing puzzles in ferroelastic community.
11.1 Disorder–Order and Disorder–Glass Transition in Nature: Anticipation of a Strain Glass Transition and Strain Glass All kinds of matter tend to take a more ordered form at low temperature to reduce entropy, as required by the third law of thermodynamics [1]. This thermodynamic requirement is the origin of a great variety of disorder-to-order transitions observed in nature. The most familiar example is the liquid-to-crystal transition, which is an ordering of atomic configuration. Ordering of other physical quantities is also well known, such as the ordering of magnetic moment, electric dipole, or lattice strain. The corresponding disorder–order transitions are ferromagnetic transition, ferroelectric transition, and ferroelastic/martensitic transition, respectively (Fig. 11.1, the left arrow). These transitions play a central role in structural and functional materials and are also an important subject in materials science and in physics [3].
X. Ren () Ferroic Physics Group, National Institute for Materials Science, Tsukuba, Japan e-mail: [email protected] T. Kakeshita et al. (eds.), Disorder and Strain-Induced Complexity in Functional Materials, Springer Series in Materials Science 148, DOI 10.1007/978-3-642-20943-7 11, © Springer-Verlag Berlin Heidelberg 2012
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Fig. 11.1 Two classes of phase transitions in nature: disorder–order and disorder–glass (frozen disorder) [2]
Contrary to the above disorder–order transitions, which are driven by a thermodynamic requirement to reduce entropy, there exists another large class of transitions – the “glass transitions”, where a disordered state is frozen into a statically disordered phase with local order only [4]. As the disordered glass state is not a favorable low-temperature state (i.e., low entropy state) from a thermodynamic consideration, disorder–glass transition is not a thermodynamic transition and it cannot be understood from thermodynamic principles. Disorder–glass transitions are conjugate transitions of their corresponding disorder–order transitions, as shown in Fig. 11.1 (the right arrow). They are often formed by doping point defects into a system showing normal disorder– order transition. The most familiar disorder–glass transition is the structural glass transition, whi
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