The structural science of functional materials

Abstract

The growing complexity of many classes of functional materials poses major challenges to structural science to which technical developments and the increasingly predictive power of computation make key contributions. These themes are clearly illustrated by the articles published in the field during the last year and especially by those in IUCrJ.An excellent illustration of the complexity of structural problem that is now being investigated in materials science is provided by the work of Zhang, Zhang et al. (2017), who examine the structural features of the martensitic transformation in Ni/Mn/Sb intermetallic compounds. The properties of such alloys are modified and can be optimized by the transformation, which alters the microstructure. The study uses scanning electron microscopy/electron back diffraction to chart the fascinating structural organizations that are induced, providing detailed structural models of these complex and intriguing transitions. The theme of phase transitions in intermetallics is also taken up in the paper of Li et al. (2018), who examine Mn/Co/Ni/Sn melt-spun ribbons and link phase behaviour to magneto-caloric properties; while the impact in this field of computation is apparent from the study of Wang et al. A field in which complexity has been long recognized is that of perovskite-structured materials, especially relating to the rich phase behaviour of compounds based on this versatile structural type. The lead zirconate/titanate solid solution (PZT) has been intensively studied over several decades, owing both to the subtlety of its structural properties and to the very wide ranging applications arising from its piezoelectric behaviour. New insight into structural changes and phase relations is provided by the study of Zhang, Yokota et al. (2017). Using a pair-distribution-function analysis based on neutron data, this paper shows how the local structure in PZT controls the long-range average structure across the so-called morphotropic phase boundary; and the analysis discovers a new monoclinic M C type structure. In addition, the role of polarization rotation in increasing the piezoelectric properties is analysed. Fig. 1 gives a diagrammatic illustration of the Pb polarization rotation paths that are revealed by the study.The paper represents a particularly elegant example of the elucidation of structureproperty relations in current materials science; while the continuing challenges posed by perovskite-structured materials is also illustrated in the work of Kang et al. (2017), which discovers new and unexpected spin configurations in magnetic phase transitions in Mndoped SmFeO 3 .The theme of structural changes during phase transitions again forms the basis of the work of Matvienko et al. (2017), which returns to structural changes during martensitic transitions and examines the role that optical microscopy can play in elucidating the mechanisms of transition by monitoring the interface migration and change in crystal shape during a transition. The approach is illustrated by the change...

Tuning gradient microstructures in immiscible polymer blends by viscosity ratio

“…The design of new functional materials often requires a precise control of the structure at different scales . In polymer blends, this task is quite challenging due to the complex relationships between their properties, microstructures, and processing conditions.…”