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Stochastic polarity formation in molecular crystals, composite materials and natural tissues

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Hulliger Jürg, Burgener Matthias, Hesterberg Rolf, Sommer Martin, Brahimi Khadidja, Aboulfadl Hanane,
Project Polaritätsbildung in molekularen Kristallen, natürlichem Gewebe und biomimetischen Materialien
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Original article (peer-reviewed)

Journal IUCrJ
Volume (Issue) 4(4)
Page(s) 360 - 368
Title of proceedings IUCrJ
DOI 10.1107/s205225251700700x

Open Access

URL http://doi.org/10.1107/S205225251700700X
Type of Open Access Publisher (Gold Open Access)

Abstract

This topical review summarizes the theoretical and experimental findings obtained over the last 20 years on the subject of growth-induced polarity formation driven by a Markov chain process. When entering the growing surface of a molecular crystal, an inorganic–organic composite or a natural tissue, the building blocks may undergo 180° orientational disorder. Driven by configurational entropy, faulted orientations can promote the conversion of a growing non-polar seed into an object showing polar domains. Similarly, orientational disorder at the interface may change a polar seed into a two-domain state. Analytical theory and Monte Carlo simulations were used to model polarity formation. Scanning pyroelectric, piezoresponse force and phase-sensitive second-harmonic microscopies are methods for investigating the spatial distribution of polarity. Summarizing results from different types of materials, a general principle is provided for obtaining growth-induced polar domains: a non-zero difference in the probabilities for 180° orientational misalignments of building blocks, together with uni-directional growth, along with Markov chain theory, can produce objects showing polar domains.
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