Dear Colleagues,

Twinning and related crystallographic transformations have always been an exciting subject for mineralogists and materials scientists. Range of conditions trigger twinning of crystals—from mechanical deformation, phase transformation, chemical stabilization to topotaxial replacement and self-assembly. While the formation mechanisms of deformation and transformation twins are well understood, there are many open questions related to the formation of growth twins, often attributed to accidental attachment during crystal growth. Recent advances in electron microscopy methods and theoretical modeling that allow studying the local structure and chemistry of twin boundaries at the atomic scale have provided a unique opportunity to resolve questions related to twin boundary structure, their thermodynamic stability, mechanisms that trigger their formation, and often, an orchestrated assembly of twin-based modulated structures.

The Special Issue invites contributions addressing fundamentals of twinning, their crystallography, twin operators, experimental atomic-scale and first principles theoretical studies of twin boundary structure and chemistry, including investigations dealing with the formation and growth of twins in diverse materials. Original studies, as well as comprehensive review papers, from earliest investigations to the latest insights into the specific topics of this Special Issue, are welcome.

Prof. Dr. Aleksander Recnik
Assist. Prof. Dr. Nina Daneu
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• crystallography of twinned crystals
• mechanical twinning
• twinning and polytypism
• tropochemical twinning
• twining through self-assembly
• growth of twinned crystals
• ab-initio calculations
• stability of twinned crystals.