Exploration of new superconductors and functional materials, and fabrication of superconducting tapes and wires of iron pnictides

Here, we review the history, theory, measurement technique and experimental results on gyrotropic phenomena including optical rotation (optical activity), electrogyration, the Faraday effect and magneto-electrogyration in transparent crystals, including examples of structural phase transitions. Relations to the absolute structure are discussed and model calculations are performed on the basis of electronic polarizability and crystal structure.

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Experimental and phenomenological aspects of circular birefringence and related properties in transparent crystals

For several decades the lattice periodicity of crystals, as shown by Laue, was considered to be their essential property. In the early sixties of the last century compounds were found which for many reasons should be called crystals, but were not lattice periodic. This opened the field of aperiodic crystals. An overview of this development is given. Many materials of this kind were found, sometimes with very interesting properties. In the beginning the development was slow, but the number of structures of this type increased enormously. In the meantime hundreds of scientists have contributed to this field using a multi-disciplinary approach.

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Aperiodic crystals and superspace concepts

Synthesis and characterization of 2D transition metal dichalcogenides: Recent progress from a vacuum surface science perspective

Through the years, mineralogical studies have produced a tremendous amount of data on the atomic arrangement and mineral properties. Quite often, structural analysis has led to elucidate the role played by minor components, giving interesting insights into the physico-chemical conditions of mineral crystallization and allowing the description of unpredictable structures that represented a body of knowledge critical for assessing their technological potentialities. Using such a rich database, containing many basic acquisitions, further steps became appropriate and possible, into the directions of more advanced knowledge frontiers. Some of these frontiers assume the name of modularity, complexity, aperiodicity, and matter organization at not conventional levels, and will be discussed in this review.

https://hal.univ-lorraine.fr/hal-02933187/document

Producing highly complicated materials. Nature does it better

The anomalous high-index faces (hkl) of the mineral calaverite (Au1 - xAgxTe2) measured goniometrically in the year 1931 by Goldschmidt, Palache & Peacock [Neues Jahrb. Mineral (1931), 63, 1-58] are re-interpreted and related to the wave vector q of the displacive incommensurate modulation which was recently found in the crystal structure. All crystal faces (including the high-index ones) can be given four low indices (hklm), using q as a fourth basis vector. From this an almost hundred-year-old anomaly in crystal morphology is in principle solved.

A. Janner

Papers

The morphology of calaverite (AuTe2) from data of 1931. Solution of an old problem of rational indices