Regensburg 2016 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 35: Thin Film Characterisation: Structure Analysis and Composition II

DS 35.1: Vortrag

Mittwoch, 9. März 2016, 15:00–15:15, H8

Transrotational microcrystals: novel solid state order formed in amorphous films — •Vladimir Yu. Kolosov — Ural Federal University, Ekaterinburg, Russia

Exotic thin crystals with unexpected transrotational microstructures [1] have been discovered by transmission electron microscopy (TEM) for crystal growth in thin (10-100 nm) amorphous films of different chemical nature (oxides, chalcogenides, metals and alloys) prepared by various methods. Primarily we use TEM bend contour technique for crystallographic orientation analysis [2]. The unusual phenomenon can be observed in situ in TEM column: dislocation independent regular internal bending of crystal lattice planes in a growing crystal. Such transrotation (unit cell translation is complicated by small rotation realized round an axis lying in the film plane) results in strong regular lattice orientation gradients (up to 300 degrees per micrometer) of different geometries: cylindrical, ellipsoidal, toroidal, saddle, etc. Transrotation is strongly increasing as the film gets thinner. Transrotational crystal resembles ideal single crystal enclosed in a curved space. Transrotational micro crystals have been eventually recognized by other authors for some vital thin film materials, i.e. PCMs (phase-chage materials) for memory, silicides, SrTiO3. Atomic model and possible mechanisms of the phenomenon are discussed.

Basing on the above findings we also propose new hypothetic transrotational nanocrystalline model of amorphous state.

[1] V.Yu. Kolosov and A.R.Tholen, Acta Mater., 48 (2000) 1829.

[2] I. E. Bolotov and V. Yu. Kolosov, Phys. Stat. Sol. 69a (1982) 85.