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Defects in crystal structure of layered material can modify the surface states. Ion bombardment is a simple way to introduce defects into a crystal lattice in the surface region. Comprehensive scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and photoemission studies are presented to uncover the impact of ion etching and thermal annealing on the atomic and electronic structure of Sb(1 1 1) surface. We reveal the unusual behavior of the Sb(1 1 1) surface after Ar+ sputtering at 300 K (RT). The 3 nm-sized terraces formed even after a prolonged ion bombardment are established by LEED. Also, an increase in density of states (DOS) at the Fermi edge is detected for the etched Sb(1 1 1) surface due to the ruptured covalent bonds (CBs).

Two new isostructural mixed-valent tellurium oxides, CsTeMoO6 (1) and RbTe1.25Mo0.75O6 (2), have been synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction and thermal analysis. Both compounds have pyrochlore-type structure with cubic space group Fd 3 ¯ m , Z = 8 and the following unit cell parameters: a = 10.5892(5) A in CsTeMoO6 and a = 10.4421(2) A in RbTe1.25Mo0.75O6. A small part of the oxygen atoms shifts from the special position 48f to the general crystallographic position 192i, because the Te4+ ion is too large for the regular pyrochlore-structure framework and causes local distortions. The thermal instability of the CsTeMoO6 and RbTe1.25Mo0.75O6 phases was found at the 449–521 °С and 381–466 °С temperatures ranges, respectively.

Due to a strong spin-orbit interaction (SOI), the surface states of Sb (111) are similar to those for topological insulators (TI) Sugawara et al. (2006). The surface states are protected by time-reversal symmetry and energy dispersion is a linear function of momentum. Defects in crystal structure lead to a local break of the surface translational symmetry and can modify surface states. It is the primary reason to study defects of Sb crystal structure and their effect on the surface states dispersion. Etching of the Sb (111) surface using Ar + ions is a common way to create defects both in a bulk and on the surface of the crystal. Sb (111) ion etching at room temperature reveals anomalous behavior of surface crystal structure. It results in formation of flat terraces of 2 nm in size. Investigation of electronic structure of the etched Sb (111) surface has demonstrated increase of density of states (DOS) at the Fermi level. The results are discussed in terms of local break of conditions of Peierls transition.

The microstructure and hardness of binary Al–Zn and Al–Mg alloys were studied both in the as-cast state and after high-pressure torsion (HPT) with 5 torsions (shear strain about 6). The size of (Al) grains and of reinforcing second-phase precipitates decreases drastically after HPT and reaches the nanometre range. During HPT, the Zn-rich supersaturated (Al) solid solution decomposes and closely approaches the equilibrium state corresponding to room temperature. The decomposition of Mg-rich supersaturated (Al) solid solution is less pronounced. In the as-cast state the hardness of the supersaturated solid solutions increases with increasing Zn and Mg content due to solid-solution hardening. However, after HPT the work hardening and Hall–Petch hardening due to the decreasing grain size compete with softening due to the decomposition of a supersaturated solid solution. As a net effect, severe plastic deformation results in softening of the binary Al–Zn and Al–Mg alloys. Softening is more pronounced in the Al–Zn alloys where HPT leads to almost full decomposition of the supersaturated solid solution.

The results of an investigation of the steady-state motion of grain boundary systems with triple junctions in high-purity aluminum are presented. In particular, the migration of systems with 111> and 110> tilt boundaries was studied. The experimental results demonstrate that the motion of grain boundary systems with triple junctions in aluminum can be controlled by slowly moving triple junctions. The influence of triple junctions depends on temperature, and it is particularly strong at low temperatures. In the high- temperature regime the motion of a connected grain boundary system is less affected by the triple junction, and, therefore, effectively controlled by the grain boundary mobility. The experiments reveal a drastic differ- ence between activation enthalpy of grain boundary and triple junction motion. Therefore, there is a tempera- ture below which triple junctions govern the motion of the connected boundary system. This temperature was found to depend on the particular grain boundary and triple junction geometry.  2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.