Polycrystalline superlattices

This work was followed by a number of researchers who confirmed the experimental results on various metallic multilayer systems (e.g. Cu/Ni [78-80] as well as on hard epitaxial and polycrystalline superlattices of nitrides, such as TiN/VN... 

Iodine oxidation of Ni(OEP) and Cu(OEP) yields polycrystalline materials with a range of stoichiometries.108 Resonance Raman studies indicate the presence of I5- in contrast to the I3 observed for larger ring macrocycles. Single crystal studies of Ni(TMP)I indicate a metal-over-metal stack arrangement but with the Ni(TMP) unit puckered. The iodine superlattice is incommensurate with the Bragg lattice.107 The room temperature conductivity is 10 Q-1 cm-1 and increases on lowering the temperature to reach a rounded maximum at 115 K. The spin susceptibility is temperature independent down to a transition temperature of 28 K, well below the conductivity maximum. Below 28 K the susceptibility decreases in an activated fashion with Ajk 60 K.108... 

Wang, Y.Y., Wong, M.S., Chia, W.J., Rechner, J. and Sproul, W.D. (1998), Synthesis and characterization of highly textured polycrystalline AlN/TiN superlattice coatings , Journal of Vacuum Science and Technology A, 16, 3341-3347. 

Yashar, P.C. and Barnett, S.A. (1999), Deposition and mechanical properties of polycrystalline Y203/Zr02 superlattices , Journal of Materials Research, 14, 3614— 3622. 

Unlike the main minerals with the rock salt structure, fluorite cleaves on 111 planes and slips on 100 in the (0 11 direction [189]. Above 200 °C, slip on jl 10 (11 0) is also possible. Above 320 °C, polycrystalline plasticity is observed with the [10 0 planes providing three independent slip systems and the 110 planes giving two more [190]. Dislocations in fluorite have been studied by etch-pitting methods, and by TEM [191] but the latter is not without difficulty, since the mineral rapidly damages under electron and ion irradiation. A cubic symmetry void superlattice can be formed in TEM if the radiation flux is not restricted [192]. 

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