Search results for "Ionic crystal"
showing 7 items of 7 documents
Ab initioand semiempirical calculations ofH−centers in MgO crystals
1999
The atomic and electronic structure of ${\mathrm{H}}^{\ensuremath{-}}$ ions substituting for ${\mathrm{O}}^{2\ensuremath{-}}$ ions in regular sites in MgO crystals are calculated using an ab initio Hartree-Fock (HF) cluster approach and its semiempirical version, intermediate neglect of the differential overlap. The theoretical optical absorption energy is predicted to be 10 eV, which is supported by analysis of experimental data for the ${\mathrm{H}}^{\ensuremath{-}}$ centers in a series of ionic crystals. The HF simulations of ${\mathrm{H}}^{\ensuremath{-}}$ ion diffusion via direct interstitial hops along the [100] axis predict an activation energy of about 3 eV.
Second-layer induced island morphologies in thin-film growth of fullerenes.
2011
Deposition of fullerenes on the CaF(2)(111) surface yields peculiar island morphologies with close similarities to previous findings for (100) surfaces of other ionic crystals. By means of noncontact atomic force microscopy we find a smooth transition from compact, triangular islands to branched hexagonal islands upon lowering the temperature. While triangular islands are two monolayers high, hexagonal islands have a base of one monolayer and exhibit a complicated structure with a second-layer outer rim and trenches oriented towards the interior. By developing a kinetic growth model we unravel the microscopic mechanisms of the structure formation.
Magneto-optical Investigations of Nanostructured Materials Based on Single Molecule Magnets Monitor Strong Environmental Effects
2007
The determination of the magnetic properties of molecular magnets in environments similar to those used in spintronic devices is fundamental for the development of applications. Single-molecule magnets (SMMs) are molecular cluster systems that display magnetic hysteresis of dynamical origin at low temperature. As they behave like perfectly monodisperse nanomagnets and show clear macroscopic quantum effects in their magnetic properties, they are extremely appealing candidates for the forthcoming generation of molecular devices: they have been proposed as efficient systems for quantum computation, ultra-high-density magnetic recording media, and molecular spintronic systems. These attractive …
A mesoscopic approach to radiation-induced defect aggregation in alkali halides stimulated by the elastic interaction of mobile Frenkel defects
1994
The radiation-induced aggregation of Frenkel defects in alkali halides is studied in terms of a mesoscopic approach. The asymmetry in elastic interactions between mobile interstitials (I–I) and bet...
Роль туннелирования в процессах накопления радиационных дефектов и в теории диффузионно-контролируемых реакций
1975
Advisor: Тале, Иварс