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Other Oxides (other + oxide)
Selected AbstractsAtomic Layer Deposition of High- k Oxides of the Group 4 Metals for Memory Applications,ADVANCED ENGINEERING MATERIALS, Issue 4 2009Jaakko Niinistö Abstract This paper reviews several high-k ALD processes potentially applicable to the production of capacitors, concentrating on very recent developments. A list of the dielectric materials under investigation consists of the oxides of several metals, including the Group 4 (Ti, Zr, Hf) elements. The binary oxides of Group 4 metals, as well as their mixtures with other oxides, doped hosts, or multi-layers in the form of nano-laminates are of interest.Several examples of our recent results are shown, including possible ALD routes to materials not previously grown, as well as advances in process development. [source] Dynamic Charge Equilibration-Morse stretch force field: Application to energetics of pure silica zeolitesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 16 2002Jan Sefcik Abstract We present the Dynamic Charge Equilibration (DQEq) method for a self-consistent treatment of charge transfer in force field modeling, where atomic charges are designed to reproduce electrostatic potentials calculated quantum mechanically. Force fields coupled with DQEq allow charges to readjust as geometry changes in classical simulations, using appropriate algorithms for periodic boundary conditions. The full electrostatic energy functional is used to derive the corresponding forces and the second derivatives (hessian) for vibrational calculations. Using DQEq electrostatics, we develop a simple nonbond force field for simulation of silica molecular sieves, where nonelectrostatic interactions are described by two-body Morse stretch terms. Energy minimization calculations with the new force field yield accurate unit cell geometries for siliceous zeolites. Relative enthalpies with respect to quartz and third-law entropies calculated from harmonic vibrational analysis agree very well with available calorimetric data: calculated SiO2 enthalpies relative to ,-quartz are within 2 kJ/mol and entropies at 298 K are within 3 J/mol K of the respective experimental values. Contributions from the zero point energy and vibrational degrees of freedom were found to be only about 1 kJ/mol for the free energy of mutual transformations between microporous silica polymorphs. The approach presented here can be applied to interfaces and other oxides as well and it is suitable for development of force fields for accurate modeling of geometry and energetics of microporous and mesoporous materials, while providing a realistic description of electrostatic fields near surfaces and inside pores of adsorbents and catalysts. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1507,1514, 2002 [source] Comment on "Orbital ordering and orbital fluctuations in transition metal oxides" [phys. stat. sol. (b) 236, No. 2, 281,288 (2003)]PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2005R. J. Radwanski Abstract We argue that the 3A2 state considered by Ole, in phys. stat. sol. (b) 236, 281 (2003) for the d2 system occurring in the V3+ ion in V2O3 and LaVO3 as well as in the Ti2+ ion in TiO and in many other oxides is wrong. The proper ground state is 3T1g , its 9-fold degeneracy is further split in a crystal by intra-atomic spin,orbit interactions and lattice distortions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Hydroxil ions in scheelite type molybdates and tungstatesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007L. Kovács Abstract The presence of hydroxil ions has been detected for the first time in as-grown scheelite type crystals. A number of stretching vibrational bands were observed in PbMoO4 and BaWO4 crystals at 8 K, while only very weak OH, absorption was found in CaMoO4, SrMoO4 and SrWO4 in the 3200,3600 cm,1 wavenumber range. The anharmonicity of the stretching modes for all bands in PbMoO4 and BaWO4 was found to be in agreement with that observed in other oxides. The model of weak coupling to a single phonon band was used to interpret the temperature dependence of the OH, band positions and halfwidths. Strong polarization dependence was observed for the OH, vibrations in both crystals indicating that the O,H dipoles incorporate the lattice along different O,O bonds. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||