Structural and luminescent properties of terbium doped strontium titanate xerogel
We report on synthesis and photoluminescence of sol-gel derived terbium doped strontium titanate on monocrystalline silicon and in the porous anodic alumina matrix. The microstructure and morphology of the samples are analyzed by X-ray diffraction and scanning electron microscope analyses. The thickness of the spin-on films deposited on silicon is about 115 and 170 nm due to the annealing temperature 750 and 1000 °C respectively. The samples reveal terbium luminescence in the visible range.
Characteristics of post-annealed SrTiO3 thin films prepared by mirror-confinement-type ECR plasma sputtering
Abstract SrTiO3 films were synthesized on Pt/Ti/SiO2/Si multilayer substrates by mirror-confinement-type ECR plasma sputtering without substrate heating. All films were found to be well crystallized at a substrate temperature below 450 K. A low temperature post-annealing of the films by electromagnetic-wave radiation drastically improved the crystallographic and electric properties of Pt/SrTiO3/Pt/Ti/SiO2/Si capacitors. The crystallinity of the films indicated little variation by post-annealing, but irradiation of electromagnetic wave was confirmed to be effective for decreasing the post-annealing time and temperature. The electric properties of films annealed without Pt upper electrodes were better than those with them, and the film dielectric constant reached a value of 260, which is nearly equal to thebulk one, at an annealing temperature of 573 K.
Control of the homopause level
Abstract This paper reviews the hypothesis that internal gravity wave breaking in the factor responsible for upper atmosphere turbulence generation and control of the number density at the homopause level. Available data from Mars and Earth support the hypothesis, originally introduced by Lindzen, that breaking thermal tides are responsible for the necessary turbulence. The lowest-order, equatorially trapped, westward-propagating diurnal tidal mode is the primary cause on the Earth, and lower-order westward-propagating semidiurnal modes are the primary cause on Mars. The frequencies and vertical wavenumbers of the responsible modes determine the eddy diffusion coefficients; energy density is only indirectly involved by determining which modes can break. A general scale relationship between tidal heating and velocity amplitude can be used to assess the breaking potential of tidal modes, and is used here as the basis for arguing that the number density at the Martian homopause is likely to have been stable over much of geologic time. Difficulties with this approach arise in the cases of Venus and Titan because of their peculiar zonal winds. For Jupiter and Saturn, internal gravity waves generated by nontidal mechanisms probably control the homopause.