| Autor: |
Horng-Yi Chang, Syh-Yuh Cheng, Ching-Iuan Sheu and Yi-Hui Wang |
| Předmět: |
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| Zdroj: |
Nanotechnology; 6/1/2003, Vol. 14 Issue 6, p603-608, 6p |
| Abstrakt: |
A perovskite shell of strontium titanate (SrTiO3) has been successfully self-grown on the surface of a titanium (Ti) particle by a hydrothermal process using Sr(OH)2·8H2O and Ti powder with or without alkaline (NaOH) solution at a temperature of 150200°C for 3 h. The obtained strontium titanate (ST) shell contained spherical grains. The shells’ crystallinity, thickness and grain size increased with an increase in the hydrothermal growth temperature. The obtained shell grain size was estimated by transmission electron microscopy to be in the range 50120 nm. The thickness of the spherical grain shell was about 400 nm for 3 h hydrothermal growth at 180°C and 600 nm for 3 h at 200°C. There was a transition zone of about 200 nm between the ST shell and the Ti core. The results are ascribed to diffusion of the Sr ions through the shell into the core to react with dissolved Ti ions in an oxygen-deficient environment. The self-grown STTi was annealed in air after sintering at 1350°C in a reducing C/CO atmosphere. This produced a coreshell structure with an ST grain boundary barrier layer. The sintered and annealed body exhibited the good nonlinear resistance properties of a varistor. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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