I am working on cerium doped SrTiO3 system. But the problem which I facing is the formation of major second phase CeO2. How can I control this problem? Although I calcined and sinter the system in the reduce air furnace in the temperature range from 1150C to 1350C.
Hi
please see this paper:
http://digital.csic.es/bitstream/10261/74571/1/All%20chemical.pdf
Are you sure that this kind of doping is possible from radius point of view? You can start reading the literature on the same topic or if you performed a published synthesis you can ask for advice to the corresponding author.
Respected Marcella Bini,
The ionic radii of Sr2+ is (1.44A or 0.144nm) while that of cerium Ce 3+(III) (1.34 A˚, 0.134nm) Ce4+ (0.087nm ) and Ti+4 (0.0605nm).
For x=.1, .2 and .3, its give the formation of solid solution, which conform that their ionic radii are comparable. But for doping above 0.3 there is major CeO2 Second phase which may due to the formation of grain boundaries. Dopant Ce ions with a small radius may form the core-shell-structured fine grains and thus the secondary phase CeO2 appears because of the segregation of small ions in the grain boundary regions, which decreased the solubility of Ce ions in Sr TiO3.
My question is that how we can control the formation of Ceo2 phase, although I sinter my sample in reducing air furnace, oxygen and nitrogen atmosphere furnace.
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