Porous CeOX/SiC nanocomposites prepared from reverse polycarbosilane-based microemulsions
Publikation: Beitrag in Fachzeitschrift › Forschungsartikel › Beigetragen › Begutachtung
Beitragende
Abstract
Reverse microemulsions consisting of aqueous cerium nitrate solution as the internal phase and polycarbosilane dissolved in heptane as the continuous phase were used as a precursor for the controlled synthesis of dispersed cerium oxide particles inside a porous SiC matrix. According to dynamic light scattering experiments, the effective diameter of the cerium hydroxide particles obtained after ammonia addition is effectively controlled in a range of 2-10 nm with the molar water/surfactant ratio (Rw = 6-16). Pyrolysis at 1200 to 1500°C produces materials with specific surface areas up to 240 m 2 g-1. Whereas crystallization of the matrix is achieved only at higher temperature, cerium oxide particles form agglomerates composed of smaller nanoparticles that tend to dissolve into the ceramic matrix at 1500°C leaving macropores behind. The high specific surface area is attributed to the presence of mesopores with a broad size distribution. Excess carbon present after pyrolysis is removed by oxidation at 900°C causing a significant decrease of the surface area for high surface area materials, whereas intermediate surface area materials (50-100 m2 g -1) show a high textural stability.
Details
Originalsprache | Englisch |
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Seiten (von - bis) | 77-83 |
Seitenumfang | 7 |
Fachzeitschrift | Chemistry of materials |
Jahrgang | 20 |
Ausgabenummer | 1 |
Publikationsstatus | Veröffentlicht - 8 Jan. 2008 |
Peer-Review-Status | Ja |