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Preparation of Dense and Porous Silicon Oxycarbide Submicrometer‐Sized Spheres Using a Modified Stöber Process
Author(s) -
Dirè Sandra,
Tagliazucca Valeria,
Salvadori Livio,
Sorarù Gian Domenico
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2011.04732.x
Subject(s) - materials science , silsesquioxane , porosity , silicon , etching (microfabrication) , chemical engineering , porous silicon , ceramic , pyrolysis , spheres , sol gel , polymer , nanotechnology , composite material , optoelectronics , physics , layer (electronics) , astronomy , engineering
Dense and highly porous silicon oxycarbide ( Si–O–C ) submicrometer‐sized spheres, with diameters in the range 100–400 nm are synthesized through pyrolysis of sol–gel‐derived hybrid precursors. A modified Stöber process is used for the synthesis of silsesquioxane submicrometer‐sized particles from different organotriethoxysilanes RTES , R=CH 3 , C 5 H 11 , and C 6 H 5 . The hybrid particles are transformed into dense inorganic Si–O–C submicrometer‐sized spheres through a pyrolysis process in controlled atmosphere and the spherical morphology is kept provided that the glass transition temperature of the silsesquioxane network is higher than the onset of the polymer‐to‐ceramic transformation. The Si–O–C spheres are stable up to 1400°C. By HF etching the silica nanodomains present in the silicon oxycarbide structure, the dense Si–O–C particles can be further engineered and transformed into highly porous Si–O–C submicrometer‐sized spheres with specific surface area up to 564 m 2 g −1 and pore volume up to 0.7 cm 3 g −1 .