Synthesis of mesoporous Si1−xGexO2 (0.10 ≤ x ≤ 0.31) using a nonionic block copolymer template

• Published in: Journal of materials chemistry Vol. 2; no. 38; pp. 8389 - 8393
• Main Authors: Szczech, Jeannine R, Lukowski, Mark A, Jin, Song
• Format: Journal Article
• Language: English
• Published: 01.01.2010
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/c0jm02057e

We have successfully synthesized mesoporous silica-germania mixed oxide (Si 1− x Ge x O 2 ) with x up to 0.31 by controlling the reaction to delay hydrolysis and condensation until the precursors have sufficiently ordered around the nonionic templating agent. Small-angle X-ray diffraction (SAXS) and transmission electron microscopy (TEM) reveal disordered worm-like mesopores for all germanium concentrations investigated, with pore periodicities of 9.8 and 10.5 nm for x 0.10 and 0.20 respectively. We confirm that the germanium and silicon are homogenous on the nanoscale using scanning transmission electron microscopy (STEM) with energy dispersive X-ray (EDX) mapping. Attempts to convert the mixed mesoporous oxides to mesoporous Si 1− x Ge x alloys via magnesiothermic reduction resulted in phase segregation. Mesoporous Si 1− x Ge x O 2 with x up to 0.31 has been synthesized using a nonionic block copolymer template. STEM analysis with EDX mapping definitively reveals for the first time that silicon and germanium are homogenous on the nanoscale when the hydrolysis reaction kinetics are carefully controlled.