Nano sized Pd particles in A SiO2 matrix by sol-gel processing

Abstract

Pd colloid containing Ormocers (ORganically MOdified CERamic) have been prepared from Pd amino complexes of the type Pd[NH2CH2CH2NH(CH2)3Si(OMe)3]2ac2 by hydrolysis and condensation (sol-gel reaction) of the silane together with SI(OEt)4 and Si(OEt)3(CH2)3OCH2CHCH2O. The amino complex formation is necessary to avoid spontaneous reduction and uncontrolled colloid formations in the liquid phase. This synthesis route leads to Pd colloid containing powders and coatings on glass. By thermal curing (temperatures up to 500°C) using different atmoshperic conditions (N2, Ar, H2/N2) brown to deep black coatings on glass with transmission values from 80 to 0% can be obtained. The average particle size can be controlled by varying the molar ratio of the used Pd salt (Pd(ac)2) and the aminosilane.