Surface segregation of transition metals in sol-gel silica films

Abstract

Silica sol-gel films (SGFs) doped with various transition metals derived by spin-coating on glass substrates and silicon wafers have been studied. Precursor solutions were prepared by mixing tetraethylorthosilicate, ethanol, water and nitrates of the transition metals (Cr, Mn, Fe, Co, Ni and Cu) using HCl as a catalyst. Remarkable segregation of metals at the surface was observed for films doped with Cu and Co. For Mn- and Ni-doped films this effect was much less, and it vanished for the films doped with Cr or Fe. The influence of boron and phosphorus upon the chemical state and the distribution of metal atoms was also analysed. The structure, optical properties and composition of the SGFs were studied and some pathways to control the dopant segregation effect were realized.

Nanostructure characterization of Co–Pd–Si–O soft magnetic nanogranular film using small-angle X-ray and neutronscattering

“…The existence of B particles provide possible effects of a surface and an interface between the substrate and the film. In previous studies, anomalous segregation and growth of Co particles in silica matrix around surface or interface have often been reported [29][30][31]. Another review also pointed out that those segregation and particle growth result in the broadening of size and shape distributions [32].…”

Functionalisation of textiles by inorganic sol–gel coatings

“…Physical modification of the oxide matrix is a universal method of preparing coatings with immobilised additives (Ad) such as inorganic colloidal metals, [27][28][29][30] oxides 31 and pigments, 32 dyes, [33][34][35][36] organic polymers, [37][38][39] or biomolecules. [40][41][42][43][44][45][46] It is even possible to immobilise living cells within coatings.…”

Optical properties of sol–gel fabricated Mn/SiO2 nanocomposites: Observation of surface plasmon resonance in Mn nanoparticles

“…The method of sol-gel-based fabrication of the thin film on various substrates has been elaborated extensively [12,22,23], and we used the silica matrix as useful medium to incorporate manganese nanoparticles. A precursor film-forming solution (sol) was prepared by mixing tetraethylorthosilane (TEOS), ethanol and water with HCl as catalyst in molar ratio 1:6:10:0.08.…”

“…[7][8][9][10]. There exist many works reporting the optical properties of Mn containing nanocomposites [11][12][13][14][15][16][17]. The optical properties of such Mn containing nanocomposites are determined by optical transitions in manganese ions and oxides.…”