Silica xerogels doped with Ge(IV), substituting for Si(IV) in the oxide network, are prepared from tetraethylorthosilicate and germanium-tetraethoxide. The sintering process is carried out in reducing atmosphere at 700 - 900°C by reaction with H2. Raman spectroscopy and high resolution transmission electron microscopy (TEM) show that reactions with H2 give rise, in the porous silica network, to uncontrolled islands of crystallites of elemental cubic germanium with average size of 50 nm. Sintering process in reducing H2 atmosphere at temperatures just below the phase separation, at about 610°C, gives materials where Ge atoms are dispersed in the matrix in conditions of incipient clustering. Evidences of segregation of germanium nanocrystals are observed with electron irradiation during TEM analysis. Furthermore, the electron beam induced precipitation leads to the formation of isolated quantum dots-like nanocrystals (5-6 nm in diameter) and with narrower size dispersion. The ranges of suitable temperature and germanium concentration are analysed, as well as the size dispersion of the resulting Ge nanophases.

Chiodini, N., Lorenzi, R., Lauria, A., Spinolo, G., & Paleari, A. (2008). Ge nanoparticles growth in Ge-doped sol-gel silica by e-beam exposure. In Nanophotonic Materials V. SPIE [10.1117/12.793310].

Ge nanoparticles growth in Ge-doped sol-gel silica by e-beam exposure

CHIODINI, NORBERTO;LORENZI, ROBERTO;LAURIA, ALESSANDRO;PALEARI, ALBERTO MARIA FELICE
2008

Abstract

Silica xerogels doped with Ge(IV), substituting for Si(IV) in the oxide network, are prepared from tetraethylorthosilicate and germanium-tetraethoxide. The sintering process is carried out in reducing atmosphere at 700 - 900°C by reaction with H2. Raman spectroscopy and high resolution transmission electron microscopy (TEM) show that reactions with H2 give rise, in the porous silica network, to uncontrolled islands of crystallites of elemental cubic germanium with average size of 50 nm. Sintering process in reducing H2 atmosphere at temperatures just below the phase separation, at about 610°C, gives materials where Ge atoms are dispersed in the matrix in conditions of incipient clustering. Evidences of segregation of germanium nanocrystals are observed with electron irradiation during TEM analysis. Furthermore, the electron beam induced precipitation leads to the formation of isolated quantum dots-like nanocrystals (5-6 nm in diameter) and with narrower size dispersion. The ranges of suitable temperature and germanium concentration are analysed, as well as the size dispersion of the resulting Ge nanophases.
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Scientifica
Colloids; Concentration (process); Dispersion (waves); Electron beam lithography; Electron beams; Electron irradiation; Gelation; Gels; High resolution electron microscopy; High resolution transmission electron microscopy; Microscopic examination; Nanocrystalline alloys; Nanocrystals; Nanostructured materials; Nanostructures; Oxides; Phase separation; Quantum electronics; Semiconductor quantum dots; Semiconductor quantum wells; Silica; Silica gel; Silicon; Sintering; Sols; Synthesis (chemical), Average sizes; Chemical synthesis; e-beam; Ge atoms; Ge nanoparticles; Germanium concentrations; Germanium nanocrystals; Porous silicas; Quantum dots; Reducing atmospheres; Silica xerogels; Sintering processes; Size dispersions; Sol - gels; Sol gel; TEM; Tetra ethyl ortho silicates, Germanium
English
SPIE Nanophotonic Materials V
9780819472502
Chiodini, N., Lorenzi, R., Lauria, A., Spinolo, G., & Paleari, A. (2008). Ge nanoparticles growth in Ge-doped sol-gel silica by e-beam exposure. In Nanophotonic Materials V. SPIE [10.1117/12.793310].
Chiodini, N; Lorenzi, R; Lauria, A; Spinolo, G; Paleari, A
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/23512
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