In order to study new and convenient sol-gel syntheses to homogene ous nanocomposites systems based on zinc sulphide clusters embedded in films of silica glass, a thiourea-functionalized silane ((EtO)3Si(CH2)3NHC(=S)NHPh, SilTu) was investigated as starting precursor. Electrospray ionization mass spectrometry (ESI-MS), FT-IR and N MR spectroscopies clearly evidence that SilTu coordinates Zn2+ ions in solution through the thiourea function. Both zinc acetate (Zn(CH3COO)2) and zinc chloride (ZnCl2) were used as zinc source. TheSilTu-Zn2+ complex is also stable under sol-gel conditions. Alcoholic solutions of SilTu, zinc acetate and tetraethoxysilane Si(OEt)4 (TEOS) were used to prepare the thin films by dip-coating. Transparent, homogeneous and crack-free layers were obtained under annealing up to 600 oC. The samples were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Beside ZnS formation, the presence of oxygenated zinc species was observed inside the silica matrix
Sol-gel synthesis of Zn-thiourea-SiO2 thin films from ((EtO)3Si(CH2)3NHC(=S)NHPh as molecular precursors
Armelao L;Barison S;Fabrizio M;Gross S;Sassi A;Seraglia R;Venzo A
2004
Abstract
In order to study new and convenient sol-gel syntheses to homogene ous nanocomposites systems based on zinc sulphide clusters embedded in films of silica glass, a thiourea-functionalized silane ((EtO)3Si(CH2)3NHC(=S)NHPh, SilTu) was investigated as starting precursor. Electrospray ionization mass spectrometry (ESI-MS), FT-IR and N MR spectroscopies clearly evidence that SilTu coordinates Zn2+ ions in solution through the thiourea function. Both zinc acetate (Zn(CH3COO)2) and zinc chloride (ZnCl2) were used as zinc source. TheSilTu-Zn2+ complex is also stable under sol-gel conditions. Alcoholic solutions of SilTu, zinc acetate and tetraethoxysilane Si(OEt)4 (TEOS) were used to prepare the thin films by dip-coating. Transparent, homogeneous and crack-free layers were obtained under annealing up to 600 oC. The samples were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Beside ZnS formation, the presence of oxygenated zinc species was observed inside the silica matrixI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
