The Er doped silica–titania or silica-titaniaalumina nanopowders were prepared by sol-gel method that represents one of the most flexible and convenient way to prepare oxide films and nanopowders. The selected molar compositions were un-doped and 0.5%Er2O3 doped 90%SiO2-10%TiO2 and 85%SiO2-10%TiO2-5%Al2O3 systems. Similar compositions were previously used for obtaining films for waveguides applications but the mechanism of the phase formation by thermal treatment of the corresponding gels was not previously approached. The gels obtained by gelation of the solutions were analyzed by thermogravimetric and thermodifferential analysis (DTA/TGA) in order to determine their thermal behavior and by IR spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) to evaluate their structure and morphology. Based on the results obtained, the gels were thermally treated at 500C and 900C. The thermally treated powders were characterized by SEM, FT-IR, X-ray diffraction (XRD) and photoluminescence (PL). The significant influence of the Er on the phase formation was established in both studied systems. Nanopulberile de silice-dioxid de titan sau silicedioxid de titan-alumină dopate cu Er au fost preparate prin metoda sol-gel care reprezintă una dintre cele mai flexibile și convenabile metode de preparare ale filmelor și nanopulberilor oxidice. Compozițiile moleculare selectate au fost cele din sistemele 90%SiO2-10%TiO2 și 85%SiO2-10%TiO2-5%Al2O3 nedopate și dopate cu 0,5% Er2O3. Compoziții similare au fost utilizate anterior pentru obținerea filmelor pentru aplicații ca ghiduri de undă, dar mecanismul de formare al fazelor prin tratamentul termic al gelurilor corespunzătoare nu a fost abordat anterior. Gelurile obținute prin gelifierea soluțiilor au fost analizate prin analiză termogravimetrică și termodiferențială (DTA / TGA) pentru a determina comportamentul lor termic și prin spectroscopie IR (FT-IR) și Microscopie Electronică de Baleaj (SEM) pentru a evalua structura și morfologia lor. Pe baza rezultatelor obținute, gelurile au fost tratate termic la 500°C și 900°C. Pulberile tratate termic au fost caracterizate prin SEM, FT-IR, difracție de raze X (XRD) și fotoluminiscență (PL). Influența semnificativă a Er + asupra formării fazelor a fost stabilită în ambele sisteme studiate.
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