Crystallisation of Semiconductive Oxides from Borate Glasses
A preparation method was developed in order to obtain undoped and doped In2O3 and SnO2 nanopowders through controlled crystallisation of borate glasses and subsequent dissolution of the matrix in acetic acid. The nano-powders have been separated through dissolution of the additionally formed non In-containing crystalline phases and the glassy phase, and then subsequently dialysed. Glasses in the systems: Na2O/B2O3/Al2O3/In2O3 / (SnO2) and Na2O/B2O3/Al2O3/SnO2/ (Sb2O3) have been studied and nanopowders of In2O3, In2O3:SnO2, SnO2 and SnO2:Sb2O3 with crystalline sizes kleiner 50 nm have been prepared through controlled crystallisation in the temperature range from 500 to 80 °C. The SnO2 doping to the In2O3 as well as the heat treatment conditions have been studied in order to determine their influence on the optical properties of the In2O3 and In2O3:SnO2 nanoparticles. The desired combination of high transparency in VIS-and non-transparency in NIR-range of the In2O3 nanoparticles is achieved through doping of In2O3 (5 mol%) with 1 mol% SnO2 and heat treatment under reduction atmosphere (5% H2 and 95% Ar).