Large-sized La$lt;inf$gt;2$lt;/inf$gt;O$lt;inf$gt;3$lt;/inf$gt;-TiO$lt;inf$gt;2$lt;/inf$gt;-SiO$lt;inf$gt;2$lt;/inf$gt; Amorphous Oxide Fabricated by Hot Press Sintering

Abstract

La2O3-TiO2 amorphous oxide has prospective applications because of its remarkable optical properties. However, due to its poor glass-forming abilities, it is difficult to prepare this material in a traditional way. The containerless solidification method can overcome this shortcoming, but the formed material size is generally restricted to be less than 10 mm. In order to obtain large-sized La2O3-TiO2 amorphous oxide, a small amount of SiO2 was added to the La2O3-TiO2 oxide system to form the amorphous oxide powders by aerodynamic levitation furnace. Subsequently, the high-density La2O3-TiO2-SiO2 materials were fabricated by vacuum hot press sintering. Compositions and microstructure properties were systematically studied by XRD and SEM. The results showed that SiO2 could improve the glass-forming ability of La2O3-TiO2. The raw powders made by aerodynamic levitation furnace were completely non-crystal, while the sintered samples had weak crystallization, which affected fully densification of sintered samples. There was a small amount of porosity in the high-density product made by vacuum hot press sintering. In addition, sintering densification mechanism of the La2O3-TiO2-SiO2 amorphous powders was analyzed. Finally, the optical property of hot pressed La2O3-TiO2-SiO2 material was investigated. It is found that La2O3-TiO2-SiO2 material still kepts high refractive index of above 2.2 in the visible light region. Small amount addition of SiO2 species improves the glass-forming abilities, yet decreases the refractive index slightly.