Glass frits as an enabler in the production process of OH−-free calcium aluminosilicate glasses

Abstract OH−-free calcium aluminosilicate (CAS) glasses present interesting properties for optical and photonic device applications. Optical properties have direct relation with SiO2 content in the glass composition. However, there is an interval (10–25 wt%) of SiO2 content which was not capable forming glassy-phase in previous works. In this study, the glass-forming ability was investigated as a function of the SiO2 content within this specific interval. The proposal was to use glass frits as precursor material to overcome this difficulty. Glass frits were produced from CAS glasses with 7 and 34 wt% of SiO2. These compositions were chosen by having a well established production procedure. Using glass frits, samples with concentration of 10, 15, 20 and 25 wt% of SiO2 were produced. With the exception of 25 wt%, all the samples vitrified, X-ray diffraction measurements reveal the amorphous nature of the prepared glasses. Raman spectroscopy and differential thermal analysis show that the samples present formation of a single phase in each sample, and these phases are between the limit phases obtained in the 7 and 34 wt% samples. In addition, mechanical, thermal, optical and thermo-optical properties of the samples were accessed. The results show that glass frits method is an alternative solution for the glass production, and, the process does not affect the sample properties comparing with the standard procedure.