Synthesis, structural characterization, and thermal properties of Ca‐ and La‐doped soda‐lime glasses by laser melting

• Published in: International journal of applied glass science Vol. 11; no. 4; pp. 699 - 706
• Main Authors: Ali, Sharafat, Wójcik, Natalia A., Jonson, Bo, Kamitsos, E.I., Li, Xinghua, Luo, Jian, Möncke, Doris
• Format: Journal Article
• Language: English
• Published: Westerville Wiley Subscription Services, Inc 01-10-2020
• Subjects: Bonding strength; Calcium ions; Carbon dioxide; Carbon dioxide lasers; Depolymerization; Evaporation; Glass; glass forming systems; IR spectroscopy; Laser beam melting; laser melting; Lasers; Lime; oxide glass; raman spectroscopy; Raw materials; Sodium; Structural analysis; Thermal stability; Thermodynamic properties; Trivalent ions
• ISSN: 2041-1286; 2041-1294
• DOI: 10.1111/ijag.15477

ABSTRACT
Laser melting techniques have been used in the preparation of unconventional glass compositions with high melting temperatures. Thus, we wanted to test the feasibility of using a CO2 laser in the preparation of nitrogen‐rich oxynitride glasses and nitride silicate glasses. Melting from oxides and metallic raw materials, we wanted to study first glass formation and possible evaporation losses of the glass components. Two glass series were prepared and studied for their structure and thermal properties, one with Ca2+‐ and a higher melting La3+‐doped soda‐lime‐silicate (SLS) series. In less than 3 minutes of laser melting, spheres of up to 6 mm diameter were successfully fabricated. The obtained glass samples were homogeneous and transparent in the visible region. X‐ray diffraction and Raman spectroscopic analysis confirmed the amorphous nature of the synthesized samples. Sodium losses increase as calcium is added to the soda‐lime‐silicate glass. As expected, increasing Ca2+ or La3+ addition lead to increased depolymerization of the silicate network. Moreover, the increases in Tg with the addition of Ca2+ or La3+ ions indicating strengthening of the soda‐lime‐silicate glass by increasing strength of the M‐O bonds of divalent and trivalent ions over monovalent sodium ions, weak Na‐O bonds also resulting in significant evaporation loss during the short laser melting times. The thermal stability decreases upon addition of Ca2+ or La3+ ions to the soda‐lime‐silicate glasses.