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

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.

Two-step synthesis of niobium doped Na–Ca–(Mg)–P–Si–O glasses

“…The qualitative interpretation of this threshold is based on the correlation between solubility and NC; low NCs denote open and fragmented glass structures, whose rapid partial dissolution in an aqueous physiological environment will lead to HA formation and bone bonding in a shorter time, compared with glasses with a more interconnected network. As a reference, the NC for the 45S5 composition would be 1.9 [31,35]. However, as was mentioned before, the phosphorus in phospho-silicate glasses most probably exist as an orthophosphate complex ([PO 4 ] 3tetrahedra) [31,32] and in this case the network connectivity (NC in Table 2) should be calculated with the use of equation [32]:…”

“…As a reference, the NC for the 45S5 composition would be 1.9 [31,35]. However, as was mentioned before, the phosphorus in phospho-silicate glasses most probably exist as an orthophosphate complex ([PO 4 ] 3tetrahedra) [31,32] and in this case the network connectivity (NC in Table 2) should be calculated with the use of equation [32]:…”

“…The other parameter, effective cationic field strength (ECFS) of the modifiers in glass may help to explain behavior of different glass properties [31,32]. For example, for glasses containing mixed modifier cations with the same valence, properties such as compactness, Young's modulus, microhardness, glass transition temperature and softening point, all increased linearly with increasing effective cationic field strength (ECFS) of the modifiers, whereas the MV and the thermal expansion coefficient decreased [32].…”

Laser‐induced modification and external pressureless joining Na2FeP2O7 on solid electrolyte

“…The he structural analysis and crystallization of the resulting glasses have been studied in recent years. [25][26][27] Such non-conventional glasses are generally melted by a CO 2 laser by floating the raw powder with gas. Instead of vitrification by ultra-fast cooling, the glass is obtained by avoiding contact between the glass melt and the container during melting to avoid inhomogeneous nucleation.…”

“…Non‐conventional glasses with few glass‐forming oxides such as SiO 2 , P 2 O 5 , and B 2 O 3 have been synthesized by laser melting. The he structural analysis and crystallization of the resulting glasses have been studied in recent years 25–27 . Such non‐conventional glasses are generally melted by a CO 2 laser by floating the raw powder with gas.…”