## 3 Results and Discussion
The T\({}_{\rm g}\) of PSAB glass frit was 390 \({}^{\circ}\)C, as shown in Figure 2. It could lead to a reduced volume of pellet due to the rearrangement and densification of the glass frits with square shape. At the second stage, the square types of pellet changed to swollen sphere after being sintered at 450 \({}^{\circ}\)C for 30 min. It indicated that flow ability is enough for laser sealing at this temperature, which is above the softening temperature of 430 \({}^{\circ}\)C as shown in Figure 2. In this stage, the wetting angle of the molten glass was \(>\)90\({}^{\circ}\). At the third stage, the wetting angle of the molten glass started to show \(<\)90\({}^{\circ}\) at 500 \({}^{\circ}\)C. It was found that the molten glass spread over FTO coated glass due to viscous flow above 550 \({}^{\circ}\)C. Finally, it was confirmed that the flow ability was found to be good for laser sealing in the temperature range of 400-430 \({}^{\circ}\)C, which is above the softening temperature of 430 \({}^{\circ}\)C, as shown in Figure 2.  
Figure 2:0 (**a**) Transmission spectra of PSAB system doped with various CuO concentrations; and (**b**) transmission spectra of PSAB system codoped with various CuO and Na\({}_{2}\)CO\({}_{3}\) concentrations. Figure 7a shows the XRD spectra for PSAB, 1 wt% CuO doped, and 1 wt% CuO-2 wt% Na\({}_{2}\)CO\({}_{3}\) codoped PSAB glasses. As can be seen from the figure, the broad hump around 20 \(\approx\) 28\({}^{\circ}\) was observed in the XRD pattern, and thus it confirmed the amorphous nature of PSAB-based glass samples are homogeneous regardless of types of dopants. The previous reports confirmed the amorphous nature from XRD in 12 mol% CuO added into the (20 \(-\) x)BaO-30 ZnO-10 Na\({}_{2}\)O-40P\({}_{2}\)O\({}_{5}\)-xCuO glass system [26]. It was reported that the above 14 wt% Na\({}_{2}\)CO\({}_{3}\) provides a nucleation site to improve the crystallization of the glass [23]. Figure 7b shows the XRD patterns of 1 wt% CuO and 2 wt% Na\({}_{2}\)CO\({}_{3}\) codoped PSAB glass system for different sintering temperatures varied from 400 to 550 \({}^{\circ}\)C, with an increment of 50 \({}^{\circ}\)C. It was observed that the broad hump at an angle (20) of 28\({}^{\circ}\) was noticed for all the temperatures, indicating the amorphous nature of the PSAB glass system irrespective of the sintered temperature. Figure 8 shows the 1 wt% CuO and 2 wt% Na\({}_{2}\)CO\({}_{3}\) codoped (a) PSAB glass ingot, (b) cross-section image of the glass fiber with 180 \(\upmu\)m diameter, and (c) glass fiber spool. The glass fiber was pulled using a draw tower. Bronze mold with a diameter of 7 mm and a length of 40 mm was used for the fabrication of glass ingot and fiber. The glass fiber was drawn in the temperature range of 500-535 \({}^{\circ}\)C. Three steps are involved in the fabrication of glass fiber. Initially, the temperature of electric furnace increased up to 500 \({}^{\circ}\)C with a heating rate of 10 \({}^{\circ}\)C/min and then followed this procedure: Seg 1. 500 \({}^{\circ}\)C for 60 min \(\rightarrow\) Seg 2. 500 \({}^{\circ}\)C for 30 min \(\rightarrow\) Seg 3. 535 \({}^{\circ}\)C for 60 min. At the final step, the bob of the preform began to fall, and then the glass fiber was drawn with an outer diameter of 400-550  
Figure 2:1 The shape change of pellets (1 wt% CuO and 2 wt% Na\({}_{2}\)CO\({}_{3}\) codoped PSAB glass system) as a function of sintering temperature; inset shows the side view of pellets. Figure 2:2 (a) XRD spectra for base PSAB system, 1 wt% CuO-doped, and 1 wt% CuO and 2 wt% Na\({}_{2}\)CO\({}_{3}\) codoped PSAB glass systems; (b) XRD spectra for codoped PSAB glass system sintered at 400–550 \({}^{\circ}\)C.  
\(\mu\)m. Finally, the fiber 180 \(\mu\)m diameter was obtained by adjusting the pulling speed with an automatic feedback system. Glass fiber was drawn to a length of 50 m. The fabricated glass fiber could be used as a fiber-type sealing material. Systematic sealing process using a fiber-type sealing material will be explained in the next figure.