## 3 Results  
### Density and Linear Shrinkage Analysis  
Physical properties of a material are one of the most important features in the field of glass and ceramic research. Table 1 displays the variation of density evaluation and linear shrinkage measurement for precursor glass sample 55 ZnO-5B\({}_{2}\)O\({}_{3}\)-40 SLS, which was heat-treated at temperatures of 600, 700, 800 and 900 \({}^{\circ}\)C for 2 h. The successful transparent ZnO-B\({}_{2}\)O\({}_{3}\)-SLS precursor glass frit sample appeared light yellowish due to the high concentration of ZnO in the glass. The electronic densimeter measurement found that the density of the ZnO-B\({}_{2}\)O\({}_{3}\)-SLS glass sample was 2.754 g/cm\({}^{3}\). This high-density value is attributed to ZnO molecules having a very high relative weight compared to other oxides contained in the glass sample. The increase in the heat-treatment temperature caused the sample density to increase. The density of the materials depends on the densities of its individual constituents. However, in the case of glass ceramics, many other factors also marginally influence the density of the final product. Some of these factors include the thermal history of the sample, measurement temperature, crystallization, creation of non-bridging oxygen's (NBOs) and change in field strength of the modifier.  
As shown in Figure 1, the density of the sample increased linearly from 2.980 to 3.545 g/cm\({}^{3}\) with progression of heating temperature. This increase was due to the structural change and compactness of the sample structure after the heat-treatment process at higher temperatures [18]. The increasing density of the glass-ceramic samples was also caused by the decrease in the total fractional porosity of the sample. In general, density increases while the porosity of the material decreases monotonically with the depth. This is expected, because differential pressures usually increase with depth. As the heat-treatment temperature increases, the grains of the sample may shift to reach a more dense packing. At that moment, additional force will be imposed on the surface of the grain contacts. Figure 1 shows the effect of increasing the heat-treatment temperature on the linear shrinkage of the sample. According  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Temperature (\({}^{\circ}\)C)** & **Density (g/cm\({}^{3}\))** & **Linear Shrinkage (\%)** \\ \hline
27 & 2.754 & 0.00 \\
600 & 2.980 & 8.85 \\
700 & 3.211 & 9.08 \\
800 & 3.358 & 9.76 \\
900 & 3.545 & 10.43 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The variation of bulk density and linear shrinkage of the 55 ZnO-5B\({}_{2}\)O\({}_{3}\)–40 SLS glass and glass-ceramic sample at various heat-treatment temperatures.  
to the diagram, the shrinkage increased linearly with the rise in heating temperature. The linear shrinkage increased from 8.85 to 10.43% with the progression of heating temperature. This increasing trend is due to the compactness of the glass-ceramic structure where the porosity in the precursor glass structure disappeared. The densification of the glass-ceramic structure also indirectly caused the density of the ceramic glass sample to increase.