## 3 Results and Discussion
reported that the particle size continuously decreased and the number of micropores increased when excessive Sn\({}^{4+}\) were substituted in the PLZT composition. The sintered density slightly decreased with the pores when Sn\({}^{4+}\) was 0.6, as seen in Figure 4. A secondary phase as a needle-shaped microstructure was formed when a 0.2 mol ratio of Sn\({}^{4+}\) was added to the composition. As a result of the composition analysis using EDS, this needle has relatively high ratios of Pb\({}^{3+}\) and Sn\({}^{4+}\) elements, so it can be estimated as the appearance of a secondary phase centered on them. Figure 5 is an XRD diffraction pattern diagram for analyzing the structure of the PLZT sintered body for Sn\({}^{4+}\) substitution. As in the microstructure figure, a secondary phase presumed to be the PbSnO\({}_{2}\) phase was confirmed in the XRD pattern analysis of the Sn\({}^{4+}\) ion at 0.2 substitution amount. However, at other substitution amounts, a perovskite single phase without a secondary phase was obtained. A study by [PERSON] [20] et al. also reported that a small amount of SnO\({}_{2}\) was precipitated when the PLZST composition was synthesized by a solid-state reaction. Based on this, it can be estimated that a small amount of unsubstituted SnO\({}_{2}\) and excess PbO react to generate a secondary phase. For a detailed structural analysis of the composition of PLZST, the results of a low-speed scan around 44-45\({}^{\circ}\) are shown in the figure on the right. Overall, a pseudocubic structure was obtained. Although the phenomenon of peak shift was confirmed with the addition of Sn\({}^{4+}\), the phenomenon of phase transition was not confirmed. Therefore, it is predicted that the addition of Sn\({}^{4+}\) does not affect the phase transition. Figure 6 shows the dielectric constant of the PLZT sintered bodies according to the substitution of Sn\({}^{4+}\) ions. The sintered body was sintered at 950  
Figure 4: Sintered density of (Pb\({}_{0.88}\), La0\({}_{12}\))(Zr\({}_{1-x}\), Sn\({}_{x}\))\({}_{0.86}\)Ti\({}_{0.14}\)O\({}_{3}\) + ZnO (2 wt%) + PbO (8 wt%) composition at 950 \({}^{\circ}\)C, according to Sn\({}^{4+}\) substitution. constant was measured at 1 KHz. The dielectric constant decreased as the substitution amount of Sn\({}^{4+}\) increased. [PERSON] [21] et al. reported that the tolerance factor is important for phase safety in perovskite structures. \[t=\frac{R_{A}+R_{O}}{\sqrt{2}(R_{B}+R_{O})} \tag{1}\]  
\(R_{A}\), \(R_{B}\), and \(R_{O}\) are the ionic radius of A-site, B-site, and oxygen-site, respectively. It is generally known that when \(t>1\), the ferroelectric phase is stable, and when \(t<1\), the antiferroelectric phase is stable. Since the Sn\({}^{4+}\) (0.069 nm) has a smaller ionic radius than the Zr\({}^{4+}\) (0.072 nm), the \(R_{B}\) value decreases as the Sn\({}^{4+}\) content gradually increases [22]. As a result, as \(t\) increases, the antiferroelectric phase becomes unstable. Therefore, as the substitution amount of Sn\({}^{4+}\) increases, the polarization decreases. It is thought that this decrease in polarization causes a decrease in the dielectric constant. Additionally, as the substitution amount of Sn\({}^{4+}\) increased from 0.5 to 0.6, the dielectric constant decreased sharply. This is confirmed to be related to the decrease in sintered density, as shown in Figure 3.  
Figure 7 shows the electrical characteristics of the sintered PLZT according to the substitution amount of Sn\({}^{4+}\). Figure 7a is the hysteresis curve of the sintered PLZT according to the substitution of Sn\({}^{4+}\). Regardless of the substitution amount of Sn\({}^{4+}\), typical anti-ferroelectric properties are shown. As the amount of substitution of Sn\({}^{4+}\) gradually increases, the breakdown electric field increases, but the polarization decreases. The above results are graphically shown in detail in Figure 7b. At 0.6, the maximum polarization decreased from about 7.5 to 4 \(\upmu\)C\(\cdot\)cm\({}^{-2}\).