# Electrophysical Properties of PZT-Type Ceramics Obtained by Two Sintering Methods
## 3 Results and Discussion  
The analysis of the crystal structure of the Pb(Zr\({}_{0.49}\)Ti\({}_{0.51}\))\({}_{0.94}\)Mn\({}_{0.021}\)Sb\({}_{0.016}\)Gd\({}_{0.012}\) W\({}_{0.012}\)O\({}_{3}\) (S) material powder at room temperature (Figure 1) shows the presence of all peaks belonging to the perovskite structure from the tetragonal phase (P4_mm_ space group). The X-ray tests also confirm that the obtained S material is single-phase, without foreign phases, e.g., a pyrochlore phase. The X-ray spectrum was matched to pattern JCPDS #04-006-3340. Microstructural SEM images of ceramic samples obtained by using the PS and HP methods are shown in Figure 2a,c. The tested materials are characterized by a microstructure consisting of densely packed grains with clearly visible edges. The microstructure of the analyzed ceramic samples stands out with high grain size uniformity, but the average grain size differs depending on the sintering technology used. Scanning microscopy analysis revealed that cracking occurs along grain boundaries and through  
The largest grains are observed in the sample obtained with the pressureless sintering method (S-PS), where the average grain size is \(d\) = 4.56 \(\upmu\)m due to the higher process temperature and its longer duration. On the other hand, smaller grains can be observed in the sample obtained with the hot-pressing method (S-HP), where the average grain size is \(d\) = 1.92 \(\upmu\)m (Figure 2b,d). Figure 3 shows the results of the qualitative EDS analysis, which confirmed the chemical composition of the S-PS and S-HP materials and excluded the participation of foreign elements and other impurities. The EDS analysis was carried out on five randomly selected micro-areas of the samples and the analysis confirmed the stoichiometric assumptions, which proves the correct selection of technological conditions. Slight percentage differences are within the limits of measurement accuracy. Figure 4a,c shows graphs \(\varepsilon(T)\) for the S-PS and S-HP ceramic samples. The temperature dependencies of the permittivity \(\varepsilon(T)\) show a similar character but with some differences. At room temperature, the permittivity values (1 kHz) are 959 for S-PS and 1245 for S-HP. In the case of the S-PS ceramic sample, an acute ferroelectric-paraelectric phase transition occurs with a high maximum permittivity value (\(\varepsilon_{\text{m}}\) = 14,018 at 1 kHz). On the other hand, in the sample obtained with the HP method, the phase transition is blurring, and a decrease in the maximum permittivity value (\(\varepsilon_{\text{m}}\) = 10,516 at 1 kHz) is observed. No frequency dispersion is observed in both ceramic samples. Figure 4b,d depicted the temperature changes in the dielectric loss factor tan\(\delta\)(\(T\)). For both samples, low values of the tan\(\delta\) are observed within the measurement range. The tan\(\delta\) dielectric loss factor value at room temperature is 0.004 and 0.011 for S-PS and S-HP, respectively. For the temperature phase transition \(T_{\text{m}}\), the tan\(\delta\) value is 0.095 for S-PS and 0.191 for S-HP. The dielectric properties depend on the ferroelectric materials' individual (internal) properties, i.e., grain size, purity, and porosity, and external factors, such as applied force, temperature, humidity, and an external electric field [51]. Figure 5 presents the cumulative results of permittivity \(\varepsilon(T)\) and tan\(\delta\)(\(T\)) as a function of temperature (for 1 kHz) for the S-PS and S-HP materials. Using pressureless sintering and hot sintering makes it possible to obtain PZT-type materials with a low dielectric loss factor and high permittivity values. The technological conditions applied in the non-pressure sintering method allowed the obtaining of ceramic samples with higher permittivity values (with a low degree of blur of the phase transition: the phase transition takes place in a narrow temperature range), along with lower values of the dielectric loss factor.