# Electrophysical Properties of PZT-Type Ceramics Obtained by Two Sintering Methods
## 1 Introduction  
Among the various functional ceramic materials, the PZT (Pb(Zr\({}_{x}\)Ti\({}_{1-y}\)O\({}_{3}\))) solid solution is of particular interest due to its excellent dielectric, ferroelectric, piezoelectric, and pyroelectric properties [1; 2]. The unique properties of PZT-type materials have contributed to a wide range of applications of this material in various fields of interest. Its excellent ability to convert mechanical energy into electrical energy and vice versa allows the use of PZT-type materials in devices such as ultrasonic transducers and ultrasonic motors [3; 4; 5], piezoelectric and acoustic transducers [6; 7], pressure sensors [8], accelerometers and actuators [9] in non-volatile memory systems and in systems described in [10; 11; 12; 13; 14; 15]. In addition, PZT-type materials are used, among other things, in electro-optical devices [16], smart home devices, and medicine, automotive, and astronautic applications. The set of physical parameters and its wide range of applications of PZT ceramic material mainly depends on the chemical composition and technological conditions of obtaining piezoelectric materials, which significantly influences its domain structure, i.e., the microstructure of the ceramic material. The quality and stability of the ceramic material's domain structure in the piezoelectric transducer's working temperature range are closely related to the final parameters of a given electronic device. Depending on titanium (Ti) and zirconium (Zr) content, the PZT solid solution has a tetragonal or rhombohedral structure, thanks to which a wide range of properties can be obtained. The most extremefunctional parameter values of the PZT material occur in the morphotropic region, which is a mixture of the tetragonal and rhombohedral phases. Thus, the physical properties of the PZT materials depend on the zirconium/titanium content (Zr/Ti) and the technological process. However, above all, appropriate doping of the main composition compound is the most effective manner to improve its functional properties [17; 18]. As a result, a multi-component solid solution of the PZT type is designed, which can be doped with acceptor (ferroelectric hard hardness) and donor (ferroelectric soft hardness) heterovalent admixtures and isovalent admixtures. Heterovalent admixtures introduced into the basic PZT composition are the source of space charge and the associated space charge field, affecting ceramics' functional properties [19; 20]. In contrast, the effects of isovalent doping PZT is determined, e.g., by the radii of the atoms, the electronic configuration of the outer electron shells, and the nature of the chemical bonds. The acceptor admixtures decrease the grain resistance and efficiently inhibit the domain motion due to the increase in oxygen vacancy, causing an increase in the ferroelectric hardness of the ferroelectric material. For example, acceptor dopants substituted in the A position of the Pb(Zr\({}_{\mathrm{r}}\)Ti\({}_{1+}\)C\({}_{3}\)) compound are K\({}^{+}\), Na\({}^{+}\), whereas in the B position they are Fe\({}^{2+}\), Fe\({}^{3+}\), Co\({}^{2+}\), Mn\({}^{2+}\), Mn\({}^{3+}\), Ni\({}^{2+}\), Mg\({}^{2+}\), Al\({}^{3+}\), Ga\({}^{3+}\), In\({}^{3+}\), Cr\({}^{3+}\), Sm\({}^{3+}\), Pr\({}^{3+}\), Tb\({}^{3+}\), Dy\({}^{3+}\), Eu\({}^{3+}\), Se\({}^{3+}\). In contrast, the donor admixtures increase the possibility of movement of other network ions under the influence of external influences (the mobility of domain walls increases) and increased bulk resistance due to the reduction in intrinsic oxygen vacancy [21]. For example, donor dopants substituted in the A position of the PZT compound are La\({}^{3+}\), Nd\({}^{3+}\), Bi\({}^{3+}\), Sb\({}^{3+}\), whereas in the B position they are Nb\({}^{5+}\), W\({}^{6+}\), Sp\({}^{5+}\). One of the crucial processes in producing PZT-type ceramics is the sintering process, which has a decisive influence on the material's microstructure and mechanical and dielectric properties [22; 23].