Technology and Dielectric Properties of the KNLN Doped with Nd3+ and Pr3+ Ions

The paper presents the technology and basic properties of three compositions of lead-free ceramics: (i) (K_0.44Na_0.52Li_0.04)NbO₃, (ii) (K_0.44Na_0.52Li_0.04)NbO₃)NbO₃ +0.5%mol Nd₂O₃ and (iii) (K_0.44Na_0.52Li_0.04)NbO₃)NbO₂+0.5%mol Pr₂O₃. Powders of the designed compositions based on KNLN were obtained with the classic ceramic technology, as a result of solid phase synthesis, from a mixture of simple oxides and carbonates. The synthesis of ceramic powders was carried out at T_s = 900°C for t_s = 4 h, while compaction by free sintering at T_sint = 1100°C for t_sint = 2 h. XRD studies have shown that doping with praseodymium and neodymium promotes the formation of the tetragonal phase in the base composition (K_0.44Na_0.52Li_0.04)NbO₃)NbO₃ at lower temperatures. On the other hand, microstructural tests have shown that the admixture of neodymium and praseodymium improves the sinterability of ceramic samples during the technological process; however, the ceramic samples still exhibit high porosity.