Larisa Andreevna Reznichenko

The paper studies the nonlinear electrical response of dispersed-crystalline lead zirconate titanate powders (PbZr[ ]Ti[ ]O ₃ , PZT) in the microwave range (8.2–12.4[ ]GHz). The main attention is paid to the influence of temperature and incident wave power on the dielectric properties of the material, especially near the morphotropic phase boundary (MPB) and phase transitions (PTs). The experiments were carried out using a waveguide measuring cell and a vector network analyzer. The results showed that the permittivity and losses of the material depend on the frequency, temperature and microwave power. A broad relaxation maximum of losses was found at ∼12[ ]GHz, which shifts to the low-frequency region upon heating. It is assumed that this maximum is due to the presence of several competing polarization mechanisms associated with the reorientation of dipoles in the B sublattice. At higher powers (>5[ ]dBm), nonlinear effects were observed, including the disappearance of the relaxation maximum, which may be due to local heating and destabilization of dipole configurations. The obtained data emphasize the importance of taking into account cooperative interactions and structural transitions when analyzing the dielectric response of PZT in the microwave range.

Samples of solid solutions of the multicomponent system [ ] [ ], [ ] and [ ], [ ], of the PZT–PZN–PMN type were obtained using conventional ceramic technology. The effect of a dc bias and temperature on the structure and dielectric properties of the solid solution was studied. X-ray diffraction analysis revealed that the ceramic solid solution is characterized by the coexistence of tetragonal and pseudocubic phases in 80:20 ratio. The obtained solid solution was found to have symmetrical “butterfly” loops, which are characteristic of classical ferroelectrics and are formed only from the second study cycle. The maximum [ ] is achieved at [ ] kV/cm; the hysteresis of the [ ] [ ] dependence decreases with increasing E, becoming practically absent at [ ] [ ]kV/cm. The temperature-dependent controllable characteristics of the dielectric were studied. The data obtained at room temperature correlate well with the X-ray diffraction data. It was concluded that the obtained data could be used in the development of high-voltage devices operating based on such materials.

The results of X-ray diffraction analysis, study of their microstructure and dielectric properties of the solid solutions (SS) (1−x)BiFeO ₃ −LiNbO ₃ are presented in this paper. A number of changes are observed in the structure of SS: perovskite ([ ]), pyrochlore ([ ] and [ ]), and ilmenite ([ ]) structures. The character of the microstructure indicates sintering with the participation of liquid phases. The dielectric properties show thermal stability in the range of room temperature to 550 K, depending on the composition. This finding suggests the feasibility of their use in high-frequency devices.