Ferroelectricity

Relaxation processes in the region of structural phase transitions on the example of ceramics based on sodium niobate

O. V. Malyshkina^a, M. Ali^ab, N. E. Malysheva^c, K. V. Patsuev<sup>a

a</sup> Tver State University, Tver, Russia
^b Tver State Medical University, Tver, Russia
^c Zhukov Air and Space Defense Academy, Tver, Russia

Abstract: Comparative studies of the temperature dependences and dispersion of the complex permittivity of sodium niobate and sodium-lithium niobate ceramics have been carried out. It is shown that the structural transition to the $R$-phase (370$^\circ$C) of sodium niobate ceramics is a ferroelectric phase transition. For sodium niobate ceramics, the existence of three fundamentally different mechanisms of relaxation processes has been established: classical (Debye type), linear, and relaxation, the existence of which is determined by the structural phase. The addition of 10% lithium niobate to the sodium niobate ceramics not only increases the temperature of the structural phase transition, but also eliminates the mechanisms for the occurrence of relaxation polarization.

Keywords: piezoelectric ceramics, lead-free materials, permittivity, relaxation processes.

Received: 15.07.2022
Revised: 15.07.2022
Accepted: 19.07.2022

DOI: 10.21883/FTT.2022.12.53649.461

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