In ANbO3 (A-Li, Na, K) single crystals besides dielectric permittivity maxima, corresponding to the known ferroelectric and antiferroelectric phase transitions, minor (T) anomalies were observed in the 100-300°C temperature range. The temperature Ta of these anomalies does not depend on measuring frequency in the 102-106 Hz range. Dilatometric studies showed that temperature dependences of relative dilatation Δ L/L have an inflexion in the vicinity of Ta. Linear correlation between Ta and the temperature TPE of the phase transition into the paraelectric phase was revealed. It is supposed that the minor (T) anomalies observed in ANbO3 crystals in the 100-300°C temperature range are due to phase transitions to the incommensurate phase.
Bibliographical noteFunding Information:
The work was partially supported by Russian Foundation for Basic Research (grants # 01-03-33119 and 02-02-17781).
- Dielectric permittivity
- Incommensurate phase
- Phase transition