Two distinct dielectric relaxation mechanisms in the low-frequency range in Bi5TiNbWO15 ceramics

Abstract

The ac data in terms of impedance and dielectric loss (tanδ) were exploited simultaneously to probe the dielectric relaxation mechanisms in Bi5TiNbWO15 ceramics. It was found that two distinct relaxation mechanisms exist in the low-frequency range (10Hz–5MHz). One is attributed to the grain boundary relaxation and the other is associated with oxygen ion diffusion. Furthermore, the temperature dependence of the oxygen vacancy relaxation strength is analogous to the Curie-Weiss law and follows the traditional point defect relaxation theory. These results could be helpful to understand the phenomena related to ferroelectric fatigue, oxygen ion conductivity, etc.

Electrical properties of CaBi4Ti4O15–Bi4Ti3O12 piezoelectric ceramics

“…The activation energies for CBT-BIT ceramics at the two separate temperature ranges are 0.86 eV and 1.42 eV, respectively. The E a1 value of 0.86 eV is comparable with the values for oxygen ion diffusion, indicating that σ dc at low temperature range from 100 1C to 200 1C, are influenced by the oxygen vacancies motion in grains [10]. The E a2 value of 1.42 eV is much higher than E a1 .…”

“…To make BLSFs more sufficient for commercial applications, lots of efforts have been made to improve their electrical properties [5]. Forming intergrowth BLSFs [4,[6][7][8][9][10][11][12][13][14][15] is an effective method and the intergrowth BLSFs usually perform enhanced electrical properties [3,7,15].…”

Ferroelectric and piezoelectric properties of Aurivillius phase intergrowth ferroelectrics and the underlying materials design

“…Figure 2a shows the dielectric permittivity of intergrowth Bi 5 TiNbWO 15 ferroelectric, as a function of temperature at measurement frequencies of 10 2 , 10 3 , 10 4 , 10 5 and 10 6 Hz, respectively. Herein the dielectric anomalies I and II shift to higher temperature with increasing frequency and are of relaxation nature that we had discussed elsewhere 18, 21, 24. Whereas the dielectric anomalies III is due to the ferroelectric–paraelectric transition, the T c is located at about 823 °C.…”

“…Let ( R g , R gb ) and ( C g , C gb ) be the resistances and capacitances of grains and grain boundaries, respectively. The experimental impedance spectra can be fitted with two semi‐circles and the resistances and capacitances of grains and grain boundaries can be deduced from the fitting results accordingly 24, 25. The electrical conductivity of the samples can therefore be calculated from the interceptions of the fitted semi‐circles on the real axis of the impedance spectra, as shown in Fig.…”

Effects of La3+ substitution on structure and temperature dependence of electrical properties of CaBi4Ti4O15–Bi4Ti3O12 ceramics

“…This is probably attributed to decreased concentrations of free charge carriers. The motion of oxygen vacancies and free electrons plays an important role in the variation of q dc of intergrowth BLSFs in the temperature range from 75 to 600°C [21,22]. As reported before, the bond strength of La-O is stronger than that of Bi-O [23,24].…”