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From the dielectric measurements of the relaxor ceramics BaBi2Ta2O9 (BBT) in a wide frequency range (101-1011 Hz) the real distribution function of the relaxation times f(τ) was calculated. The shape of the distribution function is asymmetrical in all measured temperature interval with the expressed peak of relaxation times about 10- 12 s in higher temperatures. [ABSTRACT FROM AUTHOR]

The dielectric investigation of BaBi2Nb2O9 (BBN) ceramics was performed in a broad frequency and temperature range. It was observed, that this ceramics possesses not typical ferroelectric relaxor behaviour, which is close to dipolar glass. A very diffuse phase transition is observed in the whole measured temperature range and the dielectric permittivity exhibits a strong dispersion in the frequency range from Hz to microwaves where the maximum of permittivity, Tmax, shifts to higher temperature as the frequency increases. From the frequency dependences of the real and imaginary parts of dielectric permittivity the parameters of dielectric dispersion and the real distribution function of the relaxation times f(τ) have been calculated. [ABSTRACT FROM AUTHOR]

In this paper we report the dielectric investigation results of BaBi2Ta2O9 (BBT) ceramics performed in a broad frequency and temperature range. It is shown, that this ceramics possesses the ferroelectric relaxor behaviour. A very diffuse phase transition is observed in the whole measured temperature range and the dielectric permittivity exhibits a strong dispersion in the frequency range from Hz to microwaves where the maximum of permittivity, Tmax, shifts to higher temperature as the frequency increases. From the frequency dependences of the real and imaginary parts of dielectric permittivity the parameters of dielectric dispersion have been calculated. [ABSTRACT FROM AUTHOR]

Dielectric relaxation of BaTi1-xSnxO3 ceramics is investigated by means of dielectric spectroscopy. The gradual crossover from ferroelectric to relaxor behavior is characterized by vanishing of the contribution due to domain walls and appearance of relaxation related to reorientation of polar nanosized regions. Typical behavior of relaxors is observed only in ceramics with x = 0.30, while the compositions with 0.175 ≤ x ≤ 0.25 show coexistence of both ferroelectric and relaxor features. The relaxor properties are supposed to be due to both weak random fields and disorder inherent in pure BaTiO3. [ABSTRACT FROM AUTHOR]

Abstract: Ultrasonic and piezoelectric studies of lead free ceramic system structures of (1− x)BaTiO3–xLa(Mg1/2Ti1/2)O3 (BT–LMT) are presented in this contribution. It was shown, that such materials with x =0.025, 0.05, 0.075 and 0.1 LMT content undergo phase transitions and exhibit piezoelectric effect in the low temperature phases. Anomalies of ultrasonic velocity and attenuation at phase transitions have been observed in these materials. Measurements of temperature dependencies of ultrasonic velocity and attenuation revealed anomalies related to phase transitions in these materials. It was shown that, at room temperature and under dc bias electric field, these ceramics behave as a piezoelectrics because of electrostriction. [Copyright &y& Elsevier]