Acoustic emission and dielectric studies of phase transitions within the morphotropic phase boundary of xPb(Zr1/2Ti1/2)O3-(1−x)Pb(Ni1/3Nb2/3)O3 relaxor ferroelectrics

We have carried out a combined acoustic emission(AE) and dielectricpermittivity study of the xPb(Zr1/2Ti1/2)O3-(1−x)Pb(Ni1/3Nb2/3)O3relaxor ferroelectric ceramics with compositions x=0.7–0.9 corresponding to its morphotropic phase boundary. Temperatures of all phase transitions occurring on heating are identified accurately by AE, and a direct transition between the low-temperature (rhombohedral) and high-temperature (pseudocubic) relaxor phases is found. The AE peak intensity is generally proportional to the temperature derivative of the dielectricpermittivity, in agreement with a model proposed for a thermally cycled small elastic dipole

Acoustic emission study of domain wall motion and phase transition in (1-x-y)Bi0.5Na0.5TiO3-xBaTiO(3)-yK(0.5)Na(0.5)NbO(3) lead-free piezoceramics

The ferroelectric strain hysteresis and acoustic emissions of lead-free (1 - x - y)Bi0.5Na0.5TiO3-xBaTiO3-yK0.5Na0.5NbO3 ceramics were investigated at room temperature. The field-induced antiferroelectric ??? ferroelectric phase transition as well as the ferroelectric coercive field were successfully detected. Although the strain was largest for x = 0.06 and y = 0.02, this composition showed the lowest acoustic emission signals, making it an interesting material for ultrasonic transducer applications.close161

Detection of phase transitions in sodium bismuth titanate–barium titanate single crystals by acoustic emission

Acoustic emission measurements are combined with strain, dielectric, and polarization measurements to detect phase transitions in 0.94Na0.5Bi0.5TiO3–0.06BaTiO3 single crystals during thermal cycling as well as electric field cycling at both room temperature and 140 °C. All phase transitions known from the literature (cubic↔tetragonal↔trigonal I↔trigonal II) are determined to be of first order, and the existence of the ferroelectric trigonal II phase at room temperature and its transformation into an antiferroelectric phase during heating above 130 °C is established

Acoustic emission and dielectric studies of phase transitions within the morphotropic phase boundary of xPb(Zr1/2Ti1/2)O3-(1−x)Pb(Ni1/3Nb2/3)O3 relaxor ferroelectrics

We have carried out a combined acoustic emission(AE) and dielectricpermittivity study of the xPb(Zr1/2Ti1/2)O3-(1−x)Pb(Ni1/3Nb2/3)O3relaxor ferroelectric ceramics with compositions x=0.7–0.9 corresponding to its morphotropic phase boundary. Temperatures of all phase transitions occurring on heating are identified accurately by AE, and a direct transition between the low-temperature (rhombohedral) and high-temperature (pseudocubic) relaxor phases is found. The AE peak intensity is generally proportional to the temperature derivative of the dielectricpermittivity, in agreement with a model proposed for a thermally cycled small elastic dipole.The following article appeared in Applied Physics Letters 95 (2009): 252903, and may be found at http://dx.doi.org/10.1063/1.3275730.</p

Phase Transition at a Nanometer Scale Detected by Acoustic Emission within the Cubic Phase Pb(Zn1/3Nb2/3)03-xPbTi03 Relaxor ferroelectrics

Pb(Zn1/3Nb2/3)O3−xPbTiO3 (x=4.5%–12%) relaxor ferroelectric crystals have been studied by means of acoustic emission (AE) in the 400–540 K temperature range. An anomalous AE activity independent of the ground state relaxor/morphotropic/ferroelectric crossover has been revealed at around 500 K, and it is associated with the “waterfall” feature related to the existence of polar nanoregions (PNRs). The 500 K AE anomaly is attributed to local martensitelike cubic-to-tetragonal ferroelectric transitions within the PNRs imbedded in a nonpolar (cubic) matrix

Acoustic emission study of PZN-7% PT crystals

Phase transitions in PbZn1/3Nb2/3O3-7%PbTiO3 (PZN-7%PT) relaxor ferroelectric crystals have been investigated by the acoustic emission (AE) method. Two types of transitions have been detected (i) associated with the thermally induced (on cooling) formation of intrinsic polar nanoregions (PNRs) and (ii) related to the electric-fieldinduced macroscopic phase transitions. An AE signal found near 740 K corresponds to the Bums temperature, below which the PNRs begin to form. Further cooling reveals an AE signal at 500 K, which is ascribed to the shift of PNRs along their polar direction relative to the surrounding non-polar matrix in the framework of the "phase-shifted condensed soft mode" model. Monitoring of the AE response of PZN- 7%PT crystals under an increasing [001] dc electricfield has allowed a unique in situ observation of a sequence of phase transitions, from the zero-field rhombohedral via MA monoclinic (similar to 3 kV/cm) and Mc monoclinic (similar to 16 kV/cm) to the tetragonal (similar to 19 kV/cm) phase, respectively. It is shown that AE is a very sensitive method for detecting both the PNRs kinetics and low distortion phase transitions in relaxor ferroelectrics

A new temperature scale T* in lead-based relaxor systems

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