Acoustic Emission During Phase Transition in Soft PZT Ceramics Under an Applied Electric Field

Peculiar Properties of Phase Transitions in Na0.5Bi0.5TiO3-xBaTiO3 (0<x<6) Lead-free Relaxor Ferroelectrics Seen Via Acoustic Emission

“…The waves are detected using a piezoelectric sensor, fairly often connected with the sample through a dielectric acoustic waveguide to avoid of its overheating 34 . Traditionally in FEs the AE is well proven in detection of the structural phase transitions, T c , due to arising of the domains and their mechanical interaction [35][36][37][38] as well as recently it is well proven in a study of all the characteristic temperatures in RFEs: T m , T* and T B due to arising of the PNRs and their mechanical interaction [4][5][6][7][8][9][10]33 . AE technique has been described previously elsewhere 11 .…”

Acoustic Emission from Organic Martensites

“…Despite the potentials that these materials could have for fast transduction of heat directly into motion or work, the short time scales of their transitions and frequent disintegration with explosive outcome have precluded elucidation of the underlying mechanisms and quantification of their kinetics. [38][39][40][41][42] However,unlike the continuous acoustic emission that occurs during plastic deformation with slow progression of dislocations,the response from the martensitic transitions is discontinuous.T he intensity of the acoustic bursts is several orders of magnitude higher than that of the continuous emission, and is akin to the acoustic emission generated by an avalanche or the seismic waves that precede an earthquake.H erein, we provide direct evidence that, in addition to only one brief previously reported case, [5] the phase transitions in thermosalient crystals are generally associated with outbursts of elastic energy that translate into acoustic waves.T he energy,i ntensity,a nd time scale of the thermoacoustic response is scrutinized with the mechanism of the thermosalient transition. [16][17][18][19][20][21][22][23][24][25][26][27][28] We hypothesized that the sudden release of the accrued elastic strain in thermosalient crystals,reflected in extraordinarily high velocities of the progressing habit plane,c ould generate detectable acoustic waves.I na ddition to sudden release of accumulated strain, [29,30] elastic waves can evolve by dislocations in plastic deformation, [31][32][33][34] crack formation, [35] anisotropic thermal expansion, [36,37] and rapid molecular rearrangement.…”

“…[16][17][18][19][20][21][22][23][24][25][26][27][28] We hypothesized that the sudden release of the accrued elastic strain in thermosalient crystals,reflected in extraordinarily high velocities of the progressing habit plane,c ould generate detectable acoustic waves.I na ddition to sudden release of accumulated strain, [29,30] elastic waves can evolve by dislocations in plastic deformation, [31][32][33][34] crack formation, [35] anisotropic thermal expansion, [36,37] and rapid molecular rearrangement. [38][39][40][41][42] However,unlike the continuous acoustic emission that occurs during plastic deformation with slow progression of dislocations,the response from the martensitic transitions is discontinuous.T he intensity of the acoustic bursts is several orders of magnitude higher than that of the continuous emission, and is akin to the acoustic emission generated by an avalanche or the seismic waves that precede an earthquake.H erein, we provide direct evidence that, in addition to only one brief previously reported case, [5] the phase transitions in thermosalient crystals are generally associated with outbursts of elastic energy that translate into acoustic waves.T he energy,i ntensity,a nd time scale of the thermoacoustic response is scrutinized with the mechanism of the thermosalient transition. Thea ssociated strong waves carry important information on the dynamics and mechanism of transformation; [43] not only do the results provide deeper understanding of the mechanistic and kinetic profile of the thermosalient phenomenon, but in addition to the previous conclusions,they confirm that the thermosalient materials are molecular analogues of the inorganic martensites and that the molecular solids can behave in am anner similar to metals and alloys.…”

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

“…The material's acoustic activity is, for example, sensitive to the nature of the crystallographic lattice mismatch at the interphase boundaries. Therefore, pronounced AE responses are registered through the phase transitions in normal ferroelectrics 14 as well as in relaxors. [15][16][17] In particular, the AE method has been applied to refining the phase diagram of xPT-͑1−x͒Pb͑Fe 2/3 W 1/3 ͒O 3 relaxor ferroelectric solid solution in the case where dielectric response is particularly insensitive to the phase transitions.…”

“…In contrast, relatively sharp peaks of the AE activity arise at the onset of phase transitions that are associated with acoustic waves produced by collective atomic movement. 2,14 It is noteworthy that the AE signal contains no contribution from either thermally induced stress in the heated sample or residual stress caused by preliminary mechanical polishing, since ͑a͒ a highly elastic thermally conducting glue is used also as a mechanical buffer between the sample and the waveguide and ͑b͒ the samples are routinely annealed at high temperatures, 50°C above the T m , after mechanical polishing. This explains also the very good reproducibility of the AE results.…”