Phase transformation of "chem-prep" PZT 95/5-2Nb HF1035 ceramic under quasi-static loading conditions (original) (raw)
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Ceramics International, 2012
This paper investigated the low-frequency mechanical properties of ferroelectric ceramics (PZT-5H and PZT-8) and anti-ferroelectric ceramics ((Pb 0.97Àx Ba x La 0.02 )(Zr 0.50 Ti 0.10 Sn 0.40 )O 3 , x = 0.08, 0.09, 0.10, 0.11) by a dynamic mechanical analyzer (DMA). The dynamic mechanical analysis was performed from À100 to 400 8C in temperature and 0.1-4 Hz in frequency. The dielectric properties were also measured as a comparison. The results showed an obvious turning point (T m ) where tan d reached its maximum and the modulus began to increase for all the samples. tan d revealed an relaxation region in the ferroelectric ceramics and no corresponding region in the anti-ferroelectric ceramics, which may be originated from the domain walls' motion in the ceramic. The tan d started to decrease to nearly zero around the tetragonal to cubic phase transition temperature (T c ) for all of the tested samples. #
Transformation toughening in an antiferroelectric ceramic
Due to a larger specific volume of the ferroelectric phase, the antiferroelectric-to-ferroelectric transition is believed to have an enhanced toughening effect against fracture. The toughening requires a non-recoverable transformation in the crack process zone. Complementary measurement of the crystal symmetry, dielectric constant, field-induced polarization and Raman spectrum on ceramic Pb0.99Nb0.02[(Zr0.57Sn0.43)0.92Ti0.08]0.98O3 indicates that the antiferroelectric and the ferroelectric states are equally stable at room temperature. Raman mapping further reveals the presence of the ferroelectric phase in a localized zone at the crack tip after unloading. A significant phase-transition-toughening effect is demonstrated in the antiferroelectric ceramic with both indentation fracture and R-curve experiments. The effect in this model composition leads to toughness values 50% larger than other antiferroelectric ceramics with similar compositions and 60–130% higher than ferroelectric Pb(Zr,Ti)O3 ceramics. A simple analysis confirms the toughening effect from both volumetric phase transition and deviatoric domain witching during the transformation. The results suggest that other materials near phase boundaries may have similar high fracture resistance.
Evaluation of Toughness Anisotropy on Doped PZT Ceramics as a Function of Load and Temperature
2013
The crack growth resistance behaviour of a doped lead zirconate titanate (PZT) ceramic as a function of loading conditions has been investigated over a temperature range between room temperature (RT) and 400 °C, i.e. above the Curie temperature. The stress-induced switching process has been assessed under compression tests on both preand post-indented poled specimens. Non-poled samples have been used as reference material. The change in crack length depending on the poling state before and after the tests has been measured to account for the ferroelectric/ferroelastic behaviour of the PZT material. A corresponding fracture mechanics analysis has revealed toughness anisotropy in the specimens with respect to the poling direction. Experimental findings show the effect of temperature in the domain switching process which can be enhanced by additional mechanical loading, leading to partially depolarisation of the PZT material. The effect of poling orientation coupled with temperature an...
Uniaxial stress dependence of ferroelectric properties of xPMN-(1–x)PZT ceramic systems
Applied Physics A, 2005
Effects of uniaxial compressive pre-stress on the ferroelectric properties of ceramics in the PMN-PZT system are investigated. The ceramics with a formula xPb(Mg 1/3 Nb 2/3 )O 3 -(1−x)Pb(Zr 0.52 Ti 0.48 )O 3 or xPMN-(1 − x)PZT when x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0 are prepared by a conventional mixed-oxide method. The ferroelectric properties under the uniaxial compressive pre-stress of the PMN-PZT ceramics are observed at the stress levels up to 13 MPa using a compressometer in conjunction with a modified Sawyer-Tower circuit.
Phase transition study in PLZT ferroelectric ceramics by mechanical and dielectric spectroscopies
Materials Science and Engineering: A, 2009
Measurements of anelastic and dielectric spectroscopies have been conducted in (Pb/La)(Zr/Ti)O 3 (PLZT) ferroelectric ceramics, with Zr/Ti = 65/35 and with La = 5 at.% and 8 at.%. Both the anelastic and the dielectric results have shown the presence of ferroelectric-paraelectric phase transitions around 250 • C for PLZT 5/65/35 and around 150 • C for PLZT 8/65/35, where the shift of the maximum elastic (electric) susceptibility for low temperatures with increase of lanthanum amount can be observed. The behavior of the relative variation of the elastic moduli as a function of the temperature was compared to the Landau-Devonshire theory of phase transitions. These results revealed the change of the kind of coupling between strain and order parameter in the ferroelectric-paraelectric phase transition with the increase of lanthanum concentration.
Journal of Electroceramics, 2007
An iterative automatic method is used to calculate, from impedance measurements at resonance in three sample shapes and four modes of resonance, all the directly obtained coefficients that are needed to determine the ten elastic, dielectric and piezoelectric complex coefficients of the characteristic matrix of a 6mm symmetry ferro-piezoelectric ceramic for a controlled porosity material. A soft PZT ceramic with a Morphotropic Phase Boundary (MPB) composition was studied. Samples with homogeneously distributed close porosity were prepared and tested. A fugitive phase was added to the perovskite type structure precursor powder to produce the porous materials and the samples were consolidated by die pressing.
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 1989
Absfruct-Pure (undoped) piezoelectric lead zirconate titanate (PZT) ceramic samples at compositions across the ferroelectric region of the phase diagram have been prepared from sol-gel derived fine powders. Excess lead oxide was included in the PZT powders to obtain dense (95-96 percent of theoretical density) ceramics with large grain size (> 7 pm), and to control the lead stoichiometry. The dielectric, piezoelectric, and elastic properties were measured from 4.2-300" K. At very low temperatures, the extrinsic domain wall and thermal defect motions "freeze out." The low temperature dielectric data will be used to determine coefficients in a phenomenological theory. The extrinsic contribution to the properties can then be separated from the single domain properties derived from the theory.
Structural Transformation and Pressure-Induced Phase Transition in PZT
Integrated Ferroelectrics, 2002
Angle-dispersive X-ray diffraction, Raman scattering and dielectric spectroscopy measurements versus hydrostatic pressure were carried out to follow the crystalline-to-crystalline transformation occurring in PbZr 1−x Ti x O 3 ceramic powders. Different PZT compositions under hydrostatic pressure up to 20 GPa were studied. Dielectric measurements versus pressure up to 2 GPa are discussed to bring new insights on the Pressure-composition (P-x) phase diagram. Based on these results, an updated version of the PZT (P-x) phase diagram is proposed.
Effects of uniaxial stress on dielectric properties of ferroelectric ceramics
Current Applied Physics, 2006
The effects of uniaxial stress on the dielectric properties of ceramics in PMN-PZT system are investigated. Ceramics with the formula (x)Pb(Mg 1/3 Nb 2/3)O 3-(1 À x)Pb(Zr 0.52 Ti 0.48)O 3 when x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0 are prepared by a conventional mixed-oxides method. The sintered ceramics are perovskite materials with their physical properties proportionally depending on the PMN and PZT contents. The dielectric properties under the uniaxial stress of the unpoled and poled PMN-PZT ceramics are observed at stress levels up to 5 MPa. For the unpoled ceramics, the dielectric properties do not change significantly with the applied stress and the changes are independent of the ceramic compositions. For the poled ceramics, on the other hand, the dielectric constant of the PZT-rich compositions increases slightly, while that of the PMN-rich compositions decreases with increasing applied stress. In addition, changes in the dielectric loss tangent with stress are found to be composition independent. This study clearly shows the influences of the domain reorientation , domain wall motion, degradation and depoling mechanisms on the variation of the dielectric properties of PMN-PZT ceramics under the uniaxial stress.
Journal of Alloys and Compounds, 2011
In the present work the (Pb 0.84 Ba 0.16)(Zr 0.54 Ti 0.46)O 3 (PBZT 16/54/46) ceramics has been studied from the point of view of its electrical properties. Dielectric properties of PBZT were measured within the temperature range of the ferroelectric-paraelectric (FE-PE) phase transition region. The method of fieldinduced thermally stimulated currents (FITSC) was applied and thus the thermal relaxation effects were studied. The observed field dependence of thermally stimulated depolarization currents has revealed the existence of different frequency-dependent relaxation processes in the temperature range between 200 and 400 • C. Our experiment demonstrates that modification of ferroelectric materials with isovalent ions, but bigger radii than the origin atom, significantly affect its properties, particularly the PBZT real part of electrical permittivity shows the phase transition character change from ferroelectric to relaxor and finally, that electrical examination can be effectively used for drawing decisive applications conclusions considering polarization parameters distribution.