Additional phase transition in a PbZr_0.87Ti_0.13O₃ single crystal

Abstract

PbZr 1−x Ti x O 3 (PZT) ceramics are one of the most known and widely used piezoelectric materials. In order to understand the origin of the high piezoelectricity it is essential to also understand its phase diagram. Many recent papers have reported the modification of PZT phase diagram based on ceramic experimental data. This is due to difficulties to get good quality single crystal samples. We have succeeded in getting a good quality single crystal with x = 0.13. Based on temperature changes of elastic properties we confirmed the existence of additional phase transition appearing in the PbZr 0.87 Ti 0.13 O 3 . The temperature dependence of the elastic properties was investigated by means of piezoelectric measurements and Brillouin light scattering. We discussed the correlation between anomalies of the elastic properties found in these measurements, and suggested that, except for the two wellknown phase transitions, these anomalies point to another phase transition below T c . The structure and symmetry of this crystal have been tested with use of the xray diffraction at the room temperature.

Phase Transitions and Local Polarity above TC in a PbZr0.87Ti0.13O3 Single Crystal

“…At higher temperatures, the loss of the octahedral tilts causes the space group to become R3m [19]. Recent structural studies of the PZT crystal with Ti content of x = 0.13 have shown that in 300 K the monoclinic phase Cm fits the structure better than the rhombohedral (R) one [9]. This is in line with the diagram proposed by Zhang et al (see figure 7 in [4]) for ceramics.…”

“…The reason is that the pyroelectric current and elastic compliance were measured with different heating rates. It should be noted that the temperature of 448 K is related to a transition associated with lattice instability, reported by Cordero et al and Lazar et al [7][8][9]. It has already been proven that PZT single crystals have complex domain structures over a wide temperature range [11].…”

“…Powder diffraction measurements executed on crushed transparent single PbZr 0.87 Ti 0.13 O 3 crystal grown by top-seeded solution growth (TSSG) technique had been performed at room temperature [9]. The concentrations of elements were examined by SEM technique, using JSM-5410 electron microscope by Jeol with energy dispersion x-ray spectrometer EDS by Oxford Instruments.…”

“…For a long time, the PZT phase diagram developed by Jaffe et al [2] has been accepted as the basic characterization of the PZT solid solution. However, many reports [3][4][5][6][7][8][9] show that the Jaffe's diagram needs verification. One of the reasons for it is that it was developed on the basis of ceramics only, because PZT crystals growth process has been developed only recently.…”

“…As early as 40 years ago, Whatmore et al [10] found that the diagram for ceramics differs from that for crystals. Only a few reports described the properties of PZT single crystals [1,[9][10][11][12][13][14][15][16], mainly due to above mentioned technological difficulties related to their growth. Our high quality single PbZr 0.87 Ti 0.13 O 3 crystal enabled investigations of phase transformations, domain structure, optical, dielectric, pyroelectric and elastic properties.…”