Dielectric and resonance frequency investigations of phase transitions in Nb-doped PZT95/5 and 75/25 ceramics

Abstract

The low-temperature - high-temperature rhombohedral-ferroelectric phase transition and the rhombohedral-ferroelectric - cubic-paraelectric phase transition in Nb-doped ceramics (x = 0.05 and 0.25) were investigated using dielectric and resonance frequency measurements. The dielectric behaviour in PZT(Nb)95/5 is found to obey the Curie - Weiss law above , while that of PZT(Nb)75/25 deviates from the linear Curie - Weiss law in a temperature range of above , and can be described by the relation with the exponent in the range . Dielectric dispersions are observed in the rhombohedral-ferroelectric region for both compositions. Dielectric anomalies and thermal hysteresis are observed in PZT(Nb)95/5; in contrast, no anomaly appears in PZT(Nb)75/25. Around the phase boundary region, the temperature dependences of the resonance frequencies for both compositions show remarkable anomalies. The piezoelectric constant of PZT(Nb)95/5 rapidly decreases, but that of PZT(Nb)75/25 gradually increases. These results are discussed on the basis of the coupling of M-type and R-type oxygen octahedra tilts to the polarization and strain.

Refined phase portrait of the rhombohedral region of the x–T diagram of the Pb(Zr1–x Ti x )O3 system and singularities of dielectric spectra of its solid solutions

“…In the same work, the phase diagram of the system was constructed in the interval 0.04 ≤ x ≤ 0.15. The presence of the R3c → R3m transition was later confirmed, e.g., in [6][7][8]. For example, in [6], for SSs with x = 0.07 modified with Nb and Sn, the strongest variation in the transition region was observed in the temperature dependence of the piezoelectric resonance frequency f r of the radial oscillation mode of a polarized sample.…”

“…In [7], in the study of SSs with the composition 0.65PbZrO 3 -0.35PbTiO 3 modified with La, an anomaly in the temperature dependence of the longitudinal acoustic velocity has been found. In [8], from temperature dependences of dielectric, piezoelectric, and ferroelectric characteristics of two SSs of this system with x = 0.05 and x = 0.25 doped with 1 mol% Nb 2 O 5 , an alteration in the character of the R3c → R3m transition, consisting in the practically full disappearance of anomalies of macro responses with increasing temperature in a sample with x = 0.25, was established. In [9], the presence of the R3c → R3m transition was confirmed by neutral diffraction methods with x = 0.10.…”

“…Therefore, the refinement of the position of the known phase diagram region and confirmation of the recently discovered rotational transition curve in the Rh-region of the phase diagram required additional studies with the use of other methods. To this end, we used high temperature measurements of f r with allowance for the data of [5][6][7][8].…”

Inspection of Remanent Polarization in the Ferroelectric Ceramic PZT 95/5 Through Pyroelectric Effect

“…The change of polarization during FE LT –FE HT phase transformation was tested by heating the sample to 343 K at a rate of 1 K/min (FE LT –FE HT phase transformation temperature is 333 K) 7 . A capacitor of 10 μF was used to collect pyroelectric charge, and a millivoltmeter with high resistance (>10 13 Ω) was used to measure the voltage of the capacitor.…”

Performance analysisis of PZT (0.52/0.48) for high temperature and pressure sensing applications

“…Such devices can be used in many applications such as oil and gas drilling, aeronautic and space structures, and turbines [1]. In the past, lead zirconate titanate or [Pb(Zr1-x Tix )O3] based devices have been widely used in actuators and sensors owing to their intrinsic advantages such as strong piezoelectric effect, low power, high energy densities, low cut-off frequency, fast operation, excellent electrical properties and high Curie temperature system [2,3]. Among all PZT compositions, Pb(Zr 0.52 Ti 0.48 )O 3 , where structure changes from rhombohedral-ferroelectric rhombohedral (R) to tetragonal (T) via a narrow monoclinic (M) region has been of particular interest in MEMS applications because of PZT's excellent ferroelectric and electro-optic properties at this point [4][5][6].…”