Undoped PZT Ceramics Research Articles

Sol-Gel Derived PZT and PZTN Ceramics: A Role of Sintering Temperature

PZT and Nb-doped PZT (PZTN) ceramics were fabricated from triol sol-gel derived powders. The pellets were sintered at temperatures in the range of 1050–1200°C for 2 h. Coexistence of tetragonal and rhombohedral phases was clearly observed in PZT ceramics sintered at ≤1150°C, while PZTN ceramics showed coexistence of these phases at ≥1100°C. Densities of undoped PZT ceramics were rather low but could be improved by Nb addition. Grain growth inhibition was also observed in all PZTN samples. The dielectric constant was found to depend mainly on density of the ceramics. An addition of Nb dopant into PZT improved dielectric constant values regardless of sintering temperature.

EFFECT OF RARE-EARTH (RE = La, Nd, Ce AND Gd) DOPING ON THE PIEZOELECTRIC of PZT(52:48) CERAMICS

The purpose of this research is to study the effect of doping some rare earth ions into PZT(52:48) ceramics. The ferroelectric Pb ( Zr x Ti 1-x) O 3 ceramics are well-known as piezoelectric materials for electro-mechanical transducers such as ultrasonic generator, electronic buzzer, and stress sensor, etc. The highest piezoelectric coupling coefficients as well as maximum permittivity are located near the morphotropic phase boundary (MPB). The region of phase transition between the tetragonal and rhombohedral structures in the Pb ( Zr x Ti 1-x) O 3 ceramic shows very adoptable piezoelectric characteristics due to the phase coexistence phenomena, and exhibits a sensitivity of properties to the preparation method, the composition, the firing temperatures and the kinds of additives. The purpose of this research is to study the effect of doping La , Nd , Ce and Gd into Pb ( Zr 0.52 Ti 0.48) O 3 ceramics prepared by solid state reaction. The properties include microstructure, physical properties, dielectric constant (εr) and piezoelectric properties (kp and Qm) of undoped and La , Nd , Ce and Gd doped PZT ceramics. Several effects, such as firing temperature, grain size and dopants, on the properties of PZT were also studied. The undoped PZT ceramics with Zr/Ti at 52/48 indicated the highest εr=1969 and kp= 0.381 for La doping. Doping with La , Nd , Ce and Gd led to an improvement in the εr but a reduced Qm value. The optimum values of electric properties were found in PZT (52/48) doped La with 10.0 mol% sintered at 1200°C for 2 h.

Composition dependence of the domain configuration and size in Pb(Zr1−xTix)O3 ceramics

The composition dependent variation of domain configuration and size in Pb(Zr1−xTix)O3 (PZT) has been investigated in a detailed transmission electron microscopy study in the range of 0.40⩽x⩽0.55. Single phase composition, Pb(Zr0.45Ti0.55)O3 and Pb(Zr0.60Ti0.40)O3, the former belonging to the tetragonal, the latter to the rhombohedral phase, feature small microdomain widths coupled with a pronounced bimodal domain distribution. Samples with compositions around the morphotropic phase boundary exhibit a decrease of bimodal distribution and an increase in microdomain width associated with nanodomain formation. The investigation of micro- and nanodomains, as well as the bimodal distribution of microdomains in undoped PZT ceramics, with respect to composition, is reported. We define nanodomains as “domains arranged within microdomains possessing a width of a few nanometers.” The strict alternation of the two orientation variants of microdomains is denoted as “bimodal domain distribution,” and is characterized by narrow and broad microdomains, which join each other in turn.

Optimized conditions for fabrication of La-dopant in PZT ceramics

The ferroelectric Pb(Zr x Ti 1 − x )O 3 ceramics are well known as piezoelectric materials for electro-mechanical transducers. The highest piezoelectric coupling coefficients as well as maximum permittivity are located near the morphotropic phase boundary (MPB). The region of phase transition between the tetragonal and rhombohedral structures in the Pb(Zr x Ti 1 − x )O 3 ceramic shows very adaptable piezoelectric characteristics due to the phase coexistence phenomena and exhibits a sensitivity of properties to the preparation method, the composition, the firing temperatures and the kinds of additives. The purpose of this research is to determine the optimum condition and the effect of doping La into Pb(Zr 0.52Ti 0.48)O 3 ceramics prepared by solid state reaction. The properties, such as microstructure, physical properties, dielectric constant ( ɛ r) and piezoelectric properties ( k p and Q m) of undoped and lanthanum-doped PZT ceramics were investigated. Several effects, such as firing temperature, grain size and dopant content on structure and properties of PZT have also studied. The undoped PZT ceramics with Zr/Ti at 52/48 indicated the highest ɛ r = 1101 (sintering for 1 h) and k p = 0.39 (sintering for 2 h). Doping with lanthanum ion led to an improvement in the ɛ r but a reduced Q m value. The optimum values of k p is found to be 0.48 for PLZT (1/52/48) doped with 1.00 mol% La 3+ and sintered at 1200 °C for 1 h.

수열합성법으로 제조된 PZT 분말의 특성

Conditions for formation of perovskite Pb(Zr 0.52 Ti 0.48 )O₃ phase by the hydrothermal synthesis are investigated. Pb(Zr 0.52 Ti 0.48 )O₃ ceramics were synthesized by hydrothermal process above 180℃ for 2 h reaction using 5~30 M KOH solution as a mineralizer. Particle size increases in proportion to the mineralizer concentration. As a result of EDX analysis, PZT powders synthesized using 50 M of KOH as a mineralizer were considered as 2.42 mol% K doped-PZT powders. And 2.42 mol% K doped-PZT has much higher mechanical quality factor than undoped PZT ceramics. The sintering properties showed 7.987 g/㎤ of sintered density and 3~4 ㎛ of grain size.

Internal friction in hard and soft PZT-based ceramics

This study concerns the two following commercial ceramics: PZT TRS100 (US Navy I standard: hard material) and PZT TRS600 (US Navy VI standard: soft material). These materials are PZT ceramics with various dopants. Internal friction and elastic modulus measurements have been performed versus temperature at different frequencies. Considering the hard ceramic, two relaxation peaks (R1, R2) related to oxygen vacancies–domain walls interaction were observed similarly to undoped PZT ceramics. In addition, a phase transition peak (P1) occurs at the Curie temperature. Considering the soft ceramic, only two phase transition peaks were observed. The increase of modulus associated with the phase transition internal friction peak occurs at the Curie temperature in both samples. The effects of some dopants are investigated. Some of them influence either the concentration of oxygen vacancies or the domains structure.

Internal friction study of Pb(Zr,Ti)O3 ceramics with various Zr/Ti ratios and dopants

The Pb(Zr,Ti)O3 (PZT) ceramics with Zr/Ti ratios of 30/70, 52/48 and 70/30 and the PZT(52/48) ceramics doped with La, Ta and Co at various percent were prepared by a standard solid-state reaction method, respectively. Internal friction and modulus were measured as a function of temperature at low frequencies by using a inverted torsion pendulum. Two internal friction peaks (P1 and P2), related to oxygen vacancies and domain walls, respectively, were observed in all the undoped PZT ceramics with different Zr/Ti ratios. In addition, a minimum in modulus associated with a phase transition internal friction peak appearing at Curie temperature was observed in all samples. The effects of the Zr/Ti ratios and some dopants (such as La, Ta and Co) on the internal frictions were investigated. The internal friction results indicate the changes of the concentration of oxygen vacancies and the domain structure with the variations of Zr/Ti ratios and dopants, which will be helpful in the utilities of the PZT ceramics.

Phase transitions in Nb-doped Pb(Zr0.95Ti0.05)O3 ceramics investigated by dielectric, pyroelectric and Raman scattering measurements

Dielectric and other complementary measurements were carried out in order to confirm the AO-FR(LT)-FR(HT)-PC phase sequence and to determine the temperatures of each phase transition occurring in undoped PZT ceramics with Zr/Ti ratio 95/5 and Nb-doped ceramics with 0.25 ÷ 1 weight % of Nb2O5. These measurements revealed the diffused character of particular phase transitions and especially of the AO-FR(LT) one. The AO-FR(LT) and FR(LT)-FR(HT) phase transitions occur only in the part of sample volume in the vicinities of the determined temperatures of these transitions and the first one is extremaly broadened and extended towards the low temperatures in the remaining volume of the crystal. Temperature evolution of Raman spectra and the central peak revealed changes of the structure, frequencies and intensity of the scattered light in each phase transition.

Coupled losses in PZT near the morphotropic phase boundary

Abstract A set of complex dielectric, piezoelectric and elastic constants of undoped PZT ceramics with various Zr/Ti ratios are measured in a temperature range between 4.2 K and the Curie point. In the imaginary parts there exist pronounced loss peaks below 250 K, of which the height and temperature strongly depend on the c/a ratio. For PZT close to the morphotropic phase boundary, but with prevailing rhombohedral symmetry, a second peak above 400 K is observed in all constants.