PZN Ceramics Research Articles

Effect of sintering temperature on phase formation and dielectric property of modified PLZT ceramics with addition of BT and PZN

ABSTRACT The modified-lead lanthanum zirconate titanate (PLZT) ceramics with the addition of barium titanate (BT) and lead zinc niobate (PZN) were prepared. PLZT 9/65/35–BT ceramics changed from ferroelectric rhombohedral phase to paraelectric cubic phase as the content of BT was increased. The optimized dielectric constant at room temperature and frequency of 1 kHz could be obtained when 5 mol% BT was added and the ceramic was sintered at 1275 °C (ϵr = 10463, tanδ = 0.0125). PLZT 8/40/60–PZN ceramics had a perovskite structure with a decrease of unit cell volume as the content of PZN was increased. The optimized dielectric constant at room temperature and frequency of 1 kHz could be obtained when 20 mol% PZN was added and the ceramic was sintered at 1250 °C (ϵr = 14290, tanδ = 0.0081).

Influence of synthesis method on dielectric properties of ceramics of ternary composition PMN-PT-PZN

The influence of different synthesis methods on structure formation, crystallographic aspects, and dielectric properties of PMN-PZN-PT relaxor ferroelectric ceramics were examined. Single-phase perovskite 0.7PMN-0.2PT-0.1PZN ceramics were synthesized at different sintering temperature (1100–1170 °C) by the columbite (M-I) and combustion (M-II) method. Ceramics synthesised were characterised by XRD and SEM to confirm the phase and particle size. Ceramics of composition 0.7PMN-0.2PT-0.1PZN demonstrated relatively lesser grain size and density in columbite method than combustion method. Correlations between the crystal structure, grain size and dielectric properties were established. The Ɛr max values for M-I were 16557–28328 and for M-II were 20145–25865 in the sintering temperature range 1150–1170 °C respectively.

Investigation on Structural and Electrical Property of (1-x) PLZT - x PZN Ceramics

In this study, (1-x)Pb0.92La0.08(Zr0.4Ti0.6)O3 - xPb (Zn1/3Nb2/3)O3 (PLZT-PZN, x = 0, 0.05, 0.10, 0.15 0.20 and 0.25) ceramics with pure perovskite were synthesized by mixed oxide synthetic route via a rapid vibro-milling technique. The ceramic pellets were sintered at 1250°C for 4 h. The phase formation and composition was investigated using X-ray diffraction. The dielectric properties of the densified samples were investigated by LCR meter as a function of temperature and frequency. It can be seen that when optimal amount of PZN was added to tetragonal Pb0.92La0.08(Zr0.4Ti0.6)O3 ceramics, the electrical properties were found to be optimal.

Co-firing of PZT–PMS–PZN/Ag Multilayer Actuator Prepared by Tape-Casting Method

Abstract Multilayer ceramic actuator composed of piezoelectrically active 0.90Pb(Zr0.48Ti0.52)O3–0.05Pb(Mn1/3Sb2/3)O3–0.05Pb(Zn1/3Nb2/3)O3 (PZT–PMS–PZN) layers and electrically conducting silver metal layers were fabricated. Low-temperature sinterable PZT–PMS–PZN ceramics were used as the piezoelectric layers, and silver paste was used as the conductive inner-electrode layers. PZT–PMS–PZN powder, adding 1% CuO as a sintering agent, was prepared by a conventional solid-state reaction process. The green sheet was fabricated by tape-casting method. Silver inner-electrode was printed on the green-tape sheets and the sheets were stacked, warm-pressed, and sintered at 900°C for 4 h after burning out the organic additions. The sintered multilayer ceramics actuator shows distinct layers with few defects in the interfaces. The thicknesses of the piezoelectric and conducting layers are about 40 and 6 μm, respectively. The multilayer PZT–PMS–PZN actuator, composed of 60 active piezoelectric layers, presents a longitudinal displacement of about 2.7 μm at an applied voltage of 80 V, approximately 0.1% of the total thickness of itself.

Identification and Effect of Secondary Phase in MnO2‐Doped 0.8Pb(Zr0.52Ti0.48)O3–0.2Pb(Zn1/3Nb2/3)O3 Piezoelectric Ceramics

0.8 Pb(Zr0.52Ti0.48)O3–0.2 Pb(Zn1/3Nb2/3)O3 (PZT–PZN) and 2 mol% Mn‐doped PZT–PZN ceramics were investigated to deterministically identify the presence and effect of the secondary phase in controlling electrical properties. On the basis of the X‐ray diffraction and energy dispersive spectroscopy analysis, we show that secondary phase in Mn‐doped PZT–PZN is not MnO2 precipitate, but it is related to the formation of ZnO. This result was found to be consistent with the grain growth observed in the Mn‐doped sintered ceramics and changes in ferroelectric behavior. We propose that Mn3+ substitution on Ti and Zr site induces hardening effect, whereas Mn2+ substitution on Zn‐site stabilizes the perovskite phase in synthesis of PZT–PZN.

Origin of polar nanoregions in relaxor ferroelectrics: Nonlinearity, discrete breather formation, and charge transfer

A central issue in the physics of relaxor ferroelectrics is the origin of the formation of polar nanoregions below some characteristic temperature scale. While it is often attributed to chemical disorder, random bond--random field appearance, or local symmetry lowering, it is shown here that the huge intrinsic nonlinearity of ferroelectrics gives rise to spatially limited excitations of discrete breather (DB) type, which interact strongly and self-consistently with the remaining lattice. This scenario corresponds to a two-component approach to relaxor physics with distinctive signatures in the dielectric spectra and strong charge-transfer effects. The theoretical results are compared to broadband dielectric spectroscopy on 0.2PSN-0.4PMN-0.4PZN ceramics, which provides clear evidence for the two-component scenario and the emergence of DB-like dynamics with decreasing temperature.

Surface Characterization of PZN Ceramics Prepared by a Columbite B-Site Precursor

Pyrochlore-type PZN ceramics have been obtained from a two-stage process with columbite B-site precursor. In order to determine the chemical composition of these samples, a combination between X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques has been performed. XRD analysis revealed the coexistence of unreacted PbO starting precursor and major phase of the pyrochlore-type PZN phase as average composition from the bulk volume. While different binding energies (multicomponents) of each chemical element e.g. Pb, Zn, Nb and O from the surface of PZN ceramics were identified by XPS, indicating inhomogeneous surface chemical distribution within these columbite-route samples.

Low-Temperature Sintered Pb(Zr,Ti)O3–Pb(Mn,Sb)O3–Pb(Zn,Nb)O3 for Multilayer Ceramic Actuators

A quaternary 0.90Pb(Zr0.48Ti0.52)O3–0.05Pb(Mn1/3Sb2/3)O3–0.05Pb(Zn1/3Nb2/3)O3 (0.90PZT–0.05PMS–0.05PZN) piezoelectric ceramic was synthesized by a conventional method, and CuO was adopted to lower its sintering temperature. The crystal structure, micromorphology, and electrical properties were studied in terms of CuO content. The results indicate that 1.0 wt % CuO addition significantly improves the sinterability of 0.90PZT–0.05PMS–0.05PZN ceramics, lowering the sintering temperature to 900 °C and maintaining moderate electrical properties: d33=306 pC/N, Qm=997, kp=53.6%, tan δ=0.50%, and ε33T/ε0=1350. The low-temperature sintering behavior could be explained by the formation of a transient liquid phase by CuO during sintering. Moreover, the endothermic peak at about 950 °C in the differential thermal analysis (DTA) curve of the raw ceramic powder provides further evidence of an amorphous phase. To obtain better piezoelectric properties, La2O3 was selected as the donor dopant for the 0.90PZT–0.05PMS–0.05PZN + 1.0 wt % CuO system. Our study demonstrates that La2O3 is very effective in improving piezoelectric properties, markedly increasing d33 and kp without decreasing Qm. Finally, 0.5 wt % La2O3 added 0.90PZT–0.05PMS–0.05PZN + 1.0 wt % CuO ceramics show excellent electrical properties: d33=355 pC/N, Qm=936, kp=58.4%, tan δ=0.32%, and ε33T/ε0=1590, which are quite suitable for multilayer piezoelectric ceramic actuators.

Effect of MnO2 on the Piezoelectric Properties of the 0.75Pb(Zr0.47Ti0.53)O3–0.25Pb(Zn1/3Nb2/3)O3 Ceramics

MnO2 was added to 0.75Pb(Zr0.47Ti0.53)O3–0.25Pb(Zn1/3Nb2/3)O3 (0.75PZT–0.25PZN) ceramics in order to make a high‐power piezoelectric material. The Mn4+ ion produced a defect dipole consisting of an Mn4+ ion and an oxygen vacancy that transformed the 0.75PZT–0.25PZN ceramics into hard materials. The Qm value significantly increased with the addition of MnO2 and reached a value of 1680 for the 1.5 mol% MnO2‐added 0.75PZT–0.25PZN ceramic. Moreover, this specimen exhibited a high kp of 0.53 with a ɛ3T/ɛ0 of 1518. Additionally, the 1.5 mol% MnO2‐added 0.75PZT–0.25PZN ceramics sintered at 900°C for 4 h also exhibited high piezoelectric properties of Qm=1115, kp=0.50, and ɛ3T/ɛ0=1537.

Ferroelectric Properties of Pb(Zr<sub>1/2</sub>Ti<sub>1/2</sub>)O<sub>3</sub>-Pb(Zn<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub> Ceramics under Compressive Stress Applied Perpendicular to Electric Field

Effects of perpendicular compressive stress on the ferroelectric properties of ceramics in PZT-PZN system were investigated. The (1-x)Pb(Zr1/2Ti1/2)O3-xPb(Zn1/3Nb2/3)O3 or (1-x)PZT- (x)PZN (x = 0.1-0.5) ceramics were prepared by a conventional mixed-oxide method. The ferroelectric properties were measured under compressive stress applied perpendicular to an electric field direction at stress levels up to 90 MPa using a compressometer in conjunction with a modified Sawyer-Tower circuit. It was found that with increasing compressive stress the area of the ferroelectric hysteresis (P-E) loops, the maximum polarization (Pmax), and the remanent polarization (Pr) decreased, while the coercive field (Ec) remained relatively constant. These results were interpreted through the domain switching, clamping of domain walls and de-poling mechanisms.

Effects of CuO addition on the electrical responses of the low-temperature sintered Pb(Zr0.52Ti0.48)O3–Pb(Mg1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3 ceramics

Abstract Pb(Zr 0.52 Ti 0.48 )O 3 –Pb(Mg 1/3 Nb 2/3 )O 3 –Pb(Zn 1/3 Nb 2/3 )O 3 ceramics were prepared using the conventional mixed-oxide route. The effects of CuO addition on the phase transition and electrical responses were investigated. X-ray diffraction analysis indicated that the phase of the material changed from an rhombohedral structure to a MPB structure and then a tetragonal structure when the CuO content was increased from 0.00 to 0.30 wt.%. The P – E hysteresis loops of CuO-doped PZT–PMN–PZN ceramics showed pinched shapes instead of the normal square-like P – E loops. The pinched loops were assumed to be the result of the pinning effect of the defect dipoles. Optimized electrical properties, such as d 33 = 280 pC/N, k p = 0.53, tan δ = 0.0090, Q m = 1645 and ɛ r = 982, were achieved by doping 0.20 wt.% CuO in PZT–PMN–PZN ceramics sintered at 920 °C.

Effect of Pb(Zn1/3Nb2/3)O3 Additions on Phase Structure, Ferroelectric and Dielectric Properties of PbZrO3 Ceramics

Polycrystalline samples of (1-x)PbZrO 3 −xPb(Zn 1/3 Nb 2/3 )O 3 , where x = 0.0–0.3, were prepared by the columbite method. Sintering was performed at 1,250°C for 2–4 h in PbO atmosphere. The X-ray diffraction (XRD) was used to investigate pure phase perovskite in sintered ceramics. Moreover, dielectric and ferroelectric properties have been determined via dielectric spectroscopy and hysteresis loop measurement, respectively. Complete solid solutions of the perovskite phase of PZ−PZN ceramics were obtained in all compositions. The phase transformation from orthorhombic to rhombohedral was observed at composition 0.2 < x < 0.3. Furthermore, a change from antiferroelectric behavior in the PZ ceramic to normal ferroelectric behavior in PZ−PZN ceramics was observed in composition 0.1 < x < 0.2. These results clearly show the significance of added PZN in reducing the antiferroelectric behavior in PZ ceramic.

Effect of ZnO addition on the sintering and electrical properties of (Mn,W)-doped PZT–PMS–PZN ceramics

The effect of ZnO addition on the phase structure, microstructure and dielectric and piezoelectric properties of 0.2 wt.% MnO 2 and 0.6 wt.% WO 3-doped Pb(Zr 0.52Ti 0.48)O 3–Pb(Mn 1/3Sb 2/3)O 3–Pb(Zn 1/3Nb 2/3)O 3 (PZT–PMS–PZN) ceramics was investigated. X-ray diffraction shows that the phase structure of ceramics is transformed from rhombohedral to tetragonal with the increasing of ZnO addition. The bulk density significantly increases when ZnO is added and then it slightly decreases for ZnO addition above 0.2 wt.%. SEM micrographs show the grains of ceramics are uniform and well developed by adding 0.1 wt.% ZnO. The Curie temperature ( T c) of 270 °C is obtained at the 0.1 wt.% ZnO addition. Mechanical quality factor ( Q m), electromechanical coupling factor ( K p) and piezoelectric constant ( d 33) increase firstly, and then decrease with the increasing of ZnO addition, while dielectric loss tan δ drops all the time. The Q m, K p, d 33, tan δ and T c of the ceramics show the optimum values of 1899, 0.55, 300 (pC/N), 0.0063 and 270 °C, respectively, at the lower sintering temperature of 1120 °C and with 0.1 wt.% ZnO addition.

Ferroelectric properties of Pb(Zr1/2Ti1/2)O3–Pb(Zn1/3Nb2/3)O3 ceramics under compressive stress

Effects of compressive stress on the ferroelectric properties of ceramics in PZT–PZN system were investigated. The ceramics with a formula (1− x )Pb(Zr 1/2 Ti 1/2 )O 3 – x Pb(Zn 1/3 Nb 2/3 )O 3 or (1− x )PZT–( x )PZN ( x = 0.1–0.5) were prepared by a conventional mixed-oxide method. The ferroelectric properties under the compressive stress of the PZT–PZN ceramics were observed at the stress levels up to 170 MPa using a compressometer in conjunction with a modified Sawyer–Tower circuit. It was found that with increasing compressive stress the area of the ferroelectric hysteresis ( P – E ) loops, the saturation polarization ( P sat ), the remnant polarization ( P r ), and the coercive field ( E c ) decreased. These results were interpreted through the non-180° ferroelastic domain switching processes.

Stress-dependent ferroelectric properties of Pb(Zr1/2Ti1/2)O3–Pb(Zn1/3Nb2/3)O3 ceramic systems

Abstract Effects of compressive stress on the ferroelectric properties of ceramics in PZT–PZN systems were investigated. (1 − x )Pb(Zr 1/2 Ti 1/2 )O 3 ( x Pb(Zn 1/3 Nb 2/3 )O 3 or (1 − x )PZT–( x )PZN ( x = 0.1–0.5) ceramics were prepared by a conventional mixed-oxide method. The ferroelectric properties under compressive stress of the PZT–PZN ceramics were observed at stress levels up to 170 MPa using a compressometer in conjunction with a modified Sawyer–Tower circuit. It was found that with increasing compressive stress the area of the ferroelectric hysteresis (P–E) loops, the saturation polarization ( P sat ), the remanent polarization ( P r ), and the coercive field ( E c ) decreased. These results were interpreted through the non-180° ferroelectric domain switching processes.

Effects of La2O3 Addition and PbO Excess on the Transmittance of PbZrO3–PbTiO3–Pb(Zn1/3Nb2/3)O3 Ceramics by Spark Plasma Sintering

The effects of La2O3 addition and PbO excess on the microstructures and optical properties of PbZrO3–PbTiO3–Pb(Zn1/3Nb2/3)O3 (PZ–PT–PZN) ceramics prepared by spark plasma sintering were investigated. When 1 mol% La2O3 was added, the highest transmittance of 35% at 700 nm for PZ–PT–PZN ceramics was obtained. The improved transmittance was attributed to the increased relative density and the decreased optical anisotropy. The samples containing more than 1 mol% La2O3 showed decreased transmittance, due to the appearance of secondary phases. The transmittance of PZ–PT–PZN ceramics increased slightly to 29% at 700 nm with increasing amount of excess PbO up to 10 mol% and thereafter decreased rapidly.

Low-temperature sintering of MnO2-doped PZT–PZN Piezoelectric ceramics

The effect of MnO2 addition on the microstructural evolution and piezoelectric properties of low temperature sinterable PZT–PZN ceramics was investigated. When a small amount of MnO2 (≤0.5 wt% ) was added, the Mn ions were homogeneously dissolved in the PZT–PZN ceramics, leading to full densification at a temperature as low as 930 °C. However, the further addition of MnO2 hindered the densification, causing the specimen to have a high porosity and small grain size. In addition, as the MnO2 content increased, the crystal structure of the PZT–PZN changed gradually from a tetragonal to a rhombohedral phase, due to the substitution of Mn for the B-sites in the perovskite structure. The addition of MnO2 up to a maximum of 0.5% improved the mechanical quality factor (Qm) of the PZT–PZN ceramics markedly, while keeping the kp and d33 values reasonably high. The 80% PZT–20% PZN doped with 0.4 wt% MnO2 exhibited excellent piezoelectric properties; Qm = 1,000, kp = 0.62, and d33 = 330 pC/N.

The improvement in dielectric and ferroelectric performance of PZT–PZN ceramics by thermal treatment

Abstract Pyrochlore-free lead zirconate titanate – lead zinc niobate ceramics have been systematically investigated in the as-sintered condition as well as after annealing. The ceramics were characterized by dielectric spectroscopy and Sawyer–Tower polarization (P–E) measurements. The powders of Pb[(Zr1/2Ti1/2)(1−x)–(Zn1/3Nb2/3)x]O3, where x = 0.1, 0.3 and 0.5 were prepared using the columbite–(wolframite) precursor method. The general trend seems to indicate that the annealed samples become more normal-ferroelectric-like behavior as opposed to the relaxor-ferroelectric-like behavior observed in the as-sintered state. The as-sintered 0.9PZT–0.1PZN ceramic exhibited weak relaxor-ferroelectric behavior, with a relatively low dielectric constant maximum of 14,000 measured at 1 kHz. Annealing resulted in a transition to normal-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 360 °C to 350 °C, and a dramatic increase in the dielectric constant at 1 kHz to a maximum value of 35,000 for the longer anneal. After thermal annealing at 900 °C for one week a strong enhancement of remanent polarization (Pr) was observed.

Phase transition of xPMnS-(1－x)PZN ceramics

The phase transformation of xPMnS-(1-x)PZN quaternary piezoelectric ceramics was studied and the effect of composition on phase transformation characteristics was also discussed. Results indicate that xPMnS-(1-x) PZN ceramics show disperse phase change characteristic and obvious dielectric thermal lag in the course of the phase change. The result of electronic structure investigation indicates that the disperse phase change should be attributed to the difference in strength of B—O bonds. The material has relaxation ferroelectric characteristics When x value is large (or small), and shows relatively strong disperse phase change. It has normal-relaxation ferroelectric characteristics when x value is near 0.4, and shows relatively weak disperse phase change.

Dielectric and ferroelectric characteristics of 0.7PZT–0.3PZN ceramics substituted with Sr

Lead zirconate titanate–lead zinc niobate (PZT–PZN) ceramics with compositions close to the morphotropic phase boundary were investigated as a function of Sr doping. The powders were prepared using the columbite-(wolframite) precursor method. Dielectric and ferroelectric properties of the as-sintered and annealed samples were measured. The results showed that with increasing Sr concentration dielectric constant versus temperature curves become gradually broader. Sr doping has been shown to produce a linear reduction in the transition temperature (Tm) (294.1−12.7x °C) with concentration (x). The maximum value of the dielectric constant decreased and the degree of diffuse phase transition was enhanced with Sr doping. However, the results indicated that the degree of disorder in Sr-modified PZT–PZN was further improved by thermal annealing. After thermal annealing at 900°C for 48 h a strong enhancement of dielectric constant (εr) and remanent polarization (Pr) was observed.