PbTiO3 Binary System Research Articles

Phase transition and thermal stability of 5.4BiScO3−(94.6-x)PbZrO3−xPbTiO3 ternary system with excellent piezoelectric properties

The 5.4BiScO3−(94.6-x)PbZrO3−xPbTiO3 (43.0 < x < 51.0 mol%) ternary piezoelectric ceramics were synthesized by solid-state reaction method. Phase transition from rhombohedral to tetragonal structure was identified by X-ray diffraction. In combination with piezoelectric and dielectric properties, the morphotropic phase boundary (MPB) composition was confirmed in 5.4BiScO3−47.6PbZrO3−47.0PbTiO3 ceramic with optimal piezoelectric coefficient d33 of 474 pC/N, relative dielectric constant er of 1666, mechanical coupling factor kp of 0.64 and mechanical quality factor Qm of 415 at room temperature. Besides, the 5.4BiScO3−47.6PbZrO3−47.0PbTiO3 ceramic retained most of the piezoelectric properties in broad temperature range between 40 and 300 °C, which exhibited excellent thermal stability. There were only gentle variations in d33 (Δd33/d33 = 10.6%), kp (Δkp/kp = 14.1%), Qm (ΔQm/Qm = 10.3%), and er (∂e/∂T = 13.2/°C) at 300 °C, indicating BiScO3 doping in PbZrO3−PbTiO3 binary system could form a potential candidate for high temperature applications.

Effect of Nd3+ substitution on structural, ferroelectric, magnetic and electrical properties of BiFeO3–PbTiO3 binary system

In this paper, we have reported the effect of rare earth Nd3+ ion substitution on crystal structure, ferroelectric, electrical and magnetic behavior of morphotropic phase boundary (MPB) composition of polycrystalline ceramics 0.7Bi(1−x)NdxFeO3–0.3PbTiO3(BNFPT), where x = 0, 0.05, 0.10. Rietveld refinement of XRD profiles confirms coexistence of rhombohedralR3c and tetragonal P4mmpolymorphs forming MPB for all the compositions. We observed that the remnant polarization Pr increases with increasing Nd3+ concentration. Piezoelectric studies show gradual increase in piezoelectric coefficient (d33) from 11 to 34 pC/N with increase in Nd3+ concentration for BNFPT samples. All compositions exhibit weak ferromagnetic character. For the same composition range, the study of dielectric behavior revealed gradual decrease in Curie temperature (Tc) as we increased doping content of Nd3+.

Construction of high Tc BiScO3-BiFeO3-PbTiO3 and its enhanced piezoelectric properties by sintering in oxygen atmosphere

The high-temperature piezoelectric ceramics 0.36[(1 − x)BiScO3-xBiFeO3]-0.64PbTiO3 was constructed by introducing BiFeO3 with a high Curie temperature (Tc ∼ 830 °C) in the 0.36BiScO3-0.64PbTiO3 binary system. In terms of microstructure, low-melting BiFeO3 plays a role as a sintering aid, lowering the sintering temperature of the ceramic and significantly increasing the grain size. At the same time, the crystal structure shifts from the initial morphotropic phase boundary to the tetragonal phase side, and the Tc increased gradually with increasing BiFeO3 content. Under the conventional air atmosphere sintering conditions, the Tc of the sample with x = 0.3 can reach ∼500 °C, and the piezoelectric constant d33 is 125 pC/N. Compared with that, the d33 of the same composition sample sintered in an oxygen atmosphere is increased to 165 pC/N, which is mainly due to the decrease in the content of oxygen vacancies that helps to increase poling electrical field. Moreover, the oxygen-sintered specimen exhibits an excellent thermal stability in a wide temperature range from room temperature to 450 °C, indicating that it is a promising candidate for ultra-high-temperature piezoelectric devices applications.

A new multiferroic ternary solid solution system: NdFeO3–Pb(Fe1/2Nb1/2)O3–PbTiO3

Ceramic materials were sintered from powders of the NdFeO3–Pb(Fe1/2Nb1/2)O3–PbTiO3 (NF–PFN–PT) ternary system synthesized by the conventional solid reaction method and their multiferroic properties investigated. The structure, electric and magnetic properties of the ternary system have been investigated. The introduction of Pb(Fe1/2Nb1/2)O3 into the NdFeO3–PbTiO3 binary system can effectively increase its electric properties. The ternary system exhibits enhanced piezoelectric property with optimal piezoelectric constants d33=143pC/N, reduced coercive fields EC=5.78kV/cm and remnant polarization Pr=12.8μC/cm2 for 0.10NF–0.56PFN–0.34PT, near tetragonal phase region. The Curie temperature (TC) of the NdFeO3–Pb(Fe1/2Nb1/2)O3–PbTiO3 ceramics varies in the range from 108.7°C to 67.9°C. The magnetic hysteresis loops show that the ternary system is paramagnetic originating from canting of paramagnetic sublattices in NF–PFN–PT, due to the rare earth ions Nd3+ influencing on the exchange interaction between Fe3+ ions at the octahedral sites.

Investigation of (1−x)(Bi0.94La0.06)(Ga0.05Fe0.95)O3–xPbTiO3 ceramics for high temperature applications

BiFeO3–PbTiO3 binary system doped with small amount of La3+ and Ga3+ was investigated for the development of piezoelectric ceramics with high Curie temperatures. Crystalline solutions of (1−x)(Bi0.94La0.06)(Ga0.05Fe0.95)O3–xPbTiO3 (BLGF–xPT) for x=0.35, 0.37, 0.4 and 0.45 have been fabricated by the solid-state reaction method. X-ray diffraction reveals that BLGF–PT has a single perovskite structure with a mixed phase region at x=0.35–0.37. The dielectric constant (K), loss tangent (tanδ), Curie temperature (TC), remnant polarization (Pr) and piezoelectric constant (d33) of 700, 0.021, 532°C, 30μC/cm2 and 63pC/N respectively, have been achieved for x=0.35. The strain under the electric field of 90kV/cm was measured to be 0.107% for x=0.37 and the planar electro-mechanical coupling coefficient (Kp) of 19% was stable under 310°C, about 60% of its TC, indicating high thermal stability of the piezoelectric properties.

Piezoelectric Ceramics with Compositions at the Morphotropic Phase Boundary in the BiFeO3–PbZrO3–PbTiO3 Ternary System

Since ceramics in the PbZrO3–PbTiO3 binary system display excellent piezoelectric properties and those in BiFeO3–PbTiO3 exhibit high Curie temperatures, morphotropic phase boundary (MPB) compositions in the BiFeO3–PbZrO3–PbTiO3 ternary solid solution system are investigated for the development of piezoelectric ceramics for high temperature applications. It is found that the MPB compositions in the ternary system deviate away from the mixture of two binary MPB compositions 0.70BiFeO3–0.30PbTiO3 and 0.52PbZrO3–0.48PbTiO3. With decreasing amount of BiFeO3 in the MPB compositions in the ternary system, the Curie temperature TC is observed to decrease while the piezoelectric coefficient d33 is found to increase. Accompanied with this trend are the decrease in the c/a ratio of the tetragonal phase, the increase in the dielectric constant and the decrease in the loss tangent of the ceramics at room temperature. It is further noticed that the compositions in the rhombohedral‐rich side of MPB exhibit slightly better piezoelectric properties. An example of such compositions is 0.511BiFeO3–0.326PbZrO3–0.163PbTiO3, with TC of 431°C, d33 of 101 pC/N, and the electromechanical coupling factor kp of 0.50.

Synthesis and properties of BiScO3-PbTiO3 powders and thin films using metal-organic precursor solutions

The BiScO3–PbTiO3 binary system is known to have a morphotropic phase boundary (MPB) and a higher Curie temperature than Pb(Zr,Ti)O3 and to exhibit excellent dielectric and ferroelectric properties. Perovskite BiScO3–PbTiO3 powders and thin films were synthesized via a chemical process using metal-organic precursor solutions. Homogeneous and stable precursor solutions, perovskite BiScO3–PbTiO3 single-phase powders and thin films on Pt/TiOx/SiO2/Si substrates were successfully prepared by optimizing the processing conditions. The 0.35BiScO3–0.65PbTiO3 composition was close to the MPB and had a Curie temperature of around 470°C. The electrical properties of BiScO3–PbTiO3 thin films showed a maximum at this composition. The dielectric permittivity of the 0.35BiScO3–0.65PbTiO3 thin film at the MPB was approximately 1700, with a dielectric loss tangent of less than 5% at room temperature. Furthermore, BiScO3–PbTiO3 thin films showed a typical ferroelectric polarization (P)–electric field (E) hysteresis loop. The remnant polarization (Pr) and coercive field (Ec) of the 0.35BiScO3–0.65PbTiO3 film were approximately 23 µC/cm2 and 70 kV/cm, respectively.

Effects of Pressure on Piezoelectric and Dielectric Responses of Relaxor Ferroelectric Solid Solution Pb(Mg1/3Nb2/3)O3–PbTiO3 Binary System Ceramics near a Morphotropic Phase Boundary Composition

The piezoelectric and dielectric properties of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMNT) ceramics with compositions near a morphotropic phase boundary (MPB) were investigated under pressures p up to 700 MPa at 25 °C. The resonance and antiresonance frequency characteristics of impedance and phase in the k31 mode for PMNT (67/33) and (69/31) ceramics were observed under various pressures. The effect of pressure on their responses were clearly observed. The electromechanical coupling coefficient k31 in the k31 mode increases and the electromechanical quality factor Q decreases with increasing p at pressures lower than 100 MPa. The decrease in Q with p is due to the scattering of ultrasonic waves from the domain boundary. The relative permittivity εr increases with increasing p. Such increases in both k and εr with p seem to be related to the increase in topographical domain-wall density associated with monoclinic distortions. At pressures higher than 100 MPa, their electromechanical suppression in PMNT ceramics occurs at each pressure, corresponding to the electromechanical coupling coefficient k. εr increases with pressure-induced electromechanical suppression. The change in εr with such suppression corresponds to k. Such a phenomenon seems to be due to the increase in piezoelectric load based on the increase in complex domain wall density coming from the increase in free energy with pressure.

Pressure-modulated free energy change in piezoelectric and dielectric responses for relaxor ferroelectric solid solution Pb(Mg1∕3Nb2∕3)O3–PbTiO3 binary system single crystal and ceramics near a morphotropic phase boundary composition

The electromechanical and dielectric responses in transverse and longitudinal modes for relaxor ferroelectric solid solution Pb(Mg1∕3Nb2∕3)O3–PbTiO3 (PMNT) near a morphotropic phase boundary composition were investigated under hydrostatic pressures up to 700MPa at 25°C. The effect of pressure on their responses remarkably appeared. Their electromechanical suppression in PMNT single crystal and ceramics occurs at each pressure, corresponding to electromechanical coupling coefficient k. The permittivity ε increased with pressure-induced electromechanical suppression. The change in ε with such suppression corresponds to k. Such phenomena were considered to be due to the increase in piezoelectric load based on decrease of domain size coming from increase in free energy with pressures.

Pressure-induced suppression of piezoelectric response in a Pb(Zn1∕3Nb2∕3)O3–PbTiO3 binary system single crystal near a morphotropic phase boundary

Piezoelectric properties of Pb[(Zn1∕3Nb2∕3)0.91]Ti0.09O3 single crystal poled along the [001] direction in rhombohedral phase was investigated under pressures (p) up to 700MPa at 25°C. For the transverse electromechanical property, piezoelectric response on impedance and phase frequency characteristic curves abruptly disappeared above 500MPa. For the longitudinal one, sharpness of shape in their curves at resonant and antiresonant frequencies became broader above 500MPa, and piezoelectric response rapidly depressed with p. Such rapid suppression of piezoelectric response above 500MPa is considered to be due to decrease in contribution of shear mode based on volume contraction caused by hydrostatic pressure.

Pressure dependence of piezoelectric properties of aPb(Mg1/3Nb2/3)O3–PbTiO3 binary system single crystal near a morphotropic phase boundary

The piezoelectric properties of aPb[(Mg1/3Nb2/3)0.68]Ti0.32O3 binary system single crystal poled along the [001] direction in therhombohedral phase were investigated under pressures up to 400 MPa at25 °C. For the transverse electromechanical property, the differenceΔf between the resonancefr and antiresonancefrequencies fa, the Δf/fr and the electromechanical coupling coefficientk31 value in thek31 mode withhydrostatic pressure (p) became smaller because of the increase infr and the almostconstant fa with p. The k31 value decreased by 16% at 400 MPa. On the other hand, for the longitudinal electromechanical property,the Δf, theΔf/fr and thek33 valuein the k33 mode with p remained almost constant because of the almost constantfr and fa with p. The changes in the values of the elastic compliancess11E ands33E withp were found to be largefrom the changes in fr and fa with p. s11E ands33E at 400 MPa wereestimated to be 35.4 and 75.1 × 10−12 m2 N−1, respectively. A mechanical quality factorQ almost constantwith p in thek33 mode in contrast tothe large decrease in Q in the k31 mode with p in the pressure range up to 200 MPa was observed. Ak33 value almostconstant with p is considered, on the basis of the engineered domain concept, to bedue to the stable domain configuration responsible for the longitudinalk33 mode. Furthermore, the superior piezoelectric properties of the rhombohedral [001]single crystal in the vicinity of the morphotropic phase boundary compositionwere recently pointed out to come from the large shear piezoelectric constantd15 of their single domain property. The hydrostatic pressure cannot influence thepiezoelectric properties from the viewpoint of the contribution of the large shear moded15, since the uniform pressure introduces no shearing stresses. Consequently, thek33 value measured forthe k33 mode remainedalmost constant with p in the measured pressure range.

Temperature Dependence of Piezoelectric Properties of a High Curie Temperature Pb(In1/2Nb1/2)O3-PbTiO3 Binary System Single Crystal near a Morphotropic Phase Boundary

The temperature dependence of the dielectric and piezoelectric properties of a 0.72Pb(In1/2Nb1/2)O3-0.28PbTiO3 binary system single crystal oriented along the [001] axis near a morphotropic phase boundary was investigated in poled and unpoled states. With poling, the permittivity εr and the dielectric loss tangent tan δ decrease from 2650 and 0.05 before poling to 800 and 0.01 after poling, respectively. The change in both the εr and the tan δ at the ferroelectric rhombohedral-to-tetragonal phase transition temperature Tfr with temperature are significantly reduced with poling. The electromechanical coupling coefficient in the rectangular bar mode, k33′=77%, for phase-array ultrasonic transducers was obtained using the rhombohedral 0.72Pb(In1/2Nb1/2)O3-0.28PbTiO3 single crystal oriented along the [001] axis. With increasing temperature, the value of k33′ decreases slightly in the rhombohedral phase, shows a slight anomaly around Tfr, and then remains almost constant in the tetragonal phase. Even at 200°C, the k33′ value decreases by only 5%. The piezoelectric constant d33 was 700 pC/N at room temperature.

Morphotropic ceramic solid solutions of the Pb(B3+ ½Nb½)O3 - PbTiO3 binary system

The structure, dielectric, ferroelectric and electromechanical properties of lead lutecium niobate-titanate (PLuNT) and lead erbium niobate-titanate (PErNT) binary systems are reported. The data of phase diagram, crystallographic symmetry and morphotropic phase boundaries (MPB) are provided. High values of the electromechanical coupling coefficients kp = 0.66, kt = 0.48, k31 = 0.36 of (1−x)PLuN − xPT ceramics are attained in compositions near the MPB at x≈0.41.

Structure and Properties of Hot-Pressed Pb(Lu1/2Nb1/2)O3-PbTiO3 Binary System Ceramics*

Solid solution series of the (1 - x)Pb(Lu1/2Nb1/2)O3 - x PbTiO3 binary system ceramics (PLuNT) were synthesized and hot-pressed (temperature 950°C to 1130°C, pressure 25 MPa); its structure, dielectric and piezoelectric properties were studied. Pure lutecium niobate PLuN (x = 0) has a pronounced long-range order in the B-sublattice and an antiferroelectric to paraelectric phase transition at ∼258°C. The phase structure of the PLuNT system, at room temperature, changes from a pseudomonoclinic (psd-M, space group Bmm2) to tetragonal (T, space group P4mm). The pseudomonoclinic phase extends over the 0 ≤ x ≤ 0.38 interval within which the monoclinic angle β proceeds a minimum near to 90° at x ≅ 0.2. The morphotropic region covers the interval x = 0.38 - 0.49, the concentration ratio psd-M:T≅ 1 (the morphotropic phase boundary—MPB) corresponds to x = 0.41. Within the morphotropic region, a rather strong distortion of the unit cell—(c/a - 1)≥ 0.02, β ≥ 90.37o, characteristic of “hard” piezoelectrics is maintained. Dielectric dispersion and broadening of the phase transition, features typical to relaxors, are observed within the concentration interval of 0.1 ≤ x ≤ 0.3. The highest electromechanical coupling coefficients: kp = 0.66, kt = 0.48, k31 = 0.34 of (1 - x) PLuN−xPT ceramics are attained in compositions near the MPB at x ≈ 0.41. Non-isovalent doping of PLuNT with La3+ in Pb sublattice shifts the MPB to lower values of x.