Effects of Zn/Ni Ratio and Doping Material on Piezoelectric Characteristics of Pb((Zn, Ni)1/3Nb2/3)O3–Pb(Zr, Ti)O3 Ceramics

This study investigates the effects of the Zn/Ni composition ratio and doping materials on the piezoelectric properties of PZNN-PZT ceramics for the fabrication of piezoelectric ceramics with excellent characteristics. A soft relaxor was used to improve the electrical characteristics and sinterability. The ceramics were fabricated with a base composition ratio of 0.13Pb((Zn1–xNix)1/3Nb2/3)O3–0.87Pb(Zr0.5Ti0.5)O3. The columbite phase was formed by reacting NiO and Nb2O5, which have low reactivity, as the first calcination, and the columbite precursor method was applied for the second calcination with PbO. Although the pellet was produced by sintering at a relatively low temperature of 950 °C, we obtained a dense ceramic with a high density of 7.9 g/cm3 . To improve the quality factor in the composition with a Ni/(Ni + Zn) molar ratio of 0.1, the doping materials MnO2, Fe2O3, CuO, and Bi2O3 were added and their properties were confirmed. Pure perovskite phases were formed in the ceramics of all compositions and doping materials. In particular, the PZNN-PZT ceramics doped with 0.3 wt% MnO2 showed a piezoelectric coefficient of 348 pC/N, electromechanical coupling factor of 0.59, mechanical quality factor of 345, and Curie temperature of 316 °C, which are excellent piezoelectric characteristics.

Phase diagram and dielectric properties of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics

x Pb ( In 1/2 Nb 1/2) O 3- Pb ( Mg 1/3 Nb 2/3) O 3- PbTiO 3(x PIN –y PMN –z PT ) ternary ceramics with morphotropic phase boundary (MPB) composition were synthesized by columbite precursor method. x PIN –y PMN –z PT phase diagram was investigated by x-ray diffraction and dielectric measurements. According to the results of dielectric measurements, the Curie temperatures (Tc) and rhombohedral to tetragonal phase transition temperature (Tr−t) were found to be in the range of 173–212°C and 114–155°C, respectively, indicating that the Tr-t was increased with adding PIN component. In the MPB region, the highest Tr-t = 155° C was found in 0.32PIN–0.38PMN–0.30PT ceramic, that greatly expanded temperature usage range.

Influences of Excess PbO on Optical Properties and Microstructures of La Modified 0.75Pb (Mg1/3Nb2/3)O3-0.25PbTiO3 Electro-Optic Transparent Ceramics

La-modified 0.75Pb (Mg1/3Nb2/3)O3-0.25PbTiO3(PLMNT) electro-optic (EO) transparent ceramics were synthesized through a columbite precursor method. Excess PbO (10, 15 and 20 mol %) was added to study the effect on the transparency, electro-optic effect, and microstructures of PLMNT transparent ceramics. The phase structure of different samples can be identified as single perovskite structure with no second phase detected. The average grain size increased as the concentration of excess PbO increased from 10 mol% to 20 mol%. On the contrary, the transparency decreased with the increase of the concentration of excess PbO. When the concentration of excess PbO was 10 mol%, the transmittance was about 62% at 632.8nm. The EO coefficient was calculated through measuring the birefringence as a function of electric field. The EO coefficient increased with the increase of the concentration of excess PbO and the maximum EO coefficient reached 40.6×10-16(m/V)2 when the excess PbO was 20 mol%.

Electrical Properties of (1–x)(0.8PMN-0.2PNN)-xPT Ceramics near the Morphotropic Phase Boundary

Ferroelectric ceramics of (1x)(0.8PMN0.2PNN)xPT (x = 0.280.43) were synthesized by the columbite precursor method. Their phase structures as well as the dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction (XRD) results demonstrate that the morphotropic phase boundary (MPB) of this system lies in the composition range of x = 0.31–0.37. Examination of the dielectric behavior indicates that the ceramics exhibit high dielectric constants near the MPB compositions. In addition, the piezoelectric properties of the ceramics were found quite well around the MPB. The interrelated mechanism was also discussed.

Structure and Piezoelectric Properties of PZN-PNN-PT Ceramics

(1-x)(0.64PNN-0.36PT)-x(0.91PZN-0.09PT) ferroelectric ceramics with different x were synthesized by the columbite precursor method. The phase structure and piezoelectric properties were investigated. XRD profiles implied that with the increasing of x, samples could no longer maintain the pure perovskite phase. All the compositions were found to lie within the region of the morphotropic phase boundaries (MPBs) with different contents of rhombohedral and tetragonal phases. The piezoelectric coefficients for compositions with x £ 0.30 were obviously better than those for the rest ones and the composition with x = 0.15 exhibited the largest value of d33 among all the samples. The relationship between the structure and the piezoelectric properties was discussed.

Effects of Lanthanum Modification on the Structure and Electrical Properties of PZN-PZT Ceramics

La-modified PZN-PZT compositions with representative formula Pb1-0.7xLa0.7x(Zn1/3Nb2/3)0.3- (Zr0.55Ti0.45)0.7(1-x/4)O3 were prepared by the columbite precursor method. La content, x, was varied from 0 to 8mol%. Effects of La doping on microstructure, dielectric and piezoelectric properties were investigated. The results showed that in present system La doping promotes the formation of pyrochlore phase and the phase shifted from rhombohedral to tetragonal structure with increasing La content. It was also found that La doping makes dielectric permittivity maximum decrease and the degree of diffuse phase transition enhance. Appropriate amount of La doping could improve the piezoelectric properties.