The Investigation on the Fabrication and Characterization of the Multicomponent Ceramics Based on PZT and the Relaxor PZN-PMnN Ferroelectric Materials

This chapter presents the investigation of fabrication and the physical properties of the Pb(Zr1−xTix)O3-Pb(Zn1/3Nb2/3)O3-Pb(Mn1/3Nb2/3)O3 multicomponent ceramics. The multicomponent yPb(Zr1−xTix)O3-(0.925 − y)Pb(Zn1/3Nb2/3)O3-0.075Pb(Mn1/3Nb2/3)O3 (PZT-PZN-PMnN) ceramics were synthesized by conventional solid-state reaction method (MO) combined with the B-site oxide mixing technique (BO). Research results show that the electrical properties of PZT-PZN-PMnN ceramics are optimal at a PZT content of 0.8 mol and Zr/Ti ratio of 48/52. At these contents, the ceramics have the following optimal properties: electromechanical coupling factor, kp = 0.62 and kt = 0.51; piezoelectric constant (d31) of 130 pC/N; mechanical quality factor (Qm) of 1112; dielectric loss (tan δ) of 0.005; high remanent polarization (Pr) of 30.4 μC.cm−2; and low coercive field (EC) of 6.2 kV.cm−1. Investigation of the domain structure of the two ferroelectric phases (tetragonal and rhombohedral) in the ZnO-doped PZT-PZN-PMnN with compositions at near the morphotropic phase boundary is described as follows: the 90 and 180° domains exist in the tetragonal phase, while the 71, 109, and 90° domains are located in the rhombohedral phase, and the widths of these domains were about 100 nm. Besides, the ceramics exhibited excellent temperature stability, which makes them a promising material for high-intensity ultrasound applications

STRUCTURE, MICROSTRUCTURE, AND PIEZOELECTRIC PROPERTIES OF KNLNS-BNKZ LEAD-FREE CERAMICS UNDER THE EFFECT OF DIFFERENT SINTERING TEMPERATURES

Samples of 0.96(K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 piezoelectric ceramic were fabricated with conventional ceramic techniques and sintered at different temperatures. The effect of sintering temperature (TS) on the structure, microstructure, and piezoelectric properties of the ceramics was studied in detail. The experimental results showed that with an increase of the TS temperature, the structure of the ceramics transformed from an orthorhombic-tetragonal mixed phase (O-T) at TS £ 1100 °C into a rhombohedral-tetragonal (R-T) mixed phase with a dense microstructure of uniform grain size at TS = 1110 °C. When TS was further increased (TS ³ 1120 °C), the ceramics showed only a rhombohedral phase (R). The ceramics showed the best electrical properties for TS = 1110 °C at which the rhombohedral and tetragonal (R-T) phases coexist. Specifically, the ceramic density reached its highest value (4.22 g/cm3), the electromechanical coupling coefficients kp and kt were 0.46 and 0.50, respectively, and the piezoelectric coefficient d33 was 245 pC/N.Samples of 0.96(K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 piezoelectric ceramic were fabricated with conventional ceramic techniques and sintered at different temperatures. The effect of sintering temperature (TS) on the structure, microstructure, and piezoelectric properties of the ceramics was studied in detail. The experimental results showed that with an increase of the TS temperature, the structure of the ceramics transformed from an orthorhombic-tetragonal mixed phase (O-T) at TS £ 1100 °C into a rhombohedral-tetragonal (R-T) mixed phase with a dense microstructure of uniform grain size at TS = 1110 °C. When TS was further increased (TS ³ 1120 °C), the ceramics showed only a rhombohedral phase (R). The ceramics showed the best electrical properties for TS = 1110 °C at which the rhombohedral and tetragonal (R-T) phases coexist. Specifically, the ceramic density reached its highest value (4.22 g/cm3), the electromechanical coupling coefficients kp and kt were 0.46 and 0.50, respectively, and the piezoelectric coefficient d33 was 245 pC/N

ẢNH HƯỞNG CỦA NHIỆT ĐỘ ĐẾN TÍNH CHẤT ĐIỆN MÔI, SẮT ĐIỆN VÀ ÁP ĐIỆN CỦA GỐM KNLNS-BNKZ

Traditional ceramic technology combined with a two-step sintering technique has been applied to prepare 0.96(K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 (KNLNS-BNKZ) piezoelectric ceramics. The experimental results show that the ceramic samples have a pure perovskite structure with the coexistence of tetragonal and rhombohedral phases. Effects of temperature on the dielectric, ferroelectric, and piezoelectric properties of the ceramics were investigated in detail. The results show that the characteristic parameters for the piezoelectric and ferroelectric properties of the ceramics, such as the electromechanical coupling coefficient kp, the piezoelectric factor d31, and the remnant polarization Pr are largely stable from room temperature to 100 °C.Hệ gốm 0,96(K0,48Na0,48Li0,04)(Nb0,95Sb0,05)O3-0,04Bi0.5(Na0,82K0,18)0,5ZrO3 (KNLNS-BNKZ) đã được chế tạo bằng công nghệ gốm truyền thống kết hợp với kỹ thuật thiêu kết hai bước. Kết quả thực nghiệm cho thấy vật liệu có cấu trúc perovskit với pha hỗn hợp tứ giác-mặt thoi, không có pha lạ thứ hai. Ảnh hưởng của nhiệt độ đến các tính chất điện môi, sắt điện và áp điện của mẫu gốm đã được khảo sát. Kết quả cho thấy các thông số đặc trưng cho tính chất áp điện và sắt điện của gốm như hệ số liên kết điên cơ kP, hệ số áp điện d31, độ phân cực dư Pr là khá ổn định trong khoảng nhiệt độ từ nhiệt độ phòng đến 100 °C

Relaxor ferroelectric properties of PZT-PZN-PMnN Ceramics

555-560xPb(Zr0.47Ti0.53)O3-(0.925-x)Pb(Zn1/3Nb2/3)O3-0.075Pb(Mn1/3Nb2/3)O3+0.7%wt Li2CO3 (PZT-PZN-PMnN) ceramics with x=0.65-0.9 have been prepared by two-stage calcination method. The effect of the PZT content on the relaxor behavior and ferroelectric properties of ceramics has been investigated. The degree of diffuseness () from 1.72 to 1.85 indicates that all of compositions show a diffused phase transition with the strong frequency dispersion, which is characteristic of relaxor ferroelectric materials. The sharpness of the permittivity peak shows that the compositions are gradually approached normal ferroelectric behavior when the mol fraction of PZT increases. At x = 0.80, dielectric and ferroelectric properties of ceramics are optimal with the mass density () of 7.81 g/cm3, the dielectric constant (εr) of 1230, the dielectric loss (tan) of 0.005 and the remanent polarization (Pr) of 27 mC/cm2. </span

PHYSICAL PROPERTIES OF PZT-PZN-PMnN CERAMICS WERE FABRICATED BY B-SITE OXIDE MIXING TECHNIQUE

The 0.65Pb(Zr0.47Ti0.53)]O3 - 0.275Pb(Zn1/3Nb2/3)O3 - 0.075Pb(Mn1/3Nb2/3)O3 (PZT-PZN-PMnN) ceramics were synthesized by conventional solid-state reaction method (MO) and the B-site oxide mixing technique (BO). Experimental results showed that the B-site oxide mixing technique exhibits superior behavior compared with MO method in suppressing pyrochlore phases, stabilizing perovskite structure, and improving the physical properties of PZT-PZN-PMnN ceramics. The BO ceramic samples have the optimal electromechanical properties: the electromechanical coupling factor (kp) of 0.51, (kt) of 0.38, the dielectric constant (ε) of 1100, the dielectric loss (tand) of 0.005, the maximum dielectric constant (emax) of 7614, the mechanical quality factor (Qm) of 1111 and the remanent polarization (Pr) of 20.5 mC/cm2, which makes it as a promising material for high power piezoelectric devices