Papers by Author: Xiang Ping Jiang

Abstract: Lead-free piezoelectric ceramics Na0.5Bi0.5TiO3+xmol%Co3+ (NBT-xC) were synthesized by conventional solid-state process. Effects of Co3+ addition on the phase structure, dielectric and piezo- electric properties of NBT-xC were investigated. The X-ray diffraction suggested that all specimens were rhombohedral perovskite structure. After a small addition of Co2O3, a dense microstructure with increased grains was developed. The doping with Co3+ enhanced mechanical quality factor Qm significantly, whereas piezoelectric constant d33 and electromechanical coupling factor kp decreased slightly with increasing amount of Co3+. For the ceramics with x=3, the electric properties become optimum, which are as follows: d33=~70pC/N, kp=~13%, Qm=~934, tanδ=~0.02 (1kHz), respectively. These results indicate that the Co3+ ion was considered to replace Ti4+ ion and present “hard doping” effect.

Abstract: (1-x)(Na0.5Bi0.5)TiO3-xBaTiO3 (abbreviated as NBBT100(1-x)/100x or NBBT100x) solid solution single crystals with x=0, 0.06, 0.08, 0.10, 0.20, 1.0 were grown using top-seeded solution growth (TSSG) method. Dielectric, piezoelectric and ferroelectric properties of NBBT crystals were investigated as a function of temperature, frequency, composition and crystal orientation. The temperature (Tm) corresponding to dielectric maximum and the depolarization temperature (Td) decrease with increasing x. The <001> oriented NBBT90/10 single crystal shows excellent piezoelectric performance with piezoelectric constant (d33) value about 275pC/N and exhibits relatively smaller coercive field (Ec) of 2.49 kV/mm and dielectric loss tanδ of 2.9 %, indicating a more adaptive engineered domain structure.

Abstract: Lead-free piezoelectric ceramics of (Na0.8K0.2)0.5Bi0.5TiO3+x wt.% Mn (abbreviated as NBKT-x% Mn, x=0~0.5) were synthesized by solid-state reaction. The grain growth of the ceramics was restrained by Mn-doping at a certain extent. The mechanical quality factor Qm increases and the dielectric loss tanδ decreases with the increase of Mn-doping. Best piezoelectric properties were obtained for the composition of NKBT-0.2%Mn: d33=158 pC·N-1, tanδ=2.9% at 1 kHz, Qm=110 and kp=30%. The P-E loops show that remnant polarization Pr and coercive field Ec decrease slightly with the amount of the Mn2+ increasing up to 0.2wt.% and then increase as the content of Mn2+ increases further. NKBT-0.5wt. % Mn exhibits strong ferroelectricity with remnant polarization Pr = 38μC/cm2.

Abstract: Barium titanate with A-site substituted by various amount of bismuth oxide (Ba1-x BixTiO3, abbreviated as BBT, x=0.05, 0.1, 0.15) were prepared by solid-state reaction. The effect of bismuth substitution on crystallographic phase, dielectric and ferroelectric properties was studied. The X-ray diffraction shows that the samples were crystallized into pure perovskite structure when x=0.05 and 0.1, while for x=0.15 sample, second phase appeared in the dominant perovskite phase. The temperature dependence of dielectric permittivity of the ceramics was investigated and the evolution from normal ferroelectrics to relaxor ferroelectric sates was observed. In the range 0≤x≤0.1, the temperature of dielectric peak Tm is independence of the frequency, indicating the normal ferroelectrics behavior. At x=0.15, dielectric relaxation process with a broadening distribution of the permittivity dielectric is observed.

Abstract: PZT-based slurry with Newtonian behavior was prepared for tape casting. The viscoelasti cproperties of the slurry were studied. High quality of green tape and well sintered of PZT-based thick films are obtained using the PZT-based slurry with Newtonian behavior.

Abstract: The use of lead zirconate titanate ceramics for high power application must have superior mechanical properties, the composition Pb0.98Sr0.02(Mn1/3Sb2/3)0.05Zro.48Ti0.47O3 + x wt% SiO2 (x = 0-1.0) have been studied for this purpose. The microstructures were observed to study the improvement of mechanical properties by SEM and TEM. The nano-scale secondary phase of SiO2 and PbSiO3 were observed on the grain boundary and the twinned ZrO2 was found surrounded by PMS-PZT perovskite phase. The mechanism to the occurrence of twinned ZrO2 and its content increased with increasing Si concentration are discussed in the paper. The occurrence of the nonferroelectric phase such as ZrO2, SiO2 and PbSiO3 on the grain boundary should be the main reason for great improvement of fracture strength.