Orapim Namsar

Effect of Si3N4 nanoparticulates on the mechanical and electrical properties of PZT ceramics

PZT/xSi3N4 ceramics (when x=0, 0.1, 0.5 and 1?wt.%) were prepared by a solid-state mixed-oxide method and sintered at 1125??C for 2?h. X-ray diffraction results suggested that the addition of Si3N4 nanoparticulates did not significantly affect the unit cell and tetragonality of PZT. The addition of 0.1?wt.%?Si3N4 effectively increased the density and reduced the grain size of PZT ceramics. These changes played an important role in hardness and fracture toughness improvement. The maximum room temperature dielectric constant was achieved in a PZT/0.1?wt.%?Si3N4 sample. Within the Si3N4-containing samples, the high-temperature dielectric values and ferroelectric properties seemed to increase with increasing concentrations of Si3N4.

Enhancement of fatigue endurance in ferroelectric PZT ceramic by the addition of bismuth layered SBT

Electrical fatigue properties of (1-x)PZT-xSBT ceramics (x = 0–1.0 weight fraction) were characterized. It was found that pure PZT ceramic had severe polarization fatigue. This was mainly attributed to an occurrence of the macroscopic cracks at near-electrode regions. On the contrary, pure SBT ceramic exhibited excellent fatigue resistance, which was attributed primarily to weak domain wall pinning. As small amount of SBT (0.1 ≤ x ≤ 0.3) was added into PZT, a small reduction of remanent polarization after fatigue process was observed. This demonstrated that these ceramics had high stability during the repeated domain switching due to their low oxygen vacancy concentration. Therefore, these results suggested that this new ceramic PZT-SBT system seemed to be an alternative material for replacing pure PZT in ferroelectric memory applications.

Dielectric, Polarization and Strain Response of Enhanced Complex Ceramics: The Study through Pb(Zr0.52Ti0.48)O3-SrBi2Ta2O9

Electrical properties of the (1-x)PZT-xSBT ceramics (0.1≤x≤0.3) were investigated in comparison with pure PZT and SBT ceramics. It was found that the dielectric constant increased with small addition of SBT (x = 0.1) into PZT. The hysteresis loop measurement demonstrated that the PZT-SBT ceramics showed larger remanent polarization than pure PZT and less coercive filed than pure SBT ceramic. Strain behavior showed a symmetric butterfly curve in the compositions with 0≤x≤0.3 but the low strain obtained was found in pure SBT. This research suggested that 0.9PZT-0.1SBT ceramic is a promising material to be further utilized in ferroelectric memory devices.

Polarization fatigue in ferroelectric Pb(Zr0.52Ti0.48)O3-SrBi2Nb2O9 ceramics

Ferroelectric fatigue induced by cyclic electric loading of the (1-x)PZT-xSBN ceramics (0.1 ≤ x ≤ 0.3) have been investigated in comparison with pure PZT and SBN ceramics. The results showed that pure PZT ceramic possessed severe polarization fatigue after long bipolar switching pulses. This was mainly attributed to the appearance of microstructural damage at the near-electrode regions. Whereas, pure SBN ceramic exhibited no fatigue at least up to 1 × 106 switching cycles. The fatigue-free behavior of SBN ceramics was due primarily to weak domain wall pinning. PZT-SBN ceramics showed less polarization fatigue up to 1 × 106 switching cycles than pure PZT. This could be attributed to their low oxygen vacancy concentration. Therefore, this new ceramic PZT-SBN system seems to be an alternative material for replacing PZT in ferroelectric memory applications.

Improvement of Ferroelectric Properties of PZT Ceramics by SBT Addition

(1−x)PZT-xSBT ceramics were prepared by a solid-state mixed oxide method. Phase characteristics of (1−x)PZT-xSBT ceramics showed a PZT phase and new phase in the compositions with 0.1 ≤ x ≤ 0.3, while a mainly new phase was observed in the composition with x = 0.5. The tetragonality (c/a) of PZT phase decreased with increasing in SBT content up to x = 0.3. SEM micrographs of the sample surface showed equiaxed grains of the PZT phase and irregularly-shaped grains of the new phase in samples with 0.1 ≤ x ≤ 0.3. The 0.5PZT-0.5SBT sample showed mainly irregularly-shaped grains of the new phase. The ferroelectric properties of these samples showed that the addition of small amounts of SBT (x = 0.1) into PZT increased the remanent polarization.