Tharathip Sreesattabud

Effect of ZnO Nano-Particulates on Structure and Properties of PZT/ZnO Ceramics

In this research, effect of ZnO nano-particles on structure, mechanical and electrical properties of PZT ceramics was investigated. X-ray diffraction result suggested that tetragonality of PZT decreased with increasing ZnO content. Density tended to increase with an addition of ZnO while grain size of the ceramics decreased. An addition of ZnO increased hardness of the ceramics. Maximum hardness was achieved at an addition of 0.5 wt% ZnO. Within the PZT/ZnO ceramics, increasing content of ZnO gradually increased fracture toughness. Electrical properties characterization of the ceramics showed that an addition of ZnO reduced dielectric constant and slightly lowered Curie temperature. Ferroelectric measurement found that an addition of < 0.5 wt% ZnO did not significantly change ferroelectric properties. However, these properties were degraded at higher content of ZnO.

Phase and electrical properties of PZT thin films embedded with CuO nano-particles by a hybrid sol-gel route

Pb(Zr0.52Ti0.48)O3 or PZT thin films embedded with CuO nano-particles were successfully prepared by a hybrid sol-gel process. In this process, CuO (0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 wt. %) nanopowder was suspended in an organometallic solution of PZT, and then coated on platinised silicon substrate using a spin-coating technique. The influence of CuO nano-particles’ dispersion on the phase of PZT thin films was investigated. XRD results showed a perovskite phase in all films. At the CuO concentration of 0.4–1 wt. %, a second phase was observed. The addition of CuO nano-particles affected the orientation of PZT thin films. The addition was also found to reduce the ferroelectric properties of PZT thin films. However, at 0.2 wt. % CuO concentration, the film exhibited good ferroelectric properties similar to those of PZT films. In addition, the fatigue retention properties of the PZT/CuO system was observed, and it showed 14% fatigue at 108 switching bipolar pulse cycles while the fatigue in PZT thin films was found to be 17% at the same switching bipolar pulse cycles.

Electrical Properties of Sol-Gel Derived PZT/WO3 Ceramics

PZT/xWO 3 powders were prepared from the powders synthesized by a modified triol sol-gel method. XRD and TEM results suggested that fully crystallized powders were obtained at the calcination temperature of 600°C for 4 h. A reaction between PZT and WO 3 powders seemed more pronounced with increasing WO 3 content. To prepare PZT/xWO 3 ceramics, the powders were pressed and sintered at 1100°C for 6 h. Phase characterization by XRD indicated that the concentration of WO 3 affected lattice parameters and reduced c/a ratios, especially for high content of WO 3 . SEM images showed that an addition of only 0.5 wt% WO 3 significantly decreased grain size of the ceramics. Density of the ceramics, however, did not significantly depend on WO 3 concentration below 1 wt%. Addition of suitable amount of WO 3 enhanced ferroelectric properties and reduced high-temperature dielectric loss of PZT ceramic.

Fabrication and characterization of sol-gel derived PZT/WO3 ceramics

Lead zirconate titanate/tungsten oxide (PZT/WO3) ceramics were prepared from the powders synthesized by a modified triol sol-gel processing method. In this study, the starting materials used for synthesis of PZT-sol were zirconium (IV) propoxide, titanium (IV) isopropxide, lead (II) acetate trihydrate and 1,1,1,- tris (hydroxymethyl) ethane. To prepare PZT/xWO3 powders (where x = 0, 0.5, 1 and 3 wt%), nano-sized WO3 was ultrasonically dispersed and mixed with the PZT sol, dried and calcined at 600°C for 4 h. X-ray diffraction results indicated that fully crystallized powders were obtained. Phase characterization suggested that at high WO3 concentration, the reaction between PZT and WO3 occurred during the calcination process. To prepare PZT/xWO3 ceramics, the powders were pressed and sintered at 1100°C for 6 h. Phase characterization by XRD indicated that the content of WO3 significantly affected tetragonal-to-rhombohedral phase transition. Microstructure of thermally etched samples showed that increasing the content of WO3 decreased grain size of the ceramics.

Fabrication and Characterization of PZT/CuO Thin Film

Pb(Zr0.52Ti0.48)O3 or PZT thin films embedded with CuO nano-particles were successfully prepared by a hybrid sol-gel process. In this process, CuO (0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1wt%) nanopowder was suspended in an organometallic solution of PZT, and then coated on platinised silicon substrates using a spin-coating technique. X-ray diffraction patterns showed a perovskite phase in all the films. The CuO particles were not detected in the film, but the small amount of second phase was present when CuO concentration was above 0.4 wt%. The addition of CuO nano-particles also affected the orientation of PZT films. The CuO nano-particles were generally found to reduce both dielectric and ferroelectric properties of PZT films. However, at 0.2 wt% CuO concentration, the film exhibited good ferroelectric properties which were comparable to those of pure PZT thin films.

Synthesis and Characterization of PZT Thin Films Embedded with WO3 Nanoparticles by a Hybrid Chemical Solution Route

PZT thin films embedded with WO3 nanoparticles were prepared by a hybrid chemical solution process. WO3 at 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 wt% nanopowders were suspended in an organometallic precursor solution of PZT, and then coated on platinized silicon substrate using spin-coating technique. The increase of WO3 resulted in a reduction of densification of the films. However, at 1 wt% WO3 concentration, the reaction between PZT and WO3 occurred during heat-treatment process at 600°C and seemed to improve the films density. The WO3 nanoparticles were also found to affect both dielectric and ferroelectric properties of PZT films. Moreover, the addition of WO3 nanoparticles was found to improve a fatigue phenomenon in ferroelectric PZT thin films.

Stress-dependent dielectric and ferroelectric properties of sol–gel-derived PZT/WO3 ceramics

In this study, PZT/xWO3 (where x=0, 0.5, 1 and 3wt.%) ceramics were prepared from powders derived from a triol sol–gel process. The powders were pressed and sintered at 1100 °C for 6 h. Phase characterization by XRD indicated that the concentration of WO3 affected the content of tetragonal and rhombohedral phases. The ferroelectric and dielectric properties of the ceramics were determined under compressive stress in the range of 0–130 MPa. The ferroelectric properties were reduced with increasing stress. Stress-induced domain wall motion suppression and non-180° ferroelectric domain switching processes were responsible for the changes observed for ferroelectric parameters. In addition, the dielectric constant was found to increase with stress, which could be explained by a change in domain structures and the de-aging phenomenon.

Optimal fabrication and sintering behaviors of ferroelectric PZT/WO3 ceramics

The research reports the results of an investigation into the effects of processing temperature and concentration of nano-sized WO 3 addition on phase formation, densification and grain size of PZT ceramics. Increasing the content of WO 3 addition and sintering temperature showed a complementary effect on tetragonal-to-rhombohedral phase formation. An addition of only 0.5 vol% of WO 3 was found to help increase the densities as well as dramatically reduced the grain size of the PZT/WO 3 ceramics regardless of sintering temperature used. Based on these results, optimum processing temperature is about 1200°C where high-density, high-purity PZT/WO 3 ceramics were obtained.