Amount Of WO3 Research Articles

Effect of WO3 on the structure and properties of low sintering temperature and high strength vitrified bonds

The CaOB2O3Al2O3SiO2 vitrified bonds are widely used in the manufacture of diamond abrasive tools. The effects of different amounts of WO3 on the structure and properties of the SiO2B2O3Al2O3CaO system vitrified bonds were investigated by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), bending strength, thermal expansion coefficients (CTE) and scanning electron microscope (SEM). FT-IR and XRD patterns suggested that the [BO4] tetrahedron decreased, and [BO3] triangle and CaWO4 phase increased with increasing WO3. The bending strength and thermal expansion coefficients (CTE) analyses showed that bending strength of the vitrified bonds increased with increasing WO3, which reached its maximum of 114 MPa, and the CTEs of the varied vitrified bonds approximated to 6.8020 × 10−6 °C−1. The SEM analyses showed the vitrified bond completely wetted diamond grains, enhancing the properties of vitrified bond effectively.

Photocatalytic activity of TiO2-WO3 mixed oxides in relation to electron transfer efficiency

Aiming at producing photocatalysts with minimized photoproduced electron – hole pairs recombination, a series of titanium – tungsten mixed oxides has been prepared, by coupling TiO2 with different amounts of WO3, according to an alkaline-catalyzed sol-gel method followed by an incipient wetting procedure. The photocatalysts were characterized by surface and bulk techniques and tested in both an oxidation and a reduction photocatalytic reaction, i.e. in formic acid (FA) mineralization and in Cr(VI) reduction. Tungsten was mainly present as hexagonal WO3 on the TiO2 surface, though a fraction of W migrates into the TiO2 lattice substituting Ti atoms, as evidenced by XRPD analysis. Different photoactivity scales were found in the two test reactions, both occurring in the same pH range under similar substrate-photocatalyst electrostatic interactions. In fact, photoexcited electrons transferred from the conduction band (CB) of TiO2 to the CB of coupled WO3, being energetically unable to reduce O2 molecules, easily recombine with photoproduced holes, with a consequent photoactivity decrease in FA photo-mineralization with increasing W/Ti ratio. On the contrary, coupling TiO2 with small WO3 amounts (0.2–1.0mol%) is beneficial in the removal of Cr2O72− anions. These species, being characterized by a redox potential more positive than the CB edge of WO3, may efficiently accept the electrons trapped in WO3 domains, converting into less toxic Cr(III) species. Thus, WO3 surface domains effectively promote photoproduced charge separation by efficiently trapping CB electrons; increased photocatalytic efficiency depends on the redox potential of the electron acceptor species directly (or indirectly) involved in the photocatalytic process.

Effect of WO3 content on the catalytic activity of CeO2-ZrO2-WO3 for selective catalytic reduction of NO with NH3

A series of CeO2-ZrO2-WO3 catalysts (CZW) was prepared by the hydrothermal method. The effect of WO3 content on their catalytic properties for selective reduction of NOx with NH3 was investigated. The catalysts were characterized by X-ray diffraction, N2 sorption, H2 temperature-programmed reduction, NH3 temperature-programmed desorption and NO temperature-programmed desorption techniques. It was shown that WO3 existed as amorphous species in the CZW. Introduction of WO3 in the CZW dramatically enhanced its surface acidity and gave rise to strongly adsorbed NO species, consequently increasing the catalytic activity. In addition, appropriate amounts of WO3 also increased the surface area and improved the reduction behavior of the catalyst. Compared to the CeO2-ZrO2, the CZW with 20% WO3 not only exhibited high resistivity to SO2, but also had a wider reaction temperature window. It showed a NOx conversion of > 90% at the space velocity of 60000 h−1 in the temperature range of 200–463°C.

Evaluation of oxidation behavior of laser clad CoWSi–WSi2 coating on pure Ni substrate at different temperatures

Microstructural aspects of CoWSi–WSi2 coating on pure Ni and its oxidation performance under cyclic heating and cooling conditions in air at 900, 1100 and 1300°C have been studied. The coating was applied by laser cladding process. The microstructure evaluations demonstrated that a uniform free cracks coating formed which was metallurgically bonded to the substrate. XRD and EDS analysis results showed that the coating consisted of CoWSi, WSi2 and γ-Co. The mass gain/unit area versus oxidation time plot for all the samples was parabolic indicating that the oxidation process was diffusion-controlled. The structure of scales depended on oxidation temperatures; at 900°C, a dense scale layer consisting of SiO2 and small amounts of WO3 and CoO, at 1100°C, a characteristic scale structure, namely a mixed layer structure and at 1300°C, the dense oxide scale enrichment of SiO2 and porous interdiffusion layer with low oxygen concentration was formed.

Mesoporous carbon nitride-tungsten oxide composites for enhanced photocatalytic hydrogen evolution.

Composites of mesoporous polymeric carbon nitride and tungsten(VI) oxide show very high photocatalytic activity for the evolution of hydrogen from water under visible light and in the presence of sacrificial electron donors. Already addition of very small amounts of WO3 yields up to a twofold increase in the efficiency when compared to bulk carbon nitrides and their composites and more notably even to the best reported mesoporous carbon nitride-based photocatalytic materials. The higher activity can be attributed to the high surface area and synergetic effect of the carbon nitrides and the WO3 resulting in improved charge separation through a photocatalytic solid-state Z-scheme mechanism.

Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film.

Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested.Graphical abstractWO3-surface modified TiO2 film showing better photocatalytic and photoelectrocatalytic activity.

Influences of porous structurization and Pt addition on the improvement of photocatalytic performance of WO3 particles.

Tungsten trioxide (WO3) displays excellent performance in solar-related material applications. However, this material is rare and expensive. Therefore, developing efficient materials using smaller amounts of WO3 is inevitable. In this study, we investigated how to create high photocatalytic performance of WO3 particles containing platinum (Pt, as a co-catalyst) and homogeneously spherical macropores (as a medium to enable access of large molecules and light penetration into the remote internal regions of the catalyst). The present particles were prepared by spray drying of a precursor solution containing WO3 nanoparticles, Pt solution, and polystyrene (PS) spheres (as a colloidal template). Photocatalytic studies showed that changes in particle morphology (from dense with smooth surfaces, to dense with rough surfaces, to porous structures) and added Pt effectively improved the photocatalytic performance over WO3 nanoparticles. Our results showed that the best precursor (prepared using a PS/WO3 mass ratio of 0.32 and containing Pt co-catalyst) provided WO3 particles with a photocatalytic rate of more than 5 times that of pure 10 nm WO3 nanoparticles. Moreover, the catalyst can be effectively recycled without an apparent decrease in its photocatalytic activity. The experimental results were also supported by a proposal mechanism of the photocatalytic reaction phenomenon.

Phosphotungstic acid and WO3 incorporated TiO2 thin films as novel photoanodes in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) based on phosphotungstic acid–TiO2 composites (PT) and WO3 nanoparticle incorporated TiO2 photoanodes were successfully constructed by doctor blading TiO2 paste containing PT and various amounts of WO3. Film features were investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and ultraviolet–visible spectroscopy. Photoelectrochemical properties were examined by the photocurrent–voltage (J–V) curves as well as monochromatic incident photon-to-photocurrent conversion efficiency and electrochemical impedance spectroscopy (EIS) measurements. Compared with the DSSC based on pure P25 films, that based on PT/P25 films yielded a 16.9% higher Jsc and a 21.3% higher η, while that based on PT/P25+1/70WO3 films resulted in a 49.2% higher Jsc and a 40.3% higher η. EIS data demonstrated that charge transfer resistance was clearly reduced by introducing PT and WO3 into TiO2 films. The introduction of PT and WO3 was observed to promote electron transfer and retard recombination synergistically, leading to a significant improvement in cell performance.

Photo-electrochemical properties of WO3 particulate layers

Monoclinic tungsten trioxide particle layers were prepared on FTO glass substrates by the sedimentation method and further annealing at different temperatures to improve the adhesion of WO3 particles to substrate. Linear voltammetry of these layers was measured within the periodically chopped light illumination [very narrow single peaks at 314, 365 and 404nm and the standard solar illumination (AM1.5G)]. An optimal amount of WO3 in the layer was found for each light source. Back side illumination is more advantageous only for thick layers and visible light source. Better adhesion at higher annealing temperatures resulted in more stable layers with the higher photocurrent. The increase of annealing temperature above 500°C caused the formation of undesirable crystal phases (produced by the reaction of WO3 and FTO layer) and the significant decrease in photocurrent.

Synergism between n-type WO3 and p-type δ-FeOOH semiconductors: High interfacial contacts and enhanced photocatalysis

Solar-activated p-type δ-FeOOH/n-type WO3·H2O photocatalysts with different tungsten contents were prepared by a facile method, even though single δ-FeOOH or WO3·H2O exhibits lower photocatalytic activity. The photocatalysts were extensively characterized by X-ray fluorescence spectroscopy (XRF), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), 57Fe Mössbauer spectroscopy, photoluminescence (PL), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, BET measurements and temperature programmed reduction (TPR). The photocatalytic activity was evaluated for the oxidation of rhodamine B (RhB) at different pH values. The results indicated that the photocatalytic activity of the composite was superior to that of single WO3·H2O or δ-FeOOH. The optimum amount of WO3·H2O in the composite was 60wt.%. Based on these results, we propose that photoexcited electrons in the conduction band (CB) of WO3·H2O and photogenerated holes in the valence band (VB) of δ-FeOOH quickly combine, which results in the oxidation of the RhB dye by the accumulated holes in the VB of WO3·H2O. The total organic carbon measurements suggest that a high degree of RhB mineralization was achieved under solar light. The δ-FeOOH/WO3·H2O-assisted photocatalytic degradation of RhB should occur via two competitive processes (i.e., a photocatalytic and a photosensitized process). The results indicated that RhB oxidation primarily occurs via a photocatalytic process. The results from kinetic studies using radical scavengers suggest that O2•− and h+ reactive species play key roles in the degradation of RhB. The results presented in this study provide new insights for the development of novel solar-light-driven photocatalysts and their potential application for harmful pollutant degradation.

Effects of SnO2, WO3, and ZrO2 addition on the magnetic and mechanical properties of NiCuZn ferrites

In this study, the effects of SnO2, WO3 and ZrO2 addition at levels up to 5 wt% on the magnetic and mechanical properties of Ni0.5Cu0.3Zn0.2Fe2O4 ceramics were investigated. Only Ni0.5Cu0.3Zn0.2Fe2O4 ceramic with a SnO2 addition of ≥3.5 wt% required a densification temperature of 1150 °C, while the others reached maximum densification at 1075 °C. All samples revealed a pure spinel phase and a uniform microstructure, except for the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic with the WO3 addition, which showed an exaggerated grain growth accompanied with a small amount of needle-shaped Cu0.85Zn0.15WO4 second phase. The fracture mode in the pure Ni0.5Cu0.3Zn0.2Fe2O4 ceramic revealed a transgranular phase, as the CuO second phase increased the grain boundary strength; the Ni0.5Cu0.3Zn0.2Fe2O4 ceramics sintered with 5 wt% additives showed an intergranular phase. The Vickers hardness and the bending strength of the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic were 733.6 and 62.0 MPa, respectively. The Vickers hardness of the ferrite with added SnO2 or ZrO2 showed only a slight improvement, while an apparent change (832.7) was observed with the addition of 5.0 wt% WO3. The bending strength of the ferrite was optimized at 75.7 MPa with 2.0 wt% SnO2 and at 90.5 MPa with 3.5 wt% ZrO2, while that of the ferrite sintered with WO3 added dropped gradually from 62.0 to 47.7 MPa as the amount of WO3 was increased from 0 to 5.0 wt% due to the non-uniform microstructure. The pure Ni0.5Cu0.3Zn0.2Fe2O4 ceramic sintered at 1075 °C had an initial permeability of 356.9 and a quality factor of 71.2. The addition of ZrO2 led to a significant increase in the initial permeability (588.4 at 5.0 wt% ZrO2), but a slight decline in the quality factor (56.6 at 5.0 wt% ZrO2).

Searching for the formation of TiO2 mesoporous films with durable photoactivity by synergy of WO3 and sodium using a simple sputtering and annealing process

The fabrication of anatase TiO2 thin films with a mesoporous framework by template-directing sol–gel or microemulsion method has drawn considerable attention because of the compound's highly photocatalytic and superhydrophilic properties and its potential use in a wide variety of applications, such as self-cleaning and anti-fogging. In this study, thin films of TiO2, coupled with a widely ranging amount of WO3, are sputter deposited onto soda-lime glass, and the segregation of WO3 by annealing, along with the alternation of their microstructures and underlying reaction mechanisms involving sodium, is examined. This research highlights a sputtering process to synthesize mesoporous anatase films with a refined, regular grain structure and controlled porosities, via the synergy of WO3 and sodium to form a water-soluble sodium tungstate through a simple annealing process. In contrast to what is generally agreed that sodium contaminates TiO2 photocatalysts, the films impacted by sodium exhibit exceptional durability and much better photoactivity than the undoped anatase films at degrading a hydrocarbon layer and giving a long-last super-wetting surface. The enhancement of the films’ photocatalytic activity is elucidated by structural analysis and porosity identification.

Structure and spectroscopic properties of Er3+/Ce3+ co-doped TeO2-Bi2O3-TiO2 glasses modified with various WO3 contents for 1.53 μm emission

The Er3+/Ce3+ co-doped tellurite-based glasses (TeO2-Bi2O3-TiO2) modified with various WO3 contents are prepared using conventional melt-quenching technique. The X-ray diffraction (XRD) patterns and Raman spectra of glass samples are measured to investigate the structures. The absorption spectra, the up-conversion emission spectra, the 1.53 μm band fluorescence spectra and the lifetime of Er3+:4I13/2 level are measured, and the amplification quality factors of Er3+ are calculated to evaluate the effect of WO3 contents on the 1.53 μm band spectroscopic properties. With the introduction of WO3, it is found that the prepared tellurite-based glasses maintain the amorphous structure, while the 1.53 μm band fluorescence intensity of Er3+ is improved evidently, and the fluorescence full width at half maximum (FWHM) is broadened accordingly. In addition, the prepared tellurite-based glass samples have larger bandwidth quality factor than silicate and germanate glasses. The results indicate that the prepared Er3+/Ce3+ co-doped tellurite-based glass with a certain amount of WO3 is an excellent gain medium applied for the 1.53 μm band Er3+-doped fiber amplifier (EDFA).

Er3+/Tm3+ codoped tellurite glass for blue upconversion—Structure, thermal stability and spectroscopic properties

The Er3+/Tm3+ codoped WO3 modified tellurite glasses with molar composition of (75−x)TeO2–20ZnO–5Na2O–xWO3–0.2wt%Er2O3–0.8wt%Tm2O3 (x=0,4,8,12mol%) were prepared to realize the blue upconversion emission. The absorption spectra, visible upconversion spectra and 1.53µm band fluorescence spectra of glass samples were measured, together with the quantitative calculations of relevant spectroscopic parameters of Tm3+ and energy transfer micro-parameters between Er3+ and Tm3+ ions, to evaluate the effects of WO3 oxide on the spectroscopic properties of Er3+–Tm3+ ions. It was found that the introduction of WO3 oxide can further improve the blue upconversion emission of Tm3+ through an enhanced phonon-assisted energy transfer process. Meanwhile, with the increase of WO3 amount, the thermal stability of glass hosts, characterized by the difference between the glass crystallization onset temperature and the transition temperature which obtained from the measured differential scanning calorimeter (DSC) curves, increased and no obvious crystallization peak was detected when the WO3 amount increased to 12mol%. Furthermore, the glass structure was briefly analyzed with the obtained Judd–Ofelt intensity parameters, the measured Raman spectra and X-ray diffraction (XRD) curves. The present results demonstrate the feasibility of realizing strong blue upconversion emission by introducing WO3 oxide with high phonon energy into the Er3+/Tm3+ codoped tellurite glass and also indicate its potential application as a glass host applied for the blue upconversion lasers.

Enhancement of the 1.53 μm fluorescence and energy transfer in Er3+/Yb3+/Ce3+ tri-doped WO3 modified tellurite-based glass

For the first time, the WO3 oxide with relatively high phonon energy was introduced into the Er3+/Yb3+/Ce3+ tri-doped tellurite-based glasses with composition of TeO2Bi2O3TiO2 to improve the 1.53μm band fluorescence emission. The X-ray diffraction (XRD) curves, Raman spectra, absorption spectra and 1.53μm band fluorescence spectra were measured, along with the Judd–Ofelt intensity parameters, stimulated emission and absorption cross-sections, and radiative quantum efficiencies were calculated to evaluate the effects of WO3 amount on the glass structure and spectroscopic properties especially the 1.53μm band fluorescence. It is shown that the introduction of an appropriate amount of WO3 oxide can further improve the 1.53μm band fluorescence intensity through an enhanced phonon-assisted energy transfer between Er3+/Ce3+ ions and the energy transfer mechanisms between Er3+/Yb3+ (Er3+/Ce3+) ions are investigated quantitatively in detail by calculating energy transfer microparameters and phonon contribution ratios. The results indicate that the prepared Er3+/Yb3+/Ce3+ tri-doped tellurite glass with an appropriate amount of WO3 oxide is a potential gain medium applied for the 1.53μm band broad and high-gain EDFA.

Synthesis of spherical macroporous WO3 particles and their high photocatalytic performance

Tungsten trioxide (WO3) materials have excellent performance in transferring visible-light energy and are widely used in photocatalysis, solar cells, and hydrogen generation. However, WO3 is expensive and in short supply. It is therefore important to develop efficient materials that use smaller amounts of WO3. One strategy is to produce porous materials so that the entire area of the WO3 material can be used and activated effectively. In this study, we synthesized macroporous WO3 particles using a spray-pyrolysis method with colloidal templating. Ammonium tungsten pentahydrate (ATP) was used to produce WO3 without impurities, and polystyrene (PS) spheres were used to promote spherical macropore formation. The synthesized particles were characterized using thermogravimetric analysis, X-ray diffraction, nitrogen adsorption, scanning electron microscopy, and transmission electron microscopy (TEM). Several process parameters (i.e. initial precursor concentration and mass ratio between host and template) were investigated to get highly ordered porous particles with controllable porous structure and particle outer diameter. Photocatalytic analysis results showed that the amount of PS that provided the optimum photocatalytic enhancement. Our results showed that a PS/ATP mass ratio of 0.60 provided WO3 particles with a photocatalytic rate 2.5 times that of dense WO3. TEM analysis showed that highly ordered macropores were produced, enabling better penetration and interaction of molecules and light in the deepest part of the active catalyst, resulting in enhancement of the photocatalytic rate. This method will be useful for large-scale synthesis of small amounts of WO3 with high photocatalytic performance.

Improvement of the 1.53 μm fluorescence and thermal stability in Er3+-doped WO3/B2O3 modified tellurite glass

WO3 and B2O3 oxides were introduced into the Er3+-doped tellurite glass (TeO2–ZnO–Na2O), and their effects on the 1.53μm band fluorescence of Er3+ and thermal stability of glass host were investigated. It was found that introducing a certain amount of WO3 or B2O3 could improve the thermal stability and the 1.53μm band fluorescence. Better thermal stability and stronger fluorescence intensity were realized in the B2O3 modified tellurite glasses while broader fluorescence emission spectrum was found in the WO3 modified ones. The tellurite glass containing 6mol% amount of B2O3 exhibited an increment of about 37°C in ΔT and 15% in fluorescence intensity, whereas that containing 3mol% amount of WO3 showed a broadening of 18nm in FWHM and meanwhile maintained a relatively larger ΔT compared with the conventional tellurite glass.

Structural relaxation of PbO–WO3–P2O5 glasses

The structural relaxation of three compositional series of PbO–WO3–P2O5 glasses with composition (0.5 − x/2)PbO·xWO3·(0.5 − x/2)P2O5, x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5; 0.5PbO·xWO3·(0.5 − x)P2O5, x = 0, 0.1, 0.2, and 0.3; and (0.5 − x)PbO·xWO3·0.5P2O5, x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 was studied by thermomechanical analysis. The structural relaxation was studied in the transformation region using the Tool–Narayanaswamy–Moynihan’s and Tool–Narayanaswamy–Mazurin’s models. The relaxation function of Kohlrausch Williams and Watts was used. The parameters of both models were calculated by nonlinear regression analysis of thermodilatometric curves measured by thermomechanical analyzer under the constant load. Both models very well describe the experimental data. It was found that the modulus is increasing with increasing amount of WO3 in all glasses. On the contrary, the width of the spectrum of relaxation times is decreasing with increasing amount of WO3 in all studied glasses. Both models possess the values of metastable melt thermal expansion coefficient equal to their experimental value.

Reversibility of electrosurface transfer through eutectic interfaces of MeWO4|WO3 (Me − Ca, Sr, Ba)

It is found that electrosurface transition (EST) through eutectic interfaces of (−/+)WO3|MeWO4(+/−) induced by electric field is a reversible process. In the case of the (−/+) polarity, nominally, in the “direct experiment”, macro amounts of WO3 from a W3(−) brick are drawn in the (+) direction onto the inner surface of MeWO4 forming a two-phase {ie1070-1} composite. Simultaneously, nonequivalent countertransport of Me2+ within the W3(−) brick occurs, which changes the color of W3(−) from the natural hue to dark-green. Intercalation of Me2+ into W3(−) is proved by several spectroscopic methods. The key role in the EST phenomenon belongs to a nonautonomous electrolytic phase of MeW-s formed on the contact interface with WO3|MeWO4. The composition of MeW-s is close to W/Me ≈ 2. As a result of EST, the cell acquires a more complicated structure: {fx1070-1} where |///| are interface regions occupied by the MeW-s phase. At the cathodic boundary of subcell {fx1070-2} the following process occurs: {fx1070-3}, The process at the anodic boundary is: {fx1070-4}. Ultimately, WO3 is transported in the (+) direction (into the composite) and Me2+ penetrates under the effect of the gradient in chemical potential into W3(−) forming a dark-green MexWO3 phase with its front reaching the (−) Pt electrode. After the end of the “direct experiment”, the cell polarity was changed to (+/−) and the “reverse experiment” was carried out. Now, on the cathodic boundary |4 of subcell {fx1070-5} anions (WO4)2− are generated that are discharged on boundary 3| to oxide WO3 that is intercalated into the right boundary of MeWO4 − (3), where the rightmost composite region {ie1070-2} is formed. Thus, the mass of W3(−) decreases; it becomes dark-green (see above) and the mass of the MeWO4 disk continues growing and now its structure is as follows {ie1070-3}. It is important that the left W3(+) disk that was dark-green after the “direct experiment” gradually becomes lighter in the “reverse experiment” up to its natural pale green color, i.e., Me2+ is deintercalated from it: Me2+: MexWO3 + 1/2O2 → xMe2+ + 2e + WO3. It is found that dependences of variations of disk masses Δm(Q) practically coincide for the “direct” and “reverse” experiments.

Effect of donor and acceptor dopants on fatigue properties in PZT thin films

Abstract Fatigue properties of Pb(Zr0.52Ti0.48)O3 or PZT thin films on platinized silicon substrates were investigated. Small amounts of WO3 and CuO nano-particles were added into PZT films, which showed the results of soft and hard doping characteristics, respectively. The additions also affected the fatigue properties of PZT by showing almost no hysteresis fatigue up to 108 switching bipolar pulse cycles, while the fatigue of PZT started at 106 cycles. The results suggest that the soft and hard doping could reduce the fatigue of PZT films and the oxygen vacancies play an important role in polarization degradation of the films.