PbZr056Ti044O3 (PZT) epitaxial ferroelectric thin films on a LaAlO3 (100) substrate, covered by a metallic oxide electrode La05Sr05CoO3 (LSCO) are demonstrated in this work The films are fabricated by the sol–gel method and effort was focused on thermal processing to obtain the desired epitaxial heterostructure The dielectric and ferroelectric properties of PZT thin films were measured and it was found that they are as good as in the films deposited by other thin-film methods The dielectric constant and the dissipation factor of the PZT films are, respectively, about 500 and 006 below 20 kHz The remanent polarization Pr is about 27 μC/cm2 and the coercive field Ec is about 50 kV/cm It was found that the ferroelectric properties were significantly influenced by the microstructure of the PZT layers The present study also showed that the fatigue characteristics of the epitaxial heterostructure with LSCO electrodes under a reversed electrical field are far superior to those obtained with a polycrys

Properties of epitaxial ferroelectric PbZr0.56Ti0.44O3 heterostructures with La0.5Sr0.5CoO3 metallic oxide electrodes

This article reports on the early stages of nucleation and growth and texture development of the perovskite phase in PZT(52/48) seeded and unseeded sol−gel thin films. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) revealed that, in seeded films, the perovskite phase nucleates and grows at the film surface, on seed particles and at the Pt/PZT interface. In contrast, for unseeded films, nucleation and growth of the perovskite phase only occurs from the PZT/Pt interface. At low pyrolysis temperatures, the crystalline nucleation density is much higher in seeded than in unseeded films. The perovskite phase formation process is consequently accelerated by the presence of seeds. PZT thin films with 1 mol % seeds pyrolyzed at 430 °C for 40 h exhibit a dielectric permittivity of 500 and Pr and Ec of 6.71 μC/cm2 and 80 kV/cm, respectively. Seeded PZT films heat-treated at low temperatures (around 400 °C) may be suitable for applications in which deposition is required onto glass, metallic, or p...

Early Stages of Crystallization of Sol−Gel-Derived Lead Zirconate Titanate Thin Films

In this investigation, ferroelectric thin films Pb(Zr x Ti 1− x )O 3 (PZT) with x =0.58 were deposited on Pt/Ti/Si(001) by pulsed laser deposition (PLD). The residual stresses in PZT thin films were measured by an X-ray diffractometer (XRD) and indentation fracture method. In the indentation fracture method, the surface crack model and half-penny crack model were adopted. For PZT thin films with thickness of 0.05 μm, 0.5 μm and 1.0 μm, the residual stresses determined by a half-penny crack model were −74.73 MPa, −22.86 MPa and −14.74 MPa and those measured by XRD method were −57.6 MPa, −48.5 MPa and −25.6 MPa, respectively. The residual stresses determined by a half-penny crack model were closer to the results measured by XRD. A theoretical model is proposed to predict the residual stress in PZT thin film and the analytical results are essentially consistent with the experimental results. The effect of residual stress on piezoelectric properties is also discussed. The good ferroelectrics behaviors were demonstrated ( P r =22–35 μC cm −2 , E c =25–315 kV cm −1 ) by the hysteresis loops.

http://zhouxz.xtu.edu.cn/uploads/files/1434109374.pdf

Residual stress in PZT thin films prepared by pulsed laser deposition

Ferroelectric (Ba0.67Sr0.33)Ti1.02O3 thin films have been prepared by the sol–gel technology and characterized using TGA, DTA, XRD, TEM, dielectric characterizations, and gas sensing properties. The (Ba0.67Sr0.33)Ti1.02O3 thin film devices are made on Pt-coated Si substrate to detect hydrogen gas and to study gas sensing mechanism. Experimental results show that the diode I–V behavior appears in these Pd/amorphous (Ba,Sr)TiO3 (BST) thin film/metal capacitive devices, and that the enhanced voltage shift as large as 4.5 V at 1042 ppm hydrogen gas in air has been observed. Compared with the available data in the literature, this obtained value of voltage shift in our experiment is about seven times larger than the best one reported under similar testing conditions. It has been clearly shown that the hydrogen-induced voltage shift is closely correlated with the microstructure of ferroelectric thin films and the enhancement of this polarization potential is mainly attributed to the high dielectric constant of amorphous ferroelectric thin films. In this paper, we report our experimental results of this new hydrogen gas sensor and discuss the relationship between microstructure and hydrogen gas sensitivity in these ferroelectric thin film sensors.

Microstructure and hydrogen gas sensitivity of amorphous (Ba,Sr)TiO3 thin film sensors

Ferroelectric (Ba0.67Sr0.33)Ti1.02O3 thin films have been prepared by the sol-gel technology and characterized using thermogravimetric analysis, differential thermal analysis, x-ray diffraction, dielectric characterizations, and gas sensing measurements. The (Ba0.67Sr0.33)Ti1.02O3 thin film capacitive devices are made on Si substrate to detect hydrogen gas and to study hydrogen induced interfacial polarization potential. Experimental results show that the Schottky I–V behavior appears in these Pd/amorphous (Ba,Sr)TiO3 thin film/metal capacitive devices, both in air and in diluted hydrogen gas environment, and that the enhanced interfacial dipole potential as large as 4.5 V at 1042 ppm hydrogen gas in air has been observed. Compared with the available data in the literature, the obtained value of hydrogen induced interfacial polarization potential in our experiment is about seven times larger than the best one reported under similar testing conditions. It has been clearly shown that the hydrogen induced in...

Amorphous ferroelectric (Ba0.67Sr0.33)Ti1.02O3 thin films with enhanced H2 induced interfacial polarization potential

Pin‐hole free ferroelectric (Pb,La)(Zr1−xTix)O3 thin films with uniform composition have been fabricated using the metallo‐organic precursor compounds, which were carefully home synthesized. The structural development, spectroscopic, and dielectric properties of these films have been systematically investigated using atomic force microscopy (AFM), x‐ray diffraction, Fourier transform infrared spectroscopy, Raman scattering, and dielectric measurements. It has been found from our experimental results of PZT 40/60 thin films that the overlapping of (h00) and (00l) peaks of these films in x‐ray diffraction patterns, mainly due to the small grain sizes in films, makes it very difficult to distinguish individual diffraction peaks and to identify the phases. However, Raman measurements undoubtedly reveal the Raman spectra of these films in the tetragonal phase field, demonstrating that Raman spectroscopy is an effective tool to identify structures, especially in the case of thin films having very small grains. ...

A systematic study on structural and dielectric properties of lead zirconate titanate/(Pb,La)(Zr(1−x)Ti(x))O3 thin films deposited by metallo‐organic decomposition technology

M. S. Tse

Papers

A systematic study on structural and dielectric properties of lead zirconate titanate/(Pb,La)(Zr(1−x)Ti(x))O3 thin films deposited by metallo‐organic decomposition technology