Zhan Jie Wang

Development of phases and texture in sol-gel derived lead zirconate titanate thin films prepared by three-step heat-treatment process

Lead zirconate titanate (PZT) films were fabricated by the addition of 10 mol% excess Pb to the starting solution which was spin-coated onto Pt/Ti/SiO2/Si substrates. The effect of film thickness on texture was investigated, and it is clear that the (100) texture gradually increases and the (111) texture decreases with increasing film thickness. A PtxPb intermetallic metastable phase was observed by X-ray diffraction, and it is found that the position of this peak shifted from 38.30° 2θ (d : 0.2348 nm) to 37.10° 2θ (d : 0.4213 nm) with increasing firing temperature from 350°C to 550°C. The (111) preferred orientation in the PZT film was promoted by the metastable PtxPb phase. The formation of the (100) texture of perovskite phase in the multilayer films was mainly attributed to the effects of both substrates and crystal growth rates which depend on the crystal orientation.

Effect of Pb Excess Content on Microstructure and Electrical Properties of Sol Gel Derived PZT Thin Films

Lead zirconate titanate (PZT) thin films were fabricated by a three-step heat-treatment process which involves the addition of -10, 0 and 10 mol% excess Pb to the starting solution and spin coating onto Pt/Ti/SiO 2 /Si substrates. Crystalline phases as well as preferred orientations in PZT films were investigated by X-ray diffraction analysis (XRD). The microstructure and composition of the films were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA), respectively. The well-crystallized perovskite phase and the (100) preferred orientation were obtained by adding 10% excess Pb to the starting solution. It was found that PZT films to which 10% excess Pb was added had better electric properties. The remanent polarization and the coercive field of this film were 34.8 μC/cm 2 and 41.7 kV/cm, while the dielectric constant and loss values measured at 1 kHz were approximately 1600 and 0.04, respectively. Dielectric and ferroelectric properties were correlated to the microstructure of the films.

Ferroelectric Pb(Zr0.53, Ti0.47)O3 thin films for smart MEMS

Ferroelectric thin film is the target of the interest in micro electromechanical system, memory etc. Smart MEMS is to be developed with such smart materials thin films. In spite of the success in commercialization of FRAM application, MEMS application is still under R&D state. Despite to their promising properties, there are only few reports on the use of such layers as MEMS devices. Problems for application are mainly caused by the necessary very small dimension of such devices, in contrast to limitations and tolerances of the used micro-technologies. Although deposition of piezoelectric PZT-layer using different thin-film technologies has reached an advanced state, the layers of more than 1 micron thickness needed for MEMS applications is still difficult to deposit. To deal with these problems, the structure or the function of the devices has to be coped with such technologically caused constraints, like thickness deviation and deformation by residual stress, as well as optimization of materials processing parameters. As an application of the thin films, Piezoelectric SFM and scanning mirror device are designed and fabricated as examples of the target MEMS devices with special emphases placed on materials, processing and device structure optimization

Improvement of IGC resistance of SUS 304 stainless steel by laser surface melting based on grain boundary engineering

LSM and annealing heat treatment on 304 stainless steel resulted in microstructures with high frequency of low ∑ CSL boundaries defined by the coincidence site lattice (CSL) model, especially, twin boundaries (∑3). The maximum frequency of the low Σ CSL boundaries could be 88.6% under optimal processing conditions: 947°C and 28h. The high fraction of the low-∑ CSL boundaries led to a high corrosion resistance to intergranular corrosion.LSM and annealing heat treatment on 304 stainless steel resulted in microstructures with high frequency of low ∑ CSL boundaries defined by the coincidence site lattice (CSL) model, especially, twin boundaries (∑3). The maximum frequency of the low Σ CSL boundaries could be 88.6% under optimal processing conditions: 947°C and 28h. The high fraction of the low-∑ CSL boundaries led to a high corrosion resistance to intergranular corrosion.