Preparation and Characterization of Pb(Zr,Ti)O 3 films prepared by a modified sol-gel route
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Preparation and Characterization of Pb(Zr,Ti)O3 films prepared by a modified sol-gel route Dan Jiang, Chen Zhao, Shundong Bu, and Jinrong Cheng * School of Materials Science and Engineering, Shanghai University, Shanghai, 200072, China
ABSTRACT Pb(Zr0.53Ti0.47)O3 (PZT) films have been fabricated on stainless steel substrates by a Polyvinylpirrolidone (PVP) modified sol-gel route. The single layer of about 0.26 μm was achieved by using the PVP-modified PZT sol, and Crack-free PZT films with thickness of up to 2.37 μm were fabricated by repeating the deposition process. The variations in crystallite orientation, microstructure, dielectric and ferroelectric properties of PZT films were investigated as a function of film thickness. Our results indicate that PZT films prepared on stainless steel substrates maintain good dielectric and ferroelectric properties. INTRODUCTION Up to now, lead zirconate titanate (PZT) have attracted much attention for broader application in piezoelectric actuators, micro-electro-mechanical system (MEMS), and novolatile ferroelectric random access memories (FeRAM) due to its superior dielectric, piezoelectric, and ferroelectric properties. The film thickness of PZT in the range of 0.5-10 μm is likely to be required for full elicitation of such properties [1-3]. Currently, PZT films have been deposited on the metal substrate instead of the platinized silicon wafers. The advantages of PZT films prepared on metal substrates include low cost, high frequency operation, obvious displacement, quick response, and high fracture toughness [4-6]. Among the methods of preparing PZT films, the sol-gel process is widely applied because of the low cost and easy compositional control. However, it is generally difficult to achieve crack-free films with thickness over 1 μm by the conventional sol-gel method. In order to avoid cracking, the single-layer thickness is controlled below 0.1 μm, and repetitive deposition is performed in laboratories, which is impracticable in industries [7-8]. Polyvinylpyrrolidone (PVP) has been reportedly used to fabricate BaTiO3, BaBi4Ti4O15, and Pb(Zr,Ti)O3 (PZT) ceramic films with single-layer thickness of 1.2, 0.4, and 0.75 μm, respectively [9-10]. H. Kozuka et al. previously demonstrated that the addition of PVP in alkoxide solutions allows crack-free, over submicrometer-thick ceramic coating films to be obtained via noncycled, single-step deposition [11]. In this work, we have studied a polymer-assisted sol-gel method by the addition of PVP to increase the single-layer thickness of the PZT films. It is found that the single-layer thickness of PZT films increases from 0.09 to 0.26 μm after the PZT precursors modified by PVP. The structure, dielectric and ferroelectric properties of PZT films are studied as a function of film thickness.
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EXPERIMENTAL DETAILS Tetrabutyl titanate [Ti(OC4H9)4], lead acetate trihydrate [Pb(CH3COO)2•3H2O] and tetrabutul zirconate [Zr(OC4H9)4] were used as raw materials. Ethylene glycol monomethylether (CH3OCH2CH2OH, 2-MOE) as used as solvent. T
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