【作者】 杨宇欢；

【导师】 严辉； 朱满康；

【作者基本信息】 北京工业大学 ， 材料物理与化学， 2003， 硕士

【摘要】 人工薄膜的出现是20世纪材料科学发展的重要标志。自70年代以来，薄膜材料、薄膜科学、与薄膜技术一直是高新技术研究中最活跃的研究领域之一，并己取得了突飞猛进的发展。薄膜材料与薄膜技术属于交叉学科，其发展几乎涉及所有的前沿学科，其应用与推广渗透到了各相关技术领域。正是由于薄膜材料和薄膜技术的发展才极大地促进了微电子技术、光电子技术、计算机技术、信息技术、传感器技术、航空航天技术和激光技术的发展，也为能源、机械、交通等工业部门和现代军事国防部门提供了一大批高新技术材料和器件。Ba2TiSi2O8晶体被认为是一种特殊的压电体，它具有压电性、热释电性和非线性光学特性。Ba2TiSi2O8（BTS）晶体，属四方晶系，空间点群C4v-4mm，晶格常数a=b=8.52?，c =5.21 ?，c/a=0.612，c轴为该晶体的唯一极轴。该晶体是一种极性晶体，具有压电效应；但其极轴方向在外电场的作用下难以重新定向。由Ba2TiSi2O8晶体结构可见，Ba2TiSi2O8晶体由[Si2O7]双四面体[TiO5]四方单维组成平行于{001}面的平面网层，Ba2+以10配位形式处于Si-Ti-O网层之间，其自发极化偶极距达1.14×10-26C·cm。本文用射频溅射、脉冲激光沉积和溶胶－凝胶三种方法制备Ba2TiSi2O8薄膜，并对样品性质进行研究。用射频磁控溅射法可以在Si（100）衬底上制备Ba2TiSi2O8薄膜。通过对气压的控制可以得到不同的膜厚，并且有助于控制薄膜中多元成分的组成。磁控溅射所制得Ba2TiSi2O8薄膜的为非晶态，经过后续热处理使得薄膜结晶。随着工作温度的提高从室温增加到 600oC，薄膜的结晶性逐渐变化。通过热处理的温度和时间控制得到取向良好的薄膜。本<WP=4>1． 文认为在磁控溅射法的制备过程中，通过对工作温度和热处理温度的控制可以得到取向明显的薄膜。2． 溶胶－凝胶方法制备出以Si（100）为衬底的Ba2TiSi2O8薄膜。通过对配置胶体的原料，甩胶时间、速度和后续热处理温度和时间的控制，制备出成分均匀，结构有一定取向的薄膜。3． 用PLD脉冲激光沉积法制备出以Si（100）为衬底的Ba2TiSi2O8薄膜。通过对溅射距离、时间和后续热处理温度的控制，制备出取向明显的薄膜。更多还原

【Abstract】 The mineral named Fresnoite was discovered by Alfors et al. in 1965. Fresnoite (Ba2TiSi2O8, BTS), has been believed structurally to be a piezoelectric for its noncentrosymmetric tetragonal crystal with lattice parameters a=b=0.852nm and c=0.521nm in space P4bm. Besides of its large tetragonality (c/a) of 0.61 and a unit-cell spontaneous dipole moment of 1.14×10-26C·m, piezoelectric Fresnoite possesses a high electronmechanical coupling constant, a small temperature coefficient of delay (TCD), and a low phase velocity. Moreover, Yamauchi reported the calculated TCD of Fresnoite crystal that is nearly equal to zero. Thus, it is potentially applicable for surface acoustic wave(SAW) devices. It is reported that Fresnoite has a strong optical SHG, and the Fresnoite glass ceramics give up a significant optical SHG. Those nonlinear optical properties in Fresno8ite attract more attention. Efforts have been made to prepare the Fresnorte thin film by various methods.In this paper, it is concluded that the Ba2TiSi2O8 thin films were obtained by magnetron rf sputter, PLD and Sol-Gel techniques. 1. The rf-sputter techniques prepared the Fresnoite thin film is a simple method. The compositions of thin films sputter deposited from near-stoichiometric ceramic targets of Fresnoite (Ba2TiSi2O8) were shifted so that less barium and less titanium were contained in the films. A Ba2TiSi2O8 thin film deposited at a substrate temperature of 600℃ and subsequently annealed at special degrees of temperature for 60min had characteristic of polycrystals.2. Fresnoite (Ba2TiSi2O8) piezoelectric thin films were prepared by Sol-Gel processing using Si(100) substrates. Polycrystalling Ba2TiSi2O8 thin films were obtained at relatively annealing temperatures at 750~900oC.Fresnoite (Ba2TiSi2O8) piezoelectric thin films were deposited on Si(100)<WP=6>3. substrates by pulsed laser deposition(PLD). Successively depositing polycrystalling Ba2TiSi2O8 thin films were obtained at relatively annealing temperatures at 750~800oC.更多还原