【作者】 尹奇异；

【导师】 肖定全；

【作者基本信息】 四川大学 ， 材料物理与化学， 2005， 硕士

【摘要】 本论文本着从制备新型BNT 基无铅压电陶瓷材料及展望其器件应用出发,开展了BNT 基无铅压电陶瓷的体系筛选、制备及性能研究。采用实用化的传统固相法制备工艺技术, 在五种烧结温度下制备了(1-x)Bi0.5Na0.5TiO3-x(BaaSrb)TiO3陶瓷体系中的六个组份配方的陶瓷,并把该体系简记为BNBST(100x-100a/100b),其中0<x<1,0<a<1,0<b<1,且a+b=1;根据已有的微量元素的掺杂改性原理及经验,对BNBST6-50/50 无铅压电陶瓷进行了Mn 元素的掺杂改性研究,采用传统的制备工艺,在烧结温度为1200℃时制备了BNBST+X(wt%)MnO2 陶瓷体系中的六个组份配方;通过运用X 射线衍射(XRD)、扫描电子显微镜(SEM)等分析手段,对BNBST 陶瓷及其掺锰改性后的所有陶瓷样品的晶相结构及表面形貌进行了分析表征;通过对所有陶瓷样品的压电常数、机电耦合系数、机械品质因素、介电常数—频率曲线及介质损耗—频率曲线的测试,分析了Mn 元素的添加量、烧结温度及配比含量对BNBST 无铅压电陶瓷的压电性能及介电性能的影响机理;对铁电压电性能与传统的PZT 铅基压电陶瓷较接近的无铅压电陶瓷材料的器件应用的实用化进行了剖析。通过以上诸多细致的实验研究和数据的处理分析,本论文主要得到以下具有创新性的研究结果: (1)、XRD 测试结果表明,在1125℃以上,所有陶瓷样品均为四方晶系,都具有单一钙钛矿结构,没有钙钛矿结构以外的第二相,但是在1125℃以下,都有少量的杂相;随着BNT 含量的减少,衍射峰向左偏移,晶面间距增大,体系逐渐处在三方-四方的准同型相界附近,各项性能均达到最佳。(2)、随着烧结温度的增大,所有陶瓷样品的压电常数、机电耦合系数及机更多还原

【Abstract】 To prepare new BNT-based lead-free piezoelectric ceramic materials, the system, preparation and properties of the ceramics were studied. Six compositions of (1-x)Bi0.5Na0.5TiO3-x(BaaSrb)TiO3{0<x<1,0<a<1,0<b<1,a+b=1, abbreviated as BNBST[100x-100a/100b]} ceramics were prepared by conventional ceramic fabrication technique and sintered at five variant temperatures.BNBST6-50/50 ceramics were doped with Mn. Six compositions of BNBST+X(wt%)MnO2 ceramics, which were sintered at 1200℃,were prepared by the same technique. By means of modern analyses techniques, such as XRD, SEM, the crystal structure and surface topography of all ceramic samples with either Mn-doped or not were characterized. By measuring the piezoelectric constant, electromechanical coupling factor, mechanical coupling factor, the curves of dielectric constant-frequency and the curves of dielectric loss-frequency, the effect of Mn additive, the sintering temperature and the composition on the dielectric and piezoelectric properties of the BNBST lead-free piezoelectric ceramics were analyzed. The practical applications of the lead-free piezoelectric ceramics which piezoelectric properties are near to that of lead-based ceramics were also analyzed. The innovative conclusions obtained from above-mentioned works are mainly as follows: (1) The results of the X-ray diffraction (XRD) indicate that all ceramic samples are single perovskite tetragonal phase when the sintering temperature is higher than 1125℃,but there are a small amount of miscellaneous phases when the sintering temperature is lower than 1125℃; With reduction of BNT content, the skew left of the diffraction peak, interplanar distance enlarge, the system appears nearby cubic-tetragonal morphotropic phase boundary, every property reaches the best gradually. (2) The piezoelectricity constant, electromechanical coupling coefficient and mechanical quality factor of all ceramic samples increase with the increasing of sintering temperature, but dielectric constant is reduced correspondingly, and when sintering temperature is higher than 1125℃, electromechanical coupling coefficient kp increases (up to 0.22), piezoelectric constant d33 increases (up to 101), and mechanical quality factor is reduced. (3) XRD test indicates that all ceramic samples mixed with Mn element have single perovskite tetragonal phase. The images of SEM show that all ceramic crystalline grains have obvious geometry appearance, the interplanar interface is high-visible. With the increase of Mn element, the crystalline grain is large and the grain size is from 2-3 μm to 3-4 μm, the homogeneity of the ceramic particle is reduced. It is obvious that the amount of Mn adding quantity grows and limits the grains certainly. (4) Dielectric and piezoelectric tests for BNBST+X(wt%)MnO2 ceramics show that the mechanism of mixing of Mn element is very complicated. When sintering temperature is 1200℃, the electromechanical coupling coefficient, mechanical quality factor and piezoelectricity constant of all ceramics sample increase with reduction of adding quantity of Mn element; piezoelectricity constant d33 (up to 101), mechanical quality factor Qm (up to 191), electromechanical coupling coefficient kp (up to20%) when X=0.09. The adding of Mn exerts a tremendous influence to the mechanical quality factor of the ceramic system, no matter the amount of adding quantity of Mn, mechanical quality factor is higher than the ceramics with no addition of Mn.更多还原