锆钛酸锶钡陶瓷成分调制与电学性能研究

发布时间：2018-06-16 09:43

  本文选题：无铅铁电压电陶瓷 + 固溶体　； 参考：《山东大学》2017年硕士论文

【摘要】：早在1942年,就有学者发现钛酸钡(BaTiO_3,BT)可以作为铁电压电材料。但纯的钛酸钡陶瓷的压电系数只有190 pC/N左右,这与锆钛酸铅陶瓷可以达到500-600 PC/N的压电系数相去甚远。锆钛酸铅陶瓷的优良压电性能是由于调整锆/钛元素比从而得到了准同型相界。铁电材料的机电性能与其相结构有着密切的关系。近年来,有许多工作致力于在室温下构造钛酸钡基陶瓷与铌酸钾钠基陶瓷的菱方相-正交相(R-O),正交相-四方相(O-T)以及四方相-菱方相(T-R)相界并成功的在温度-组分相图中得到了分离的多晶相转变区域(PPT)或者准同型相界(MPB)。比如说,可以通过掺入较大的B位离子,来得到O-T以及R-O的多晶转变区域。但这两个区域往往在相隔很远的组分区域内。基于以上的一些经验,本论文尝试在钛酸钡陶瓷中寻找一个合适的组分使钛酸钡基的固溶体存在两个甚至多个铁电相的过渡共存,从而得到优良的机电性能。在元素周期表中,锶元素(Sr)位于钡元素(Ba)上方,而锆元素(Zr)则正好处于钛元素(Ti)的下方。也就是说,每一种元素都能够与钛酸钡形成连续固溶体。在本工作中,首先以固相反应法合成了锆钛酸锶钡陶瓷(Ba_(0.95)Sr_(0.05)Zr_xTi_(1-x)O_3,BSZT,x=0.05,0.10,0.15,0.20).研究结果表明,当锆含量为 5%时,在 1400℃下烧结的陶瓷样品具有最优异的机电性能。在此条件下,锆钛酸锶钡陶瓷的剩余极化强度为12.1 μC/cm2,介电常数峰值ε_r~(peak) ≈12600,室温下的介电常数为ε_r~(RT)≈ 3500,其压电系数为355pC/N。居里温度大约在100℃左右。为了进一步研究锆钛酸锶钡陶瓷的相结构与其机电性能的关系,本论文又以固相反应法合成了锆钛酸锶钡陶瓷(Ba_(0.95)Sr_(0.08)Zr_xTi_(1-x)O_3,BSZT,x=0.0 1-0.10)。通过控制掺杂元素和组成比以在室温附近产生相邻的相界,从而达到相对于组成成分稳定的压电性能。基于多晶相转变(PPT)温度组成(TppT-x)关系的优化设计,本论文在BSZT陶瓷中成功合并了室温附近的正交相-四方相(O-T)和菱方相-正交相(R-O)的PPT区域。研究表明,室温附近的两个相邻PPT区域在性能增强方面表现出不同的特征。然而,由于相界的接近,Ba0.95Sr0.05ZrxTi(1-x)O3陶瓷在相当宽的组成范围(0.02≤X≤0.07)中,在室温附近表现出优异的压电性能,包括大的压电系数(312pC/N≤d≤d33≤365pC/N)和高的机电耦合系数k_p(0.42≤k_p≤0.49)。该方法可以应用于具有多种掺杂元素的其它铁电陶瓷,其协同效果,可以使得化合物的两个相界在应用温度附近彼此靠近,从而可以实现在相当宽的组成范围内保持较强的机电性能。
[Abstract]:As early as 1942, some scholars found that barium titanate can be used as ferroelectric material. However, the piezoelectric coefficient of pure barium titanate ceramics is only about 190pC / N, which is far from the piezoelectric coefficient of 500-600PC / N of lead zirconate titanate ceramics. The excellent piezoelectric properties of lead zirconate titanate ceramics are due to the adjustment of the zirconium / titanium ratio to obtain the quasi-homogenous phase boundary. The mechanical and electrical properties of ferroelectric materials are closely related to their phase structure. In recent years A lot of work has been done to construct the rhombohedral, orthorhombic, orthotropic, tetragonal and tetragonal / rhombohedral phase boundaries of barium titanate and potassium sodium niobate ceramics at room temperature. The separated polycrystalline phase transition region (PPTT) or the quasi-homogeneous phase boundary (MPB) have been obtained. For example, the polycrystalline transition regions of O-T and R-O can be obtained by doping larger B-site ions. However, these two regions are often located in distant constituent subregions. Based on the above experiences, this paper attempts to find a suitable component in barium titanate ceramics to make the solid solution of barium titanate exist two or more ferroelectric phase transition coexistence, thus obtaining excellent mechanical and electrical properties. In the periodic table, strontium (Sr) is located above the barium (Ba), and the zirconium (ZrR) is just below the Ti (Ti). That is, each element can form a continuous solid solution with barium titanate. In this work, first of all, barium strontium zirconate ceramics have been synthesized by solid state reaction method. The results show that the ceramic samples sintered at 1400 鈩，

本文编号：2026234