BST纳米复合材料的制备与表征

发布时间：2018-04-06 02:28

本文选题：钛酸锶钡　切入点：化学共沉淀　出处：《苏州大学》2015年硕士论文

【摘要】：陶瓷基介电复合材料在无线通信行业中有广泛的使用。传统的介电陶瓷材料虽然具有较高的介电常数,但是机械强度差,易碎,不易加工成型。这些缺点极大的限制了陶瓷材料在嵌入式电容器和高储能器件中的应用。聚合物基体易于加工,机械性能优异,价格低廉,但介电常数低。因此陶瓷基高分子复合材料,既能够确保介电陶瓷卓越的介电性能,又能表现出聚合物基体优异的机械性能。本文以聚苯乙烯(PS)为聚合物基体,陶瓷填料选用为钛酸锶钡(Ba1-xSrxTi O3,BST),通过对BST纳米颗粒的表面修饰,从而提高复合材料的热学与介电性能。相关的研究内容和结果如下所述:(1)介电粉末BST的制备:以Ti OSO4,Sr Cl2·6H2O,Ba Cl2·2H2O为原材料,采用化学共沉淀制备BST纳米粉末。采用XRD、FT-IR、SEM、TEM、TGA、DSC、宽频介电-阻抗谱仪等方法对样品进行表征。探究了沉淀剂与不同Na Cl的添加量对BST粉末的晶型、结构形貌、介电性能等影响。测试结果说明:在最佳的工艺条件下制备的BST的结构是典型的立方体钙钛矿型,此时BST具有最佳的介电性能。(2)BST纳米颗粒表面修饰及其复合材料的制备:首先通过在BST纳米颗粒上包覆油酸,从而获得油酸修饰的BST,并在TG,XRD,FT-IR,TEM,SEM得到验证,其次通过溶液共混,将其改性的BST纳米颗粒均匀的分布在PS聚合物基体,没有发现明显的团聚。其次,以陶瓷纳米颗粒BST和导电高分子聚合物聚苯胺(PANI)为填料,首先通过原位乳液聚合制备出BST-PANI杂化粒子,最后制备出BST-PANI/PS三相介电复合材料。介电性能实验表明,当BST-PANI的含量不超过30 wt%时,BST-PANI/PS三相介电复合材料的介电常数受频率的影响较小,同时介电常数远远大于BST/PS二相介电复合材料。最后,二相或三相复合材料的热学性能(包括玻璃化转变温度与热学稳定性)相比于纯的聚合物基体都有一定幅度的提高。
[Abstract]:Ceramic based dielectric composites are widely used in wireless communication industry.Although the traditional dielectric ceramic materials have high dielectric constant, but the mechanical strength is poor, fragile, difficult to process.These shortcomings greatly limit the application of ceramic materials in embedded capacitors and high energy storage devices.Polymer matrix is easy to process, excellent mechanical properties, low price, but low dielectric constant.Therefore, ceramic matrix polymer composites can not only ensure excellent dielectric properties of dielectric ceramics, but also exhibit excellent mechanical properties of polymer matrix.In this paper, polystyrene (PS) as polymer matrix and ceramic filler as barium strontium titanate (barium strontium titanate) Ba1-xSrxTiO3 (BST) are used to improve the thermal and dielectric properties of the composites by surface modification of BST nanoparticles.The related research contents and results are as follows: (1) the preparation of BST: using TIO _ (4) O _ (4) O _ (4) O _ (4) Sr Cl2 _ (6) H _ 2O _ (6) Ba Cl2 2H2O as raw material, BST nano-powders were prepared by chemical coprecipitation.The samples were characterized by XRDX FT-IRT-SEMGA-TGADSCand wide-band dielectric impedance spectrometer.The effects of precipitator and NaCl on the crystal shape, morphology and dielectric properties of BST powder were investigated.The test results show that the structure of BST prepared under the optimum technological conditions is a typical cubic perovskite type.At this time, BST has the best dielectric properties. The surface modification of BST nanoparticles and the preparation of its composites. Firstly, oleic acid is coated on the BST nanoparticles to obtain oleic acid modified BSTs.The modified BST nanoparticles were uniformly distributed in the PS polymer matrix and no obvious agglomeration was found.Secondly, BST-PANI hybrid particles were prepared by in-situ emulsion polymerization with ceramic nanoparticles BST and conductive polymer Polyaniline (pan) as fillers. Finally, BST-PANI/PS three-phase dielectric composites were prepared.The dielectric property experiments show that when the content of BST-PANI is less than 30 wt%, the dielectric constant of BST-PANI- PS three-phase dielectric composite is less affected by frequency, and the dielectric constant is much larger than that of BST/PS two-phase dielectric composite.Finally, the thermal properties of the two-phase or three-phase composites (including glass transition temperature and thermal stability) are improved by a certain extent compared with the pure polymer matrix.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.758.2

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