【作者】 栾世军；

【导师】 隋万美；

【作者基本信息】 青岛大学 ， 材料学， 2006， 硕士

【摘要】 钛酸锶钡（BST）材料具有高介电常数、较低的介电损耗、低的居里温度等特点,在高密度动态存储器（DRAMs）、微波调谐器件等方面拥有广阔的应用前景。多年来,该类材料一直是国内外研究的热点之一。 本论文首次以Ba（NO₃）₂-Sr（NO₃）₂-TiO（NO₃）₂-C₆H₈O₇·H₂O为反应体系,采用溶胶低温燃烧合成法制备了BST超细粉末。以正交试验考察了柠檬酸与金属离子的摩尔比、溶胶pH值、燃烧及热处理温度对合成粉体粒径的影响,得到的工艺参数最优组合为,n（柠檬酸）:n（金属离子）=1.5:1,pH=7,燃烧及热处理温度为650℃。 采用低温燃烧法合成的粉体按常规烧结制备了Ba_0.6Sr_0.4TiO₃陶瓷,1300℃烧结的样品在10kHz频率下,25℃时的介电性能为:ε_r=5074,tgδ=0.0025,具有较高的介电常数和较低的介电损耗。 铁电移相材料是目前有关移相材料领域内研究的一个热点。通过向BST体材中添加各种改性剂可获得所需的BST移相材料的介电性能。向BST材料中添加MgO可以降低材料的介电常数和介电损耗。本论文以溶胶低温燃烧法制备Ba_0.6Sr_0.4TiO₃纳米粉体,与质量含量为50%的MgO纳米粉体作为起始原料,制备了Ba_0.6Sr_0.4TiO₃/MgO复相陶瓷,测得1200℃,1250℃烧结的样品在100kHz频率下的室温（25℃）介电常数和介电损耗分别为:ε_r=157,tgδ=0.0018;ε_r=161,tgδ=0.00225。在10kHz下,介电常数的调谐性比其它研究者的结果有显著提高,在1kV/mm的偏置电场下均达到20%以上,完全达到铁电移相材料的使用要求。更多还原

【Abstract】 Barium strontium titanate （BST） materials have characteristics such as high dielectric constant, small dielectric loss and low Curie temperature. The paraelectric barium strontium titanate has the potential applications in the fields of cell capacitor of the dynamic random access memory devices （DRAMs）, tunable microwave device applications. Recently, Investigation of BST has been continued growth.In this paper, with the starting materials of Ba（NO₃）₂-Sr（NO₃）₂-TiO（NO₃）₂ -C₆H₈O₇.H₂O, nano-particle Ba_o.7Sr_o.3TiO₃ powders were prepared by low-temperature combustion synthesis of sol at the first time. The effects of the molar ratio of citric acid and metal ions, pH value of the sol and burning temperatures on the particle size were investigated by the cross experiment method. The optimum fabrication process parameters were as follows, the molar ratio of citric acid to metal ions is 1.5 to 1, the pH value is 7 and the thermal treatment temperature is 650°C.Ba_o.6Sr_o.4TiO₃ ceramic samples were fabricated by conventional ceramic processing with a starting powders prepared by low-temperature combustion synthesis of sol. The sample sintered at 1300°C has a higher dielectric constant value of 5074 and a lower dielectric loss value of 0.0025 at 10kHz and 25 °C.The study on ferroelectric phase shift materials is very important in the fields of phase shifter. The excellent dielectric properties of BST for phase shifter can be obtained by adding some second phase to form multiphase materials. Adding magnesia into BST can reduce the dielectric constant and dielectric loss of BST. In this paper, Ba_o.6Sr_o.4TiO₃/MgO multiphase ceramic material was prepared using Ba_o.6Sr_o.4TiO₃ c powders fabricated by low-temperature combustion synthesis of sol and 50wt% MgO nano- powders as starting materials. The results show that the samples sintered at 1200°C and 1250°C have the dielectric constant values of 157 and 161, the dielectric loss values of 0.0018 and 0.00225 at 100kHz and 25°C. The tunability of the material reached more than 20% under applying lkV/mm dc bias field at 10kHz. The result is higher than any other results of the same materials. The higher tunability of the material can meet the requirement of ferroelectric phase shift materials completely.更多还原