高温稳定型MLCC陶瓷的制备与研究

【作者】 王力；

【导师】 张树人；

【作者基本信息】 电子科技大学 ， 材料科学与工程， 2010， 硕士

【摘要】 多层陶瓷电容器(MLCC)由于具有结构紧凑、体积小、比容高、介电损耗低、价格低廉等诸多优点,被广泛应用于各类电子设备。随着地下勘探、航空航天和军用移动通讯等设备的使用环境越来越恶劣,例如,用来探寻油气储量的电子设备,可能需要承受超过200℃的温度,这就要求再次扩大多层陶瓷电容器能正常工作的温度范围,因此,研究高温MLCC材料是目前多层陶瓷电容器发展的一个重要方向。目前,BaTiO3(BT)以其极高的介电常数成为了MLCC的主要原料,但其居里温度过低的弱点限制着它的发展。和BaTiO3一样有着钙钛矿结构的钛酸铋钠(BNT)受到了人们的关注,但难以极化的特性却使得它无法批量化生产,而BNT与BT的复合材料(Bi0.5Na0.5)1-xBaxTiO3(BNBT)兼有两者的优点,有望成为高温可靠型MLCC产品的新材料。本论文针对这些材料的特点,分别以BNBT-Ca(BNBCT),BNBT-La-Nb与(Bi0.5Na0.5)1-xCaxTiO3-Mn(BNCT-Mn)为基料,深入分析掺杂改性和工艺条件对陶瓷介电性能的影响。主要内容如下:1.对BNBCT体系进行了三种助烧剂(硼硅酸盐、CuV2O6、CuBi2O4)掺杂,将陶瓷烧结温度降低到了1120℃,将并对降烧后的基料进行稀土掺杂研究,最终在烧结温度1120℃下获得了-55℃~ 250℃的宽温范围内,满足X9R标准的高温可靠型MLCC;2.研制了BNBT-La-Nb和BNCT-Mn陶瓷材料,分别研究了主要成分和CaCO3掺杂对体系的影响,并研究了Fe2O3掺杂对BNCT-Mn烧结机制和介电性能的影响;3.研究了工艺对陶瓷材料介电性能的影响。实验表明球磨时间越长,材料的损耗越小;相较于La离子的内掺杂,外掺杂的BNBT-La-Nb体系的容温特性得到了更大的改善。更多还原

【Abstract】 Multilayer ceramic capacitors (MLCCs) have been widely used in electronic equipments, attributed to compact structure, small size, high specific volume, low dielectric loss and low cost. Harsh environments, such as underground exploration, aerospace and military, require MLCCs to extend their working temperature, at the same time maintain good electrical properties. For example, the working temperature for oil exploring and gas reserves must be raised above 200℃. Therefore, developments of high-temperature capacitors are of great importance.Currently, BaTiO3 (BT) is one of the most important materials for MLCC products because of its high dielectric constant, but the low Curie temperature limits its applications in high-temperature capacitors. Bi0.5Na0.5TiO3 (BNT), which has a high Curie temperature of 320℃and the same perovskite structure with BT, has attracted much attention. However, it is difficult to be practical used due to polarization problems. The solid solution of BT and BNT (BNBT), which has advantages of BT and BNT, is hopeful to to become a new material for high-temperature stable MLCC products. According to the characteristics of these materials, the dielectric properties of the systems affected by the dopings and sintering processes were deeply studied. The systems were on the base of BNBCT,BNBT-La-Nb and BNCT-Mn materials. The main results are as follows:1. Three sintering aids (Boron- silicate, CuV2O6, CuBi2O4) were doped to BNBCT ceramics and the sintering temperature was reduced to 1120℃. After that, the effects of rare-earth elements doping on the dielectric properties of low-temperature sintered BNBCT ceramics were studied. Finally, high-temperatiure capacitor materials which meet the X9R specification in a wide temperature range from -55℃to 250℃were achieved.2. The effects of major components and CaCO3 on the microstructure and dielectric properties of BNBT-La-Nb and BNCT-Mn system were investigated. Moreover, the addition of Fe2O3 on the sintering mechanism and dielectric properties of BNCT-Mn system were investigated. 3. The effects of ball milling time and doping methods on the microstructure and dielectric properties of multi-layer ceramic capacitors are investigated in detail. The results revealed that a longer milling time would bring to a lower dielectric loss. The temperature characteristic of capacitance for La outside-doped BNBT-La-Nb system was greatly improved, compared with La inside-doped system.更多还原