BST/MgO复相陶瓷的制备与性能

以溶胶低温燃烧合成法制备了BaSr Ti O3超细粉末,与商品MgO纳米粉体同为原料,按质量比1∶1的比例制备了BST/MgO复相陶瓷材料。分别在1 150,1 200,1250℃,利用SEM、XRD和LCR对制备出的BST/MgO复相陶瓷的显微结构与介电性能进行了测试分析。结果表明,BaSr Ti O3/MgO复相陶瓷可在1 250℃烧结致密,烧结温度比固相法低150℃左右。介电常数下降至160左右,介电常数对偏压的调谐性达到20%以上（1 kV/mm）。     

钛酸钡锶复盐超微陶瓷粉末制备以及粉末结构测定

本文首次报道采用简单低耗的有机介质化学共沉淀法,制备超微陶瓷粉末钛酸钡锶复盐(Ba_xSr(1-x)TiO_3)。由扫描电镜观测其平均粒径在0.45μm以下。由X-粉晶衍射图得到,该复盐粉末属于BaTiO_3(四方)与SrTiO3(立方)的混晶。     

Synthesis of nonstoichiometric M-type barium ferrite nanobelt by spark plasma sintering method

This study investigated the feasibility of ultrafast crystallization of M-type barium ferrite when the coprecipitation precursors in stoichiometric proportions as BaFe12O19, Fe(OH)3 and BaCO3 nanoparticles, had been heated by spark plasma sintering (SPS) process. The results show that SPS method may realize the ultrafast crystallization of M-type barium ferrite, absolutely prevent the crystallization of intermediate phase α-Fe2O3, and significantly decrease the crystallization temperature of M-type barium ferrite. The sintered samples obtained at 800℃ by sintering the precursors for 10 minutes are a kind of multiphase ferrites composed of major phase M-type barium ferrite and trace amount of BaFe0.24Fe0.76O2.88. It is discovered that M-type barium ferrites in the holes of the sintered samples are in nanobelt microstructure about 100-300 nm in width and several micrometers in length. These M-type barium ferrite nanobelts are non-stoichiometric and may be expressed as BaFe12 xO19 1.5x (-4.77≤x≤6.50). Their composistions suggest completely random Fe-rich or Ba-rich domains.     

BaO-SiO_2-B_2O_3-TiO_2系统玻璃结构X射线光电子能谱和核磁共振

利用Ｘ射线光电子能谱（ＸＰＳ）和核磁共振（ＮＭＲ）研究了ＢａＯＳｉＯ２Ｂ２Ｏ３ＴｉＯ２系统玻璃。结果表明该系统玻璃中Ｔｉ４＋的配位数以［ＴｉＯ４］为主。根据其Ｔｉ２ｐ电子结合能值的变化可认为：随ＴｉＯ２含量的增加,［ＴｉＯ４］有向［ＴｉＯ６］转变的趋势。这种转变发生在ＴｉＯ２摩尔分数约为２０％处。ＮＭＲ研究结果显示玻璃样品中,随ＴｉＯ２和Ｂ２Ｏ３含量的增加四配位硼所占的比例Ｎ４值下降,且玻璃中Ｔｉ４＋形成四配位的能力大于Ｂ３＋。     

利用星风吸积模型计算钡星的重元素丰度

为进一步探讨钡星的形成机制,采用了Yutaka Komiya(2007)建立的双星星风吸积模型,计算了4颗钡星的s-元素丰度,并和观测结果作了比较.结果发现,中子辐照量在重元素核合成方面起主导作用,同时检验了Yutaka Komiya模型的合理性.     

Effect of SiO2 addition on the dielectric properties and microstructure of BaTiO3-based ceramics in reducing sintering

The effect of SiO₂ doping on the sintering behavior, microstructure, and dielectric properties of BaTiO₃-based ceramics has been investigated. Silica was added to the BaTiO₃-based powder prepared by the solid state method with 0.075mol%, 0.15mol%, and 0.3mol%, respectively. The SiO₂-doped BaTiO₃-based ceramic with high density and uniform grain size were obtained, which were sintered in reducing atmosphere. A scanning electron microscope, X-ray diffraction, and LCR meter were used to determine the microstructure as well as the dielectric properties. SiO₂ can form a liquid phase belonging to the ternary system of BaO-TiO₂-SiO₂, leading to the formation of BaTiO₃ ceramics with high density at a lower sintering temperature. The SiO₂-doped BaTiO₃-based ceramics can be sintered to a theoretical density higher than 95% at 1220℃ with a soaking time of 2 h. The dielectric constants of the sample with 0.15mol% SiO₂ addition sintered at 1220℃ is about 9000. Doping with a small amount of silica can improve the sintering and dielectric properties of BaTiO₃-based ceramics.     

球形碳酸钡粉体的制备及生产实践

在球形碳酸钡粉体的合成小试研究的基础上进行了放大试验,并应用于生产实践.得出了生产工艺的控制条件为BaCl2·2H2O浓度230g·m-3,NH4HCO3浓度100g·m-3,体积比12;反应温度45～50℃,加料方式为对加,保温陈化30 min,干燥温度为300℃;同时确定了生产中的关键操作单元及设备;获得了含量99.80%、压缩密度为2.42g·cm-3、氯密度为3.862 g·cm-3、粒径0.5μm左右的球形碳酸钡粉体产品.     

碳热还原重晶石无氧工艺研究

针对利用重晶石生产碳酸钡工艺中,因氧气气氛而存在钡利用率低、熟料中产生大量酸溶性钡,导致钡渣排放量大等问题。采用N_2保护对重晶石还原工艺进行了改进,考察了反应温度、反应时间、物料配比和重晶石粒度对水溶性钡及酸溶性钡得率的影响。结果表明,在反应温度为1 000℃,反应时间为40 min,物料质量配比为重晶石∶活性炭=6∶1,重晶石粒度为180~200 mesh的工艺条件下,水溶性BaS得率可达到90.27%,酸溶性钡为7.61%。     

高纯碳酸钡生产工艺的研究

探讨了复分解沉淀法生产电子级高纯碳酸钡工艺中，加料方式、反应温度、陈化时间对产物中杂质Ｃａ＾２＋、Ｃｌ＾－的影响，优选出最佳工艺条件，使产品中的Ｃａ＾２＋、Ｃｌ＾－含量均低于０．０３％。