【作者】 魏雪松；

【导师】 吴顺华；

【作者基本信息】 天津大学 ， 微电子学与固体电子学， 2011， 博士

【摘要】 本文以制备高介电常数低温烧结陶瓷材料为目标,通过添加不同烧结助剂来降低Ba_6-3x(Nd_1-yBi_y)_8+2xTi₁₈O₅₄ （x=2/3,0≤y≤1） （BNTB）系统陶瓷的烧结温度,研究了各种烧结助剂和实验工艺对BNTB系统陶瓷烧结性能、相组成、微观结构和介电性能的影响,并揭示了其低温烧结的机理。主要研究内容及结果如下:1.添加Bi₂O₃-TiO₂复合氧化物将Ba_6-3x(Nd_1-yBi_y)_8+2xTi₁₈O₅₄ （x=2/3,y=0.2） （BNTB0.2）陶瓷的烧结温度降到了1160℃,这是低温时形成的Bi₂O₃液相和Bi₂O₃-TiO₂低共熔液相的作用。CaO-B₂O3-SiO₂ （CBS）玻璃和Li2O-B₂O3-SiO₂ （LBS）玻璃将Ba_6-3x(Nd_1-yBi_y)_8+2xTi₁₈O₅₄ （x=2/3,y=0.6） （BNTB0.6）陶瓷的烧结温度降到了900℃以下,它们的熔点分别为700℃和744℃,在低温时形成液相,促进BNTB0.6陶瓷的烧结。CBS玻璃中Ca离子对BNTB0.6陶瓷中Ba离子的取代以及LBS玻璃和BNTB0.6陶瓷生成Li_0.5Nd_0.5TiO₃的反应都能促进BNTB0.6陶瓷的烧结。复合添加LBS玻璃和LiF-BaF2将BNTB0.6陶瓷的烧结温度降到了850℃,这是因为LiF-BaF2中的F离子取代LBS玻璃结构中的部分O离子,使LBS玻璃中的负离子团解聚,引起LBS玻璃熔体粘度降低,加快液相烧结过程。2.随着Bi₂O₃-TiO₂复合氧化物添加量的增加,BNTB0.2陶瓷的εr和τε增大,这是由其晶胞体积的增大和Bi离子对Nd离子的取代引起的,而其tanδ则先减小后增大。添加CBS玻璃和LBS玻璃的BNTB0.6陶瓷,随着其晶粒长大,气孔减少,致密度提高,BNTB0.6陶瓷的εr增大,tanδ减小,而当CBS玻璃和LBS玻璃过量时,又使BNTB0.6陶瓷的气孔增加,致密度降低,导致其εr减小,tanδ增大,而且BNTB0.6陶瓷中出现的一些异常长大的晶粒也会使其tanδ增大。3.系统研究了实验工艺对添加10.0 wt% LBS玻璃和1.0 wt% LiF-BaF2的BNTB0.6陶瓷的烧结性能、微观结构和介电性能的影响,得到其预烧温度为1000℃、球磨时间为10h、烧结温度为850℃、保温时间为2h时性能最佳。4.得到了三种低温烧结且性能较好的高介电常数陶瓷材料。（1）添加7.0 wt% CBS玻璃的BNTB0.6陶瓷在875℃烧结2h的介电性能为:εr=73.34,tanδ=0.003,τε=（?）17ppm/℃。（2）添加10.0 wt% LBS玻璃的BNTB0.6陶瓷在875℃烧结2h的介电性能为:εr=75.34, tanδ=0.003,τε=（?）26ppm/℃。（3）复合添加1.0 wt% LiF-BaF2和10.0 wt% LBS玻璃的BNTB0.6陶瓷在850℃烧结2h的介电性能为:εr=75.89,tanδ=0.002,τε=（?）24ppm/℃。更多还原

【Abstract】 For the purpose to prepare middle or high permittivity LTCC ceramic materials, Ba_6-3x(Nd_1-yBi_y)_8+2xTi₁₈O₅₄ （x=2/3, 0≤y≤1） （BNTB） system ceramics were selected as the research objects in this dissertation. The sintering temperature of BNTB system ceramics was reduced by adding different sintering aids. The effects of different sintering aids and experimental techniques on sintering behavior, phase composition, microstructure, dielectric properties and the low temperature sintering mechanisms were studied systematically. Research contents and results are as follows:1. The addition of Bi₂O₃-TiO₂ composite oxide can decrease the sintering temperature of Ba_6-3x(Nd_1-yBi_y)_8+2xTi₁₈O₅₄ （x=2/3,y=0.2） （BNTB0.2） ceramic to 1160℃, which was caused by the Bi₂O₃ liquid phase and Bi₂O₃-TiO₂ eutectic liquid phase. The addition of CaO-B₂O3-SiO₂ （CBS） glass and Li2O-B₂O3-SiO₂ （LBS） glass can decrease the sintering temperature of BNTB0.6 ceramic to below 900℃. The melting point of CBS glass is about 700℃and the melting point of LBS glass is 744℃, which can form liquid phase at low temperature and promote the sintering process of BNTB0.6 ceramic. The substitution of Ba ions in BNTB0.6 by Ca ions in CBS glass and the reaction between LBS glass and BNTB0.6 ceramic to produce Li_0.5Nd_0.5TiO₃ can accelerate the sintering of ceramic. The combined addition of LBS glass and LiF-BaF2 can decrease the sintering temperature of BNTB0.6 ceramic to 850℃. The substitution of oxygen ions in LBS glass structure by F ion in LiF-BaF2 can disaggregate the anion conglomeration, which can decrease the viscosity of LBS molten glass and accelerate the liquid phase sintering process.2. With the increase of Bi₂O₃-TiO₂ composite oxide, theεr andτεof BNTB0.2 ceramic increase, which was caused by the increase of unit cell volume of BNTB0.2 ceramic and the substitution of Nd ions in BNTB0.2 by Bi ions in Bi₂O₃-TiO₂. The tanδof BNTB0.2 ceramic first decrease and then increase. As for BNTB0.6 ceramic doped with CBS glass and LBS glass, with the growth of grains, the decrease of pores, the increase of density, the dielectric constant of BNTB0.6 ceramic increased and the dielectric loss of BNTB0.6 ceramic decreased. The excessive CBS glass and LBS glass led to the increase of pores and the decrease of density, which caused the decrease of dielectric constant and the increase of dielectric loss. The abnormal grain growth of BNTB0.6 ceramic would also caused the increase of dielectric loss.3. The effects of experimental techniques on the sintering behavior, microstructure and dielectric properties of BNTB0.6 ceramic doped with 10.0 wt% LBS glass and 1.0 wt% LiF-BaF2 were studied systematically. The optical properties were achieved when presintering temperature is 1000℃, milling time is 10h, sintering temperature is 850℃and soaking time is 2h.4. Three kinds of dielectric ceramics which had excellent properties were acquired. （1） The BNTB0.6 ceramic doped with 7.0 wt% CBS glass sintered at 875℃for 2h had excellent dielectric properties ofεr=73.34, tanδ=0.003,τε=（?）17ppm/℃. （2） The BNTB0.6 ceramic doped with 10.0 wt% LBS glass sintered at 875℃for 2h had excellent dielectric properties ofεr=75.34, tanδ=0.003,τε=（?）26ppm/℃. （3） The BNTB0.6 ceramic doped with 1.0 wt% LiF-BaF2 and 10.0 wt% LBS glass sintered at 850℃for 2h had excellent dielectric properties ofεr=75.89, tanδ=0.002,τε=（?）24ppm/℃.更多还原