中温烧结X9R陶瓷材料研究
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摘要
随着电子信息终端设备在高温极端环境下的应用,能适应于高温条件下工作的MLCC成为迫切需要。BaTiO_3是一种性能优良的陶瓷介电材料,宽温型BaTiO_3基介质陶瓷电容器是当前陶瓷电容的研究方向之一。钛酸钡是一种重要的铁电相晶体材料,但纯BaTiO_3在130℃附近存在着介电常数异常的居里峰,使得介电性能急剧恶化,制约着其在高温介质陶瓷中的应用。
通过适当的掺杂及控制工艺条件可以获得介电性能优良的BaTiO_3基介电材料,本文重点讨论了掺杂介质粉体初始粒度及烧结制度对BaTiO_3基陶瓷介电性能的影响。根据所制备的介质陶瓷样片的T-C曲线及SEM形貌图,深入分析了粉体粒度和烧结制度对BaTiO3基介质陶瓷介电性能的影响,并制备出了符合EIA X9R标准的介质陶瓷。
介质粉体的初始粒度对介质陶瓷的介电性能有着重要影响,论文中通过采用不同粒径的球磨介质和球磨不同的时间,制备出了不同粒度的初始粉体。实验表明,初始粉体粒度对系统最终的介电性能有着重要影响。当粉体粒度减小,将具有更大的比表面积,表面原子数急剧增多,这些表面原子由于原子配位不足和高表面能而具有高活性。
在同样的烧结温度下,粉体粒度更小和比表面积更大,能更有效地抑制BaTiO_3晶粒生长并产生细晶效应。掺杂元素对BaTiO_3颗粒进行均匀的包裹形成更多的壳-芯晶粒,即铁电相BaTiO3晶核的比例减小,而顺电相晶壳的体积比增大,使得居里峰压平展宽,介电常数变化率趋于平缓,提高掺杂BaTiO_3陶瓷的介电-温度性能。同时,BaTiO_3粒度的减小导致晶粒中壳/芯体积比增大,壳芯之间失配产生的内应力随之增加,BaTiO_3陶瓷由四方相转变为赝立方相,使居里点Tc提高。
烧结制度对电子陶瓷的物理和电学特性有着重要的影响,烧结温度对晶粒的生长、空洞的密度、杂质离子的扩散分布、晶相的组成等有着重要的作用,并对介质陶瓷最终的介电性能产生重要影响。通过控制烧结温度和保温时间,文中制备了符合EIA X9R标准的介质陶瓷,主要性能指标:室温介电常数ε25oC>1820,tanδ≈1.6%,在-55℃～200℃最大介电常数变化率不超过±15%。
As electronic information terminal equipments are applied into the high temperature environment of extreme heat, MLCCs adapting to the hash working condition, become urgent need now. BaTiO_3 has an excellent performance of dielectric properties, and BaTiO3-based dielectric ceramic capacitors with wide-raged working temperature, is the research direction of the ceramic capacitors. Barium titanate is a kind of important ferroelectric phase crystal materials, however purifed-BaTiO_3 has abnormal dielectric constants at Curie peak around 130℃, which makes dielectric properties worse sharply and restricts the application in the high temperature.
Through proper-doping and control of preparing technology, BaTiO3-based dielectric material can be obtained with a fine dielectric properties. The effect of initial size of medium and sintering-temperature to BaTiO3-based dielectric ceramics is discussed especially in the paper. According to the T-C curve and SEM morphology of dielectric ceramic sample, the role of powder size and sintering steps to BaTiO3-based dielectric ceramic is analysed deeply, and a kind of dielectric ceramic meeting the specification of EIA X9R is prepared.
The dielectric property of ceramic is greatly influenced by the initial size of medium size, and different particle sizes of powder is prepared by different milling-balls and variant milling time in the paper. In the experiments, it is showed that the dielectric properties of the system is greatly influenced by the initial powder size . With the decrease of powder size, the surface energy of particle is enhanced and the amount of surface atoms will also be increased, which will be active due to inadequate atom and high surface energy.
Under the condition of invariable sintering temperature,the growth of BaTiO_3 grain can be more effectively restricted with smaller specific surface area and smaller powder size ,and fine-grain effect can be produced.
More shell-core grain can be formed with the doping elements distributing into BaTiO_3 particles greatly, and the volume of ferroelectric phase core is increased while the volume of shell decreased. The dielectric property of doping BaTiO_3 is enhanced with the Curie peak flat and a slowing rate of dielectric constant. At the same time, the ratio of core to shell is increased with the decrease of BaTiO_3 grain size, and the crystal phase of BaTiO3 is changed from tetragonal phase to the artifact cubic. Because the increase of inner-stress mismatch between the shell and core, the Curie Point is shifted to higher temperature.
The physical and electrical properties of ceramics are greatly influenced by sintering process, and the growth of grain、density of holes、the distribution of doping elements and the crystal phase are affected by the sintering temperature, which also determine the final dielectric properties. The dielectric ceramic meeting EIA X9R specification, were made through the controlling of sintering temperature and keeping time. The main performance indexes are as follows:ε25oC>1820、tanδ≈1.6%、△ε\ε≤±15% (-55℃～200℃).
通过适当的掺杂及控制工艺条件可以获得介电性能优良的BaTiO_3基介电材料,本文重点讨论了掺杂介质粉体初始粒度及烧结制度对BaTiO_3基陶瓷介电性能的影响。根据所制备的介质陶瓷样片的T-C曲线及SEM形貌图,深入分析了粉体粒度和烧结制度对BaTiO3基介质陶瓷介电性能的影响,并制备出了符合EIA X9R标准的介质陶瓷。
介质粉体的初始粒度对介质陶瓷的介电性能有着重要影响,论文中通过采用不同粒径的球磨介质和球磨不同的时间,制备出了不同粒度的初始粉体。实验表明,初始粉体粒度对系统最终的介电性能有着重要影响。当粉体粒度减小,将具有更大的比表面积,表面原子数急剧增多,这些表面原子由于原子配位不足和高表面能而具有高活性。
在同样的烧结温度下,粉体粒度更小和比表面积更大,能更有效地抑制BaTiO_3晶粒生长并产生细晶效应。掺杂元素对BaTiO_3颗粒进行均匀的包裹形成更多的壳-芯晶粒,即铁电相BaTiO3晶核的比例减小,而顺电相晶壳的体积比增大,使得居里峰压平展宽,介电常数变化率趋于平缓,提高掺杂BaTiO_3陶瓷的介电-温度性能。同时,BaTiO_3粒度的减小导致晶粒中壳/芯体积比增大,壳芯之间失配产生的内应力随之增加,BaTiO_3陶瓷由四方相转变为赝立方相,使居里点Tc提高。
烧结制度对电子陶瓷的物理和电学特性有着重要的影响,烧结温度对晶粒的生长、空洞的密度、杂质离子的扩散分布、晶相的组成等有着重要的作用,并对介质陶瓷最终的介电性能产生重要影响。通过控制烧结温度和保温时间,文中制备了符合EIA X9R标准的介质陶瓷,主要性能指标:室温介电常数ε25oC>1820,tanδ≈1.6%,在-55℃～200℃最大介电常数变化率不超过±15%。
As electronic information terminal equipments are applied into the high temperature environment of extreme heat, MLCCs adapting to the hash working condition, become urgent need now. BaTiO_3 has an excellent performance of dielectric properties, and BaTiO3-based dielectric ceramic capacitors with wide-raged working temperature, is the research direction of the ceramic capacitors. Barium titanate is a kind of important ferroelectric phase crystal materials, however purifed-BaTiO_3 has abnormal dielectric constants at Curie peak around 130℃, which makes dielectric properties worse sharply and restricts the application in the high temperature.
Through proper-doping and control of preparing technology, BaTiO3-based dielectric material can be obtained with a fine dielectric properties. The effect of initial size of medium and sintering-temperature to BaTiO3-based dielectric ceramics is discussed especially in the paper. According to the T-C curve and SEM morphology of dielectric ceramic sample, the role of powder size and sintering steps to BaTiO3-based dielectric ceramic is analysed deeply, and a kind of dielectric ceramic meeting the specification of EIA X9R is prepared.
The dielectric property of ceramic is greatly influenced by the initial size of medium size, and different particle sizes of powder is prepared by different milling-balls and variant milling time in the paper. In the experiments, it is showed that the dielectric properties of the system is greatly influenced by the initial powder size . With the decrease of powder size, the surface energy of particle is enhanced and the amount of surface atoms will also be increased, which will be active due to inadequate atom and high surface energy.
Under the condition of invariable sintering temperature,the growth of BaTiO_3 grain can be more effectively restricted with smaller specific surface area and smaller powder size ,and fine-grain effect can be produced.
More shell-core grain can be formed with the doping elements distributing into BaTiO_3 particles greatly, and the volume of ferroelectric phase core is increased while the volume of shell decreased. The dielectric property of doping BaTiO_3 is enhanced with the Curie peak flat and a slowing rate of dielectric constant. At the same time, the ratio of core to shell is increased with the decrease of BaTiO_3 grain size, and the crystal phase of BaTiO3 is changed from tetragonal phase to the artifact cubic. Because the increase of inner-stress mismatch between the shell and core, the Curie Point is shifted to higher temperature.
The physical and electrical properties of ceramics are greatly influenced by sintering process, and the growth of grain、density of holes、the distribution of doping elements and the crystal phase are affected by the sintering temperature, which also determine the final dielectric properties. The dielectric ceramic meeting EIA X9R specification, were made through the controlling of sintering temperature and keeping time. The main performance indexes are as follows:ε25oC>1820、tanδ≈1.6%、△ε\ε≤±15% (-55℃～200℃).
引文
[1]李树尘,现代功能材料应用与发展,成都:西南交通大学社,1994:1-50
[2] A.J.Moulson著,李世普译,电子陶瓷材料性能应用,武汉:武汉理工大学出版社,1993:1-11
[3]李玲,功能材料与纳米技术,化学工业出版社,2002年7月:1-10
[4]邓湘云,李建保,王晓慧等,MLCC的发展趋势及在军用电子设备中的应用,电子元件与材料,2006,5(5):l-6
[5]张宇,张承琚,王永春,多层陶瓷电容器及其发展趋势,2005,23(4):374-376
[6]薛泉林,高压陶瓷电容器及其应用新动向[J],电子元件与材料,2000,19(2): 34–37
[7] Sakabe Y, Reynolds T, Base-metal electrode capacitors, American Cerami Society Bulletin, 2002, 81(10):24-26
[8]陈雷,王晓慧,李龙土,BME MLCC中陶瓷-金属界面行为的研究,电子元件与材料,2007,26(1):56 - 58
[9]杨邦朝,冯哲圣,卢云,多层陶瓷电容器技术现状及未来发展趋势,电子元件与材料,2001年12月:17-19
[10]王森,纪箴,张跃等,MLCC用高介电常数陶瓷介质材料的研究现状及发展趋势,2003,2(3),228-231
[11]陈祥冲,黄新友,多层陶瓷电容器研究现状和发展展望,2004,9(18):12-14
[12]李波,张树人等BaTiO3- R2O3-MgO系介质的稀土掺杂效应,材料研究学报,2008,22(4):433-438
[13] Y.Park, Y.H.Kim, H.G.Kim, The effect of grain size on dielectric behavior of BaTiO3 based X7R materials,Materials Letters, 1996,28:101-106
[14] XiaoHui Wang, RenZheng Chen, ZhiLun Gui, etal, The grain size effect on dielectric properties of BaTiO3 based ceramics, Materials Science and Engineering B99 (2003):199-202
[15]李言荣,恽正中,电子材料导论,清华大学出版社,2001
[16]张延平,电子陶瓷材料物化基础,北京:电子工业出版社, 1996:45-67
[17]刘梅冬,许毓春,压电铁电材料与器件,华中理工大学出版社,1990
[18]莫以豪等,半导体陶瓷及其敏感元件,上海:科学技术出版社,1983
[19] T. Hiramatsu , T. Tamura, N. Wada, H. Tamura, Y. Sakabe, Effects of grain boundary on dielectric properties in fine-grained BaTiO3 ceramics, Materials Scienceand Engineering, 2005,B 120:55–58
[20] Y.Park, Influence of Additives in Z5U and Y5V Capacitor Rept.No.EBA9009053, Samsung Advanced Institute of Technology , Kyunggi, Korea,1990
[21] M.F.Yan, Microstructual Control in the Processing of Electronic Ceramics, Mater.Sci.Eng, 1981,48:53-72
[22]郭炜,李玲霞,吴霞宛等,掺杂稀土元素对BaTiO3,系统介电性能的影响,功能材料与器件学报,2004,10(1):103—106.
[23]李标荣,莫以豪,王筱珍,无机介电材料,上海:上海科学技术出版社,1986:50-60
[24]刘梅冬,许毓春,压电铁电材料与器件,华中理工大学出版社,1990
[25]唐斌,张树人等,BaTiO3陶瓷中Gd、Ce的掺杂效应研究,功能材料与器件学报,2006,12 (5):404-408
[26]赵培峰,孙乐民,纳米钛酸钡微粉的制备,材料开发与应用,2003,18(1):39～42
[27]栾伟玲,高濂,郭景坤,硅酸盐学报,1999,27(1):84-88
[28]李波,张树人,周晓华等,粒度对纳米掺杂BaTi03陶瓷结构和性能的影响,材料研究学报,2006,20(6):641-646
[29] Ying Yuan, Min Du, Shuren Zhang, Effects of BiNbO4 on the microstructure and dielectric properties of BaTiO3-based ceramics, J Mater Sci:Mater Electron, 2009,20:157-162
[30]罗金玲,周志刚,亚纳米铁电陶瓷介电性能的粒度效应,1995,10(2):209-213
[31]曹秀华,姚卿敏,杨智华,球磨工艺对Ni-1VILCC用BaTiO3:分散形态的影响,电子工艺技术,2005,26(1):29-31
[32]Young Hoon Song, Jin Hyun Hwang,Young Ho Han, Effects of Y2O3 on Temperature Stability of Acceptor-Doped BaTiO3,Japanese Journal of Applied Physics,2005,44(3):1310-1313
[33] Yuan Ying, Zhang Shuren, Li Changmin, The effect of doping process on microstructure and dielectric properties of BaTiO3-based X7R materials, Journal of Materials Science: Materials in Electronics, 2004,15:601-606
[34] Zhou Xiaohua, Zhang Shuren,Yuan Ying,etal, Preparation of BaTiO3-Based Nonreducible X7R Dielectric Materials Via Nanometer Powder Doping, J Mater Sci: Mater Electron , 2006,17: 133-136
[35]施剑林,高性能陶瓷与先进陶瓷固相烧结理论研究进展,21世纪青年学者论坛,20(5):124-128
[36]李达,陈沙鸥,邵渭泉等,先进陶瓷材料固相烧结理论研究进展,材料导报,2007,21(9):6-12
[37] Y.Yuan,S.R.Zhang, X.H.Zhou,etal, Effect of Nb2O5 doping on the microstructure and the dielectric temperature characteristics of BaTiO3 ceramic, J Mater Sci., 2009,44:3751-3757
[38]谢磊,吴霞宛等,工艺对中温烧结高温高介MLC介质电性能的影响,1999,1:9-13
[39]李波,张树人等BaTiO3- R2O3-MgO系介质的稀土掺杂效应,材料研究学报,2008,22(4):433-438
[2] A.J.Moulson著,李世普译,电子陶瓷材料性能应用,武汉:武汉理工大学出版社,1993:1-11
[3]李玲,功能材料与纳米技术,化学工业出版社,2002年7月:1-10
[4]邓湘云,李建保,王晓慧等,MLCC的发展趋势及在军用电子设备中的应用,电子元件与材料,2006,5(5):l-6
[5]张宇,张承琚,王永春,多层陶瓷电容器及其发展趋势,2005,23(4):374-376
[6]薛泉林,高压陶瓷电容器及其应用新动向[J],电子元件与材料,2000,19(2): 34–37
[7] Sakabe Y, Reynolds T, Base-metal electrode capacitors, American Cerami Society Bulletin, 2002, 81(10):24-26
[8]陈雷,王晓慧,李龙土,BME MLCC中陶瓷-金属界面行为的研究,电子元件与材料,2007,26(1):56 - 58
[9]杨邦朝,冯哲圣,卢云,多层陶瓷电容器技术现状及未来发展趋势,电子元件与材料,2001年12月:17-19
[10]王森,纪箴,张跃等,MLCC用高介电常数陶瓷介质材料的研究现状及发展趋势,2003,2(3),228-231
[11]陈祥冲,黄新友,多层陶瓷电容器研究现状和发展展望,2004,9(18):12-14
[12]李波,张树人等BaTiO3- R2O3-MgO系介质的稀土掺杂效应,材料研究学报,2008,22(4):433-438
[13] Y.Park, Y.H.Kim, H.G.Kim, The effect of grain size on dielectric behavior of BaTiO3 based X7R materials,Materials Letters, 1996,28:101-106
[14] XiaoHui Wang, RenZheng Chen, ZhiLun Gui, etal, The grain size effect on dielectric properties of BaTiO3 based ceramics, Materials Science and Engineering B99 (2003):199-202
[15]李言荣,恽正中,电子材料导论,清华大学出版社,2001
[16]张延平,电子陶瓷材料物化基础,北京:电子工业出版社, 1996:45-67
[17]刘梅冬,许毓春,压电铁电材料与器件,华中理工大学出版社,1990
[18]莫以豪等,半导体陶瓷及其敏感元件,上海:科学技术出版社,1983
[19] T. Hiramatsu , T. Tamura, N. Wada, H. Tamura, Y. Sakabe, Effects of grain boundary on dielectric properties in fine-grained BaTiO3 ceramics, Materials Scienceand Engineering, 2005,B 120:55–58
[20] Y.Park, Influence of Additives in Z5U and Y5V Capacitor Rept.No.EBA9009053, Samsung Advanced Institute of Technology , Kyunggi, Korea,1990
[21] M.F.Yan, Microstructual Control in the Processing of Electronic Ceramics, Mater.Sci.Eng, 1981,48:53-72
[22]郭炜,李玲霞,吴霞宛等,掺杂稀土元素对BaTiO3,系统介电性能的影响,功能材料与器件学报,2004,10(1):103—106.
[23]李标荣,莫以豪,王筱珍,无机介电材料,上海:上海科学技术出版社,1986:50-60
[24]刘梅冬,许毓春,压电铁电材料与器件,华中理工大学出版社,1990
[25]唐斌,张树人等,BaTiO3陶瓷中Gd、Ce的掺杂效应研究,功能材料与器件学报,2006,12 (5):404-408
[26]赵培峰,孙乐民,纳米钛酸钡微粉的制备,材料开发与应用,2003,18(1):39～42
[27]栾伟玲,高濂,郭景坤,硅酸盐学报,1999,27(1):84-88
[28]李波,张树人,周晓华等,粒度对纳米掺杂BaTi03陶瓷结构和性能的影响,材料研究学报,2006,20(6):641-646
[29] Ying Yuan, Min Du, Shuren Zhang, Effects of BiNbO4 on the microstructure and dielectric properties of BaTiO3-based ceramics, J Mater Sci:Mater Electron, 2009,20:157-162
[30]罗金玲,周志刚,亚纳米铁电陶瓷介电性能的粒度效应,1995,10(2):209-213
[31]曹秀华,姚卿敏,杨智华,球磨工艺对Ni-1VILCC用BaTiO3:分散形态的影响,电子工艺技术,2005,26(1):29-31
[32]Young Hoon Song, Jin Hyun Hwang,Young Ho Han, Effects of Y2O3 on Temperature Stability of Acceptor-Doped BaTiO3,Japanese Journal of Applied Physics,2005,44(3):1310-1313
[33] Yuan Ying, Zhang Shuren, Li Changmin, The effect of doping process on microstructure and dielectric properties of BaTiO3-based X7R materials, Journal of Materials Science: Materials in Electronics, 2004,15:601-606
[34] Zhou Xiaohua, Zhang Shuren,Yuan Ying,etal, Preparation of BaTiO3-Based Nonreducible X7R Dielectric Materials Via Nanometer Powder Doping, J Mater Sci: Mater Electron , 2006,17: 133-136
[35]施剑林,高性能陶瓷与先进陶瓷固相烧结理论研究进展,21世纪青年学者论坛,20(5):124-128
[36]李达,陈沙鸥,邵渭泉等,先进陶瓷材料固相烧结理论研究进展,材料导报,2007,21(9):6-12
[37] Y.Yuan,S.R.Zhang, X.H.Zhou,etal, Effect of Nb2O5 doping on the microstructure and the dielectric temperature characteristics of BaTiO3 ceramic, J Mater Sci., 2009,44:3751-3757
[38]谢磊,吴霞宛等,工艺对中温烧结高温高介MLC介质电性能的影响,1999,1:9-13
[39]李波,张树人等BaTiO3- R2O3-MgO系介质的稀土掺杂效应,材料研究学报,2008,22(4):433-438