BaTiO_3基半导体陶瓷细晶化及低温烧结特性的研究
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摘要
随着科学技术的飞速发展,电子元器件的微型化、多功能化及片式化已成为当今电子技术发展的主流,热敏电阻作为电子元器件中不可缺少的一份子,其片式化也势在必行。而制备多层片式PTCR热敏元件主要难题是制备细晶陶瓷和降低陶瓷的烧结温度以实现陶瓷层和电极间的共烧。本文以制备叠层片式PTCR热敏元件为最终目标,主要研究了为得到细晶陶瓷而进行的纳米粉体的制备技术以及PTCR陶瓷的低温烧结技术。
本文采用不同的方法制备了纳米BaTiO_3粉体,系统研究了水热法制备纳米BaTiO_3粉体中反应温度、时间、反应前驱物浓度和钡钛比对粉体性能的影响。发现随反应温度和时间的增加,粉体粒径增大,当前驱物Ba/Ti=2时,反应温度为160℃,时间为2h,可得到产品粒径为32nm,Ba/Ti=0.9520的纯净的钙钛矿结构的BaTiO_3粉体。而采用溶胶-凝胶法也合成了粒径为100-200nm的结晶度良好BaTiO_3粉体。
分别研究了共沉淀包覆掺杂法和化学混合掺杂法对PTCR陶瓷的性能的影响,发现采用共沉淀包覆掺杂法能使掺杂元素在陶瓷中分布更为均匀,从而得到微观结构均一的陶瓷。当Y(NO_3)3掺杂浓度为0.3 mol%并在1250℃保温1h时烧结,样品的室温电阻率为37.8Ω·cm,升阻比为4.8个数量级,电阻-温度系数α为56%。用两步烧结法控制晶粒尺寸,在1250℃保温5min得到了样品晶粒尺寸为1-2μm,室温电阻率为46.8Ω·cm,升阻比为3.5个数量级。
为降低BaTiO_3基PTCR陶瓷的烧结温度,提出了在陶瓷中添加BaO-B2O_3-SiO_2-MnCl_2-LiF烧结助剂的方法。研究了该烧结助剂中LiF对BaTiO_3基PTCR陶瓷微观结构和电性能的影响。实验结果表明:加入0.05 mol LiF的BBSML_2烧结助剂可使陶瓷在低温烧结过程中产生充分的液相,在1050℃烧结得到样品的室温电阻率为151Ω·cm,升阻比为5.6х10~3。
With the rapid development of science and technology, the miniaturization, multifunctionalization and chip technology of electronic components have become as the mainstream. As an integral part of electronic components, the chip technology is also imperative. The main problem of preparing multilayer chip components PTCR is the preparation of fine grained ceramics and lower sintering temperature of PTCR ceramic in order to achieve co-firing between ceramic layers and electrodes. This thesis made the preparation of multilayer chip PTCR thermistor element as the ultimate goal, mainly studied on preparation of fine-grained ceramic powders and sintering PTCR ceramics with low temperature.
Several kinds of nano BaTiO_3 powder were prepared by different methods. The effects of the reaction temperature, time and material match of the hydrothermal synthesis on the properties of nano BaTiO_3 were investigated. The particle size of BaTiO_3 increased with the reaction temperature and time increased. By optimizing the condition of reactive system, we could prepare pure BaTiO_3 powder with particle size of 32nm, and Ba / Ti of 0.9520 in perovskite structure. The sol - gel method could also synthesize BaTiO_3 powder with particle size of 100-200 nm.
The effect of doping method (liquid deposition coating; conventional ball-milling mixing) on microstructure and electrical properties of nano-grained BaTiO_3 ceramics were investigated. The results showed that the liquid deposition coating method produced a homogeneous distribution of the additive in nano-grained BaTiO_3 ceramics, and obtained homogeneous microstructures. The samples with 0.3 mol% Y(NO_3)3 resulted in low room-temperature resistivity of 37.8Ω·cm, ratio of log (Rmax/Rmin) of 4.8 and temperature coefficient of resistance of 56%/℃. Two-step sintering method was used to control grain growth. The samples sintered at 1250℃for 5 mins resulted in the average grain size of 1-2μm, room-temperature resistivity of 46.8ΩΩcm, and ratio of log (Rmax/Rmin) of 3.5.
In order to lowering the sintering temperature of BaTiO_3-based PTCR ceramics, the BaO-B2O_3-SiO_2-MnCl_2-LiF sintering aid was proposed to add in. The effects of BaO-B2O_3-SiO_2-MnCl_2-LiF sintering aid on microstructures and PTCR characteristics of BaTiO_3 ceramics were investigated. The experiment results indicated that PTCR ceramics with 0.5 mol% LiF could produce enough liquid at sintering process and result in low room-temperature resistivity of 151 cm and a resistivity jump of 5.6х10~3.
本文采用不同的方法制备了纳米BaTiO_3粉体,系统研究了水热法制备纳米BaTiO_3粉体中反应温度、时间、反应前驱物浓度和钡钛比对粉体性能的影响。发现随反应温度和时间的增加,粉体粒径增大,当前驱物Ba/Ti=2时,反应温度为160℃,时间为2h,可得到产品粒径为32nm,Ba/Ti=0.9520的纯净的钙钛矿结构的BaTiO_3粉体。而采用溶胶-凝胶法也合成了粒径为100-200nm的结晶度良好BaTiO_3粉体。
分别研究了共沉淀包覆掺杂法和化学混合掺杂法对PTCR陶瓷的性能的影响,发现采用共沉淀包覆掺杂法能使掺杂元素在陶瓷中分布更为均匀,从而得到微观结构均一的陶瓷。当Y(NO_3)3掺杂浓度为0.3 mol%并在1250℃保温1h时烧结,样品的室温电阻率为37.8Ω·cm,升阻比为4.8个数量级,电阻-温度系数α为56%。用两步烧结法控制晶粒尺寸,在1250℃保温5min得到了样品晶粒尺寸为1-2μm,室温电阻率为46.8Ω·cm,升阻比为3.5个数量级。
为降低BaTiO_3基PTCR陶瓷的烧结温度,提出了在陶瓷中添加BaO-B2O_3-SiO_2-MnCl_2-LiF烧结助剂的方法。研究了该烧结助剂中LiF对BaTiO_3基PTCR陶瓷微观结构和电性能的影响。实验结果表明:加入0.05 mol LiF的BBSML_2烧结助剂可使陶瓷在低温烧结过程中产生充分的液相,在1050℃烧结得到样品的室温电阻率为151Ω·cm,升阻比为5.6х10~3。
With the rapid development of science and technology, the miniaturization, multifunctionalization and chip technology of electronic components have become as the mainstream. As an integral part of electronic components, the chip technology is also imperative. The main problem of preparing multilayer chip components PTCR is the preparation of fine grained ceramics and lower sintering temperature of PTCR ceramic in order to achieve co-firing between ceramic layers and electrodes. This thesis made the preparation of multilayer chip PTCR thermistor element as the ultimate goal, mainly studied on preparation of fine-grained ceramic powders and sintering PTCR ceramics with low temperature.
Several kinds of nano BaTiO_3 powder were prepared by different methods. The effects of the reaction temperature, time and material match of the hydrothermal synthesis on the properties of nano BaTiO_3 were investigated. The particle size of BaTiO_3 increased with the reaction temperature and time increased. By optimizing the condition of reactive system, we could prepare pure BaTiO_3 powder with particle size of 32nm, and Ba / Ti of 0.9520 in perovskite structure. The sol - gel method could also synthesize BaTiO_3 powder with particle size of 100-200 nm.
The effect of doping method (liquid deposition coating; conventional ball-milling mixing) on microstructure and electrical properties of nano-grained BaTiO_3 ceramics were investigated. The results showed that the liquid deposition coating method produced a homogeneous distribution of the additive in nano-grained BaTiO_3 ceramics, and obtained homogeneous microstructures. The samples with 0.3 mol% Y(NO_3)3 resulted in low room-temperature resistivity of 37.8Ω·cm, ratio of log (Rmax/Rmin) of 4.8 and temperature coefficient of resistance of 56%/℃. Two-step sintering method was used to control grain growth. The samples sintered at 1250℃for 5 mins resulted in the average grain size of 1-2μm, room-temperature resistivity of 46.8ΩΩcm, and ratio of log (Rmax/Rmin) of 3.5.
In order to lowering the sintering temperature of BaTiO_3-based PTCR ceramics, the BaO-B2O_3-SiO_2-MnCl_2-LiF sintering aid was proposed to add in. The effects of BaO-B2O_3-SiO_2-MnCl_2-LiF sintering aid on microstructures and PTCR characteristics of BaTiO_3 ceramics were investigated. The experiment results indicated that PTCR ceramics with 0.5 mol% LiF could produce enough liquid at sintering process and result in low room-temperature resistivity of 151 cm and a resistivity jump of 5.6х10~3.
引文
[1]周东祥,龚树萍. PTC材料及应用.武汉:华中理工大学出版社, 1989,1~66
[2]吴兆华,周德俭.表面组装技术基础. (第1版).北京:国防工业出版社,2002. 1~8
[3]向勇,谢道华,张昊.片式元器件与SMT技术新进展.电子工艺技术,2001, 22(3): 93~95
[4]薛泉林.叠层PTC热敏电阻器的近期研制动向.江苏陶瓷, 1996, 29(2): 27~30
[5]西村弘治,鶴田智広,渡辺浩一.積層型PTCRサーミスタ及びその製造方法.日本,特開平10-12404, 1998.1~4
[6]佐野晴信.積層型半导体ャテミック素子.日本,特開平5-159903, 1993.1~6
[7] Heywang W. Barium titanate as a semiconductor with blocking layers. Solid State Electronics. 1961, 44(2): 51~58
[8] Heywang W. Resistivity anomaly in doped barium titanate. Joural of the American Ceramic Society. 1964, 47(10):484~490
[9] Jonker G H. Some aspects of semiconducting barium titanate, Solid State Electron, 1964, 7: 895~903
[10] Daniels J, Hardtl K H. The PTC effect of barium titanate, Philips Technical Review, 1978, 38(3): 73~82
[11] Desu S B, Payne D A. Interfacial segregation in perovskites: I Theory. Journal of the American Ceramic Society. 1990, 73(11): 3391~3397
[12] Desu S B,Payne D A. Interfacial segregation in perovskites: II Experimental evidence. Journal of the American Ceramic Society. 1990, 73(11): 3398~3406
[13]程书芬. BaTiO3基PTCR细晶陶瓷的制备及性能研究[博士学位论文].华中科技大学图书馆. 2007.
[14] Cifici E, Rahaman M N, Shumsky M. Hydrothermal precipitation and characterization of nanocrystalline BaTiO3 particles. Journal of the Materials sciences. 2001, 36(20):4875~4882
[15]施尔畏,夏长泰,仲维卓等.水热条件下钛酸钡粉体晶粒形成机理.硅酸盐学报. 1996, 24(1): 45~52
[16] Zhou Y, Wang W, Jia D, et al. Synthesis of SrBi2Ta2O9 nanocrystalline powder by a modified sol-gel process using bismuth subnitrate as bismuth source. Materials Chemistry and Physics. 2002, 77(1): 60~64
[17] Xie D, Pan W. Study on BaBi4Ti4O15 nano-scaled powders prepared by sol-gel method. Materials Letters. 2003, 57(9): 2970~2974
[18]张立德,牟季美.纳米材料学,沈阳:辽宁科学技术出版社, 1994: 88~90
[19] Testino A, Buscaglia M T, Viviani M, et al.Synthesis of BaTiO3 Particles with Tailored Size by Precipitation from Aqueous Solutions. Journal of the American Ceramic Society. 2004. 87(1): 79~83
[20] Leach C, Seaton J. Local Variability in PTC Thermistor Grain Boundary Structures, Wiley InterScience. 2008, 30(2): 339~346
[21] Lai C H, Weng C T, Tseng T Y, et al. The effects of Nd2O3 additives and Al2O3-SiO2-TiO2 sintering aids on the electrical resistivity of (Ba,Sr)TiO3 PTCR ceramics. Materials Chemistry and Physics. 1995, 40(3): 168~172
[22]高濂,孙静,刘阳桥.纳米粉体的分散及表面改性.北京:化学工业出版社,2003.207
[23] Park M B, Cho N H. Chemical and structural features of the grain boundaries in semiconducting BaTiO3 ceramics prepared from surface-coated powders Solid State Ionics. 2002, 154(1): 407~412
[24] Chen I W, Wang X H. Singtering dense nanocrystalline ceramics without final-stage grain growth. Nature. 2000, 404(1):168~171
[25] Wang X H, Deng X Y, Bai H L, et al. Two-Step Sintering of Ceramics with Constant Grain-Size, II: BaTiO3 and Ni–Cu–Zn Ferrite. Journal of the American Ceramic Society. 2006, 89(2): 438~443
[26] Ye F, Liu L M, Zhang J X, et al. Synthesis of silicon nitride-barium aluminosilicate self-reinforced ceramic composite by a two-step pressureless sintering. Composites Science and Technology. 2005, 65(10): 2233~2239
[27] Vo¨ltzke D, Abicht H P. The influence of different additives and the mode of theiraddition on the sintering behavior and the properties of semiconducting barium titanate ceramics. Solid State Sciences. 2000, 2(1): 149~159
[28] Brzozowski E., Caballero A.C., Villegas M, et al.Effect of doping method on microstructural and defect profile of Sb–BaTiO3. Journal of the European Ceramic Society. 2006, 26(7): 2327~2336
[29]郝虎在,田玉明.不同施主掺杂对(Sr0.3Ba0.7)TiO3系热敏LPTC电阻率的影响,电子器件. 2001, 4(9): 24
[30]赖希伟.钛酸钡系热敏电阻器的工艺改进.电子元件与材料. 1997, 16(6): 27~30
[31]杨华斌,刘心宇,骆颖.烧结工艺对BaTiO3基PTCR电阻-温度系数的影响,电工材料. 2005, 4(10): 17~21
[32] Zubair M A, Leach C. The influence of cooling rate and SiO2 additions on grain boundary structure of Mn-doped PTC thermistors. Journal of the European Ceramic Society. 2008, 28(6): 1845~1855
[33] Wang X.H., Chen P L, Chen I W. Two-step Singtering of ceramics with constant grain-size. Journal of the American Ceramic Society. 2006, 89(2): 431~437
[34]姜胜林,周东祥,龚树萍. AST液相掺杂对低电阻率、高抗电强度BaTiO3基热敏陶瓷显微结构及电性能影响.功能材料. 2002, 33(5):532~533
[35] HO I C. Semiconducting barium titanate ceramics prepared by boron-containing liquid-phase sintering. Journal of the American Ceramic Society. 1994, 77(3): 829~832
[36]唐小锋,陈海龙,周志刚. PTCR陶瓷材料的超低温烧结.无机材料学报. 2000, 15(4): 697~702
[37]孔明日,姜胜林,涂文芳,黄兆祥. BBSM烧结助剂对低温烧结PTCR陶瓷性能的影响.电子材料与元件. 2009, 28(11):23~25
[38] Pradel A, Ribes M. Electrical properties of lithium conductive silicon sulfide glasses prepared by twin roller quenching.So1id State Ionics. 1986, 18(19): 351~355
[39] Jeon H P, Lee S K, Kim S W. et al. Effects of BaO–B2O3–SiO2 glass additive ondensification and dielectric properties of BaTiO3 ceramics. Materials Chemistry and Physics.2005, 94(1): 185~189
[40] Matjaz V, Danilo S. Robert C, et al. A mechanism for low-temperature sintering. Journal of the European Ceramic Society. 2006, 26(8): 2777~2783
[41]万帅,吕文中.锌硼玻璃掺杂低压ZnO压敏电阻电性能及晶粒生长动力学研究.无机材料学报. 2010, 25(2): 157~162
[42]霍洛威著.玻璃的物理性质.游恩薄译.北京:轻工业出版社, 1985, 101~234
[43] Valant M, Suvorov D. Low-Temperature Sintering of (Ba0.6Sr0.4)TiO3. Journal of the American Ceramic Society. 2004, 87(7): 1222~1226
[2]吴兆华,周德俭.表面组装技术基础. (第1版).北京:国防工业出版社,2002. 1~8
[3]向勇,谢道华,张昊.片式元器件与SMT技术新进展.电子工艺技术,2001, 22(3): 93~95
[4]薛泉林.叠层PTC热敏电阻器的近期研制动向.江苏陶瓷, 1996, 29(2): 27~30
[5]西村弘治,鶴田智広,渡辺浩一.積層型PTCRサーミスタ及びその製造方法.日本,特開平10-12404, 1998.1~4
[6]佐野晴信.積層型半导体ャテミック素子.日本,特開平5-159903, 1993.1~6
[7] Heywang W. Barium titanate as a semiconductor with blocking layers. Solid State Electronics. 1961, 44(2): 51~58
[8] Heywang W. Resistivity anomaly in doped barium titanate. Joural of the American Ceramic Society. 1964, 47(10):484~490
[9] Jonker G H. Some aspects of semiconducting barium titanate, Solid State Electron, 1964, 7: 895~903
[10] Daniels J, Hardtl K H. The PTC effect of barium titanate, Philips Technical Review, 1978, 38(3): 73~82
[11] Desu S B, Payne D A. Interfacial segregation in perovskites: I Theory. Journal of the American Ceramic Society. 1990, 73(11): 3391~3397
[12] Desu S B,Payne D A. Interfacial segregation in perovskites: II Experimental evidence. Journal of the American Ceramic Society. 1990, 73(11): 3398~3406
[13]程书芬. BaTiO3基PTCR细晶陶瓷的制备及性能研究[博士学位论文].华中科技大学图书馆. 2007.
[14] Cifici E, Rahaman M N, Shumsky M. Hydrothermal precipitation and characterization of nanocrystalline BaTiO3 particles. Journal of the Materials sciences. 2001, 36(20):4875~4882
[15]施尔畏,夏长泰,仲维卓等.水热条件下钛酸钡粉体晶粒形成机理.硅酸盐学报. 1996, 24(1): 45~52
[16] Zhou Y, Wang W, Jia D, et al. Synthesis of SrBi2Ta2O9 nanocrystalline powder by a modified sol-gel process using bismuth subnitrate as bismuth source. Materials Chemistry and Physics. 2002, 77(1): 60~64
[17] Xie D, Pan W. Study on BaBi4Ti4O15 nano-scaled powders prepared by sol-gel method. Materials Letters. 2003, 57(9): 2970~2974
[18]张立德,牟季美.纳米材料学,沈阳:辽宁科学技术出版社, 1994: 88~90
[19] Testino A, Buscaglia M T, Viviani M, et al.Synthesis of BaTiO3 Particles with Tailored Size by Precipitation from Aqueous Solutions. Journal of the American Ceramic Society. 2004. 87(1): 79~83
[20] Leach C, Seaton J. Local Variability in PTC Thermistor Grain Boundary Structures, Wiley InterScience. 2008, 30(2): 339~346
[21] Lai C H, Weng C T, Tseng T Y, et al. The effects of Nd2O3 additives and Al2O3-SiO2-TiO2 sintering aids on the electrical resistivity of (Ba,Sr)TiO3 PTCR ceramics. Materials Chemistry and Physics. 1995, 40(3): 168~172
[22]高濂,孙静,刘阳桥.纳米粉体的分散及表面改性.北京:化学工业出版社,2003.207
[23] Park M B, Cho N H. Chemical and structural features of the grain boundaries in semiconducting BaTiO3 ceramics prepared from surface-coated powders Solid State Ionics. 2002, 154(1): 407~412
[24] Chen I W, Wang X H. Singtering dense nanocrystalline ceramics without final-stage grain growth. Nature. 2000, 404(1):168~171
[25] Wang X H, Deng X Y, Bai H L, et al. Two-Step Sintering of Ceramics with Constant Grain-Size, II: BaTiO3 and Ni–Cu–Zn Ferrite. Journal of the American Ceramic Society. 2006, 89(2): 438~443
[26] Ye F, Liu L M, Zhang J X, et al. Synthesis of silicon nitride-barium aluminosilicate self-reinforced ceramic composite by a two-step pressureless sintering. Composites Science and Technology. 2005, 65(10): 2233~2239
[27] Vo¨ltzke D, Abicht H P. The influence of different additives and the mode of theiraddition on the sintering behavior and the properties of semiconducting barium titanate ceramics. Solid State Sciences. 2000, 2(1): 149~159
[28] Brzozowski E., Caballero A.C., Villegas M, et al.Effect of doping method on microstructural and defect profile of Sb–BaTiO3. Journal of the European Ceramic Society. 2006, 26(7): 2327~2336
[29]郝虎在,田玉明.不同施主掺杂对(Sr0.3Ba0.7)TiO3系热敏LPTC电阻率的影响,电子器件. 2001, 4(9): 24
[30]赖希伟.钛酸钡系热敏电阻器的工艺改进.电子元件与材料. 1997, 16(6): 27~30
[31]杨华斌,刘心宇,骆颖.烧结工艺对BaTiO3基PTCR电阻-温度系数的影响,电工材料. 2005, 4(10): 17~21
[32] Zubair M A, Leach C. The influence of cooling rate and SiO2 additions on grain boundary structure of Mn-doped PTC thermistors. Journal of the European Ceramic Society. 2008, 28(6): 1845~1855
[33] Wang X.H., Chen P L, Chen I W. Two-step Singtering of ceramics with constant grain-size. Journal of the American Ceramic Society. 2006, 89(2): 431~437
[34]姜胜林,周东祥,龚树萍. AST液相掺杂对低电阻率、高抗电强度BaTiO3基热敏陶瓷显微结构及电性能影响.功能材料. 2002, 33(5):532~533
[35] HO I C. Semiconducting barium titanate ceramics prepared by boron-containing liquid-phase sintering. Journal of the American Ceramic Society. 1994, 77(3): 829~832
[36]唐小锋,陈海龙,周志刚. PTCR陶瓷材料的超低温烧结.无机材料学报. 2000, 15(4): 697~702
[37]孔明日,姜胜林,涂文芳,黄兆祥. BBSM烧结助剂对低温烧结PTCR陶瓷性能的影响.电子材料与元件. 2009, 28(11):23~25
[38] Pradel A, Ribes M. Electrical properties of lithium conductive silicon sulfide glasses prepared by twin roller quenching.So1id State Ionics. 1986, 18(19): 351~355
[39] Jeon H P, Lee S K, Kim S W. et al. Effects of BaO–B2O3–SiO2 glass additive ondensification and dielectric properties of BaTiO3 ceramics. Materials Chemistry and Physics.2005, 94(1): 185~189
[40] Matjaz V, Danilo S. Robert C, et al. A mechanism for low-temperature sintering. Journal of the European Ceramic Society. 2006, 26(8): 2777~2783
[41]万帅,吕文中.锌硼玻璃掺杂低压ZnO压敏电阻电性能及晶粒生长动力学研究.无机材料学报. 2010, 25(2): 157~162
[42]霍洛威著.玻璃的物理性质.游恩薄译.北京:轻工业出版社, 1985, 101~234
[43] Valant M, Suvorov D. Low-Temperature Sintering of (Ba0.6Sr0.4)TiO3. Journal of the American Ceramic Society. 2004, 87(7): 1222~1226