低温烧结宽温稳定性MLCC介质材料研究
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摘要
现在多层陶瓷电容器(MLCC)技术的发展比较快,X7R MLCC由于具有高介电常数和较好的温度稳定性(-55℃～125℃,?C/C25℃≤±15%)应用较为广泛;而X8R MLCC(-55℃～150℃,?C/C25℃≤±15%)目前研究较多,但为了节约成本降低能耗提高市场竞争力需要降低X8R陶瓷的烧结温度(约降低到1000℃左右)。
像天然气井、油井,我们要下去测它的温度、压力,而它现在已经达到很深了(约五六千米),最高工作温度可以达到200℃,这就要求MLCC能够在更宽的温度范围内具有高可靠性。因此低温烧结宽温稳定性MLCC介质材料是目前多层陶瓷电容器发展的一个重要方向。
本论文以高Ag(Ag≥70%)的Ag-Pd合金作为内电极,BaTiO3为基料的MLCC瓷料为研究对象,通过调整配方和调整工艺等手段,降低了陶瓷烧结温度、提高了MLCC的温度应用范围。实验研究的主要成果和结论如下:
1.研究了玻璃(钾硼硅和钡铜硼玻璃)、Cu2+离子、以及金属粉末Mg、Al掺杂对降低BaTiO3陶瓷烧结温度及介电性能的影响,结果发现都有一定的降烧作用,但Cu2+离子对降烧的效果最明显且对介电性能的改善最好。
2.研究了提高绝缘电阻的方法(中和多余的电子或空穴的方法和掺杂CaZrO3),发现这两种方法都起到了较好的效果。
3.研究了工艺(球磨时间、压制的圆片大小)和粒径(掺杂剂颗粒大小、BT基料颗粒大小)对介电性能的影响,发现工艺和粒径对介电性能都有较大的影响。
4.研究了Nb2O5、CuNb2O6掺杂对BT-Nb-Zn体系的影响,MgO掺杂对BT-Nb-Mg体系的影响,发现CuNb2O6能够平坦温度特性,而MgO对改善温度特性效果不佳。
5.初步研究了耐高温材料的制备,制备的瓷料基本满足工程要求。
6.最后将实验室圆片和工厂圆片及MLCC产品的介电性能做了比较,并给出了一个MLCC产品的瓷粉检验报告。
Multi-layer ceramic capacitors (MLCC) technology is faster. X7R MLCC with high dielectric constant and good temperature stability(-55℃～125℃,?C/C25℃≤±15%)is widely used. For X8R MLCC(-55℃～150℃,?C/C25℃≤±15%)research is now more ,However, in order to save cost and reduce energy consumptionin need to lower the sintering temperature of X8R ceramic material.(approximately reduced to about 1000℃).
As gas wells and oil wells , we have to go measure its temperature and pressure, it has now reached a very deep (about 5,6 km), maximum working temperature can reach 200℃, this requires the MLCC to the wider temperature range with high reliability .Therefore, lower the sintering temperature and wide temperature stability of MLCC ceramic material is an important direction of development.
This paper with the high Ag (Ag≥70%) of the Ag-Pd alloy as the inner electrode, BaTiO3-based MLCC ceramic material as the research object. By adjusting the formulation and processes and other means to reduce the sintering temperature, improve the range of temperature applications of MLCC. The main experimental results and conclusions are as follows:
1. The effects of the glass, Cu2+, and Mg, Al on reduce the sintering temperature and dielectric properties doped BaTiO3 ceramics. The results showed that there are some effect, but the Cu2+ is the best on burning down and improvement of the dielectric properties .
2. Researched the methods of improvement the insulation resistance (neutralize in excess of the electron or hole and CaZrO3 doping), found both methods have a good effect.
3. The effects of the process (milling time, suppress the wafer size) and size (dopant particle size, BT base material particle size) on the dielectric properties, found the technology and particle size on dielectric properties have a large impact.
4. The effects of the Nb2O5, CuNb2O6 doped BT-Nb-Zn system and MgO doped BT-Nb-Mg system on dielectric properties, found CuNb2O6 temperature characteristics can be flat, but MgO is ineffective on improvement the temperature characteristics.
5. Preliminary studied the high-temperature material preparation, preparation of ceramic materials basic engineering requirements.
6. Finally, laboratory wafer and factory wafer and MLCC products on dielectric properties were compared, and gived an inspection reports of MLCC products ceramic powders.
像天然气井、油井,我们要下去测它的温度、压力,而它现在已经达到很深了(约五六千米),最高工作温度可以达到200℃,这就要求MLCC能够在更宽的温度范围内具有高可靠性。因此低温烧结宽温稳定性MLCC介质材料是目前多层陶瓷电容器发展的一个重要方向。
本论文以高Ag(Ag≥70%)的Ag-Pd合金作为内电极,BaTiO3为基料的MLCC瓷料为研究对象,通过调整配方和调整工艺等手段,降低了陶瓷烧结温度、提高了MLCC的温度应用范围。实验研究的主要成果和结论如下:
1.研究了玻璃(钾硼硅和钡铜硼玻璃)、Cu2+离子、以及金属粉末Mg、Al掺杂对降低BaTiO3陶瓷烧结温度及介电性能的影响,结果发现都有一定的降烧作用,但Cu2+离子对降烧的效果最明显且对介电性能的改善最好。
2.研究了提高绝缘电阻的方法(中和多余的电子或空穴的方法和掺杂CaZrO3),发现这两种方法都起到了较好的效果。
3.研究了工艺(球磨时间、压制的圆片大小)和粒径(掺杂剂颗粒大小、BT基料颗粒大小)对介电性能的影响,发现工艺和粒径对介电性能都有较大的影响。
4.研究了Nb2O5、CuNb2O6掺杂对BT-Nb-Zn体系的影响,MgO掺杂对BT-Nb-Mg体系的影响,发现CuNb2O6能够平坦温度特性,而MgO对改善温度特性效果不佳。
5.初步研究了耐高温材料的制备,制备的瓷料基本满足工程要求。
6.最后将实验室圆片和工厂圆片及MLCC产品的介电性能做了比较,并给出了一个MLCC产品的瓷粉检验报告。
Multi-layer ceramic capacitors (MLCC) technology is faster. X7R MLCC with high dielectric constant and good temperature stability(-55℃～125℃,?C/C25℃≤±15%)is widely used. For X8R MLCC(-55℃～150℃,?C/C25℃≤±15%)research is now more ,However, in order to save cost and reduce energy consumptionin need to lower the sintering temperature of X8R ceramic material.(approximately reduced to about 1000℃).
As gas wells and oil wells , we have to go measure its temperature and pressure, it has now reached a very deep (about 5,6 km), maximum working temperature can reach 200℃, this requires the MLCC to the wider temperature range with high reliability .Therefore, lower the sintering temperature and wide temperature stability of MLCC ceramic material is an important direction of development.
This paper with the high Ag (Ag≥70%) of the Ag-Pd alloy as the inner electrode, BaTiO3-based MLCC ceramic material as the research object. By adjusting the formulation and processes and other means to reduce the sintering temperature, improve the range of temperature applications of MLCC. The main experimental results and conclusions are as follows:
1. The effects of the glass, Cu2+, and Mg, Al on reduce the sintering temperature and dielectric properties doped BaTiO3 ceramics. The results showed that there are some effect, but the Cu2+ is the best on burning down and improvement of the dielectric properties .
2. Researched the methods of improvement the insulation resistance (neutralize in excess of the electron or hole and CaZrO3 doping), found both methods have a good effect.
3. The effects of the process (milling time, suppress the wafer size) and size (dopant particle size, BT base material particle size) on the dielectric properties, found the technology and particle size on dielectric properties have a large impact.
4. The effects of the Nb2O5, CuNb2O6 doped BT-Nb-Zn system and MgO doped BT-Nb-Mg system on dielectric properties, found CuNb2O6 temperature characteristics can be flat, but MgO is ineffective on improvement the temperature characteristics.
5. Preliminary studied the high-temperature material preparation, preparation of ceramic materials basic engineering requirements.
6. Finally, laboratory wafer and factory wafer and MLCC products on dielectric properties were compared, and gived an inspection reports of MLCC products ceramic powders.
引文
[1] Kishi H, Mizuno Y, Chazono H. Base-metal electrode-multilayer ceramic capacitors: Past, present and future perspectives. Japanese Journal of Applied Physics, 2003, 42(1): 1-5.
[2]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, 25(5):1-6.
[3] Sakabe Y. Multilayer ceramic capacitors, Current Opinion in Solid State and Materials Science,1997, 25(5):1-6.
[4]吴顺华,苏皓,王国庆,等.一种温度超稳定型电子陶瓷材料的组成及其制造方法.中国专利,200410093859, 2005-07-13.
[5] Maher Galeb H, Maher Samir. High dielectric constant very low fired X7R ceramic capacitor, and powder for making. United States Patent: 6727200, 2004.
[6] Wilson James M, Symes Jr, Walter J. Low fire X7R dielectric compositions and capacitors made therefrom. United States Patent: 5571767, 1996.
[7]王晓慧,马超,李龙土,等.低温烧结的温度稳定型多层陶瓷电容器介质材料.中国专利,200610011784.3, 2006.
[8]吴顺华,苏皓,王国庆,等.一种温度超稳定型电子陶瓷材料的组成及其制造方法.中国专利, 200410093859, 2005.
[9] Merz W J. The Electric and Optical Behavior of BaTiO3 Single-Domain Crystals. Physical Review, 1949, 76(8): 1221.
[10] Merz W J. Double Hysteresis Loop of BaTiO3 at the Curie Point. Physical Review, 1953, 91(3): 513.
[11] Merz W J. The Dielectric Behavior of BaTiO3 Single-Domain Crystals. Physical Review, 1949, 75(4): 687.
[12] Arlt G, Hennings D, With G D. Dielectric properties of fine-grained barium titanate ceramics. Journal of Applied Physics, 1985, 58(4): 1619-1625.
[13] Leonard M R, Safari A. Crystallite and grain size effects in BaTiO3. Ferroelectrics, 1996. ISAF '96., Proceedings of the Tenth IEEE International Symposium, 1996, 1003-1005.
[14] Frey M H, Payne D A. Grain-size effect on structure and phase transformations for barium titanate. Physical Review B, 1996, 54(5): 3158.
[15] Begg B D, Vance E R, Nowotny J. Effect of Particle Size on the Room-Temperature Crystal Structure of Barium Titanate. Journal of the American Ceramic Society, 1994, 77(12): 3186-3192.
[16] Lee B W, Auh K H. Effect of grain size and mechanical processing on the dielectric properties of BaTiO3. Journal of Materials Research, 1995, 10(6): 1418-1423.
[17] Buessem W R, Cross L E, Goswami A K. Phenomenological theory of high permittivity in fine-grained barium titanate. Journal of the American Ceramic Society, 1966, 49(1): 33-36.
[18] Bell A J, Moulson A J, Cross L E. Effect of grain size on the permittivity of BaTiO3. Ferroelectrics, 1983, 54(1-4): 487-490.
[19] Okazaki K, Kashiwabara S. Microstructure and Dielectric Properties of high Permittivity Ceramics. J. Ceram. Assoc. Japan, 1965, 73(3-11): 60-66.
[20] Kahn M. Effects of Sintering and Grain Growth on the Distribution of Niobium Addition in Barium Titanate Ceramics: [Ph. D. Thesis]. PA: Pennsylvania State University, 1969.
[21] Park Y, Kim Y H, Kim H G. The effect of grain size on dielectric behavior of BaTiO3 based X7R materials. Materials Letters, 1996, 28(1-3): 101-106.
[22]张勤勇,李言荣,蒋书文,等.钛原子位置对立方BaTiO3电子结构的影响.原子与分子物理学报, 2006, 1:12-16.
[23] Sakabe Y, Wada N, Hiramatsu T, et al. Dielectric properties of fine-grained BaTiO3 ceramics doped with CaO. Japanese Journal of Applied Physics, 2002, 41(11 B): 6922-6925.
[24] Lin J-N, Wu T-B. Wetting reaction between lithium fluoride and barium titanate. Journal of the American Ceramic Society, 1989, 72(9): 1709-1712.
[25] Lu H-Y,Bow J-S,Deng W-H. Core-Shel Structures in ZrO2-Modified BaTiO3 Ceramic. Journal of the American Ceramic Society,1990,73(12):3562-3568.
[26] Armstrong T R,Morgens L E, Maurice A K ,et al. Effects of Zirconia on Microstructutre and Dielectric Properties of Barium Titanate Ceramics . Journal of the American Ceramics Society ,1989, 72(4):605-611.
[27] Begg B D, Finnie K S, Vance E R. Raman Study of the Relationship between Room-Temperature Tetragonality and the Curie Point of Barium Titanate. Journal of the American Ceramic Society, 1996, 79(10): 2666-2672.
[28] Kurata N, Kuwabara M. Semiconducting-Insulating Transition for Highly Donor-Dopod Barium Titanate Ceramics. Journal of the American Ceramic Society, 1993, 76(6): 1605-1608.
[29] Morrison F D, Sinclair D C, West A R. Electrical and structural characteristics of lanthanum-doped barium titanate ceramics. Journal of Applied Physics, 1999, 86(11): 6355-6366.
[30] Hennings D F K, Schreinemacher B, Schreinemacher H. High-permittivity dielectric ceramics with high endurance. Journal of the European Ceramic Society, 1994, 13(1): 81-88.
[31] Chen A, Zhi Y, Zhi J, et al. Synthesis and characterization of Ba(Ti1-xCex)O3 ceramics. Journal of the European Ceramic Society, 1997, 17(10): 1217-1221.
[32] Baxter P, Hellicar N J, Lewis B. Effect of additives of limited solid solubility on ferroelectric properties of barium titanate ceramics. Journal of the American Ceramic Society, 1959, 42(10): 465-470.
[33] Okazki K .Ceramic Engineering for Dielectrics-Fourth Edition . Tokyo :Gakken-sha Publishing Co.Ltd,1992, 281-285.
[34] Nagai T, Iijima K, Hwang H J, et al. Effect of MgO Doping on the Phase Transformations of BaTiO3. Journal of the American Ceramic Society, 2000, 83(1): 107-12.
[35] Ern V, Newnham R E. Effect of WO3 on Dielectric Properties of BaTiO3 Ceramics. Journal of the American Ceramic Society, 1961, 44(4): 199-199.
[36] Uchino K, Sadanaga E, Hirose T. Dependence of the Crystal Structure on Particle Size in Barium Titanate. Journal of the American Ceramic Society, 1989, 72(8): 1555-1558.
[37] Qi J Q, Chen W P, Wang Y, et al. Dielectric properties of barium titanate ceramics doped by B2O3 vapor. Journal of Applied Physics, 2004, 96(11): 6937-6939.
[38] Kahn M. Influence of Grain Growth on Dielectric Properties of Nb-Doped BaTiO3. Journal of the American Ceramic Society, 1971, 54(9): 455-457.
[39] Subbarao E C, Shirane G. Dielectric and Structural Studies in the Systems Ba(Ti, Nb)O3 and Ba(Ti, Ta)O3. Journal of the American Ceramic Society, 1959, 42(6): 279-284.
[40] Murugaraj P, Kutty T, Subba Rao M. Diffuse phase transformations in neodymium-doped BaTiO3 ceramics. Journal of Materials Science, 1986, 21(10): 3521-3527.
[41] Baeten F, Derks B, Coppens W, et al. Barium titanate characterization by differential scanning calorimetry. Journal of the European Ceramic Society, 2006, 26(4-5): 589-592.
[42] Circuit designer`s notebook, Understanding Insulation Resistance,American Technical Ceramics :American Technical Ceramics·www.atceramics.com.
[43] Armstrong T R, Buchanan R C. Influence of Core-Shell Grains on the Internal Stress State and Permittivity Response of Zirconia-Modified Barium Titanate. J Am Ceram Soc, 1990, 73(5):1268-1273.
[44] Kuwabara M, Matsuda H, Kurata N, et al. Shift of the Curie Point of Barium Titanate Ceramics with Sintering Temperature. Journal of the American Ceramic Society, 1997, 80(10): 2590-2596.
[45] Park Y, KIM H G. Pressure and temperature dependence of the dielectric properties in the perovskite solution of Gd-doped barium titanate. Journal of Materials Science Letters, 1998, 17(2): 157-158.
[46] Wang X-H, Chen R-Z, Gui Z-L, et al. The grain size effect on dielectric properties of BaTiO3 based ceramics. Materials Science and Engineering B, 2003, 99(1-3): 199-202.
[47] Li T, Li L, Zhao J, et al. Modulation effect of Mn2+ on dielectric properties of BaTiO3-based X7R materials. Materials Letters, 2000, 44(1): 1-5.
[48] Kobayashi H, Uchida T, Sato S, et al. Dielectric ceramic composition and electronic device. United States Patent, 6764976, 2002-08-23.
[49] Kazushige I, Akira S. Dielectric ceramic composition and electronic device. United States Patent, 7262146, 2007-08-28.
[2]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, 25(5):1-6.
[3] Sakabe Y. Multilayer ceramic capacitors, Current Opinion in Solid State and Materials Science,1997, 25(5):1-6.
[4]吴顺华,苏皓,王国庆,等.一种温度超稳定型电子陶瓷材料的组成及其制造方法.中国专利,200410093859, 2005-07-13.
[5] Maher Galeb H, Maher Samir. High dielectric constant very low fired X7R ceramic capacitor, and powder for making. United States Patent: 6727200, 2004.
[6] Wilson James M, Symes Jr, Walter J. Low fire X7R dielectric compositions and capacitors made therefrom. United States Patent: 5571767, 1996.
[7]王晓慧,马超,李龙土,等.低温烧结的温度稳定型多层陶瓷电容器介质材料.中国专利,200610011784.3, 2006.
[8]吴顺华,苏皓,王国庆,等.一种温度超稳定型电子陶瓷材料的组成及其制造方法.中国专利, 200410093859, 2005.
[9] Merz W J. The Electric and Optical Behavior of BaTiO3 Single-Domain Crystals. Physical Review, 1949, 76(8): 1221.
[10] Merz W J. Double Hysteresis Loop of BaTiO3 at the Curie Point. Physical Review, 1953, 91(3): 513.
[11] Merz W J. The Dielectric Behavior of BaTiO3 Single-Domain Crystals. Physical Review, 1949, 75(4): 687.
[12] Arlt G, Hennings D, With G D. Dielectric properties of fine-grained barium titanate ceramics. Journal of Applied Physics, 1985, 58(4): 1619-1625.
[13] Leonard M R, Safari A. Crystallite and grain size effects in BaTiO3. Ferroelectrics, 1996. ISAF '96., Proceedings of the Tenth IEEE International Symposium, 1996, 1003-1005.
[14] Frey M H, Payne D A. Grain-size effect on structure and phase transformations for barium titanate. Physical Review B, 1996, 54(5): 3158.
[15] Begg B D, Vance E R, Nowotny J. Effect of Particle Size on the Room-Temperature Crystal Structure of Barium Titanate. Journal of the American Ceramic Society, 1994, 77(12): 3186-3192.
[16] Lee B W, Auh K H. Effect of grain size and mechanical processing on the dielectric properties of BaTiO3. Journal of Materials Research, 1995, 10(6): 1418-1423.
[17] Buessem W R, Cross L E, Goswami A K. Phenomenological theory of high permittivity in fine-grained barium titanate. Journal of the American Ceramic Society, 1966, 49(1): 33-36.
[18] Bell A J, Moulson A J, Cross L E. Effect of grain size on the permittivity of BaTiO3. Ferroelectrics, 1983, 54(1-4): 487-490.
[19] Okazaki K, Kashiwabara S. Microstructure and Dielectric Properties of high Permittivity Ceramics. J. Ceram. Assoc. Japan, 1965, 73(3-11): 60-66.
[20] Kahn M. Effects of Sintering and Grain Growth on the Distribution of Niobium Addition in Barium Titanate Ceramics: [Ph. D. Thesis]. PA: Pennsylvania State University, 1969.
[21] Park Y, Kim Y H, Kim H G. The effect of grain size on dielectric behavior of BaTiO3 based X7R materials. Materials Letters, 1996, 28(1-3): 101-106.
[22]张勤勇,李言荣,蒋书文,等.钛原子位置对立方BaTiO3电子结构的影响.原子与分子物理学报, 2006, 1:12-16.
[23] Sakabe Y, Wada N, Hiramatsu T, et al. Dielectric properties of fine-grained BaTiO3 ceramics doped with CaO. Japanese Journal of Applied Physics, 2002, 41(11 B): 6922-6925.
[24] Lin J-N, Wu T-B. Wetting reaction between lithium fluoride and barium titanate. Journal of the American Ceramic Society, 1989, 72(9): 1709-1712.
[25] Lu H-Y,Bow J-S,Deng W-H. Core-Shel Structures in ZrO2-Modified BaTiO3 Ceramic. Journal of the American Ceramic Society,1990,73(12):3562-3568.
[26] Armstrong T R,Morgens L E, Maurice A K ,et al. Effects of Zirconia on Microstructutre and Dielectric Properties of Barium Titanate Ceramics . Journal of the American Ceramics Society ,1989, 72(4):605-611.
[27] Begg B D, Finnie K S, Vance E R. Raman Study of the Relationship between Room-Temperature Tetragonality and the Curie Point of Barium Titanate. Journal of the American Ceramic Society, 1996, 79(10): 2666-2672.
[28] Kurata N, Kuwabara M. Semiconducting-Insulating Transition for Highly Donor-Dopod Barium Titanate Ceramics. Journal of the American Ceramic Society, 1993, 76(6): 1605-1608.
[29] Morrison F D, Sinclair D C, West A R. Electrical and structural characteristics of lanthanum-doped barium titanate ceramics. Journal of Applied Physics, 1999, 86(11): 6355-6366.
[30] Hennings D F K, Schreinemacher B, Schreinemacher H. High-permittivity dielectric ceramics with high endurance. Journal of the European Ceramic Society, 1994, 13(1): 81-88.
[31] Chen A, Zhi Y, Zhi J, et al. Synthesis and characterization of Ba(Ti1-xCex)O3 ceramics. Journal of the European Ceramic Society, 1997, 17(10): 1217-1221.
[32] Baxter P, Hellicar N J, Lewis B. Effect of additives of limited solid solubility on ferroelectric properties of barium titanate ceramics. Journal of the American Ceramic Society, 1959, 42(10): 465-470.
[33] Okazki K .Ceramic Engineering for Dielectrics-Fourth Edition . Tokyo :Gakken-sha Publishing Co.Ltd,1992, 281-285.
[34] Nagai T, Iijima K, Hwang H J, et al. Effect of MgO Doping on the Phase Transformations of BaTiO3. Journal of the American Ceramic Society, 2000, 83(1): 107-12.
[35] Ern V, Newnham R E. Effect of WO3 on Dielectric Properties of BaTiO3 Ceramics. Journal of the American Ceramic Society, 1961, 44(4): 199-199.
[36] Uchino K, Sadanaga E, Hirose T. Dependence of the Crystal Structure on Particle Size in Barium Titanate. Journal of the American Ceramic Society, 1989, 72(8): 1555-1558.
[37] Qi J Q, Chen W P, Wang Y, et al. Dielectric properties of barium titanate ceramics doped by B2O3 vapor. Journal of Applied Physics, 2004, 96(11): 6937-6939.
[38] Kahn M. Influence of Grain Growth on Dielectric Properties of Nb-Doped BaTiO3. Journal of the American Ceramic Society, 1971, 54(9): 455-457.
[39] Subbarao E C, Shirane G. Dielectric and Structural Studies in the Systems Ba(Ti, Nb)O3 and Ba(Ti, Ta)O3. Journal of the American Ceramic Society, 1959, 42(6): 279-284.
[40] Murugaraj P, Kutty T, Subba Rao M. Diffuse phase transformations in neodymium-doped BaTiO3 ceramics. Journal of Materials Science, 1986, 21(10): 3521-3527.
[41] Baeten F, Derks B, Coppens W, et al. Barium titanate characterization by differential scanning calorimetry. Journal of the European Ceramic Society, 2006, 26(4-5): 589-592.
[42] Circuit designer`s notebook, Understanding Insulation Resistance,American Technical Ceramics :American Technical Ceramics·www.atceramics.com.
[43] Armstrong T R, Buchanan R C. Influence of Core-Shell Grains on the Internal Stress State and Permittivity Response of Zirconia-Modified Barium Titanate. J Am Ceram Soc, 1990, 73(5):1268-1273.
[44] Kuwabara M, Matsuda H, Kurata N, et al. Shift of the Curie Point of Barium Titanate Ceramics with Sintering Temperature. Journal of the American Ceramic Society, 1997, 80(10): 2590-2596.
[45] Park Y, KIM H G. Pressure and temperature dependence of the dielectric properties in the perovskite solution of Gd-doped barium titanate. Journal of Materials Science Letters, 1998, 17(2): 157-158.
[46] Wang X-H, Chen R-Z, Gui Z-L, et al. The grain size effect on dielectric properties of BaTiO3 based ceramics. Materials Science and Engineering B, 2003, 99(1-3): 199-202.
[47] Li T, Li L, Zhao J, et al. Modulation effect of Mn2+ on dielectric properties of BaTiO3-based X7R materials. Materials Letters, 2000, 44(1): 1-5.
[48] Kobayashi H, Uchida T, Sato S, et al. Dielectric ceramic composition and electronic device. United States Patent, 6764976, 2002-08-23.
[49] Kazushige I, Akira S. Dielectric ceramic composition and electronic device. United States Patent, 7262146, 2007-08-28.