钛酸钡压电陶瓷的制备与物性研究
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摘要
BaTiO3是历史上发现最早的一种压电陶瓷材料。但是,BaTiO3基压电陶瓷目前在实际应用中已很少见。然而,随着可持续经济社会对无铅化要求的日益增强,BaTiO3基陶瓷作为一类很有希望替代PZT的无铅压电材料又重新受到重视。
本课题组曾率先对固相反应途径制备的BaTiO3陶瓷的压电晶粒尺寸效应进行了系统的研究,发现了压电常数d33随着晶粒尺寸的减小而增大的物理现象。但是,通过固相反应途径和利用普通烧结工艺制备小晶粒、高致密度的BaTiO3陶瓷在实验上有一定的困难。在此背景下,本论文从原料和制备工艺的两个方面探讨了提高BaTiO3陶瓷压电性能的可能性。在原料方面,尝试了利用水热法合成的钛酸钡微粉作原料制备钛酸钡陶瓷；在制备工艺方面,对球磨工艺(延长球磨时间或者使用纳米超细研磨设备研磨粉料)和烧结工艺(采取两步烧结方式或热压烧结方式)进行了探索。
本论文使用水热法合成的颗粒度为100nm的BaTiO3微粉为原料,分别采用普通烧结、两步烧结和热压烧结方式制备了陶瓷样品,并对其介电特性和压电性能进行了比较研究。其中,在温度为1170℃、压力为600kg\cm2下保温1小时的条件下进行热压烧结所制备的陶瓷样品的平均晶粒尺寸为5.6μm、相对密度为98.7%,其d33值在室温下达到485pC/N,而在10℃时d33峰值则高达574pC/N。通过两步烧结方式,制备出了d33值在室温下达到405pC/N、于9℃时d33峰值达到442pC/N的BaTiO3陶瓷样品。该样品的相对密度为95.9%,其微观组织结构中大晶粒和小晶粒同时共存,大晶粒的平均晶粒尺寸约为60μm、小晶粒的平均晶粒尺寸约为2.1μm。利用热压烧结和普通烧结制备了具有不同晶粒尺寸的一系列BaTiO3陶瓷样品,考察了d33、kp、相变点和介电常数随晶粒尺寸的变化,并与以通常固相反应途径所制备的BaTiO3陶瓷的晶粒尺寸效应进行了比较。
本论文探讨了二次球磨时间条件对所制备的BaTiO3陶瓷的物性影响。利用固相反应途径制备BaTiO3陶瓷时,通常把二次球磨的时间条件设为12小时。在本论文的研究中,考察了将二次球磨时间延长至18小时所产生的效果。实验上使用二次球磨时间条件分别为12小时和18小时制得的BaTiO3微粉,进行了以各种烧结方式(普通烧结、两步烧结和热压烧结)制备陶瓷样品的摸索。研究发现,将二次球磨的时间条件从12小时延长到18小时时,BaTiO3微粉的平均颗粒尺寸从0.4μm减小到0.2μm。所制备出的BaTiO3陶瓷样品的压电活性也得到了一定的提高。以普通烧结方式所制备的BaTiO3陶瓷样品的室温d33值从365pC/N提高到395pC/N,而利用两步烧结方式所制备的BaTiO3陶瓷样品的室温d33值则从390pC/N提高到413pC/N。
本论文还进行了利用纳米超细研磨设备制备BaTiO3微粉的尝试。将研磨时间条件在1h至3h之间进行变化,制得了一系列颗粒度不同的BaTiO3微粉。扫描电子显微镜观察显示,BaTiO3微粉的颗粒径的尺寸大小依次在0.5μm至0.1μm之间发生变化。通过对BaTiO3微粉的XRD分析和所制备的BaTiO3陶瓷的相变点的分析得知,将研磨时间设定超过2.5小时所得到的BaTiO3微粉中已经有较多量的杂质的混入。利用]各种不同研磨时间条件下研磨得到的BaTiO3微粉、以各种烧结方式(普通烧结、两步烧结和热压烧结)制备出了BaTiO3陶瓷样品,并考察了它们的压电性质。在该实验中,研磨时间条件设为1h、利用普通烧结方法制备出的陶瓷样品呈现比较好的压电性能,其d33值和kp值分别达到了260pC/N和33.4%；研磨时间条件设为1.25h、采用两步烧结方法制备出的陶瓷样品所呈现最好的压电性能为d33=265pC/N、kp=33.7%。
Barium titanate (BaTiO3) is historically the first ceramic piezoelectric material, from which the phenomenon that poled polycrystalline ferroelectric ceramics show piezoelectricity was found. Nowadays, its main technical applications are no longer as a piezoelectric but as a dielectric material instead. However, because of the increasingly strong social demand in the continuous and sustainable development, the BaTiO3-based ceramics draw again much interest in recent years as a promising type of lead-free piezoelectric materials to replace PZT.
Previously, our group has made the systematical study of piezoelectric grain-size effect in those BaTiO3ceramics prepared through the convential solid-state reation route, where an interesting physical phenomenon that d33increases with decreasing the average grain size was found. On the other hand, a problem that it is experimentally diffult to fabricate the fine-grained dense BaTiO3ceramics by means of ordinary sintering was encountered. Under the circumstances, this thesis explored the possibility of enhancing the piezoelectric properties for the BaTiO3ceramics, mainly from the following two aspects. In the aspect of raw material, the author made an attempt of adopting a hydrothermally-synthesized BaTiO3fine powder to fabricate the BaTiO3ceramics. In the aspect of ceramic processing, different milling ways (extending the second ball-milling time or using a new type of milling machine) and sintering techniques (two-step sintering or hot-press sintering) were tested.
Using the hydrothermally-synthesized BaTiO3powder that has the uniformly distributed grain sizes with its average particle size of about100nm as raw material, various types of BaTiO3ceramics were prepared by ordinary sintering, two-step sintering and hot-press sintering, repectively. Their dielectric and piezoelectric properties were investigated. Among the BaTiO3ceramics prepared by hot-press sintering, the one densified under the condition of1170℃-1h-600kg/cm2has the best piezolectric properties. It shows a d33value of485pC/N at room temperature and the remarkbly d33high peak value of574pC/N at10℃. For those BaTiO3ceramics prepared by two-step sintering, the one densified under the condition of1350℃-lmin-1190C-4h exhibits the best piezolectric properties. Its d33value at room temperature is405pC/N, while the d33peak value at9℃is442pC/N. The dielectric and piezoelectric grain-size effects were also investigated for those BaTiO3ceramics that were densiffied by ordinary sintering and hot-press sintering, respectively.
The second ball-milling time of12h had been the standard processing condition when preparing the BaTiO3ceramics via conventional solid-state reaction route in our laboratory. This thesis examined the resultant effect when extending the second ball-milling time to18h. Various types of BaTiO3ceramics were prepared by ordinary sintering, two-step sintering and hot-press sintering, respectively, using the BaTiO3powders fabricated under different second milling condtions (either12h or18h). It was found that the average particle size of the obtained BaTiO3powder decreases from0.4μm to0.2μm and the the d33value of the obtained BaTiO3ceramic increases when extending the second balling time to18h. The d33value of the BaTiO3ceramic densified by ordinary sintering increases from365pC/N to395pC/N, while that of the one densified by hot-press one increases from390pC/N to413pC/N.
A new milling method was also attemped instead of the second ball milling on the usual planetary milling machine, using a recently purchased milling machine "Mini-easy nano fine mills". The milling time condition was varied between0.5h and3h. The average particle sizes of the corresponding BaTiO3powders were found to show a reduction change in the range from0.5μm to0.1μm. From the results obtained from XRD analysis of the BaTiO3powders and the temperature values of phase transitions obtained from dielectric permittivity vs. temperature measurement of the resultant BaTiO3ceramics, detectable amounts of impurities have been incorporated into those BaTiO3powders with the milling time over2.5h. Using these BaTiO3powders with the different milling time condtions, various types of BaTiO3ceramics were prepared by ordinary sintering, two-step sintering and hot-press sintering, respectively. Piezoelectric properties were examined for these BaTiO3ceramics. It was found that the BaTiO3ceramics prepared from those BaTiO3powders having the milling time of1h or1.25h show the better piezolectric properties. The BaTiO3ceramic that were prepared from the BaTiO3powder with the milling time of1h and densified by ordinary sintering has the d33value of260pC/N and the kp value of33.4%. For the one that was prepared from the BaTiO3powder with the milling time of1.25h and densified by two-step sintering displays the d33value of265pC/N and the kp value of33.7%.
本课题组曾率先对固相反应途径制备的BaTiO3陶瓷的压电晶粒尺寸效应进行了系统的研究,发现了压电常数d33随着晶粒尺寸的减小而增大的物理现象。但是,通过固相反应途径和利用普通烧结工艺制备小晶粒、高致密度的BaTiO3陶瓷在实验上有一定的困难。在此背景下,本论文从原料和制备工艺的两个方面探讨了提高BaTiO3陶瓷压电性能的可能性。在原料方面,尝试了利用水热法合成的钛酸钡微粉作原料制备钛酸钡陶瓷；在制备工艺方面,对球磨工艺(延长球磨时间或者使用纳米超细研磨设备研磨粉料)和烧结工艺(采取两步烧结方式或热压烧结方式)进行了探索。
本论文使用水热法合成的颗粒度为100nm的BaTiO3微粉为原料,分别采用普通烧结、两步烧结和热压烧结方式制备了陶瓷样品,并对其介电特性和压电性能进行了比较研究。其中,在温度为1170℃、压力为600kg\cm2下保温1小时的条件下进行热压烧结所制备的陶瓷样品的平均晶粒尺寸为5.6μm、相对密度为98.7%,其d33值在室温下达到485pC/N,而在10℃时d33峰值则高达574pC/N。通过两步烧结方式,制备出了d33值在室温下达到405pC/N、于9℃时d33峰值达到442pC/N的BaTiO3陶瓷样品。该样品的相对密度为95.9%,其微观组织结构中大晶粒和小晶粒同时共存,大晶粒的平均晶粒尺寸约为60μm、小晶粒的平均晶粒尺寸约为2.1μm。利用热压烧结和普通烧结制备了具有不同晶粒尺寸的一系列BaTiO3陶瓷样品,考察了d33、kp、相变点和介电常数随晶粒尺寸的变化,并与以通常固相反应途径所制备的BaTiO3陶瓷的晶粒尺寸效应进行了比较。
本论文探讨了二次球磨时间条件对所制备的BaTiO3陶瓷的物性影响。利用固相反应途径制备BaTiO3陶瓷时,通常把二次球磨的时间条件设为12小时。在本论文的研究中,考察了将二次球磨时间延长至18小时所产生的效果。实验上使用二次球磨时间条件分别为12小时和18小时制得的BaTiO3微粉,进行了以各种烧结方式(普通烧结、两步烧结和热压烧结)制备陶瓷样品的摸索。研究发现,将二次球磨的时间条件从12小时延长到18小时时,BaTiO3微粉的平均颗粒尺寸从0.4μm减小到0.2μm。所制备出的BaTiO3陶瓷样品的压电活性也得到了一定的提高。以普通烧结方式所制备的BaTiO3陶瓷样品的室温d33值从365pC/N提高到395pC/N,而利用两步烧结方式所制备的BaTiO3陶瓷样品的室温d33值则从390pC/N提高到413pC/N。
本论文还进行了利用纳米超细研磨设备制备BaTiO3微粉的尝试。将研磨时间条件在1h至3h之间进行变化,制得了一系列颗粒度不同的BaTiO3微粉。扫描电子显微镜观察显示,BaTiO3微粉的颗粒径的尺寸大小依次在0.5μm至0.1μm之间发生变化。通过对BaTiO3微粉的XRD分析和所制备的BaTiO3陶瓷的相变点的分析得知,将研磨时间设定超过2.5小时所得到的BaTiO3微粉中已经有较多量的杂质的混入。利用]各种不同研磨时间条件下研磨得到的BaTiO3微粉、以各种烧结方式(普通烧结、两步烧结和热压烧结)制备出了BaTiO3陶瓷样品,并考察了它们的压电性质。在该实验中,研磨时间条件设为1h、利用普通烧结方法制备出的陶瓷样品呈现比较好的压电性能,其d33值和kp值分别达到了260pC/N和33.4%；研磨时间条件设为1.25h、采用两步烧结方法制备出的陶瓷样品所呈现最好的压电性能为d33=265pC/N、kp=33.7%。
Barium titanate (BaTiO3) is historically the first ceramic piezoelectric material, from which the phenomenon that poled polycrystalline ferroelectric ceramics show piezoelectricity was found. Nowadays, its main technical applications are no longer as a piezoelectric but as a dielectric material instead. However, because of the increasingly strong social demand in the continuous and sustainable development, the BaTiO3-based ceramics draw again much interest in recent years as a promising type of lead-free piezoelectric materials to replace PZT.
Previously, our group has made the systematical study of piezoelectric grain-size effect in those BaTiO3ceramics prepared through the convential solid-state reation route, where an interesting physical phenomenon that d33increases with decreasing the average grain size was found. On the other hand, a problem that it is experimentally diffult to fabricate the fine-grained dense BaTiO3ceramics by means of ordinary sintering was encountered. Under the circumstances, this thesis explored the possibility of enhancing the piezoelectric properties for the BaTiO3ceramics, mainly from the following two aspects. In the aspect of raw material, the author made an attempt of adopting a hydrothermally-synthesized BaTiO3fine powder to fabricate the BaTiO3ceramics. In the aspect of ceramic processing, different milling ways (extending the second ball-milling time or using a new type of milling machine) and sintering techniques (two-step sintering or hot-press sintering) were tested.
Using the hydrothermally-synthesized BaTiO3powder that has the uniformly distributed grain sizes with its average particle size of about100nm as raw material, various types of BaTiO3ceramics were prepared by ordinary sintering, two-step sintering and hot-press sintering, repectively. Their dielectric and piezoelectric properties were investigated. Among the BaTiO3ceramics prepared by hot-press sintering, the one densified under the condition of1170℃-1h-600kg/cm2has the best piezolectric properties. It shows a d33value of485pC/N at room temperature and the remarkbly d33high peak value of574pC/N at10℃. For those BaTiO3ceramics prepared by two-step sintering, the one densified under the condition of1350℃-lmin-1190C-4h exhibits the best piezolectric properties. Its d33value at room temperature is405pC/N, while the d33peak value at9℃is442pC/N. The dielectric and piezoelectric grain-size effects were also investigated for those BaTiO3ceramics that were densiffied by ordinary sintering and hot-press sintering, respectively.
The second ball-milling time of12h had been the standard processing condition when preparing the BaTiO3ceramics via conventional solid-state reaction route in our laboratory. This thesis examined the resultant effect when extending the second ball-milling time to18h. Various types of BaTiO3ceramics were prepared by ordinary sintering, two-step sintering and hot-press sintering, respectively, using the BaTiO3powders fabricated under different second milling condtions (either12h or18h). It was found that the average particle size of the obtained BaTiO3powder decreases from0.4μm to0.2μm and the the d33value of the obtained BaTiO3ceramic increases when extending the second balling time to18h. The d33value of the BaTiO3ceramic densified by ordinary sintering increases from365pC/N to395pC/N, while that of the one densified by hot-press one increases from390pC/N to413pC/N.
A new milling method was also attemped instead of the second ball milling on the usual planetary milling machine, using a recently purchased milling machine "Mini-easy nano fine mills". The milling time condition was varied between0.5h and3h. The average particle sizes of the corresponding BaTiO3powders were found to show a reduction change in the range from0.5μm to0.1μm. From the results obtained from XRD analysis of the BaTiO3powders and the temperature values of phase transitions obtained from dielectric permittivity vs. temperature measurement of the resultant BaTiO3ceramics, detectable amounts of impurities have been incorporated into those BaTiO3powders with the milling time over2.5h. Using these BaTiO3powders with the different milling time condtions, various types of BaTiO3ceramics were prepared by ordinary sintering, two-step sintering and hot-press sintering, respectively. Piezoelectric properties were examined for these BaTiO3ceramics. It was found that the BaTiO3ceramics prepared from those BaTiO3powders having the milling time of1h or1.25h show the better piezolectric properties. The BaTiO3ceramic that were prepared from the BaTiO3powder with the milling time of1h and densified by ordinary sintering has the d33value of260pC/N and the kp value of33.4%. For the one that was prepared from the BaTiO3powder with the milling time of1.25h and densified by two-step sintering displays the d33value of265pC/N and the kp value of33.7%.
引文
[1]林声和,叶至碧,王裕斌：压电陶瓷,国防工业出版社,北京(1979)
[2]J.C.伯福特,G.W.泰勒：极性介质及其应用,科学出版社,北京(1988)
[3]Jaffe B, Cook WR, Jaffe H. Piezoelectric Ceramics. London:Academic; 1971. pp.53-114.
[4]Karaki T, Yan K, Adachi M. Appl Phys Expr 2008;1:111402.
[5]Takahashi H, Numamoto Y, Tani J, Tsurekawa S. Jpn J Appl Phys 2008; 47:8468.
[6]Wada S, Takeda K, Muraishi T, Kakemoto H, Tsurumi T, Kimura T. Jpn J Appl Phys 2007; 46:7039.
[7]S. F. Shao, J. L. Zhang et al, High piezoelectric properties and domain configuration in BaTiO3 ceramics obtained through solid-state reaction route, J. Physics D:Appl. Phys.,41 (2008) 125408.
[8]Yoshio A, Mikiya S. Piezoelectric ceramic material and its production[P].JP-11-180769, 1999-07-06.
[9]Y. W. Liao, D. Q. Xiao, D. M. Lin et al., "The effects of CeO2-doping on piezoelectric and dielectric properties of Bi0.5(Na1-x-yKxLiy)0.5TiO3 piezoelectric ceramics", Mat. Sci. Eng. B-Solid 133 (1-3),172-176 (2006).
[10]张雷,沈建兴,李传山等.无铅压电陶瓷制备方法的研究进展[J].硅酸盐通报,2007,26(5)：957-961.
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[2]J.C.伯福特,G.W.泰勒：极性介质及其应用,科学出版社,北京(1988)
[3]Jaffe B, Cook WR, Jaffe H. Piezoelectric Ceramics. London:Academic; 1971. pp.53-114.
[4]Karaki T, Yan K, Adachi M. Appl Phys Expr 2008;1:111402.
[5]Takahashi H, Numamoto Y, Tani J, Tsurekawa S. Jpn J Appl Phys 2008; 47:8468.
[6]Wada S, Takeda K, Muraishi T, Kakemoto H, Tsurumi T, Kimura T. Jpn J Appl Phys 2007; 46:7039.
[7]S. F. Shao, J. L. Zhang et al, High piezoelectric properties and domain configuration in BaTiO3 ceramics obtained through solid-state reaction route, J. Physics D:Appl. Phys.,41 (2008) 125408.
[8]Yoshio A, Mikiya S. Piezoelectric ceramic material and its production[P].JP-11-180769, 1999-07-06.
[9]Y. W. Liao, D. Q. Xiao, D. M. Lin et al., "The effects of CeO2-doping on piezoelectric and dielectric properties of Bi0.5(Na1-x-yKxLiy)0.5TiO3 piezoelectric ceramics", Mat. Sci. Eng. B-Solid 133 (1-3),172-176 (2006).
[10]张雷,沈建兴,李传山等.无铅压电陶瓷制备方法的研究进展[J].硅酸盐通报,2007,26(5)：957-961.
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