两种铌酸盐无铅压电陶瓷的制备和物性研究
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摘要
由于铅对人体和环境的危害性，铅含量很高的传统的铅基压电陶瓷的应用受到极大挑战。因此，发展无铅系环境协调性压电陶瓷成为一项紧迫且具有重大实用意义的课题。本论文利用传统固相反应法制备了(K_xNa_(1-x))_(1-y)Li_yNbO_3和Sr_(2-x)Ca_xNaNb_5O_(15)(分别简写为KNLN和SCNN)两种体系的无铅压电陶瓷，系统地研究了其微观形貌、结晶结构、介电和压电等方面的物理性质。
(K,Na)NbO_3基陶瓷(KNN)以其优异的压电性能成为目前无铅压电陶瓷材料的研究热点。近年对KNN基压电陶瓷的研究，主要集中在这两个方面：(1)探索具有更优异压电性能的KNN基陶瓷组分；(2)研究引起KNN基陶瓷呈现优异压电性能的物理机制，如准同型相界、晶体结构相变等。
本论文中关于(K_Na_(1-x))_(1-y)Li_yNbO_3体系压电陶瓷的研究侧重于对晶体结构随组分变化的规律性和晶体结构相变对压电性能的影响方面。对于(K_(0．50)Na_(0．50))_(1-y)Li_yNbO_3(y=0-0．08)压电陶瓷的研究，证实了文献报道的晶体结构和压电性能随组分变化的结果。对于(K_xNa_(1-x))_(0．94)Li_(0．06)NbO_3(X=0．30-0．70)压电陶瓷的研究，发现了晶体结构随着组分x变化发生正交-四方-正交的变化，相界分别位于x=0．40和x=0．60处。在所研究的(K_xNa_(1-x))_(1-y)Li_yNbO_3陶瓷体系中，两种组分分别为(K_(0．50)Na_(0.50))_(0．935)Li_(0．065)NbO_3和(K_(0．45)Na_(0．55))_(0．94)Li_(0．06)NbO_3的陶瓷样品呈现出比较优异的压电性能(d_(33)>200pC／N，k_p>45％)。由介电温谱测量得到的这两种组分的陶瓷样品的正交-四方晶体结构相变温度分别为27℃和35℃。推测它们的良好压电性能应与在室温附近发生的正交-四方相变有着密切的关联性。
本论文中制备的钨青铜结构Sr_(2-x)Ca_xNaNb_5O_(15)(x=0-0．15)无铅压电陶瓷的d_(33)为70pC／N左右，室温介电常数大于1400，室温介电损耗小于1％，相对密度大于92％。当Ca~(2+)的添加量x超过0．15时，相对密度、平均晶粒尺寸和压电性能均开始降低。组分为x=0．10的Sr_(1．9)Ca_(0．1)NaNb_5O_(15)陶瓷具有良好的压电性能(d_(33)=74pC／N，k_p=8．2％，Q_m=923)，具有一定应用价值。
The application of traditional lead-based piezoelectric ceramics which contain high lead are strongly challenged because the lead can cause serious damage to human and environment. As a result, the development of lead-free and environmentally-friendly piezoelectric ceramics becomes an urgent and of great practical significance task. In this paper, two type of lead-free piezoelectric ceramics of (K_xNa_(1-x))_(1-y)Li_yNbO_3 and Sr_(2-x)Ca_x NaNb_5O_(15)(abbreviated to KNLN and SCNN, respectively) were fabricated by solid-state reaction technique. Microstructure, crystallographic stucture, dielectric and piezoelectric properties of those two type of ceramics were investigated systematically.
The (K,Na)NbO_3 (KNN) based ceramics have been paid much attention because of their enhanced piezoelectric properties. At present, the investigation on KNN-based ceramics is concentrated on two aspects, (1) exploring the KNN-based compositions with more enhanced piezoelectric properties, and (2) researching on factors which improve the piezoelectric properties of KNN-based ceramics, such as morphotropic phase boundary (MPB) and polymorphic phase transition.
In first part of this paper, the variety of polymorphic structural phase transition(PPT) and the influence of PPT to the piezoelectric properties were mainly discussed. In (K_(0.50)Na_(0.50))_(1-y)Li_yNbO_3 (y=0-0.08) ceramics, with the increase of Li content y the experimental result of PPT and the piezoelectric properties are generally in agreement with that in previous literature. In (K_xNa_(1-x))_(0.94)Li_(0.06)NbO_3(x=0.30-0. 70) ceramics, with the increase of K content x it exists an orthorhombic-tetragonal- orthorhombic phase transition and the phase boundaries are located at x=0.40 and x=0.60, respectively. Two ceramic samples of (K_(0.50)Na_(0.50))_(0.935)Li_(0.065)NbO_3 and (K_(0.45)Na_(0.55))_(0.94)Li_(0.06)NbO_3 show the best piezoelectric properties of d_(33)>200pC/N and k_p>45%. The orthorhombic-tetragonal phase transition temperatures of these two samples are 27℃and 35℃, respectively. It can be speculated that the nice piezoelectric properties of those two samples are mainly related to the existence of orthorhombic-tetragonal phase transition at room temperature.
In second part of this paper, the Sr_(2-x)Ca_xNaNb_5O_(15) piezoelectric ceramics with tungsten bronze structure show the piezoelectric properties of d_(33)-70pC/N, dielectric constantε_1>1400, dielectric loss tgδ<1% and relatice densityρ>92%. For SCNN ceramics, the relative density, the average grain size and the piezoelectric properties begin to decrease when the Ca~(2+) content exceeds 0.15. The ceramic sample of Sr_(1.9)Ca_(0.1)NaNb_5O_(15) reveals the better piezoelectric properties of d_(33)=74pC/N, k_p=8.2% and Q_m=923.
(K,Na)NbO_3基陶瓷(KNN)以其优异的压电性能成为目前无铅压电陶瓷材料的研究热点。近年对KNN基压电陶瓷的研究，主要集中在这两个方面：(1)探索具有更优异压电性能的KNN基陶瓷组分；(2)研究引起KNN基陶瓷呈现优异压电性能的物理机制，如准同型相界、晶体结构相变等。
本论文中关于(K_Na_(1-x))_(1-y)Li_yNbO_3体系压电陶瓷的研究侧重于对晶体结构随组分变化的规律性和晶体结构相变对压电性能的影响方面。对于(K_(0．50)Na_(0．50))_(1-y)Li_yNbO_3(y=0-0．08)压电陶瓷的研究，证实了文献报道的晶体结构和压电性能随组分变化的结果。对于(K_xNa_(1-x))_(0．94)Li_(0．06)NbO_3(X=0．30-0．70)压电陶瓷的研究，发现了晶体结构随着组分x变化发生正交-四方-正交的变化，相界分别位于x=0．40和x=0．60处。在所研究的(K_xNa_(1-x))_(1-y)Li_yNbO_3陶瓷体系中，两种组分分别为(K_(0．50)Na_(0.50))_(0．935)Li_(0．065)NbO_3和(K_(0．45)Na_(0．55))_(0．94)Li_(0．06)NbO_3的陶瓷样品呈现出比较优异的压电性能(d_(33)>200pC／N，k_p>45％)。由介电温谱测量得到的这两种组分的陶瓷样品的正交-四方晶体结构相变温度分别为27℃和35℃。推测它们的良好压电性能应与在室温附近发生的正交-四方相变有着密切的关联性。
本论文中制备的钨青铜结构Sr_(2-x)Ca_xNaNb_5O_(15)(x=0-0．15)无铅压电陶瓷的d_(33)为70pC／N左右，室温介电常数大于1400，室温介电损耗小于1％，相对密度大于92％。当Ca~(2+)的添加量x超过0．15时，相对密度、平均晶粒尺寸和压电性能均开始降低。组分为x=0．10的Sr_(1．9)Ca_(0．1)NaNb_5O_(15)陶瓷具有良好的压电性能(d_(33)=74pC／N，k_p=8．2％，Q_m=923)，具有一定应用价值。
The application of traditional lead-based piezoelectric ceramics which contain high lead are strongly challenged because the lead can cause serious damage to human and environment. As a result, the development of lead-free and environmentally-friendly piezoelectric ceramics becomes an urgent and of great practical significance task. In this paper, two type of lead-free piezoelectric ceramics of (K_xNa_(1-x))_(1-y)Li_yNbO_3 and Sr_(2-x)Ca_x NaNb_5O_(15)(abbreviated to KNLN and SCNN, respectively) were fabricated by solid-state reaction technique. Microstructure, crystallographic stucture, dielectric and piezoelectric properties of those two type of ceramics were investigated systematically.
The (K,Na)NbO_3 (KNN) based ceramics have been paid much attention because of their enhanced piezoelectric properties. At present, the investigation on KNN-based ceramics is concentrated on two aspects, (1) exploring the KNN-based compositions with more enhanced piezoelectric properties, and (2) researching on factors which improve the piezoelectric properties of KNN-based ceramics, such as morphotropic phase boundary (MPB) and polymorphic phase transition.
In first part of this paper, the variety of polymorphic structural phase transition(PPT) and the influence of PPT to the piezoelectric properties were mainly discussed. In (K_(0.50)Na_(0.50))_(1-y)Li_yNbO_3 (y=0-0.08) ceramics, with the increase of Li content y the experimental result of PPT and the piezoelectric properties are generally in agreement with that in previous literature. In (K_xNa_(1-x))_(0.94)Li_(0.06)NbO_3(x=0.30-0. 70) ceramics, with the increase of K content x it exists an orthorhombic-tetragonal- orthorhombic phase transition and the phase boundaries are located at x=0.40 and x=0.60, respectively. Two ceramic samples of (K_(0.50)Na_(0.50))_(0.935)Li_(0.065)NbO_3 and (K_(0.45)Na_(0.55))_(0.94)Li_(0.06)NbO_3 show the best piezoelectric properties of d_(33)>200pC/N and k_p>45%. The orthorhombic-tetragonal phase transition temperatures of these two samples are 27℃and 35℃, respectively. It can be speculated that the nice piezoelectric properties of those two samples are mainly related to the existence of orthorhombic-tetragonal phase transition at room temperature.
In second part of this paper, the Sr_(2-x)Ca_xNaNb_5O_(15) piezoelectric ceramics with tungsten bronze structure show the piezoelectric properties of d_(33)-70pC/N, dielectric constantε_1>1400, dielectric loss tgδ<1% and relatice densityρ>92%. For SCNN ceramics, the relative density, the average grain size and the piezoelectric properties begin to decrease when the Ca~(2+) content exceeds 0.15. The ceramic sample of Sr_(1.9)Ca_(0.1)NaNb_5O_(15) reveals the better piezoelectric properties of d_(33)=74pC/N, k_p=8.2% and Q_m=923.
引文
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[7] Jimenez R., Castro A., and Jimenez B., Evidence of ferroelastic-ferroelasticphase transition in BiMo_xW_(1-x)O_6 compounds[J]. Applied Physics Letters, 2003.83(16): 3350-3352.
[8] Xie R., Akimune Y, Wang R., et al., Spark Plasma Sintering of TungstenBronze Sr_(2-x)Ca_xNaNb_5O_(15) (x = 0.1) Piezoelectric Ceramics: Ⅱ, ElectricalProperties[J]. Journal of the American Ceramic Society, 2002. 85(11): p.2731-2737.
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[1] Hollenstein E., Davis M., Damjanovic D., et al., Piezoelectric properties of Li-and Ta-modified (K_(0.5)Na_(0.5))NbO_3 ceramics[J]. Applied Physics Letters, 2005. 87(18): 182905-3.
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[1] Hollenstein E., Davis M., Damjanovic D., et al., Piezoelectric properties of Li-and Ta-modified (K_(0.5)Na_(0.5))NbO_3 ceramics[J]. Applied Physics Letters, 2005. 87(18): 182905-3.
[2] Saito Y., Takao H., Tani T., et al., Lead-free piezoceramics[J]. Nature, 2004. 432(7013): 84-87.
[3] Park H.-Y., Ahn C.-W., Song H.-C, et al., Microstructure and piezoelectric??properties of 0.95(Na_(0.5)K_(0.5))NbO_3-0.05BaTi03 ceramics[J]. Applied PhysicsLetters, 2006. 89(6): 062906-3.
[4] Zang G-Z., Wang J.-R, Chen H.-C, et al., Perovskite(Na_(0.5)K_(0.5))_(1-x)(LiSb)_xNb_(1-x)O_3 lead-free piezoceramics[J]. Applied PhysicsLetters, 2006. 88(21): 212908-3.
[5] Du H., Tang F., Luo F., et al., Effect of poling condition on piezoelectricproperties of (K_(0.5)Na_(0.5))NbO_3-LiNbO_3 lead-free piezoelectric ceramics[J].Materials Science and Engineering: B. 2007. 175-179.
[6] Saito Y. and Takao H., High performance lead-free piezoelectric ceramics inthe (K,Na)NbO_3-LiTaO_3 solid solution system[J]. Ferroelectrics, 2006. 338:17-32.
[7] Wu J., Xiao D., Wang Y., et al., Effect of K content on the dielectric,piezoelectric, and ferroelectric properties of 0.95(K_xNa_(1-x))NbO_3-0.05LiSbO_3lead-free ceramics[J]. Journal of Applied Physics, 2008.103: 024102.
[8] Wu L., Zhang J., Zheng P., et al., Phase Coexistence and High PiezoelectricProperties in (K_(0.40)Na_(0.60))_(0.96)Li_(0.04)Nb_(0.80)Ta_(0.20)O_3 Ceramics[J]. Journal ofPhysics D: Applied Physics, 2008.41: 035402-035407.
[9] Wu L., Zhang J., Zheng P., et al., Influnence of morphotopic phase bourdarieson physical properties in (K,Na,Li)Nb_(0.80)Ta_(0.20)O_3 ceramics[J]. Journal ofPhysics D: Applied Physics, 2007. 40: 3527-3530.
[10] Klein N., Hollenstein E., Damjanovic D., et al., A study of the phase diagramof (K,Na,Li)NbO_3 determined by dielectric and piezoelectric measurements,and Raman spectroscopy[J]. Journal of Applied Physics, 2007. 102(1):014112-8.
[11] Chang Y, Yang Z., Hou Y, et al., Effects of Li content on the phase structureand electrical properties of lead-free (K_(0.46-x/2)Na_(0.54-x/2)Li_x)(Nb_(0.76)Ta_(0.20)Sb_(0.04))O_3ceramics[J]. Applied Physics Letters, 2007. 90(23): 232905-3.
[12] Guo Y, Kakimoto K.-i., and Ohsato H., Phase transitional behavior andpiezoelectric properties of (Na_(0.5)K_(0.5))NbO_3-LiNbO_3 ceramics[J]. AppliedPhysics Letters, 2004. 85(18): 4121-4123.
[13] Lin D., Kwok K. W., Lam K. H., et al., Structure, piezoelectric and ferroelectric properties of Li- and Sb-modified K_(0.5)Na_(0.5)NbO_3 lead-free ceramics[J], Journal of Physics D: Applied Physics, 2007.40: 3500-35305.
[14] Zhang S., Xia R., and Shrout T. R., Modified (K_(0.5)Na_(0.5))NbO_3 based lead-free piezoelectrics with broad temperature usage range[J]. Applied Physics Letters, 2007. 91(13): 132913-3.
[15] Du H., Zhou W., Luo F., et al., Perovskite lithium and bismuth modified potassium-sodium niobium lead-free ceramics for high temperature applications[J]. Applied Physics Letters, 2007. 91: 182909.
[16] Matsuo K., Xie R., Akimune Y., et al., Preparation of lead-free Sr_(2-x)Ca_xNaNb_5O_(15) (x=0.1)-based piezoceramics with tungsten bronze stucture[J]. Journal of the Ceramic Society of Japan, 2002.110(5): 491-494.
[17] Xie R., Akimune Y., Wang R., et al., Dielectric and piezoelectric properties of Barium-substituted Sr_(1.9)Ca_(0.1)NaNb_5O_(15) ceramics[J]. Japanese Journal of Applied Physics, 2003. 42(12): 7404-7409.