Na0.5K0.5NbO3无铅压电陶瓷放电等离子烧结的制备工艺

由于Na,K在高温下容易挥发,因而采用普通陶瓷烧结工艺难以得到致密的碱金属铌酸盐系陶瓷,只能通过热压烧结制备高密度的铌酸钾钠(NaNbO3-KNbO3)系无铅压电陶瓷.本研究采用放电等离子烧结(SparkPlasma Sintering,SPS)技术,通过配料、研磨混料、焙烧、SPS烧结、退火工艺后,制备出白色略带黄色的Na0.5K0.5NbO3压电陶瓷试样.在烧结过程中,没有观察到明显的碱挥发,试样密度随烧结温度的增加而增大,860℃以上温度烧结时,试样的密度达到4.22g/cm3(为理论密度的92%).采用分步极化方法对试样进行极化,即先在高温下用低电压极化,再在低温下用高电压极化,极化后样品的压电常数d33为37pC/N～49pC/N.     

铌酸钾钠无铅压电陶瓷掺杂及制备技术现状

铌酸钾钠无铅压电陶瓷因具有环境友好型、良好的电学性能、较好的居里温度等成为当前压电铁电材料的研究热点之一,广泛应用于科技、工业等方面。综述近年来铌酸钾钠压电陶瓷材料的研究进展,主要从金属离子及其氧化物掺杂、稀土离子,以及其他化合物掺杂等方面对铌酸钾钠的掺杂制备进行总结,从热压烧结、微波烧结及放电等离子烧结等方面对其烧结技术进行论述,从激光脉冲沉积技术、射频磁控溅射法等方面对其成形工艺进行综述。结果表明,对铌酸钾钠压电陶瓷进行掺杂制备及采取先进的烧结技术可以明显提升其电学性能,铌酸钾钠压电陶瓷薄膜和涂层的制备拓展了铌酸钾钠的应用范围,使其可以应用于国防、航空航天及通信等方面。最后对铌酸钾钠的发展趋势进行总结。主要从铌酸钾钠陶瓷的掺杂制备、烧结工艺及成形工艺等方面进行综述,对铌酸钾钠压电陶瓷在各领域的研究有一定理论与参考意义。     

KxNa1-xNbO3无铅压电陶瓷的制备工艺分析

采用同相合成及常压烧结法制备了铌酸钾钠(KNN)无铅压电陶瓷,利用阿基米德排水法测定陶瓷的密度,通过X射线衍射进行陶瓷的物相分析,使用扫描电镜(SEM)观察了陶瓷的表面形貌.分析了相组成、烧结温度和保温时间对陶瓷烧结性能的影响.结果表明:采用固相合成法制备的KNN无铅压电陶瓷为具有钙钛矿结构的固溶体;钾取代立方相NaNbO3中的钠使晶格发生畸变及晶格常数变大,引起了致密度下降、晶粒尺寸增大;在合适的温度范围内,延长保温时间,提高烧结温度有利于晶体的发育与长大;烧结温度过高或保温时间过长,在烧结过程中Na、K元素易挥发从而导致陶瓷致密度下降.     

Li、Sb、Ta共掺杂对铌酸钾钠基无铅压电陶瓷相结构和压电性能的影响

采用固相法及常压普通烧结方法,制备了Li、Sb、Ta共掺杂的铌酸钾钠基无铅压电陶瓷(Na0.52K0.44Li0.04)(Nb1-x-ySbxTay)O3,通过调节x、y在0至0.10之间的取值,研究Sb、Ta两种元素共掺杂对铌酸钾钠基陶瓷相结构、压电和介电性能的影响,获得优化的掺杂比例。在研究的组成范围内,随着Sb含量的增加,所得样品均存在一个由正交相向四方相的O-T相变,而随Ta含量的增加,相组成没有变化,且存在一个成分窗口,对应一系列具有较优压电性能的组分。在x=0.05,y=0.06的组分附近时,性能达到最优,d33～334pC/N,Kp～0.35,介电常数约为1900,介电损耗约为2.7%,Pr～16.4μC/cm2,Ec～8.4kV/cm。     

烧结温度对0.9PbZr0.52Ti0.48O3-0.1NaNbO3压电陶瓷结构及电学性能的影响

采用传统固相烧结法制备了钠过量的0.9PbZr0.52Ti0.48O3-0.1NaNbO3(PZT-NN)压电陶瓷,研究了烧结温度对PZT-NN陶瓷晶体结构及其电学性能的影响。XRD结果表明,不同温度烧结的PZT-NN陶瓷均为单一钙钛矿结构,在1125~1150℃温区烧结时,陶瓷发生了由四方相向正交相的相变。随烧结温度进一步升高,压电常数d33、介电常数εr以及剩余极化强度Pr均呈递减趋势,烧结温度为1125℃的PZT-NN陶瓷具有较好的电学性能:d33=218pC/N,εr=851,tanδ=0.02。PZT-NN陶瓷的相对密度随烧结温度的升高而增大,在1150℃时达到95%,钠过量的NaNbO3加入使PZT陶瓷的致密化烧结温度降低了50~150℃。     

0.95(K0.5Na0.5)NbO3-0.05Li(Nb0.5Sb0.5)O3无铅压电陶瓷的显微结构分析与电学性能

采用传统固相反应合成法制备0.95(K0.5Na0.5)NbO3-0.05Li(Nb0.5Sb0.5)O3基无铅压电陶瓷,研究了烧结温度对0.95(K0.5Na0.5)NbO3-0.05Li(Nb0.5Sb0.5)O3陶瓷相结构、显微组织和压电介电性能的影响。结果表明,在960~1060℃的温度区间内,所得到的一系列烧结样品在室温下均为纯的钙钛矿型结构,未观察到第二相出现;随着烧结温度的升高,晶粒的平均尺寸显示出先增大后减小的趋势,在1020℃时晶粒的平均粒径达到最大值3.5μm。电学性能分析表明,烧结温度为1020℃时,该体系陶瓷压电介电性能达到最优值:d33=245pC/N,kp=0.42,tanδ=0.03,ε3T3/ε0=640,Ec=2.1kV/mm,Pr=20μC/cm2。     

0-3型改性PZT／IPN压电复合材料的制备和性能研究

以溶胶-凝胶法制备改性PZT纳米陶瓷粉体，粉体直径50nm左右。以改性PZT陶瓷粉体为压电相，以同步法制备的互穿聚合物网络（IPN）为基体相，采用溶液混合法制备0-3型改性PZT／IPN复合材料。采用自制极化装置对复合体系进行电晕极化，极化电压为9．5kV、极化温度为100℃、极化时间为45min。对不同改性PZT含量的复合材料介电、压电性能检测结果表明：复合材料介电性能和压电性能介于有机和无机体系之间。随着PZT陶瓷含量的增加，复合材料的电性能参数逐渐接近陶瓷相。     

Li2CO3掺杂BaTiO3无铅压电陶瓷的低温烧结

以Li2CO3作为烧结助剂,采用传统固相烧结法制备BaTiO3陶瓷。研究了烧结温度(1000~1150℃)和Li2CO3添加质量分数(0%~5%)对BaTiO3陶瓷结构和电学性能的影响。结果表明:Li2CO3的掺入有效地促进了陶瓷的烧结,使BaTiO3的烧结温度从1300℃以上降低到1050℃。X射线衍射结果表明:未掺Li2CO3的BaTiO3陶瓷样品为四方相结构,掺Li2CO3的BaTiO3陶瓷样品为正交相结构。Li2CO3掺量为1%的陶瓷样品具有较高的致密度,且在1050℃时获得最大值,其相对密度可达94%。当烧结温度为1100℃时,BaTiO3陶瓷的压电常数d33获得最大值,且d33随着Li2CO3掺量的增加而降低。其中Li2CO3掺量为1%时陶瓷具有较好的电性能:d33=200pC/N,εr=1322,TC=115℃。     

Pb[(Mg1/3Nb2/3)0.536(Ni1/3Nb2/3)0.128Ti0.336]O3陶瓷的结构和电学性能

通过铌铁矿预产物法制备出了Pb[(Mgq/3Nb2/3)0.536(Ni1/3Nb2/3)0.128Ti0.336]O3铁电陶瓷,并对其结构和电学性能进行了研究.结果表明,该三元体系组成处在准同型相界区域,1kHz时的介电常数极值达到45540,剩余极化强度为37uC/gm2,压电系数d33也达到780pC/N.烧结时有效地抑制PbO的挥发对于获得高性能的铅系铁电陶瓷有决定性的影响.     

烧结温度对PMSZT压电陶瓷性能的影响

探讨了烧结温度对SiO2掺杂锑锰锆钛酸铅Pb(Mn1、3Sb2、3)0.05Zr0.47Ti0.48O3(简称PMSZT)压电陶瓷性能的影响.通过X射线衍射及扫描电镜分析Pb(Mn1、3Sb2、3)0.05Zr0.47Ti0.48O3 0.1%(SiO2)(质量分数)陶瓷的相组成和显微结构.结果表明合成温度900℃时,可以得到钙钛矿结构.对于适量SiO2掺杂PMSZT压电陶瓷,可以在1100～1150℃时烧结实现致密化,并且介电压电性能较好,当烧结温度为1100℃时综合性能最佳,E33T/ε0=1290,tanδ=0.45%,d33=264 pC/N,Kp=0.59,Qm=2400.     

(0.96Bi_(0.5)Na_(0.5)TiO_3~-0.04BaTiO_3)-(0.98K_(0.5)Na_(0.5)NbO_3~-0.02LiTaO_3)无铅压电陶瓷的结构分析与性能研究

研究了(1-x)(0.96Bi_0.5Na_0.5TiO_3-0.04BaTiO_3)-x(0.98K_0.5Na_0.5NbO_3-0.02LiTaO_3)(BNTBT-KNNLT)体系在0≤x≤0.07这一组分区域的结构和性能.X射线衍射谱发现,这一系列组分在室温下形成纯钙钛矿型固溶体,没有其他杂相产生.(111)峰的峰位和峰形随组分的变化有规律的变化.随着KNNLT组分的加入,压电及介电等性能有比较明显的改变.压电性能随KNNLT的加入出现最大值.当x=0.02时,压电常数d_(33)=125 pC/N.介电常数在室温下随组分的增加而增加.电滞回线的结果显示,尽管在BNTBT中掺杂了KNNLT,这一系列的压电陶瓷仍然具有较大的矫顽场.当x=0.02时,室温下介电常数和剩余极化强度分别为:ε_r=1455,P_r=32.3 μC/cm~2.实验结果表明适量的KNNLT掺杂进BNTBT中可以改善BNTBT的压电和介电性能.     

Ca0.075Sr0.925Bi4Ti4O15铁电陶瓷的性能

用溶胶凝胶法制备了Ca0.075Sr0.925Bi4Ti4O15(简称CSBTi)铁电陶瓷样品,研究了烧结温度对CSBTi铁电陶瓷性能的影响。结果表明:1180℃温度下烧结的CSBTi铁电陶瓷样品的铁电性能得到明显改善,剩余极化强度2Pr为19.4μC/cm2,矫顽场强度Ec为72.5kV/cm;压电常数为d33=9.8pC/N;居里温度TC=543℃,随着测试频率的增加,室温下相对介电常数εr的峰值逐渐下降,而对应的居里温度TC则随之上升,表现出弛豫铁电体的特征。     

多铁性陶瓷BiFeO_3-PbTiO_3-BaTiO_3的介电、压电及其老化性能研究

采用高温固相法制备了钙钛矿结构的0.7BiFeO_3-0.2PbTiO_3-0.1BaTiO_3陶瓷,研究了该陶瓷的介电性能、压电性能及其老化性能。结果表明,该陶瓷是一种非常有潜力的高温压电陶瓷,其介电常数和介电损耗分别为390和0.015,铁电居里温度TC约为600℃,压电常数d_(33)约为100 pC/N,压电常数的时间稳定性和热稳定性好,热退极化温度Td约为500℃。压电常数热退极化机理主要为内在的剩余极化老化,辅以低浓度氧空位等外在缺陷对畴壁的钉扎作用。     

Piezoelectric and dielectric properties of Lix（K0.46Na0.54） 1-xNb0.86Ta0.1 Sb0.04O3 lead-free ceramics

Lead-free piezoelectric ceramics Lix（K0.46Na0.54）1-xNb0.86Ta0.1Sb0.0403 （with x ranging from 0 to 0.1） were synthesized by conventional solid state sintering method. The effect of cationic substitution of Li for K and Na in the A sites of perovskite lattice on the structure, phase transition behavior and electrical properties were investigated. Morphotropic phase boundaries（MPB） between orthorhombic and tetragonal phase are found in the composition range of 0.06≤x≤0.08. Analogous to Pb（Zr, Ti）O3, the dielectric and piezoelectric properties are enhanced for the composition near the morphotropic phase boundary. The Li0.06（K0.46Na0.54）0.94- Nb0.86Ta0.1Sb0.04O3 ceramics show excellent electrical properties, that is, piezoelectric constant d33=215 pC/N, planar electromechanical coupling factor kp=41%, dielectric constant ε33^T /ε0=1 303, and dielectric loss tan δ=2.45%. The results indicate that Lix（K0.46Na0.54）1 -xNb0.86Ta0.1Sb0.0403 ceramic is a promising lead-free piezoelectric material.     

Characterization of sol-gel synthesised lead-free (1 − x)Na0.5Bi0.5TiO3-xBaTiO3-based ceramics

The crystal structure, microstructure, dielectric and ferroelectric properties of (1 − x)Na_0.5Bi_0.5TiO₃-xBaTiO₃ ceramics with x = 0, 0.03, 0.05, 0.07 and 0.1 are investigated. A structural variation according to the system composition was investigated by X-ray diffraction (XRD) analyses. The results revealed that the synthesis temperature for pure perovskite phase powder prepared by the present sol-gel process is much lower (800 °C), and a rhombohedral-tetragonal morphotropic phase boundary (MPB) is found for x = 0.07 composition which showing the highest remanent polarization value and the smallest coercive field. The optimum dielectric and piezoelectric properties were found with the 0.93Na_0.5Bi_0.5TiO₃-0.07BaTiO₃ composition. The piezoelectric constant d₃₃ is 120 pC/N and good polarization behaviour was observed with remanent polarization (P_r) of 12.18 pC/cm², coercive field (E_c) of 2.11 kV/mm, and enhanced dielectric properties ?_r > 1500 at room temperature. The 0.93Na_0.5Bi_0.5TiO₃-0.07BaTiO₃-based ceramic is a promising lead-free piezoelectric candidate for applications in different devices.     

Dielectric and piezoelectric properties of low-temperature sintered lead zirconate titanate ceramics with 0.78PbO-0.22CuO flux addition

Liquid phase sintering of lead zirconate titanate (abbreviated as PZT) ceramics with a 0.78 PbO-0.22 CuO (10:1 in weight ratio) flux was investigated. A small amount sintering flux consisting of a stoichiometrically mixed oxide of PbO-CuO with a eutectic composition successfully accelerated densification of the PZT ceramics far below the conventional sintering temperature. With the 3 wt% flux additions, full densifications of the PZT ceramics were achieved at temperatures as low as 825 °C. The results obtained in the crystal structure, microstructure, and electrical property analyses suggest that the Cu²⁺ impurity ion substitutes as an acceptor center for the perovskite B-site without forming isolated secondary phases. Defect associates of the Cu²⁺ impurities and charge compensating oxygen vacancies appear to affect dielectric and piezoelectric properties of the sintered PZT samples in both positive and negative ways by forming defect dipoles. When the Cu²⁺ content is small, slightly improved dielectric and piezoelectric performances were achieved, though ferroelectric relaxation was obviously developed at the higher Cu²⁺ contents. For the PZT samples sintered at 825 °C with 3 wt% flux addition, relative dielectric permittivity was 2200 and dielectric loss was less than 2%. Remnant polarization, coercive fields, and piezoelectric coefficient (d₃₃) were 32 μC/cm², 8.9 kV/cm and 373 pC/N, respectively.     

溶胶-凝胶法制备Ni掺杂CaCu3Ti4O12陶瓷的显微组织及电性能（英文）

采用溶胶凝胶法制备掺杂不同含量NiO(CaCu3NixTi4O12+x,x=0, 0.1, 0.2, 0.3)的CCTO陶瓷,通过扫描电镜和 X 射线衍射对其显微组织和相成分进行了分析,并研究了NiO掺杂对CCTO介电和压敏性能的影响。研究结果表明:Ni对CCTO陶瓷的相位成分没有影响,与用传统固相法制得的样品相比,用溶胶-凝胶法制成的样品具有更小的晶粒尺寸。从介电测量结果来看,当 x=0.2 时,样品具有最高的介电常数和最低的介电损耗。当x=0.3时,得到最低的漏电流,最小值为 0.295,同时,具有最高的阀值电压与非线性系数,最大值分别为1326V/mm和3.1。     

Effect of sintering temperature on the structure and properties of cerium-doped 0.94(Bi0.5Na0.5)TiO3–0.06BaTiO3 piezoelectric ceramics

Phase structure, microstructure, dielectric and piezoelectric properties of 0.4 wt% CeO₂ doped 0.94(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃ (Ce-BNT6BT) ceramics sintered in the temperature range from 1120 to 1200 °C have been investigated as a candidate for lead-free piezoelectric ceramics. Tetragonal phase played an important role in improvement of electrical properties and the density of the ceramics. Dielectric constant decreased slightly with the increase of sintering temperature in ferroelectric region but a reverse phenomenon occurred in antiferroelectric and paraelectric regions, suggesting that interfacial polarizations were improved with the increase of sintering temperature and domain walls of ferroelectricity became active after depolarization. At room temperature, Ce-BNT6BT ceramics sintered at 1180 °C showed good performances: dielectric constant was 914 at 1 kHz, thick coupling factor k_t was 0.52, and the ratio of k_t/k_p was 2.3. The ceramics were suitable for narrowband filters and ultrasonic transducers in commercial applications.