制备工艺对新型大各向异性压电陶瓷材料性能的影响

通过在钙改性钛酸铅陶瓷材料中添加少量Pb(Zn1/2W1/2)O3、Pb(Ni1/3Nb2/3)O3和MnCO3,研制出了一种既有大机械品质因数又有大各向异性的压电陶瓷新材料,在预烧温度为845－905℃和烧结温度为1130－1190℃的范围内对新材料的微观结构、性能进行了讨论。当预烧温度为860－885℃,烧结温度为1160－1180℃时,样品在压电性能较佳,该材料可用于制作高温高频换能器。     

0.84(K_(0.48)Na_(0.52))NbO_3-0.16K_(0.56)Li_(0.38)NbO_(2.97)无铅压电陶瓷的多层膜工艺研究

采用多层膜工艺制备了0.84(K0.48Na0.52)NbO3-0.16K0.56Li0.38NbO2.97无铅压电陶瓷,研究了不同烧结温度和保温时间对陶瓷的密度、物相、微观形貌以及介电和压电性能的影响。结果表明,所有烧结条件下得到的陶瓷都是钙钛矿结构和少量钨青铜结构的混合相,而且室温下陶瓷都处于多型相变区域。1050℃烧结8 min得到的陶瓷断面晶粒均匀,相对密度达到95%以上,并且获得最优的介电和压电性能:介电常数为εr=618,介电损耗为tanδ=0.03,压电常数为d33=112 pC/N。与传统制备工艺相比,多层膜工艺大大降低了烧结温度,缩短了烧结时间,有效地抑制了K、Na的挥发。     

烧结温度对Cu优化LNKN无铅压电陶瓷结构和性能的影响

用传统固相烧结工艺制备Li0.06(Na0.5K0.5)0.94NbO3+0.8mol%CuO(LNKN-Cu0.8)无铅压电陶瓷。研究烧结温度对LNKN-Cu0.8无铅压电陶瓷致密度、相结构、微观结构及电学性能的影响。结果发现致密度随烧结温度的升高先增大后降低,在1020℃烧结时达到最大值95%。在所研究的烧结温度范围内,陶瓷都生成了单一钙钛矿结构。虽然没有发现正交和四方两相共存的准同型相界,但由于致密度和微观形貌的影响,在1020℃烧结时,陶瓷的压电性能达到最优值:d33=196pC/N。     

钴铁氧体/锆钛酸铅复合陶瓷材料制备及性能分析

为了得到性能优良的钴铁氧体/锆钛酸铅复合陶瓷材料,首先制备了CoFe2O4和Pb(Zr0.52Ti0.48)O3粉末,然后按照5种配比在4个温度下烧结成了CFO/PZT复合陶瓷样品。测量了烧结样品的XRD图谱、密度、SEM图像、压电性能和磁电性能,分析了CFO和PZT的配比以及烧结温度对样品性能的影响。结果表明,烧结温度升高,样品的致密度呈升高的趋势,压电性能得到改善;CFO含量越高,压电常数下降越大;直流磁场接近饱和场时,磁电转化系数最大。     

改性偏铌酸铅高温压电陶瓷材料的研究

偏铌酸铅是一种性能很有特色却又制备困难的高温压电陶瓷材料，而采用少量Ｍｅ＾２＋置换和微量稀有元素氧化物添杂方法，获得了压电性能和工艺性能均十分优良的改性偏铌酸铅高温压电陶瓷材料，并以热力学熵稳定原理，定性地解释了少量置换与微量添杂对稳定铁电相的作用，同时也对这种压电陶瓷材料的高温压电特性和高温下的应用进行了研究与试验，结果表明，这种材料是一种可以在４００℃下应用的高温压电陶瓷材料。     

陶瓷材料烧结致密化过程的元胞自动机模拟

为研究陶瓷材料烧结致密化过程,以晶界能和晶界曲率生长驱动力理论为基础,建立了含有气孔的二相晶粒生长的元胞自动机模型,对陶瓷材料烧结致密化过程进行了模拟,并与制备的Al2O3/TiN陶瓷材料进行对比.结果表明,模型可有效地模拟陶瓷材料烧结时晶粒的生长及气孔的湮灭情况,能较好地再现烧结致密化过程,模拟结果与制备的陶瓷材料微观形貌组织十分接近.     

含有烧结助剂的复相陶瓷材料烧结过程的元胞自动机模拟

基于晶界能和晶界曲率的晶粒生长驱动力理论,建立了含有烧结助剂的复相陶瓷晶粒生长的元胞自动机模型并进行了模拟。结果表明,烧结助剂对晶界有着强烈的钉扎作用,其晶粒生长指数小于未含烧结助剂时的生长指数。模拟结果与制备的含有烧结助剂的Al2O3／TiN复相陶瓷材料微观形貌组织吻合,表明所建立的模型适用于含有烧结助剂的陶瓷材料烧...     

烧结温度对锆钛酸铅-铌镁酸铅压电陶瓷结构的影响

采用铌铁矿预产物合成法在不同烧结温度下制备组成在准同型相界附近的锆钛酸铅-铌镁酸铅压电陶瓷。采用X射线衍射、拉曼光谱、扫描电镜以及介电温谱对制备陶瓷样品进行表征分析和性能测试。结果表明:所有陶瓷样品的相组成均为纯钙钛矿相;随着烧结温度的升高,陶瓷的相结构由菱方-四方两相共存转变为单一菱方相。对陶瓷断口的观察表明:随着烧结温度的升高,晶粒逐渐长大,陶瓷逐渐致密;陶瓷的平均晶粒尺寸约为3~4μm。制备的压电陶瓷在1 200℃烧结的试样峰值相对介电常数高达19 520,居里温度为310℃。     

PMSZT压电陶瓷的烧结工艺研究

大功率压电陶瓷要求材料不但在强场下有小的介质损耗,大的机械品质因数,同时兼备一定的压电常数和机电耦合系数.当然一般说来,Qm提高的话,Kp、d33就会降低,所以我们希望在保证高Qm情况下,尽可能提高压电应变系数d33和机电耦合系数Kp.微观结构对陶瓷性能有着重要的影响,通过选择合理的烧结制度改变材料的微观结构,可以提高材料的性能.本文研究升温速度和保温时间对PMSZT大功率压电陶瓷的相组成、显微结构及电性能的影响.结果发现升温速度过快或过慢会使材料致密性下降.烧结温度1240 ℃保温1 h时,晶粒致密均匀,居里温度最低.随着保温时间的缩短或延长,居里温度增加.电性能在保温1 h时达最佳:ε33T/ε0=1700,d33=336×pC/N,Kp=0.655,Qm=2200,tanδ=0.0030.PMSZT陶瓷介电和压电性能良好,可以满足了大功率材料的使用要求.     

低温合成压电陶瓷材料

日本东京工学院开发了一种加工温度比传统方法低的合成锆酸钛酸铅压电陶瓷材料(商品名PZT)的方法。传统 PZT 制造法在高于1000℃熔炼和混合铅、锆和钛的氧化物,然后烧结。这种方     

Properties of multilayer composite thin films based on morphotropic phase boundary Pb(Mg1/3Nb2/3)O3-PbTiO3

It has been reported that ferroelectric and piezoelectric properties of Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMNT) thin films, with compositions close to the morphotropic phase boundary (MPB), show lower values than those reported for bulk ceramics with the same composition, which has been attributed to a reduction of the remnant polarization caused by the small size of the grains in the films. An alternative has been proposed to take full advantage of the excellent piezoelectric properties of polycrystalline PMNT in thin film form: a multilayer configuration that uses ferroelectric layers with large remnant polarization, in this case PbTiO₃, to generate an internal electric bias within the PMNT layers and, thus, anchor an induced polarization on them, resulting in a consequent large piezoelectric behavior. The detailed study of the properties of these multilayer composite films reveals the complex correlations that arise in these heterostructures, which are key for the design of optimized piezoelectric films based on MPB PMNT.     

Effects of sintering temperature on dielectric and piezoelectric properties of KNN-LS-BF-0.4mol%CuO lead-free piezoelectric ceramics

KNN-LS-BF-0.4mol%CuO piezoelectric ceramics were prepared by the traditional sintering method. The effects of sintering temperature on the dielectric and piezoelectric properties of KNN-LS-BF-0.4mol%CuO ceramics were studied. The results reveal that the sintering temperature has significant influence on the microstructure and the properties of KNN-LS-BF-0.4mol%CuO ceramics. With the increase of sintering temperature from 1,040 to 1,080 °C, the grains become more homogeneous and more tight-arrangement, resulting in the higher relative density as well as the best dielectric and piezoelectric properties. However, the properties of the samples would be deteriorated as they are sintered over 1,080 °C.     

Er3+掺杂弛豫铁电材料PMNT的单晶生长与性能表征

按照0.71Pb(Mg_1/3Nb_2/3)O₃-0.26PbTiO₃-0.03Pb(Er_1/2Nb_1/2)O₃化学式所示组分比例, 采用分步高温固相反应合成出Er³⁺掺杂PMNT多晶, 通过熔体坩埚下降法生长出尺寸φ25 mm×100 mm的Er³⁺掺杂PMNT晶体, Er³⁺离子以三元固溶体组元方式被掺杂进入钙钛矿相铁电体晶格; 测试了Er³⁺掺杂PMNT晶片的介电、压电与铁电性能以及上转换发光性能。结果表明, Er³⁺掺杂PMNT晶体呈现跟三方相纯PMNT晶体相近的介电、压电与铁电性能; 在980 nm激发光作用下, 该掺杂晶体呈现出Er³⁺离子特有的较强上转换荧光发射, 并且极化后掺杂晶体的上转换发光强度得到增强。     

相组成对PMN-PT陶瓷压电性能的影响

研究了ＰＭＮ－ＰＴ陶瓷在准同型相界（ＭＰＢ）区域、不同烧结温度下,化学组成、相组成对陶瓷压电性能的影响．发现对于同一化学组成的陶瓷,随着烧结温度的上升,发生了菱方相→四方相的相转变,同时随着菱方相、四方相相比例的接近,陶瓷的压电性能有显著的提高．而在不同烧结温度下,最佳压电性能所对应的化学组成有微小的变化．据此认为,陶瓷的压电性能不仅与化学组成有关,而且与相组成也密切相关,随着烧结温度的变化,发生了准同型相界的微小移动     

TiO2和MgO微量添加剂对Al2O3陶瓷烧结致密化的影响

通过在氧化名中添加微量氧化钛和氧化镁,利用无压烧结工艺,制备了具有明显各向异性晶粒的氧化铝块材,研究了氧化钛、氧化镁的添加量和烧结温度对材料显微结构和致密度的影响,与单纯添加氧化钛的氧化铝材料相比,氧化镁的加入细化了氧化铝的晶粒,因此,可以通过调整氧化镁的加入量,在保持氧化铝晶粒各向异性形貌的同时,调整晶粒的尺寸,最终得到比较均匀的显微结构。     

Effect of excess PbO and sintering temperature on the templated grain growth of Pb(Mg<Subscript>1/3</Subscript>Nb<Subscript>2/3</Subscript>)<Subscript>0.67</Subscript>Ti<Subscript>0.33</Subscript>O<Subscript>3</Subscript> polycrystals

The effect of excess lead oxide and sintering temperature on the microstructure evolution in the templated grain growth (TGG) of the Pb(Mg_1/3Nb_{2/ 3})_0.67Ti_0.33O₃ (PMNT67/33) polycrystals was investigated. By adding excess PbO in the precursor of PMNT ceramics, the textured structure of PMNT polycrystals was obtained near SrTiO₃ (ST) template by the conventional ceramic technique. The texture profiles developed progressively with increasing the concentration of excess PbO. A suitable sintering temperature is also very essential to grow a thick textured layer and avoid a second phase. Furthermore, the through-thickness of the PMNT textured layer is strongly influenced by the uniaxial compact-pressure of preparing the ST seeded PMNT specimen.     

Self-separated PZT thick films with bulk-like piezoelectric and electromechanical properties

Self-separated Pb(Zr(0.52)Ti(0.48))O(3) (PZT) films were processed by a hydrothermal deposition and a rapid thermal separation method, followed by a sol-gel filling and sintering process. The films possess excellent piezoelectric and electromechanical properties close to those of bulk material. The maximum remnant polarization is over 30 μC/cm(2) and the electromechanical coupling factor (k(t)) reaches as high as 0.52. The unique microstructure characteristics of the PZT films, such as their highly dense structure, columnar grains, well-connected grain boundaries, and well-dispersed nanopores, could all contribute to the enhanced piezoelectric and electromechanical properties.     

Modified single crystals for high-power underwater projectors

Underwater electroacoustic projectors using single crystals based on the lead magnesium niobate-lead titanate (PMNT) composition were investigated. The large electromechanical coupling coefficient (k(33) > 0.90) and piezoelectric coefficient (d(33) > 1500 pC/N) of PMNT have been demonstrated to improve transducer bandwidth and source level relative to conventional piezoelectric ceramics. The low mechanical quality factor (Q(M) < 200) and low temperature stability (T(RT) < 95°C) of PMNT, however, limit its utility in high-power, high-duty-cycle applications. Use of modified single crystals was shown to result in transducers which exhibit up to 5 dB improvement in source level over PMNT when operated at resonance. Compared with a PZT4 transducer, these modified crystals offer similar source level and power handling capability at resonance, but the available bandwidth is doubled and a 6 dB improvement in maximum source level is achieved when driven off resonance.     

弛豫铁电单晶及织构陶瓷的研究进展

综述了近年来弛豫铁电单晶和织构陶瓷的制备及其介电、压电性能的研究进展。弛豫铁电单晶的制备方法主要有高温溶液法、布里奇曼法和固态再结晶法，尺寸可达40mm以上，(001)切片压电常数d33最大可达3000pC／N，k3达到0.93，但是成分不均匀仍是影响晶体压电性能的一个主要因素。织构陶瓷的制备方法主要为固态再结晶法(TGG法和RTGG法)，其耗时短、成本低，压电性能可达到单晶的60％～80％，介电常数甚至可以超过部分单晶，是一个新的发展方向。     

Effects of Bi excess on the structure and electrical properties of high-temperature BiFeO3–BaTiO3 piezoelectric ceramics

BiFeO₃–BTiO₃(BF–BT) ceramics as a promising candidate for lead-free high-temperature piezoelectric ceramics were studied with a special emphasis on the compositional dependence of piezoelectric properties. Excess Bi was added to compensate for the evaporation of Bi³⁺ ions during sintering and this addition was found to be effective in improving the piezoelectric properties of BF–BT ceramics. The microstructure, dielectric and piezoelectric properties of excess Bi doped BF–BT ceramics were investigated. Maximum piezoelectric constant d ₃₃ = 142 pC/N and k _p = 0.302 were obtained with 0.04 Bi doping. At the same time, an enhanced Curie temperature T _c, 452 °C, was obtained. The combination of improved piezoelectric properties and increased T _c makes these ceramics suitable for elevated temperature piezoelectric devices.