Effects of Excess Barium on the Structure and Electrical Properties of (Ba,Ca)TiO<Subscript>3</Subscript> Piezoelectric Ceramics with High Mechanical Quality Factors

Manganese-doped Ba_0.925Ca_0.075TiO₃ lead-free piezoelectric ceramics (abbreviated as BCT) with high mechanical quality factor were synthesized by conventional solid-state reaction method. The effects of excess Ba on the crystal structure, microstructure, and electrical properties of the ceramics were systematically investigated. X-ray diffraction and Raman spectra revealed that Ca²⁺ ions were pushed from Ba sites to Ti sites of BCT when 1.5 mol% extra Ba²⁺ ions were added after sintering. The grain size of the ceramics was decreased by adding extra Ba²⁺ ions. The mechanical quality factor and resistivity of the ceramics decreased dramatically when the excess Ba was more than 1.5 mol%. High piezoelectric coefficients ( d₃₃ = 150–190 pC/N ) and high mechanical quality factors ( Q_m = 1 000–1 200 ) were obtained in the ceramics when the excess of Ba was between 0.5 mol% and 1 mol%. These results indicated that the properties of BCT ceramics could be tailored by adjusting the content of Ba.     

Microstructures and Electrical Properties of Bi_(0.5)-(Na_(1-x-y)K_xLi_y)_(0.5)TiO_3 Lead-free Piezoelectric Ceramics

The microstructures and electrical properties of Bi0.5(Na1-x-yKxLiy)0.5TiO3 lead-free piezoelectric ceramics were studied.These ceramics were prepared by conventional ceramic technique.XRD analysis reveals that the ceramics possess almost pure perovskite phase when y≤0.2.The SEM results show that,with more amounts of Li+,the crystalline grain growing speed is accelerated,and the sintering temperature can effectively be decreased.The measurements of piezoelectric properties indicate that the ceramics with relatively low amount of Li+ and high amount of K+ have comparatively large piezoelectricity.The dielectric measurements show that the ceramics have properties like relaxor ferroelectrics and diffuse phase transition(DPT) at Td and Tc,respectively.The results of ferroelectric measurements reveal the system has relatively higher remanent polarization Pr(27.6 μC/cm2) and lower coercive field Ec(37.5 kV/cm).     

Ba（Zr0．06 Ti0．94）O3－BiFeO3复合陶瓷的介电、铁电及压电性能研究

采用高温固相法制备出Ba（Zr0．06Ti0．94）O3－x％BiFeO3（x＝0．2,0．4,0．6,0．8）系列复合陶瓷,并研究了其相结构、介电、铁电和压电性质．XRD结果表明,所有样品均呈现典型的钙钛矿四方相结构,而样品的晶格常数随着BiFeO3的含量改变发生了一定变化．介电－温度图谱表明,复合陶瓷的相变温度和介电常数都受到了BiFeO3成分影响,室温介电常数随着BiFeO3含量的增加不断增大,并且复合陶瓷中存在弥散相变．所有样品均显示出明显的铁电与压电特性,并且随着BiFeO3含量变化,两种特性呈现出相同的变化趋势．     

锰掺杂对四元系压电陶瓷压电性能的影响

采用传统的电子陶瓷工艺制备了高性能四元系压电陶瓷（PZN－PMS－PZT－γMnO2)，考察了不同剂量锰掺杂对压电陶瓷的压电性能的影响，包括：居里温度（Tc）、机电耦合系数（kp)、压电常数（d33)和机械品质因素（Qm)，由于内偏置场的影响，居里温度Tc随锰含量的增加而增加，kp和d33随Mn含量的增加而减小，而Qm表现出较复杂的变化规律，随Mn含量的增加Qm先增加，当质量分散γ＝0．2％时，达到最大值1000，当γ＝0．2％时，Qm下降，实验结果表明：当质量分数γ＝0．2t%的锰掺杂压电陶瓷具有较好的压电性能：Tc=349℃、kp=0.60,d33=380(10s^-12C／N和Qm=1000。     

Phase Structure,Microstructure and Electrical Properties of K_xNa_((1-x))NbO_3 Piezoelectric Ceramics with Different K/Na Ratio

The K_xNa_((1-x))NbO_3(x=0.45, 0.46, 0.47, 0.48, 0.49, 0.50) lead-free piezoelectric ceramics was fabricated by conventional solid-state sintering method. It was found that the ratio of alkaline metal would affect the microstructure, bulk density, and optimum sintering temperatures of ceramics. Meanwhile, the electrical properties were also influenced by modulating the K/Na ratio, exhibiting corresponding composition-dependent properties. The optimum electrical properties of K_xNa_((1-x))NbO_3 such as piezoelectric constant d_(33) = 115 pC/N, mechanical quality factor Q_m = 20, Curie temperature Tc = 365 ~oC, ε_(33)~T/ε_0= 588.1, dielectric loss tan δ = 0.024, bulk density(ρ) = 3.08 g/cm~3, remnant polarization(P_r) = 8.87 μC/cm~2 and coercive field(Ec) = 13.79 kV/cm were obtained at x = 0.46.     

Phase Structure and Electrical Properties of La2O3-doped BiInO3-PbTiO3 Ceramics with High Curie Temperature

The phase structure and electrical properties of pure and La2O3-doped BiInOa-PbTiO3 (BI-PT) ceramics were studied respectively.In (1-x)BI-xPT (x=0.72-0.80) ceramics,the stability of tetragonal phase increased with increasing x,and pure perovskite structure was obtained for x=0.80 ceramics.The phase transition temperature range was between 575 ℃ and 600 ℃for x=0.72-0.80 ceramics,higher than that of PT (～490 ℃).The c/a ratio almost linearly decreased with increasing La2O3 content in x=0.80 ceramics.It is believed that Pb2+ vacancies were formed by La3+ substituting Pb2+ in La2O3-doped BI-PT ceramics.Tc shifted to lower temperature by 30 ℃/mol% La2O3.The maximum dielectric constant 8557 around 559 ℃ was exhibited in 0.5mol%-doped BI-0.80PT ceramics.La2O3-doped ceramics could be poled resulting from decreasing of c/a ratio and improving of dielectric loss and resistivity.The maximum piezoelectric coefficient d33 was 12 pC/N for 2mol%-doped BI-0.80PT ceramics.     

受主杂质Mn对（Ba,Pb）TiO3系高温PTC热敏陶瓷的影响

本文研究了(Ba,Pb)TiO_3系高温PTC半导体陶瓷中半导化与其烧结工艺、铅空位、钡空位和施、受主杂质等相互之间的关系。着重分析讨论了引入受主杂质Mn对材料的半导化的影响,并采用复合缺陷模型自洽地解释了实验现象。     

铜掺杂对于铌钽酸盐压电陶瓷性能的影响

采用传统固相反应烧结方法制备(K0.44Na0.52Li0.04)(Nb0.80Ta0.20)O3-x%(质量分数)CuO(x=0～0.9)陶瓷,研究其压电和介电性能随x的变化关系,同时应用XRD、SEM和阻抗分析仪对陶瓷的显微结构和电性能进行分析.实验发现,当x=0.3时,陶瓷电学性能相对较好.     

Ce4+及La3+掺杂对(Bi0.5Na0.5) Ba0.06TiO3 陶瓷压电性能的影响

采用固相法制备工艺制备了质量分数CeO2(0-0.6%)和La2O3(0-1.3%)掺杂的(Bi0.5Na0.5)0.94Ba0.06TiO3(BNBT6)无铅压电陶瓷.研究了合成产物的晶体结构、压电性能以及压电常数温度稳定系数.结果表明:所有组成均呈三方结构的钙钛矿型固溶体特征;当CeO2掺杂量为质量分数0.4%、La2O3掺杂量为质量分数1.0%时,陶瓷具有较好的压电性能,与纯BNBT6相比,分别提高了12%和15%;2种掺杂离子均能够改善陶瓷材料压电性能的温度稳定性.     

Influence of Excessive SiO_2 or TiO_2 on the Electric Properties of Ba_(0.92)Ca_(0.08)TiO_3 PTCR Ceramics

The dependence of electrical properties of Ba0.92Ca0.08TiO3 PTC ceramics on the SYO2 or TiO2 content was studied. The dependence of room, temperature resistivity on the SiO2 content was determined by the variation of the microstructure of Ba0.92Ca0.08TiO3 PTC ceramics . It was shown that a small amount of excessive TiO2 (2mol% ) added could increase the dielectric constant of materials, and it results in a reducing of the potential height (e·) of grain boundary. Thus, samples with particularly low room temperature resistivity were obtained. The relationship of PTC effect with the TiO2 content was also discussed by using the chemistry defect theory . The inferior PTC effect caused by excessive TiO2 may be concerned with the behavior of oxygen vacancies in the grains of ceramics.     

(1-x)Mg_2TiO_4-xSrTiO_3陶瓷的物相组成、显微结构以及微波介电性能

采用固相反应法制备了(1-x)Mg_2TiO_4-xSrTiO_3(w(x)=4%,6%,8%,10%)微波介质陶瓷,研究了不同SrTiO_3添加量以及烧结温度对该陶瓷体系的物相组成、显微结构以及微波介电性能的影响。XRD分析结果表明,所有陶瓷样品为两相共存,没有第二相的存在。SrTiO_3的添加能够促进Mg2TiO4陶瓷的烧结,同时陶瓷在1 375~1 425℃范围内均表现出较高的致密度。当x=0.08,烧结温度为1 400℃,保温4h时,陶瓷具有优良的微波介电性能,εr=17.1,Q×f=65 130GHz,τf=-9.8ppm/℃。     

(Ba,Pb)TiO_3系高温PTC半导体材料研究

本文研究了含铅高温PTC半导体陶瓷材料的性能和工艺特点。采用快速烧结法获得了性能优良的(Ba,Pb)TiO_3系半导体材料。     

（Ba,Pb）TiO3陶瓷湿敏特性的研究

介绍对(Ba,Pb)TiO_3陶瓷的湿敏特性的研究结果,从表面电导及表面势垒的观点出发,分析其吸湿特性,并给出定性解释。     

Effect of Sintering Time on Structure and Properties in CuO-doping KNN-LS-BF Piezoelectric Ceramics

The 0.6 mol% CuO-doping 0.996(0.95 Na_(0.5)K_(0.5)NbO_3-0.05 LiSbO_3)-0.004 FeBiO_3(KNN-LSBF-CuO) piezoelectric ceramics were synthesized by a solid-state reaction technique, and the structure and piezoelectric properties dependence of sintering time in KNN-LS-BF-CuO ceramics were studied. It is found that all the samples sintered for various time are perovskite structure mixed with orthorhombic symmetry phase and tetragonal phase, but the sintering time has significant influences on the crystalline and properties. When the sintering time increases from 2 hours to 6 hours, the grain of KNN-LS-BF-CuO ceramics becomes more homogeneous and more tight-arrangement. The experimental results reveal that the longer sintering time than 4 hours is beneficial for improving partial properties, such as d_(33), tgδ, and Q_m, but is adverse to ε_r and k_p, the KNNLS-BF-CuO ceramics with optimum properties can be synthesized for 6 hours at 1 060 ℃.     

(Ba,Eu)TiO_3细晶粒陶瓷制备中的影响因素

采用冷压陶瓷技术,分别在1 400℃和1 300℃制备了具有四方结构的(Ba_(1-x)Eu_x)TiO_3和(Ba_(1-x)Eu_x)Ti_(1-x/8)O_3陶瓷.应用X射线衍射(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究Eu含量、Ti空位缺陷和陶瓷化烧结温度的变化对制备(Ba,Eu)TiO_3细晶粒陶瓷的影响因素.结果表明:当x=0.05时,1 300℃制备的(Ba_(1-x)Eu_x)Ti_(1-x/8)O_3陶瓷细化到平均晶粒尺寸小于1μm,1 400℃制备的(Ba_(1-x)Eu_x)TiO_3陶瓷却畸变生长到5μm.而x=0.03时,(Ba_(1-x)Eu_x)TiO_3陶瓷仍能细化到1μm.说明较高的陶瓷化烧结温度并不是晶粒生长的主要原因,Ti空位的存在起到抑制晶粒生长的作用.x≥0.07时,(Ba_(1-x)Eu_x)TiO_3陶瓷为大于5μm的粗晶粒陶瓷,说明Eu含量的继续增加不能抑制晶粒生长.     

液相烧结对Ba(Ti0.91Zr0.09)O3陶瓷介电性能的影响

采用固相反应法制备了添加1wt%CuO-BaO混合物的Ba(Ti0.91Zr0.09)O3铁电陶瓷,借助XRD、SEM、Agilent4284测试仪,讨论了加入CuO-BaO混合物对Ba(Ti0.91Zr0.09)O3铁电陶瓷的烧结温度、相结构、显微组织及介电性能的影响.结果表明:添加1wt%CuO-BaO混合物,能有效降低Ba(Ti0.91Zr0.09)O3的烧结温度,室温介电常数高,介电损耗小.在1MHZ下εTl=3 150,tgδ=0.06,并且伴有介电弛豫现象.     

Ba1-xBix(Ti0.9Zr0.1)O3陶瓷的介电弛豫特征

采用固相反应法制备了Ba1-xBix(Ti0.9Zr0.1)O3(x=0.01,0.02,0.03,0.04)陶瓷,X射线衍射分析表明所有样品均是四方晶体结构,3%mol的Bi3+能够完全溶入钙钛矿晶格中.不同频率下Ba1-xBix(Ti0.9Zr0.1)O3陶瓷的介电温谱显示所有样品均表现出弥散相变的特征,在x≥0....     

Zn_(1/3)Nb_(2/3)含量对xPMnS-(1-x)PZN性能的影响

以xPMnS-(1-x)PZN四元系压电陶瓷为研究对象,通过研究Zn1/3Nb2/3含量的变化对0.5PMnS-0.5aPZN材料结构与性能的影响,获得具有高压电活性的0.5PMnS-0.5aPZN陶瓷材料。结果表明,四方相结构的0.5PMnS-0.5aPZN材料压电活性优于三方相结构,性能最好的组成位于MPB(四方相边界)附近靠近四方相含量较高的区域,组成Zn1/3Nb2/3含量的变化影响了MPB的位置。     

SiC复合(Ba,Pb)TiO3系PTC热敏陶瓷的研究

以（Ba,Pb)TiO3为主要原料，适当引入半导化施主元素，用SiC进行复合制备样品。研究烧成条件对产物的影响，讨论每种掺杂剂对材料的PTC热敏特性及微观形貌的影响，确定每种掺杂剂的最佳掺量，并对其半导机理进行分析。     

(Ba_(1-3x/2)Ce_xCa_(x/2))Ti_(1-x/4)O_3陶瓷的结构及介电性能研究

采用X射线衍射(XRD)、拉曼光谱(RS)、电子顺磁共振(EPR)、扫描电子显微镜(SEM)和介电测试技术研究(Ba1-3x/2CexCax/2)Ti1-x/4O3陶瓷的结构及介电性能.结果表明:随掺杂量x增加,发生四方-立方结构转变,以45°附近两个分立的(002)/(200)衍射峰演变为单一对称的(200)衍射峰为标志;(Ba1-3x/2CexCax/2)Ti1-x/4O3陶瓷显示一级相变(FPT)的介电行为,具有较高的介电常数和低介电损耗(tanδ0.04).