Synthesis and Piezoelectric Properties of Lead-free （ Bi0.5 Na0.5 ）1-x（BaaSrb）xTiO3 Ceramics

A new group of lead-free piezoelectric ceramics,（Bi0.5 Na0.5）1-x（BaaSrb）xTiO3（abbreviated as BNBST[100x-100a/100b],0〈x〈1,a＋b=1）,was synthesized.The ceramics were prepared by conventional ceramic sintering technique,and the ceramics with density of 95% of the theoretical one can be sintered without the atmosphere control during the sintering process.The results of the X-ray diffraction（XRD） data show that the ceramics possess a single perovskite phase.The measurements of dielectric and piezoelectric properties reveal that the ceramics provide relatively high piezoelectric charge constant d33 and high planar electromechanical coupling factor kp.For the BNBST6-95/5 ceramics,d33 is equal to 170pC/N,and kp is equal to 32.0%.The fabrication technique for these ceramics is conventional and stable.     

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).     

(Na_(0.5)K_(0.5))NbO_3基无铅压电陶瓷压电常数的研究

针对目前无铅压电陶瓷的压电常数d33偏小的情况,采用传统的烧结方法制备了(Na0.5K0.5)NbO3基无铅压电陶瓷(Na0.5K0.45Li0.05)Nb0.95-xSbxTa0.05O3(x=0.03,0.06,0.09,0.12),研究了在Li和Ta含量固定的情况下,Sb元素的添加量和烧结温度对陶瓷的压电常数的影响.研究结果表明,适量Sb元素的掺杂可以大幅度提高陶瓷的压电常数d33,陶瓷样品的压电常数d33随着Sb含量的增加先增大后减小.烧结温度可以影响陶瓷的密度,进而影响其压电常数.在1130℃的最佳烧结温度下,Sb含量x=0.09时,陶瓷样品表现出最佳的压电性能,压电常数d33=328 pC/N.     

纳米Na0.5Bi0.5TiO3粉体的水热合成研究

以Bi(NO3)3·5H2O、Ti(OC4H9)4为原料,研究和分析了水热条件下Na0.5Bi0.5TiO3(BNT)晶体生长和形成的影响因素.结果表明,在反应温度为160～180℃,保温时间为4～16h,NaOH浓度为4～12mol/L的条件下可制备出高纯度的纳米Na0.5Bi0.5TiO3粉体,其颗粒尺寸约为15～60nm.     

Li元素对Bi0.5Na0.5TiO3基无铅压电陶瓷压电性能的影响

针对目前无铅压电陶瓷的压电常数d33偏小的情况,采用传统的固相反应烧结方法制备得到了高压电性能的Bi0.5Na0.5TiO3基无铅压电陶瓷Bi0.5(Na0.7K0.3-xLix)0.5TiO3(x=0.04,0.08,0.12,0.16,0.20),研究了Li元素的添加量对陶瓷的烧结温度以及压电性能的影响.研究结果表明,Li元素对K的替代可以降低陶瓷的烧结温度,提高样品致密度,适量的Li可以大幅度提高陶瓷的压电性能.陶瓷样品的压电常数d33和平面机电耦合系数kp随着Li含量的增加先增大后减小,在1 090 ℃的烧结温度下,Li含量x=0.08时的陶瓷样品表现出最佳的压电性能,压电常数d33=212 pC/N,平面机电耦合系数kp=33%.     

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.     

Effect of doped Mn on piezoelectric properties of (Na_(0.5)Bi_(0.5))_ (0.92)Ba_(0.08)TiO_3 lead-free ceramics

1INTRODUCTION Therehasbeengreatinterestinthestudiesof thelead freematerialswithdielectric,piezoelectricandferroelectricpropertiesinthefieldoffunction almaterialsfortheiramiabilitytoenvironment. (Na1/2)TiO3(NBT)ceramicshavebeenwidelystudiedbecauseoftheirrelativelylargeremnant polarization(Pr)of38μC/cm2andcoercivefieldof 73kV/cm[1].However,NBTcannotreplacelead zirconatetitanate(PZT)basedceramicsbecausethepiezoelectricpropertiesofNBTarestillnot comparabletothoseofPZT[24].Recently,m…     

La2O3掺杂对(Bi1/2Na1/2)0.94Ba0.06TiO3陶瓷性能与微结构的影响

采用传统陶瓷工艺方法制备了La2O3掺杂(Bi1/2Na1/2)0.94Ba0.06TiOa(BNBT6)无铅压电陶瓷,系统地研究了La2O3掺杂对该体系陶瓷介电、压电性能与微观结构的影响.结果表明:该体系具有很高的压电常数,是单一的钙钛矿结构,La2O3的添加对晶粒生长具有一定的抑制作用,线收缩率和相对密度增大.室温介电常数随着La2O3掺杂量的增加而增大.与不添加La2O3的陶瓷样品相比,添加少量La2O3可以使体系的弛豫特征更为明显.当掺杂量为0.1 wt%时,该体系陶瓷具有较好的综合性能:d3a=160 pC/N,kp=0.322.当掺杂量达到0.5 wt%以后,陶瓷的压电性能严重降低.     

极化对Bi基压电陶瓷BNT-BKT-BiFeO3介电特性的影响

为了改善无铅压电陶瓷介电性能,采用传统陶瓷制备方法,制备一种新型Bi基钙钛矿型三元系无铅压电陶瓷(1-x-y)BNT-xBKT-yBiFeO3,并研究极化对该体系陶瓷介电性能的影响以及介电性能随频率的变化规律。结果表明：极化后的介电常数和介电损耗低于极化前。极化前的介电常数和介电损耗随BiFeO3含量的增加变化不明显,极化后的介电常数和介电损耗随BiFeO3含量的增加而增加。极化前和极化后的介电常数和介电损耗随BKT含量的增加而增加。介电常数和介电损耗随频率增加分别降低和增加,但降低和增加速率随频率增加而降低。     

(Bi_(1/2)Na_(1/2))_(1-x)Ba_xTiO_3系无铅压电陶瓷的现状

综述了(Bi1/2Na1/2)1-xBaxTiO3系无铅压电陶瓷的最新研究进展。简述了A位非化学计量改性及几种较成功的掺杂改性方法。将A位掺杂(如La3+)、B位掺杂(如Co3+、Nb5+)以及综合掺杂(如Ce3+、Ce4+)的优缺点和掺杂机理进行了归类比较。解释了各系统中相应掺杂引起性能变化的原因,为进一步开展无铅压电陶瓷的研究提供参考。     

Microstructure, crystalline phase and electrical properties of Li0.06（Na0.5K0.5）0.94Nb（1-2x/5）MgxO3 lead-free piezoelectric ceramics

MgO-modified Li0.06(Na0.5K0.5)0.94NbO3(L6NKN) lead-free piezoelectric ceramics were synthesized by normal sintering at a relatively low temperature of 1000°C.The crystalline phase,microstructure,and electrical properties of the ceramics were investigated with a special emphasis on the influence of MgO content.The addition of MgO effectively improves the sinterability of the L6NKN ceramics.X-ray diffraction analysis indicates that the morphotropic phase boundary(MPB) separating orthorhombic and tetragonal ph...     

Effect of Li content on the microstructure and properties of lead-free piezoelectric （K0.5Na0.5）1-xLixNbO3 ceramics prepared by SPS

Lead-free piezoelectric （K0.5sNa0.5）1-xLixNbO3 （x = 0at%-20at%） ceramics were synthesized by spark plasma sintering （SPS） at low temperature and the effects of LiNbO3 addition on its crystal structure and properties were also studied. When the Li content was less than 6at%, a single proveskite phase with the similar structure of （K0.5Na0.5）NbO3 was formed; and a secondary phase with K3Li2Nb5O15 structure was observed in the 6at% 〈 x 〈 20at% compositional range. Furthermore, LiNbO3 existed as the third phase when the Li content was higher than 8at%. The grain sizes increased from 200-500 nm to 5-8 μm when the K3Li2Nb5O15 and LiNbO3 like phases were formed. With increasing Li content, the relative density of the ceramics first decreased from 97% to 93% and then kept constant. The piezoelectric coefficient d33, dielectric constant, and planner electromechanical coupling factor exhibited a decreasing tendency with increasing Li content because of the decrease in density and the formation of the secondary phase such as K3Li2Nb5O15 and LiNbO3. The formation of dense microstructure with a single phase is necessary in improving the properties of the （K0.5Na0.5）1-xLixNbO3 ceramics.     

Struchre and Electrical Properties of (Na0.5Bi0.5)0.94Ba0.06TiO3 Ceramic with 0.5 wt% of MnO

The structure and electrical properties of(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramic doped with 0.5 wt% of MnO were investigated in comparison with those of(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramic.It was ascertained that the MnO addition did not cause remarkable change in crystal structure and microstructure.The MnO addition mainly displayed a hard effect on the electrical properties,an increase of coercive field(Ec)and mechanical quality factor(Qm)together with a decrease of dielectric constant(?r)and piezoelectric constant(d33).An enhancement of electromechanical coupling factor(kp)with the MnO addition was obtained too.An essential relation between the piezoelectric properties and ferroelectric nature of the ceramics was detected.It was found that the piezoelectric properties of the ceramics highly depended on the corporative contribution of remanent polarization(Pr)and coercive field.     

Pb(Li_(1/4)Nb_(3/4))O_3-Pb(Mg_(1/3)Nb_(2/3))O_3-Pb(ZrTi)O_3四元系压电变压器陶瓷材料研究

通过Ｐｂ（Ｌｉ１／４Ｎｂ３／４）０．０６（Ｍｇ１／３Ｎｂ２／３）０．０６（Ｚｒ０．８８－ＸＴｉＸ）Ｏ３四元系压电陶瓷材料的改性研究，发现此系列压电材料具有高的Ｋｐ（０．５８）、Ｑｍ（２８００）、ε（１０５０）值，且ｔａｎδＢＮＤ０．００８之内，且具有较好的老化特性，适合作为变压器陶瓷材料使用．用该系统材料制作的压电变压器，具有较高的升压比和机电转换效率．在负载为８８０ＭΩ时，升压比高达１１７０；而当负载为５０ＭΩ时，其机电转换效率最高，为９２％．     

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。     

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．     

Electrical and Magnetic Properties of Electron Doped BixCa1-xMnO3 （0〈x ≤0.33） Ceramics

Measurements of crystal structures, electrical and magnetic properties for the electron doped BixCa1-xMnO3 （0〈x≤〈0.33） reveal the presence of a variety of notable changes in correlation with magnetic transitions and charge ordering. Samples with x〈0.2 in general show a clear ferromagnetic transitions around 130 K. On the other hand, samples with 0.2≤x≤0.33 show much more complex low-temperature magnetic properties perhaps due to the coupling between the magnetic states and orbital/charge ordering. Structural transformations and structural modulations in the x=0.25 and 0.33 samples have been observed by transmission electron microscopy.     

Ba1+x(Mg1/3Nb2/3)O3 陶瓷的烧结行为和微波介电性能

研究了A位Ba离子化学计量比变化对Ba(Mg1/3Nb2/3)O3陶瓷烧结行为、微观结构和微波介电性能的影响.结果表明,Ba缺量可促进Ba(Mg1/3Nb2/3)O3烧结和B位1∶2有序,而Ba过量则阻碍Ba(Mg1/3Nb2/3)O3烧结和B位1∶2有序.Ba缺量促进Ba(Mg1/3Nb2/3)O3烧结和B位1∶2有序是由于Ba缺位的存在,而Ba过量阻碍Ba(Mg1/3Nb2/3)O3烧结则是由于过量的Ba可能以游离态存在于晶界,阻碍了晶界的移动,从而降低了Ba(Mg1/3Nb2/3)O3陶瓷的烧结性能,抑制了致密化过程.Ba缺量对Ba(Mg1/3Nb2/3)O3陶瓷的介电常数影响不大.Ba缺量越多,材料的Qf值越低.