铋基无铅压电陶瓷Bi0.5(Na0.82K0.18)0.5TiO3-BiCrO3的微观组织与电性能

采用传统陶瓷制备方法,制备一种新型无铅压电陶瓷 (1-x)Bi0.5(Na0.82K0.18)0.5TiO3-xBiCrO3 (BNKT-BCx).研究Bi基铁电体BiCrO3对BNKT-BCx陶瓷晶体结构和压电介电性能的影响.结果表明:在所研究的组成范围内,陶瓷材料的主体结构为纯钙钛矿固溶体,微量BiCrO3(x=0～0.02,摩尔分数)不改变陶瓷的晶体结构;当BiCrO3含量x＞0.02时,晶体结构由三方、四方共存转变为伪立方结构,并出现明显的第二相;当x=0.015时,d33=168 pC/N;当x=0.01时,kp=0.32,为该体系压电性能的最大值;随BiCrO3含量的增加,陶瓷的低温介电反常峰向低温移动,高温介电反常峰向高温移动,反铁电相区域增加,弥散指数增加.     

Microstructure and electrical properties of Ti-modified (Na0.5K0.5)(TiχNb1-χ)O3 lead-free piezoelectric ceramics

Ti-Modified (Na0.5K0.5)(TixNb1-x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buffed powder process at 1020℃ for 2 h. The microstructures, and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction re-suits indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and densified the microstructure with a decreased grain size. The highest relative density reached more than 90%. The highest piezoelectric dielectric coefficient d33 and planar mode electro mechanical coupling coefficient kp were 110 pC/N and 19.5%, which were obtained in the NKNT ceramic with 1 mol% Ti. The piezoelectric properties of the NKNT ceramics were enhanced by aging in air for a period of time owing to the compensation of oxygen vacancies.     

Microstructure and electrical properties of Ti-modified (Na0.5K0.5)(TixNb1?x)O3 lead-free piezoelectric ceramics

Ti-Modified (Na_0.5K_0.5)(Ti _x Nb_1−x )O₃ (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures, and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction results indicated that Ti⁴⁺ had diffused into the (Na_0.5K_0.5)NbO₃ lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na_0.5K_0.5)NbO₃ solid solution effectively reduced the sintering temperature and densified the microstructure with a decreased grain size. The highest relative density reached more than 90%. The highest piezoelectric dielectric coefficient d ₃₃ and planar mode electromechanical coupling coefficient k _p were 110 pC/N and 19.5%, which were obtained in the NKNT ceramic with 1 mol% Ti. The piezoelectric properties of the NKNT ceramics were enhanced by aging in air for a period of time owing to the compensation of oxygen vacancies.     

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.     

(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.     

Ferroelectric and piezoelectric properties of SrZrO3-modified Bi0.5Na0.5TiO3 lead-free ceramics

The lead-free SrZrO₃-modified Bi_0.5Na_0.5TiO₃ (BNT-SZ100x, with x=0–0.15) ceramics were fabricated by a conventional solid-state reaction method. The effects of SZ addition on BNT ceramics were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), ferroelectric and electric field-induced strain characterizations. XRD analysis revealed a pure perovskite phase without any traces of secondary phases. Ferroelectric and bipolar field induced-strain curves indicated a disruption of ferroelectric order upon SZ addition into BNT ceramics. A maximum value of remnant polarization (32 µC/cm²) and piezoelectric constant (102 pC/N) was observed at 5% (mole fraction) of SZ. Maximum value of the electric field-induced strain (S_max=0.24%) corresponding to normalized strain (S_max/E_max= d^*₃₃= 340 pm/V) was obtained at BNT-SZ9.     

掺Sr改性Bi0．5（Na0．8K0．2）0．5TiO3无铅压电陶瓷的微观结构和性能研究

采用传统的陶瓷工艺制备了Sr掺杂Bi0.5（Na0.8K0．2）0．5TiO3无铅压电陶瓷（化学式为[Bi0.5（Na0.8K0．2）0．5]1-xSrxTiO3，x=0～0．1），研究了Sr掺杂对陶瓷样品的微观结构、压电以及介电性能的影响。X射线衍射结果表明：当掺杂量较小时（x=0，0．02），样品为四方相；随着掺杂量的增加（x=0．04～0．1），样品逐渐转变为三方相。压电与介电性能测试结果表明：样品的压电常数西3和机电耦合系数kp开始时都随着X的增加而逐渐增大，并分别在x=0．06和x=0．04时达到最大值，其后随着X的增加都逐渐减小：样品的介电常数ε^T33／ε0则随X的增加而几乎线性增加。在x=0．06时，样品的d33=178pC／N，kp=31％，ε^T33／ε0=850。     

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。     

保温时间对0．98（K0．5Na0．5）NbO3-0．02LaFeO3陶瓷电性能的影响

研究保温时间对0．98（K0.5Na0.5）NbO3-0．02LaFeO3（缩写为0．98KNN-0．02LF）无铅陶瓷相结构、显微组织、介电性能及铁电性能的影响。所有烧结样品均为纯的伪立方钙钛矿相,保温时间对相结构影响不大。随着保温时间的延长,样品的XRD衍射峰逐渐增强,并且向低角度移动。SEM观察结果显示,随着保温时间的延长,陶瓷样品的致密性提高,晶粒异常长大并出现孪晶结构。介电温谱表明,随着保温时间的延长,介电性能有所降低。电滞回线结果表明,2Pr随着保温时间的延长而增大的程度有所减小,而2E略有增加。在1150℃烧结2h得的到陶瓷的性能较优：εr=2253,tanδ〈5％,2Pr=34．51μC／cm2,2Ec=5．07kV／mm。     

B_2O_3添加对(Zn_(0.5)Mg_(0.5))Nb_2O_6陶瓷微波介电性能的影响

研究了B_2O_3助烧剂对(Zn_0.5Mg_0.5)Nb_2O_6陶瓷的烧结温度、微观结构、相结构及微波介电性能的影响.结果表明,助烧剂B_2O_3的添加有助于降低(Zn_0.5Mg_0.5)Nb_2O_6陶瓷的烧结温度,可以将(Zn_0.5Mg_0.5)Nb_2O_6陶瓷的烧结温度降低到950 ℃.其中掺杂2%B_2O_3(质量分数,下同)的(Zn_0.5Mg_0.5)Nb_2O_6陶瓷,在950 ℃烧结可获得结构致密的烧结体,并且具有较佳的介电性能:ε_r = 20.7,Q×f= 60156 GHz.     

Influence of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> doping on the properties of KBT-NBT-BT lead-free piezoelectric ceramics

0.144(K0.5Bi0.5)TiO3-0.85(Na0.5Bi0.5)TiO3-0.006BaTiO3(KBT-NBT-BT) lead-free piezoelectric ceramics were prepared using a conventional solid state method.The influence of Sb2O3 doping on the crystal phase,surface microstructure and properties of the KBT-NBT-BT lead-free piezoelectric ceramics were investigated using X-ray diffraction(XRD),scanning electron microscope(SEM) and other analytical methods.The results show that all compositions are of pure perovskite structure solid states.Sb2O3 doping does not influence the microstructure of KBT-NBT-BT lead-free piezoelectric ceramics obviously in the Sb2O3 doping range of 0.1-0.5 wt.%.Sb2O3 functions as a donor when doped small amount,while functions as a acceptor when doped large amount.The piezoelectric strain constant(d33) increases first and then decreases;the dielectric constant(ε3T3/ε0) and the dielectric loss(tanδ) decrease continuously when the amount of Sb2O3 dopant increases.When the doping amount of Sb2O3 is 0.1 wt.%,the KBT-NBT-BT piezoelectric ceramics with good comprehensive properties are obtained,whose d33,ε3T3/ε0 and tanδ are 147 pC/N,1510 and 4.2%,respectively.     

Bi掺杂对Ba_(6-3x)La_(8+2x)(Ti_(0.95)Zr_(0.05))_(18)O_(54)(x=2/3)陶瓷的烧结性能和介电性能的影响

采用传统固相反应法制备Ba6-3x(La1-mBim)8+2x(Ti0.95Zr0.05)18O54(x=2/3)微波介质陶瓷,研究Bi掺杂对Ba6-3xLa8+2x(Ti0.95Zr0.05)18O54(x=2/3)陶瓷的烧结性能、微观结构以及介电性能的影响。结果表明:当0m0.4时,Bi3+取代A1位的La3+生成单相类钨青铜型固溶体;当Bi3+的掺杂量超过这个范围时,La0.176Bi0.824O1.5作为第二相出现在固溶体中;Bi3+的掺入使Ba6-3xLa8+2x(Ti0.95Zr0.05)18O54(x=2/3)陶瓷的烧结温度从1400℃降低到1300℃,同时,其介电常数大幅度提高,谐振频率温度系数减小,但品质因数急剧减小;当m=0.05时,1350℃下保温2h烧结获得的陶瓷具有微波介电性能,εr=88.63,Q·f=4395GHz,τf=6.25×10-6/℃。     

烧结工艺对0.95(K_(0.5)Na_(0.5))NbO_3-0.05Ba(Zr_(0.05)Ti_(0.95))O_3无铅陶瓷组织和电性能的影响

采用两步烧结法制备了0.95(K_(0.5)Na_(0.5))NbO_3-0.05Ba(Zr_(0.05)Ti_(0.95))O_3无铅压电陶瓷,并研究了烧结工艺对陶瓷微观结构和电学性能的影响。结果表明,0.95KNN-0.05BZT可以在较宽的温度区间内使用两步烧结法制备,并且提高第一步烧结的温度以及延长第二步的保温时间可以改善0.95KNN-0.05BZT陶瓷的密度、压电性能和介电性能的作用。最佳工艺参数为1 190℃/10 min/1 050℃/15 h,其性能如下d_(33)=136.7 pC/N、k_p=50%、εr=1698和tanδ=0.023。     

Effects of Na/K ratio on the phase structure and electrical properties of Na_xK_(1-x)NbO_3 lead-free piezoelectric ceramics

Lead-free piezoelectric NaxK1-xNbO3(x = 0.3-0.8)(NKN) ceramics were fabricated by normal sintering at 1060°C for 2 h.Microstructures and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na content.The grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary(MPB) in NaxK1-xNbO3 ceramics.Such MPB-like behavior contributes to the enhanced piezoelectric coefficient d33 of 122 pC/N, planar-mode electromechanical coupling coefficient kP of 28.6%, and dielectric constant εr of 703, respectively for the Na0.7K0.3NbO3 ceramic.Cubic temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 420°C and 200°C, respectively.     

Effects of Cr2O3 doping on the electrical properties and the temperature stabilities of PZT binary piezoelectric ceramics

The ceramics with Pb1.04Zr0.52Ti0.48O3 + z wt.% Cr2O3 were prepared using the traditional technique.The effects of Cr2O3 doping on the phase structure,the microstructure,and the electrical properties of ceramics were investigated.Meanwhile,the temperature stabilities of the resonant frequency (fr) were studied.The results showed that the △fr/fr,25℃ decreased with the addition of 0.2 wt.% - 0.8 wt.% Cr2O3 as compared with the undoped samples.The minimum value (-0.182%) of △fr/fr,25℃ was obtained for z = 0.6 wt.% Cr2O3 samples that sintered at 1260℃.The values of εT33/ε0 = 1650,tanδ = 0.006,d33 = 328 pC/N,Kp= 0.63,Qm = 2300 were obtained when Cr2O3 was 0.6 wt.%,which exhibited more excellent piezoelectric properties than other compositions such as those with z = 0.2 wt.%,0.4 wt.%,and 0.8 wt.%,but had a similar value as compared with the undoped samples.When the Cr2O3 additive increased,the Curie temperature moved toward low temperature and the changes of resonant frequency changed from positive to negative with increasing temperature.     

准同型相界附近PMN-PT陶瓷的介电与压电性能

采用铌铁矿预产物合成法制备了组成在相界附近的(1-x)Pb(Mg1/3Nb2/3)O3-x PbTiO3弛豫铁电陶瓷.陶瓷样品X射线衍射相组成和相结构分析表明:所有陶瓷样品均为纯钙钛矿相,没有检测出其它杂相;而且组成在x=0.33 mol处存在一准同型相界(MPB),在该相界附近三方相和四方相共存,而远离该相界则分别为纯三方相和四方相.在该相界附近组成具有优异的介电和压电性能:εm～38000,Ec～5 kV/cm,P～31.5 μC/cm2,d33～500 pC/N,这主要是由于宏观上的三方和四方两相共存,或微观上的微畴和宏畴共存引起的.     

Effects of CeO2 doping on the structure and properties of PSN-PZN-PMS-PZT piezoelectric ceramics

Quinary system piezoelectric ceramics PSN-PZN-PMS-PZT were prepared by using a two-step method. The effects of CeO2 doping on piezoelectric and dielectric properties of the system were investigated at morphotropic phase boundary （MPB）. The results reveal that the relative dielectric constant ε33^T｜ε0, the Curie temperature To, the piezoelectric constant d33, the mechanical quality factor Qm, and the electromechanical coupling coefficient Kp are changed with the increase of CeO2 content. On the other hand, the effects of CeO2 doping on the dielectric properties of PSN-PZN-PMS-PZT piezoelectric ceramics at high electric field are consistent with the change at weak electric field. The values of dielectric constant and dielectric loss are enhanced with the increasing of electric field.     

微波烧结ZrO_(2(n))/Al_2O_3复合陶瓷工艺与组织

以纳米ZrO2、微米Al2O3为原料,采用微波烧结方式制备ZrO2/Al2O3复相陶瓷。探讨了烧结温度和保温时间对试样线收缩率、相对体积密度、硬度和断裂韧性的影响。结果表明,烧结温度1550℃,保温时间10 min,可得到较高的硬度(13 350 MPa)和较好的断裂韧度(6.41 MPa.m1/2),烧结过程中发生了m-ZrO2转变为t-ZrO2相变,nano-ZrO2的加入使Al2O3形成內晶型结构;试样的断裂方式为沿晶断裂和穿晶断裂并存;ZrO/AlO复合陶瓷主要通过应力诱导相变和内晶型结构进行增韧。