Effect of sintering temperature and composition on microstructure and properties of PMS-PZT ceramics

The piezoelectric ceramics xPb（Mn1/3Sb2/3）O3-（1-x）Pb（Zr1/2Ti1/2）O3 （abbreviated as PMS-PZT） were synthesized by traditional ceramics process. The effect of sintering temperature and the amount of Pb（Mn1/3Sb2/3）O3 （abbreviated as PMS） on phase structure, microstructure, piezoelectric and dielectric properties of PMS-PZT ceramics was investigated. The results show that the pure perovskite phase is in all ceramics specimens, the phase structure of PMS-PZT ceramics changes from tetragonal phase to single rhombohedral phase with the increasing amount of PMS. The dielectric constant εr, Curie temperature Tc, electromechanical coupling factor kp and piezoelectric constant d33 decrease, whereas the mechanical quality factor Qm and dielectric loss tanδ increase with the increasing amount of PMS in system. The optimum sintering temperature is 1 200-1 250 ℃. It is concluded that the PMS-PZT （x=0.07） ceramics sintered at 1 250 ℃ is suitable for high-power piezoelectric transformer. These properties include εr=674.8, tanδ =0.005 25, kp=0.658, Qm= 1 520, d33=230 pC/N, Tc=275 ℃.     

Preparation and properties of （K0.5Na0.5）NbO3-LiNbO3 ceramics

The lead-free piezoelectric ceramics （1-x）（K0.5Na0.5）NbO3-xLiNbO3（abbreviated as KNLN） were synthesized by a traditional solid state reaction. The effects of Li^＋ on the sintering characteristic, the phase structure and piezoelectric properties of KNLN ceramics were investigated. The sintering temperature of KNN-based ceramics is decreased by doping Li^＋ and the range of the sintering temperature is narrow. The KNLN ceramics exhibit an enhanced piezoelectric properties with the piezoelectric constant d33 value of 180-200 pC/N, The electromechanical coupling coefficients kp is 35%-40%. The results show that （1-x）（K0.5Na0.5）-NbO3-xLiNbO3 （x=0.05, 0.06） is a promising high-temperature lead free piezoelectric ceramic.     

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.     

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.     

Effect of poling condition on piezoelectric properties of （K0.5Na0.5）NbO3 ceramics

The lead-free piezoelectric ceramics （K0.5Na0.5）NbO3 （abbreviated as KNN） with the relative density of 97.6% were synthesized by press-less sintering owing to the careful control of processing conditions. The phase structure of KNN ceramics was analyzed. The results show that the pure perovskite phase with orthorhombic symmetry is in all ceramics specimens. The effect of poling conditions on the piezoelectric properties of KNN ceramics was investigated. The results show that the piezoelectric constant d33 and electromechanical coupling factor kp increase with poling field, poling temperature and poling time increasing, then decrease because of electric broken. Take into account of poling conditions and piezoelectric properties of pure KNN ceramics, the optimum poling conditions for pure KNN ceramics are poling field of 4 kV/mm, poling temperature of 140 ℃ and poling time of 20-25 min.     

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.     

Effects of Na/K ratio on the phase structure and electrical properties of Na<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>K<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>NbO<Subscript>3</Subscript> 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 dif...     

Modified phase transition and electrical properties of [Li0.05(Na0.535K0.48)0.95]-(Nb0.94Sb0.06)O3 lead-free piezoelectric ceramic by sintering temperature

Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investigated with a special emphasis on the influence of the sintering temperature. A polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry was observed when the sintering temperature was raised from 1040 to 1050 ℃, whereby the piezoelectric coefficient d33 and the electromechanic...     

Microstructure and electrical properties of Sc2O3-doped CaCu3Ti4O12 ceramics

CaCu3Ti4O12 ceramics doped with different contents of Sc2O3(mol%, x = 0, 0.05, 0.10, 0.15, and 0.20) were prepared by the traditional solid-state reaction method. Scanning electron microscope(SEM) and X-ray diffraction(XRD) were used in the microstructural studies of the specimen, and the electrical properties were investigated. XRD results show that the Sc has no influence on the phase composition. The results from the dielectric measurements show that further increase of Sc doping could decrease the dielectric loss slightly. A high dielectric constant and low dielectric loss can be achieved when the doping concentration is 0.10 mol%.     

Microstructure and electrical properties of Ti-modified (Na_(0.5)K_(0.5))(Ti_xNb_(1-x))O_3 lead-free piezoelectric ceramics

Ti-Modified (Na0.5K0.5)(TixNb1-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 re-sults 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...     

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.     

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。     

(1-x)K0.5Na0.5NbO3-xLiBiO3无铅压电陶瓷的结构与压电性能（英文）

采用传统固相反应制备了(1-x)(K0.5Na0.5)NbO3–xLiBiO3[(1–x)KNN–xLB](x=0,0.0005,0.001,0.002,0.004,0.006,0.008,0.010)压电陶瓷,并分析研究了其微结构及电性能。结果表明,LB 掺杂的 KNN 陶瓷主要形成了钙钛矿结构,没有检测到第二相的存在,并且陶瓷的相结构出现直接由正交相过渡到立方相的"反常"转变;随着LB 掺杂量的增加,晶粒尺寸逐渐细化,陶瓷的压电常数d33、平面机电耦合系数kp先略有增加后显著下降,且分别在x=0.002和 x=0.001时达到最大值,分别为115pC/N和0.2701;陶瓷的介电常数εr随x增大先增加后略有降低,当 x=0.006时获得最大值,为871.8。     

Effect of MnO doping on the structure, microstructure and electrical properties of the (K,Na,Li)(Nb,Ta,Sb)O3 lead-free piezoceramics

Mn²⁺-doped (K,Na,Li)(Nb,Ta,Sb)O₃ lead-free piezoelectric ceramics have been prepared by a conventional sintering technique. The effects of Mn²⁺ doping on the phase structure, microstructure and ferro-piezoelectric properties of the ceramics have been evaluated. MnO doping modifies the (K,Na,Li)(Nb,Ta,Sb)O₃ structure, giving rise to the appearance of a TTB-like secondary phase and to changes on the orthorhombic to tetragonal phase transition temperature. The modification of this temperature induces a reduction of the piezoelectric constants, which is accompanied by an increase on the mechanical quality factor. Mn²⁺ ions incorporate into the perovskite structure in different off ways depending on their concentration.     

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.     

(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.     

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℃。     

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℃。