(K_(0.5)Na_(0.5))NbO_3-CaZrO_3基无铅压电陶瓷的相结构和压电性能研究

采用传统陶瓷工艺制备了(1-x)(K0.5Na0.5)NbO3-xCaZrO3(简称KNN-CZ)无铅压电陶瓷。分析了陶瓷样品的相结构组成。测试结果表明:所有陶瓷样品均为钙钛矿相,未发现其它晶相。随着CaZrO3含量的增加,(1-x)KNNxCZ陶瓷的相结构由正交相转变为四方相,最后变为立方相。研究了不同CaZrO3含量对压电性能的影响,实验表明:当CaZrO3含量为0.05mol时,压电常数d33和径向机电耦合系数kp分别达到了最大值196pC/N和0.35。(1-x)KNNxCZ(x=0.05)陶瓷的压电性能展现了良好的温度稳定性和经时稳定性,这些结果表明(1-x)KNN-xCZ(x=0.05)陶瓷是一种优良的无铅压电备选材料。     

水热法制备Na_(0.5)Bi_(0.5)TiO_3陶瓷及其性能

以五水硝酸铋(Bi(NO_3)_3·5H_2O)和二氧化钛(TiO_2)为原料,氢氧化钠(NaOH)为矿化剂,采用水热法合成了具有钙钛矿结构的钛酸铋钠Na_(0.5)Bi_(0.5)TiO_3(BNT)无铅压电陶瓷粉体和陶瓷。利用X射线衍射仪(XRD)对产物晶体结构进行表征,用扫描电镜(SEM)观察产物粉体的表观形貌和粒径,并测试了陶瓷的电性能。结果表明,在200℃反应4h,NaOH浓度为6 mol/L,可以水热合成出单一晶相,粒径约为200nm的BNT粉体,用此粉体在1130℃烧结的陶瓷的介电常数ε_r=385.26,压电系数d_(33)=98cP/N。     

(1-x)Li0.05(K0.5Na0.5)0.95NbO3-x(Bi0.5Na0.5)TiO3无铅压电陶瓷的结构与电性能研究

采用固相反应法制备了(1-x)Li0.05(K0.5Na0.5)0.95NbO3-x(Bi0.5Na0.5)TiO3(LKNN-BNT)无铅压电陶瓷,研究了BNT的添加量x(0,0.005,0.01,0.02)对LKNN-BNT陶瓷的结构与电性能影响。X射线衍射(XRD)分析结果表明当x≤0.005时,陶瓷为正交钙钛矿结构,而当x≥0.01时,陶瓷则转变为四方钙钛矿结构,说明该陶瓷的多型相转变(PPT)区域为0.005相似文献   

K0.5Na0.5NbO3-BaCu0.5W0.5O3无铅压电陶瓷的结构与性能

以传统固相法工艺制备(1-x)K0.5Na0.5NbO3-xBaCu0.5W0.5O3[(1-x)KNN-xBCW]无铅压电陶瓷,研究不同BCW掺量(x=0％,0.1％,0.25％,0.5％,1.0％,摩尔分数,下同)对KNN陶瓷的晶体结构和电性能的影响,结果表明:x＜0.5％时,KNN陶瓷的相结构没有改变,仍为正交相...     

掺杂对(Na_(1/2)K_(1/2))NbO_3-CaTiO_3无铅陶瓷烧结温度和电学性能的影响

通过传统固相反应法、利用两步合成工艺,在常压、960～1160℃烧结制备0.95(Na1/2K1/2)NbO3-0.05CaTiO3(0.95NKN-0.05CT)及WO3、CuO掺杂0.95NKN-0.05CT无铅压电陶瓷。X射线衍射分析表明:960℃和1020℃烧结制备的掺杂前后的0.95NKN-0.05CT陶瓷均为纯钙钛矿结构。随着CuO掺杂量的增加及烧结温度的升高,CuO掺杂0.95NKN-0.05CT陶瓷中出现杂相,并伴随着压电性能的下降。添加第二组元CaTiO3和氧化物掺杂可增加(Na1/2K1/2)NbO3(NKN)陶瓷的致密度,同时烧成陶瓷的介电、铁电和压电性能也有明显改善。摩尔分数分别为1%和2%CuO掺杂0.95NKN-0.05CT陶瓷的压电常数分别达到165pC/N和140pC/N。     

(1-x)KNN-xNKBT无铅压电陶瓷的结构及其电性能研究

采用传统固相法制备了(1-x)K0.5Na0.5NbO3-x(Na0.8K0.2)0.5Bi0.5TiO3(x=0-5%)无铅压电陶瓷,研究了(Na0.8K0.2)0.5Bi0.5TiO3的不同引入量对其物相结构、显微形貌、介电性能以及压电性能的影响。结果表明:所有样品都具有钙钛矿结构;随着x的增加,室温下样品从正交相逐渐向四方相过渡并且居里温度向低温方向移动,样品的压电常数d33与机电耦合系数kp均先升高后降低。该体系多晶型转变PPT位于2%≤x≤3%,当x=3%时,样品的压电性能达到最佳,其中:d33=189pC/N,kp=41%,Qm=96,tanδ=0.028。     

微波水热法制备(1-x) K0.55Na0.45NbO3-xLiSbO3系无铅压电陶瓷

以分析纯NaOH,KOH,Li2CO3,Nb2O5,Sb2O3等为原料,采用微波水热法合成(1-x)K0.55Na0.45NbO3-xLiSbO3(KNNLS,x =0.03～0.07mol)粉体,分析了粉体的晶体结构与形貌.以该粉体制备压电陶瓷,系统研究了LiSbO3含量对压电陶瓷结构与性能的影响.研究结果表明:微波水热法在220℃下保温30min可以合成具有纯正交钙钛矿结构的KNNLS(x=0.03～0.07)粉体,粉体呈立方状,尺寸约0.5～1μm.利用该粉体制备的压电陶瓷结构致密,晶粒大小分布均匀.当x=0.05时,该组成陶瓷具有最佳的综合压电性能:压电常数d33=110 pC/N,平面机电耦合系数kp=0.29,介电常数εT33/ε0=466,介质损耗tanδ =1.4％以及机械品质因素Qm=107.     

微波水热温度对KNLNS粉体及陶瓷晶体结构与性能的影响

采用微波水热法制备了(K0.5005Na0.4275Li0.05)(Nb0.95Sb0.05)O3(KNLNS)无铅压电粉体,研究了不同微波水热温度条件下合成KNLNS粉体并以此粉体制备的陶瓷的晶体结构、显微形貌和介电性能.研究结果表明:当粉体合成温度为180℃时,粉体及陶瓷均不具有纯钙钛矿晶体结构,介电性能不佳;合成温度高于190℃,粉体及陶瓷均具有正交纯钙钛矿结构,粉体形貌呈立方状.合成温度高于200℃,对粉体及陶瓷的晶体结构和介电性能影响较小.     

制备工艺对0.95(K_(0.5)Na_(0.5))NbO_3-0.05CaZrO_3基无铅陶瓷压电性能的影响

采用传统陶瓷工艺制备了0.95(K0.5Na0.5)NbO3-0.05CaZrO3无铅压电陶瓷。研究了烧结温度和极化工艺对陶瓷压电性能的影响。结果表明:随着烧结温度的提高,0.95(K0.5Na0.5)NbO3-0.05CaZrO3陶瓷的体积密度增大,在1170℃时达到最大值,同时d33和kp,在此温度也分别达到他们的最大值210pC/N和0.40。极化工艺对0.95(K0.5Na0.5)NbO3-0.05CaZrO3陶瓷的压电性能有明显的影响,0.95(K0.5Na0.5)NbO3-0.05CaZrO3陶瓷的最佳极化温度是70℃,最佳极化电场是4kV/mm。     

(1-x)K0.49Na0.51NbO3-xLiNbO3无铅压电陶瓷的性能

用传统固相烧结法制备(1-x)K0.49Na0.51NbO3-xNbO3(KNNLN,x=0.00～0.08,摩尔分数)体系无铅压电陶瓷.用x射线衍射仪及精密阻抗分析仪等研究不同掺量LiNbO3掺杂后对KNNLN体系陶瓷的晶体结构和电性能的影响.结果表明:在研究组成范围内,LiNbO3加入后能够形成单一钙钛矿结构的固溶...     

（1－x）Bi0．5（Na0．8K0．2）0．5TiO3－xKSbO3压电陶瓷的制备及性能研究

采用传统固相法制备了新型（1－x）Bi0．5（Na0．8K0．2）0．5TiO3－xKSbO3无铅压电陶瓷,利用XRD、 SEM等测试技术表征了该陶瓷的晶体结构、表面形貌、压电和介电性能。研究结果表明,在所研究的组成范围内陶瓷材料均能形成纯的钙钛矿固溶体。在室温下,当KSbO3的掺杂量为1％时,该体系表现出较好的介电性能：εr和tanδ分别为2231和0．055。     

Sr_(0.5)Sm_(0.5)CoO_3超细陶瓷粉体的制备与性能

采用低温燃烧法和共沉淀法制备了Sr0.5Sm0.5CoO3(SSC)超细陶瓷粉体。应用综合热分析、X射线衍射仪、扫描电子显微镜和元素分析仪等对陶瓷粉体的组成、结构和形貌进行了表征。结果表明:采用低温燃烧法制备的SSC为近似球形、粒径小于200nm的超细钙钛矿结构的粉体;用共沉淀法制备了粒径约为500nm,具有钙钛矿结构的SSC超细粉体。低温燃烧法制备的SSC粉体在1150℃烧结致密,共沉淀法制备的SSC粉体在1200℃烧结致密。低温燃烧法和共沉淀法制备的SSC陶瓷膜在空气流速为1.12×10-4mol/s,氦气流速为6.70×10-5mol/s,900℃的条件下,透氧速率分别为4.61×10-7mol/(s·cm2)和4.46×10-7mol/(s·cm2)。     

An efficient approach for direct synthesis of K0.5Na0.5NbO3 powders

Pure K_0.5Na_0.5NbO₃ powders were prepared at low temperatures by an efficient method using Na₂CO₃, K₂CO₃ and Nb₂O₅ as raw materials and urea as fuel. The phase evolution of the powders was investigated by X-ray diffractometer (XRD) and thermo gravimetric analysis-differential scanning calorimeter (TG-DSC). The phase composition and morphology of the powders were characterized by electron probe microanalysis (EPMA) and scanning electron microscope (SEM), respectively. The results reveal that single-phase K_0.5Na_0.5NbO₃ powder can be obtained at 550 °C by the method. The as-prepared powder is stoichimetric, fine and well-developed.     

柠檬酸盐法制备Na0.5Bi0.5TiO3陶瓷粉体的工艺研究

本实验采用柠檬酸盐法制备（NaBi）0.5TiO3无铅压电陶瓷粉体,系统研究了柠檬酸浓度、溶液pH值、煅烧温度等工艺条件对制备的影响。经研究分析,当柠檬酸浓度C=9%,溶液pH=7.5时,能形成透明、均匀、稳定的溶胶,且形成时间最短;650℃下煅烧2h能够合成单一的钙钛矿结构的钛酸铋钠晶相,比传统固相反应法煅烧温度降低了200℃。     

溶胶–凝胶法制备(Na0.50+xK0.50-2xLix)Nb0.9Ta0.1O3无铅压电陶瓷及其性能

采用溶胶–凝胶法制备Li+取代(K0.5Na0.5)+及Ta5+取代Nb5+的(K0.5Na0.5)NbO3陶瓷粉体,采用无压烧结工艺制备(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3(x=0,0.02,0.04)陶瓷样品。研究了前驱体煅烧温度对陶瓷粉体物相组成的影响。分析了不同Li+掺杂量对样品物相组成、微观结构、体积密度及电学性能的影响。结果表明:前驱体的最佳煅烧温度为600℃,通过透射电子显微镜分析陶瓷粉体的粒径为49 nm;不同Li+掺杂量制备的(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷样品均为正交相钙钛矿结构;随着Li+掺杂量的增加,(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷的体积密度先增大后减小,介电常数逐渐升高,压电常数先降低再升高,剩余极化强度逐渐升高。Li+掺杂量x为0.04时样品的压电常数(d33=94 pC/N)、相对介电常数(εr=684.33)及剩余极化强度(Pr=98.27μC/cm2)较好。     

Preparation and Properties of （Na0.50＋xK0.50-2xLix）Nb0.9Ta0.1O3 Lead-Free Piezoelectric Ceramics by Sol-Gel Method

采用溶胶–凝胶法制备Li＋取代（K0.5Na0.5）＋及Ta5＋取代Nb5＋的（K0.5Na0.5）NbO3陶瓷粉体,采用无压烧结工艺制备（Na0.50＋xK0.50–2xLix）Nb0.9Ta0.1O3（x=0,0.02,0.04）陶瓷样品。研究了前驱体煅烧温度对陶瓷粉体物相组成的影响。分析了不同Li＋掺杂量对样品物相组成、微观结构、体积密度及电学性能的影响。结果表明：前驱体的最佳煅烧温度为600℃,通过透射电子显微镜分析陶瓷粉体的粒径为49nm;不同Li＋掺杂量制备的（Na0.50＋xK0.50–2xLix）Nb0.9Ta0.1O3陶瓷样品均为正交相钙钛矿结构;随着Li＋掺杂量的增加,（Na0.50＋xK0.50–2xLix）Nb0.9Ta0.1O3陶瓷的体积密度先增大后减小,介电常数逐渐升高,压电常数先降低再升高,剩余极化强度逐渐升高。Li＋掺杂量x为0.04时样品的压电常数（d33=94pC/N）、相对介电常数（εr=684.33）及剩余极化强度（Pr=98.27μC/cm2）较好。     

Tetragonal tungsten bronze phase potential in increasing the piezoelectricity of sol-gel synthesized (K0.5Na0.5)1-xLixNbO3 ceramics

(K,Na)NbO₃ (KNN)-based ceramics have been proven to be formidable candidates among lead-free piezoelectric materials, yet poor reproducibility always hinders their progress. In the present study, the effects of low lithium substitution on the electrical properties and microstructure of (K_0.5Na_0.5)_1-xLi_xNbO₃ (KNLN) ceramics were investigated. All samples were synthesized by the sol-gel method. The Curie temperature (T_C) of the ceramics shifted to higher temperature and gradually decreased the monoclinic-tetragonal (T_M-T) phase transition. Li⁺ substitution had a prominent effect on the ferroelectric properties and improved the piezoelectric coefficient (d₃₃) up to 181 pC/N. X-Ray Diffraction (XRD) studies and Field Emission Scanning Electron Microscopy (FESEM) images revealed an inevitable tetragonal tungsten bronze (TTB) secondary phase, which was formed during the preparation process. It was demonstrated that the volatilization of Li⁺ cations facilitated TTB growth. The coexistence of two different phase structures proved to enhance the KNN piezoelectric performance.     

白光发光二极管用荧光粉Ca0.5Sr0.5MoO4:Eu3+的制备及表征

采用以柠檬酸作为螯合剂的溶胶-凝胶法成功制备了新型纳米级红色荧光粉Ca0.5Sr0.5MoO4:Eu3+.通过X射线衍射、扫描电镜和荧光光谱等对该荧光粉进行了表征.结果表明:该荧光粉平均粒径为700 nm,在近紫外区395nm和蓝光区467nm光激发下都可发射出615 nm处的强烈红光,此外,Ca0.5Sr0.5MoO...     

(K0.5Na0.5)(TaxNb1-x)O3无铅压电陶瓷的性能特征

采用传统电子陶瓷制备工艺制备了(K0.5Na0.5)(TaxNb1-x)O3无铅压电陶瓷。研究了不同Ta含量下(K0.5Na0.5)(TaxNb1-x)O3陶瓷的晶相组成及性能特征。结果表明,(K0.5Na0.5)(TaxNb1-x)O3陶瓷在低Ta含量时形成单一斜方相固溶体,但Ta含量达到0.08mol后则有K6Ta10.8O30次晶相产生。随着Ta的加入,陶瓷的体积密度逐渐增大,居里温度(Tc)逐渐降低。当Ta含量为0.08mol时陶瓷具有良好的铁电、压电性能和介电稳定性能,其压电常数d33为76pC/N。     

High Piezoelectric Voltage Coefficient in Structured Lead‐Free (K,Na,Li)NbO3 Particulate—Epoxy Composites

A high‐voltage coefficient has been found in lead‐free piezoelectric particulate composites based on epoxy with lead‐free (K_0.50Na_0.50)_0.94Li_0.06NbO₃ (KNLN) piezoceramic particles with a natural cubic morphology. The KNLN powder used in the composites has been prepared using a new solid‐state double calcination processing route. These particles were subsequently used to create random and structured KNLN‐epoxy composites. Using dielectrophoresis, these natural cubical KNLN particles were structured into one‐dimensional chains inside the epoxy matrix. Composites produced with these powders showed piezoelectric properties about a factor of 2 higher than those of composites processed with conventionally calcined KNLN powders. The dielectrophoretically structured KNLN‐epoxy composites with optimized particle size and morphology showed excellent piezoelectric properties, which can replace lead containing piezoelectric composites for sensor and energy harvesting applications in future.