Effects of temperature on hydrostatic pressure-induced FE-AFE phase transition in PbLa(Zr, Sn, Ti)O3 ceramics

Hydrostatic pressure-induced ferroelectricantiferroelectric (FE-AFE) phase transition and the pressure dependence of dielectric properties in La-doped Pb(Zr,Sn, Ti)O₃ ceramics were researched; the effects of temperature on hydrostatic pressure-induced FE-AFE phase transition and dielectric properties of the samples were studied. It was found that the temperature made the FE-AFE phase transition pressure decrease, and there existed the behavior of dielectric frequency dispersion and phase transition diffusion in the dielectric-pressure spectrum. These phenomena were very useful to enrich and develop the knowledge on the diffused phase transition behavior of polycomponent relaxor ferroelectric.     

准同型相界附近0.02Pb(Zn_(1/3)Nb_(2/3))O_3-0.50Pb(Ni_(1/3)Nb_(2/3))O_3-0.48Pb(Zr_xTi_(1-x))O_3陶瓷压电性能研究

采用传统固相反应法制备四元系0.02Pb(Zn1/3Nb2/3)O3-0.50Pb(Ni1/3Nb2/3)O3-0.48Pb(ZrxTi1-x)O3(0.29≤x≤0.34)陶瓷.观察样品的晶相结构和显微结构,测试压电性能和介电性能.随着Zr/Ti比的增大,晶相从四方相向三方相转变.发现准同型相界位置在x=0.32附近.1 240℃烧结的0.02PZN-0.50PNN-0.48PZ32T陶瓷展现了良好的压电性能,压电常数d33为715 p C/N,机电耦合系数kp为0.541,剩余极化强度Pr为25.5μC/cm2,矫顽场强Ec为5.6 k V/cm.新的压电材料适合高性能压电器件应用,且简单的制备方法给生产带来极大便利.     

Pyroelectric spectrum in Pb(Zr,Sn,Ti)O3 antiferroelectric- ferroelectric ceramics

The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFEA-AFEB or ferroelectric FEL-FEH transition, which are not detected by the conventional dielectric measurement.     

Sr2Bi4-x/3Ti5-xNbxO18陶瓷的铁电介电性能

对Sr2Bi4-x/3Ti5-xNbxO18(x=0,0.003,0.018,0.048,0.096)陶瓷样品的铁电和介电性能进行了测量.结果表明,Sr2Bi4Ti5O18样品的剩余极化2Pr为0.22 C·m-2,少量Nb掺杂可使样品的2Pr有明显提高,当x=0.018时,2Pr达到最大为0.34 C·m-2.介电损耗随温度的变化关系曲线上存在P1,P2,P3 3个介电损耗峰,分别在70,230,290℃附近.低温部分的2个损耗峰具有介电弛豫的特征,其弛豫机制被认为是点缺陷与畴界之间的相互作用.通过激活参数的计算以及损耗峰随不同Bi过量的变化,可以确定P1,P2峰的弛豫机制与Sr,Ti空位有关.随着Nb掺杂量的增加,P1,P2峰逐渐降低,表明Nb掺杂降低了样品中缺陷的浓度,从而使得样品的2Pr明显提高.     

0.85PZN-0.10BT-0.05PT陶瓷烧结工艺及性能

采用二次合成法制备了 0 .85Pb(Zn1/3Nb2 /3) O3 0 .1 0 Ba Ti O3 0 .0 5Pb Ti O3弛豫铁电陶瓷 ,探讨了烧结温度对陶瓷相结构和晶粒的影响 ,优化了烧结工艺 ,并在此基础上研究了陶瓷的介电性能和电致伸缩性能。结果表明 ,陶瓷中钙钛矿相的含量随烧结温度的升高而不断增加 ,而升高预烧温度对提高钙钛矿相的结构稳定性不利。优化烧结工艺后 ,获得了 1 0 0 %钙钛矿相的陶瓷 ,其峰值介电常数为 60 67,在电场为 2 0 0 0 V/ mm时电致应变可达 5.5× 1 0 -4 。     

Dy掺杂Sr2Bi4Ti5O18陶瓷的介电性能

采用固相烧结工艺制备了Sr2Bi4-xDyxTi5O18(x=0，0．25)陶瓷样品，用X射线衍射对其微结构进行了分析，并测量了样品的铁电、介电性能．Sr2Bi.75Dy0.25Ti5O18样品的X射线谱上出现SrTiO3衍射峰，其介电损耗随温度的关系曲线上存在明显的弛豫损耗峰P1，该损耗峰的激活能为0．4eV，可以确定该峰是由氧空位引起的．结果表明：离子半径较小的Dy3 很难进入类钙钛矿层，造成样品中大量的A位空位，使得氧空位浓度增加．氧空位的存在会导致很强的畴钉扎，从而极化降低。     

BaxSr(1-x)TiO3弛豫铁电体的制备及性能研究

用传统的固相反应法制备Ba0．5Sr0.5TiO3和Ba0.7Sr0.3TiO3 2种Ba,Sr比的BST陶瓷体．并研究了其介电性和弛豫性,由频谱关系和温谱关系了解到,A位取代的BST复合钙钛矿结构仍具有和铅系B位取代陶瓷相类似的弛豫性。     

Y2O3掺杂对BaZrxTi1-xO3陶瓷介电性能的影响

研究BaZrxTi1-xO3 (x=0,0.1,0.2,0.3)陶瓷中掺杂0.1％(按物质的量计算,下同)Y2O3对铁电-顺电相变温度的影响.发现0.1％Y2O3的掺杂使BaTiO3的铁电-顺电相变的居里温度向高温偏移了约20℃,不同Zr含量的样品也发生了一定程度的高温偏移.在-40℃到140℃的测量温度范围内介电频率弥散现象极弱,峰值介电常数可以达到8000,损耗峰值为0.05以下.随Zr含量的增加,损耗峰快速移向低温.与文献报道的结果比较,证实Y以A位替代Ba为主.     

溶胶-凝胶法制备0．85Pb（Mg1／3Nb2／3）O3—0．15PbTiO3铁电陶瓷及其性能研究

以无机盐和氧化物为原料,柠檬酸和乙二胺四乙酸(EDTA)为复合螯合剂,乙二醇为溶剂,采用溶胶-凝胶法制备了0.85Pb(Mg1/3Nb2/3)O3-0.15PbTiO3(PMN-PT)铁电陶瓷粉体及其烧结体.并通过XRD和SEM分析了PMN-PT钙钛矿相的形成和烧结体的显微结构.讨论了不同烧结温度对陶瓷显微结构、介电、铁电及压电性能的影响.结果表明采用溶胶-凝胶法制备的PMN-PT陶瓷适宜烧结温度为1 100℃,比常规固相合成法制备PMN-PT陶瓷的温度低100～200℃,且该条件下烧结的陶瓷性能优异:d33=252 pC/N,Pr=17.8 μC/cm2.     

以LaNiO3作为底电极的Pb(Zr0.3,Ti0.7)O3铁电薄膜的性能研究

采用溶胶－凝胶法在Si(100）衬底上制备了LaNiO3薄膜，采用相同方法在LaNiO3/Si(100）上制备了Pb（Zr0.3,Ti0.7）薄膜，对LaNiO3薄膜和Pb(Zr0.3,Ti0.7）O3薄膜的结晶性，表面形貌和电性能进行了研究。     

Pyroelectric spectrum in Pb(Zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics

The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(Zr,Sn,Ti)O₃ antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFE_A-AFE_B or ferroelectric FE_L-FE_H transition, which are not detected by the conventional dielectric measurement.     

Ca[(Li1/3Nb2/3)1-xTi3x]O3-δ陶瓷微波介电性能研究

研究了添加B2O3的Ca[(Li1/3Nb2/3)1-xTi3x]O3-δ(0≤x≤0.2)(CLNT)陶瓷的微波介电性能.在整个组分范围内检测到单一的正交相.随着x从0增加到0.2,介电常数(k)将从30增至89,Qf值则下降到3820GHz,谐振频率温度系数(TCF)从-16×10-6/℃增加到22.4×10-6/℃.当B2O3添加1.0%时,CLNT陶瓷的烧结温度可以从1150℃降至970℃而不降低微波介电性能.940℃烧结后,x=0.1试样的微波性能为k=50,Qf=6500GHz,温度系数为-7.6×10-6/℃.     

Relaxor behavior of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 ceramics

n the present work, the phase transitions and relaxor behavior of (1−x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (PMN-PT, x = 0.2―0.4) ferroelectric ceramics have been investigated by means of X-ray diffraction, di-electric spectroscopy, the P-E hysteresis loop measurements and Raman scattering techniques. Structural analysis revealed that with the increase of PbTiO₃ content, PMN-PT ceramics experienced a gradual phase transition process from rhombohedral to tetragonal. It is usually believed that such kinds of phase transitions resulted in the linear decrease of relaxation degree. Surprisingly, our analy-sis of the dielectric spectra revealed that the indicator of the degree of diffuseness γ reached the maximum value near morphotropic phase boundary (MPB) (x = 0.32), then decreased with the further increase of PbTiO₃ content. The large dielectric relaxor feature near MPB may be attributed to the for-mation of ordered nanodomains, resulting from complex coexisting nanostructures. Further, the P-E hysteresis loop measurements and Raman analysis of the B-site cation order correlated well with the dielectric measurement results. It was found that the hysteresis loop squareness R_sq received the minimum value while the inverse of the value of full wide of half maximum (FWHM) of A_1g mode reached the maximum value at MPB composition, which showed similar trends to γ.     

铌铁酸铅-钛酸铅铁电陶瓷的结构相变

 通过钨锰铁矿预合成法制备了铌铁酸铅-钛酸铅(1-x)Pb(Fe_1/2Nb_1/2)O₃-xPbTiO₃ (PFN-PT)铁电陶瓷。X-ray衍射（XRD）测量和密度测试表明,1150 ℃烧结2.5 h制备的PFN-PT陶瓷呈现纯钙钛矿结构和较高的致密度。随着PbTiO₃（PT）质量含量的增加,PFN-PT的晶体结构从三方相向四方相转变,伴随着晶胞体积的减小和钙钛矿结构四方性因子（c/a）的增大。PFN-PT陶瓷呈现明显的介电频率色散现象,随着PT含量的增加,介电常数最大值温度T_m/T_C升高,介电响应从弥散、宽化的介电峰变得相对尖锐,介电损耗减小,频率色散现象减弱。MnO₂掺杂有效地改善了PFN-PT陶瓷的介电性能。w=0.25% MnO₂掺杂的0.66PFN-0.34PT陶瓷100 kHz的最大介电常数ε_m为13254,室温介电损耗tanδ为0.003 63,饱和极化强度P_s为6.18μC/cm2,矫顽场E_c为1.1 kV/mm,压电应变常量d₃₃为98pC/N。     

Properties of PbLa（Zr,Sn, Ti）O3 ceramics near ferroelectric-antiferroelectric phase boundary

Shirane found in the middle of the 20th century that the solid solution PZT had a lot of fine characteristics and carried out detailed researches[1]. The critical phase transition field of antiferroelectric decreased by adding titanate. Titanate expands t…     

Ca(Sm0.5Nb0.5)O3介质陶瓷的微波烧结

通过改变微波烧结温度和保温时间,优化Ca( Sm0.5 Nb0.5) O3 (CSN)陶瓷的微波烧结工艺,用X线衍射仪(XRD)、扫描电镜(SEM)和微波网络分析仪等对试样进行表征.从相组成、显微结构及微波介电性能等方面对微波烧结试样与常规烧结试样进行对比分析.结果表明:微波烧结可大幅降低CSN的烧结温度,促进试样的致密化,其物相组成和传统烧结试样无明显差别;微波烧结还可以改善CSN陶瓷的微波介电性能,在1 375℃微波烧结30 min可获得优异的微波介电性能,介电常数(εr)=20.08,品质因数(Q×f)=37.03 THz,谐振频率温度系数(Tf)=-10.2×10-6℃-1.     

PZT 基铁电陶瓷材料 F-P 相变及其热物理性质

用激光闪光法研究了ＰＺＴ为基铁电陶瓷材料［Ｐｂ（Ｓｂ，Ｎｂ，Ｚｒ，Ｔｉ）Ｏ３］的ＦＰ相变及其热物理性质。实验发现，铁电相到顺电相的变化发生时，热扩散率和导热系数随温度发生异常变化。根据其热物性曲线出现的突变点所确定的相变温度与用电学法测定的居里温度ＴＣ吻合良好。据此，闪光法可以作为研究铁电材料相变的一个新的手段和判据。     

Shock wave compression of poled Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3 ceramics: Depoling currents in axial and normal modes

We used a 100-mm diameter gas gun to investigate the output currents due to the sudden depolarization of poled Pb 0.99 [(Zr 0.90 Sn 0.10) 0.96 Ti 0.04 ] 0.98 Nb 0.02 O 3 ceramics under shock wave compression.We conducted shock wave experiments for the normal/axial mode with the polarization vector perpendicular/antiparallel to the shock vector.The shock pressure was in the range of 0.23 to 4.50 GPa.We measured the depoling currents under short-circuit,high-impedance,and breakdown conditions.Under the short-circuit condition,the dependence of the released charge on the shock pressure demonstrates the evolution of the ferroelectric-to-antiferroelectric phase transition.The onset pressure of the phase transition is between 0.23 and 0.61 GPa,and phase transition occurs completely above 1.22 GPa.The increasing load resistance decreases the released charge and increases the released energy.The results indicate that Pb[(ZrSn)Ti]NbOceramic is a good candidate for a pulsed power generator.     

Ba(Zn0.5W0.5)O3掺杂对Ba[(Zn0.2CO0.8)0.33Nb0.66]O3微波介质陶瓷的影响

用传统固相法制备了Ba(Zn0.5W0.5)O3掺杂Ba[(Zn0.2Co0.8)0.33Nb0.66]O3微波介质陶瓷,通过XRD和HP8720ES网络分析仪分别对其晶体结构和微波介电性能进行了研究.实验结果表明,少量的Ba(Zn0.5W0.5)O3可以把体系的烧结温度从1430℃降低到1380℃,促进了烧结.在烧结过程中Zn的挥发会促使掺入的Ba(Zn0.5W0.5)O3转变成BaWO4,以第二相的形式存在于陶瓷样品表面,而内部并没有明显的第二相生成.这说明烧结过程中Zn的扩散很有限.在微波介电性能方面,随着Ba(Zn0.5W0.5)O3的掺杂量的增加,Ba[(Zn0.2Co0.8)0.33Nb0.66]O3的相对介电常数(εr)略有减小,谐振频率的温度系数(Tf)略有增大,而其Q×f值则在测量误差范围内波动不大,说明掺入少量的Ba(Zn0.5W0.5)O3对Ba[(Zn0.2Co0.8)0.33Nb0.66]O3在微波频率下的品质因数影响不大.     

A位掺杂Sr1-xLa2x/3Bi4Ti4O15陶瓷的铁电介电性能

Sr1-xL a2x/3B i4T i4O15(SLBT-x,x=0.00~0.75)陶瓷居里温度(tC)随掺杂量的增加而降低,显示掺杂导致晶格畸变减小,这是由于L a3 取代Sr2 位而产生的A位空位弱化了相邻T iO6八面体的耦合作用所致.样品介电峰峰高随掺杂量增加而降低,峰形宽化,表现出弥散相变的特征,这是由于L a3 和Sr2 离子半径的差异以及高掺杂量下L a3 离子部分进入铋氧层所致.样品的剩余极化(2Pr)在掺杂量为0.3时增加到23.1×10-2C.m-2,同时矫顽场降低到79.6×105V.m-1,高价掺杂所形成的偶极子缺陷使得样品铁电性能明显改善.