BaTiO_3-Bi(Ni_(2/3)Nb_(1/3))O_3弛豫铁电陶瓷结构、介电与储能性能研究

采用固相法制备(1-x)BaTiO_3-xBi(Ni_(2/3)Nb_(1/3))O_3(x=3,5,7,10,15,20mol%)(简称BTBNN)弛豫铁电陶瓷,研究了BTBNN陶瓷的结构、介电性能和铁电性能.研究结果表明,Bi(Ni2/3Nb1/3)O3(简称BNN)可以有效降低BaTiO3陶瓷的烧结温度.XRD表明BTBNN陶瓷的晶体结构随BNN含量的增加从四方相转变为伪立方的钙钛矿结构.介电温谱结果表明BTBNN陶瓷表现出弛豫铁电陶瓷的特征,最大介电常数εm随BNN含量增加逐渐减小,而最大介电常数对应的温度Tm呈现先减小后增加的趋势.当x=20mol%时,BTBNN陶瓷获得250kV/cm的击穿电场和2.03J/cm3的可释放能量密度.     

新铌酸盐A5LaSn3Nb7O30(A=Ba,Sr)的结构与介电特性

通过固相反应法,在AO-La2O3-SnO2-Nb2O5(A=Ba,Sr)体系合成了填满型钨青铜结构新铌酸盐Ba5LaSn3Nb7O30与Sr5LaSn3Nb7O30。采用X射线衍射分析和扫描电镜进行了结构分析,并测试了其介电性能。结果表明:Ba5LaSn3Nb7O30与Sr5LaSn3Nb7O30室温时均为四方钨青铜结构顺电相,其陶瓷体都具有高的介电常数、低的介电损耗与较小的介电常数温度系数。频率为1 MHz时,Ba5LaSn3Nb7O30陶瓷体的室温相对介电常数为171,介电损耗约为1.2×10-3;Sr5LaSn3Nb7O30陶瓷体的室温相对介电常数为164,介电损耗约为5.4×10-4。     

Cr_2O_3及Nb_2O_5掺杂CaCu_3Ti_4O_(12)陶瓷结构与介电性能

采用固相法制备了Cr2O3、Nb2O5掺杂的钛酸钙铜基高介电陶瓷,研究了Cr2O3、Nb2O5掺杂对CaCu3Ti4O12(CCTO)陶瓷晶体结构、显微结构及介电性能的影响.结果表明:当掺杂量x在所研究区域质量分数0~0.8%之间时,样品均形成纯钙钛矿固溶体;两种掺杂对钛酸钙铜陶瓷的晶体生长均有抑制作用,Cr2O3掺杂的样品在1100℃致密成瓷,Nb2O5掺杂的样品在1080℃致密成瓷;当Cr2O3掺杂量为质量分数0.4%、Nb2O5掺杂量为质量分数0.4%时,与纯CCTO相比,两种掺杂对陶瓷的介电性能均有明显的改善作用,室温、1kHz下陶瓷的介电损耗分别为0.04、0.17,Cr2O3掺杂钛酸钙铜陶瓷性能要优于Nb2O5掺杂的钛酸钙铜陶瓷.     

Y3+取代Bi3+对Bi2(Zn1/3Nb2/3)2O7陶瓷烧结温度的影响

采用固相反应制备Bi2(Zn1/3Nb2/3)2O7微波陶瓷,并借助X射线、扫描电镜、LCR4284测试仪,研究Y3 取代Bi3 对Bi2(Zn1/3Nb2/3)2O7陶瓷烧结特性及介电性能的影响。研究结果表明:随着Y3 替代量的增加,晶粒尺寸减小,介电常数先减小后增大,烧结温度升高;适量的Y3 替代可以获得性能很好的BZN介质材料。     

新型Ruddlesden-Popper相Sr_3Sn_2O_7陶瓷铁电体

为了寻求新的混合非常规铁电体,采用固相法合成了具有Ruddlesden-Popper结构的Sr3Sn2O7陶瓷,并研究了该材料的介电与铁电性能.通过X射线衍射分析检测Sr3Sn2O7的相组成,采用扫描电镜与能谱分析仪分析Sr3Sn2O7陶瓷的微观形貌与元素含量,采用不同频率下的介电温谱测量和电滞回线测量对样品的介电与铁电性能进行表征.结果显示,制备的Sr3Sn2O7陶瓷为单一正交相结构,其晶胞参数a=2.062 72 nm,b=0.572 49 nm,c=0.570 03 nm,样品在不同频率下测得的介电温谱在132℃存在一个明显的介电峰,同时其电滞回线显示明显的室温铁电性,居里温度约为132℃.     

Ba(ZrxTi1-x)O3弛豫铁电体的介电性能研究

采用传统的固相反应法制备了0.2% Nb2O5掺杂的Ba(Zr0.15Ti0.85)O3弛豫铁电陶瓷,测量了不同温度下的介电频谱;讨论了介电常数的频率和温度特性;结果表明:由于掺铌BZT陶瓷内部结构的不均匀,导致多种弛豫时间的不对称分布,实际的Cole-Cole图不是理论上的半圆,而是偏离半圆的鼠标形式,BZT陶瓷在Zr质量分数为0.15时仍具有弛豫性;在介温曲线中,由于漏导电流的存在,tgδ-T曲线在高温部分有上翘现象.     

BiFeO3-SrBi2Nb2O9铁电陶瓷的结构及性质

用高能振动技术制备了单相层状结构的BiFeO3-SrBiNb2O9的铁电陶瓷，研究了BiFeO3的掺杂对SrBi2Nb2O9微观结构和介电性能的影响，分析了陶瓷的介电性质．     

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.     

新铌酸盐A5NdSn3Nb7O30的合成与介电特性

通过固相反应法在AO-Nd2O3-SnO2-Nb2O5(A=Ba,Sr)体系中合成了填满型钨青铜结构新铌酸盐A5NdSn3Nb7O30。分别采用X射线衍射分析和扫描电镜进行了结构分析,并进行了介电性能测试。结果表明,它们室温时都为四方钨青铜结构顺电相。A5NdSn3Nb7O30(A=Ba,Sr)陶瓷体具有高的室温相对介电常数,1 MHz时分别为182与144;低的介电损耗,分别为1.8×10-3和6.2×10-4;其介电常数温度系数(τε)分别为-1 071×10-6K-1和-507×10-6K-1。     

液相烧结对Ba(Ti0.91Zr0.09)O3陶瓷介电性能的影响

采用固相反应法制备了添加1wt%CuO-BaO混合物的Ba(Ti0.91Zr0.09)O3铁电陶瓷,借助XRD、SEM、Agilent4284测试仪,讨论了加入CuO-BaO混合物对Ba(Ti0.91Zr0.09)O3铁电陶瓷的烧结温度、相结构、显微组织及介电性能的影响.结果表明:添加1wt%CuO-BaO混合物,能有效降低Ba(Ti0.91Zr0.09)O3的烧结温度,室温介电常数高,介电损耗小.在1MHZ下εTl=3 150,tgδ=0.06,并且伴有介电弛豫现象.     

稀土Nd掺杂对Sr（Fe0.5Nb0.5）O3基介质陶瓷巨介电性能的影响

铁铌酸锶是一种重要的介质材料,具有复合钙钛矿结构,同其他介质材料相比,具有相对高的介电常数的优点,在高储能等领域有重要的应用潜力,是一种用途广泛的功能陶瓷材料．实验以Sr（Fe0.5Nb0.5）O3基陶瓷为研究对象,研究了稀土Nd掺杂对该系陶瓷巨介电性能的影响．结果表明：随着Nd抖掺杂量的增加,陶瓷样品的介电常数逐渐变大;随着温度的上升,陶瓷体系的介电常数也逐渐增大;Nd抖含量x≤0．10时,陶瓷样品有着良好的频率稳定性,x=0．10的陶瓷样品在100kHZ下有着良好的温度稳定性．     

Pb(Mg1/3Nb2/3)O3-PbTiO3-BaTiO3 Complex Perovskite Ferroelectric Ceramics with High Dielectric Constant and Low Firing Temperature

The effects of different firing temperatures on the stability of perovskite phase, grain size, and dielectric properties were investigated by XRD, TEM, SEM and dielectric measurements. The dielectric ceramics of Pb(Mg1/3Nb2/3)O3-PbTiO3-BaTiO3 system were obtained by chemical coprecipitation in water. The ceramics have higher dielectric constant (7003-9714), lower firing temperature(950-1150℃), quite uniform microstructure with grain size less than 2.5 mp, and lower temperature coefficients of capacitance. As a re-sult, it was confirmed that the simple and low cost chemical route used namely coprecipitation in water is a desired method for preparinghigh property dielectfic materials applicable to multilayer capacitors.     

铌镁酸铅、钛酸铅系材料介电性能研究

本文主要是对Pb(Mg1/3Nb2/3)O3与PbTiO3混合后材料的介电性能作了研究，分析了随着Pb-TiO3含量的增加，材料的介电常数、居里温度的变化并通过测定样品的烧成密度确定材料的烧成制度。     

Preparation,structure and dielectric properties of tungsten bronze ferroelectrics in SrO-Eu<Subscript>2</Subscript>O<Subscript>3</Subscript>-TiO<Subscript>2</Subscript>-Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> system

Compounds Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 with filled tetragonal tungsten bronze structure were prepared,and the dielectric characteristics and ferroelectric transition were investigated.Both ceramics displayed weak frequency dependence in room temperature dielectric constant,which decreased from 125 to 118 for Sr4Eu2Ti4Nb6O30,from 206 to 195 for Sr5EuTi3Nb7O30 in the frequency range of 10 kHz to 1 MHz.The present ceramics showed a diffuse ferroelectric phase transition.The frequency independent transition temperature (Tm) indicated the above compounds had no relaxor property.The diffuseness (γ) was 1.45 and 1.64 for Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 respectively.The weak ferroelectric of the present materials are indicated from the P-E hysteresis loops,and a small 2Pr of 0.596 μC/cm2 and 0.068 μC/cm2 were observed for Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 respectively.     

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.     

中温烧结Mg_4Nb_2O_9-CaTiO_3陶瓷相结构的研究

采用传统固态反应方法制备了(1-x)Mg4Nb2O9+xCaTiO3[(1-x)MN-xCT]复合陶瓷。探讨了烧结温度、组分x对Mg4Nb2O9/CaTiO3复合材料相结构的影响。通过XRD和EDS进行物相分析。实验结果表明:V2O5添加能够有效降低Mg4Nb2O9/CaTiO3陶瓷的烧结温度;(1-x)MN-xCT复相的形成主要取决于烧结温度和x的含量。1150℃烧结、0.5≤x≤0.7范围内,形成了Mg4Nb2O9/CaTiO3复相,无新相生成,但元素在不同相之间发生了扩散。     

锂盐助烧0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3陶瓷的介电性能

采用铌铁矿预产物合成法制备了锂盐（Li2CO3,LiNO3,LiF）助烧0.68 Pb(Mg1/3Nb2/3)O3-0.32 PbTiO3 [PMN-PT] 弛豫铁电陶瓷。采用XRD分析陶瓷相组成,并对其介电性能进行了测试,结果表明：所有陶瓷样品均为纯钙钛矿相,无任何其它杂相出现;添加Li2CO3和LiNO3使PMN-PT陶瓷的介电损耗降低,而介电常数峰宽、介电弛豫特性以及居里点等变化不明显;但添加LiF使PMN-PT陶瓷的介电损耗增大,介电常数峰变宽,介电弛豫更明显,以及居里点下降。极化后锂盐助烧PMN-PT陶瓷的介电常数和损耗峰均表现为双峰,第一个峰为三方铁电相-四方铁电相的相变峰,约80 ℃左右;第二个峰为四方铁电相-顺电相的相变峰,对添加LiF的试样约为130 ℃,其余试样约为150 ℃。这主要是由于添加Li2CO3和LiNO3试样只发生Li＋在PMNT的B位置换产生氧空位,而添加LiF试样可以通过F－取代反应产生铅空位来补偿Li＋取代产生的氧空位。     

Sintering and dielectric properties of fine-grained BaTiO3 ceramics

A new sintering method, spark plasma sintering (SPS), is described for the sintering of fine-grained BaTiO₃ ceramics. Dense ceramics with fine grain size of near 170 run are obtained using SPS at low temperature of 900°C without holding time. The dielectric measurements of various grain size specimens show that the dielectric constants decrease with the reduce of grain size, and diffuse phase transition showed in the dielectric-temperature spectra. The variation in dielectric properties with grain size is explained.     

Ho3+离子在BaTiO3陶瓷中自补偿模式探索及反常介电性质

采用冷压陶瓷技术制备(Ba_1-xHo_x)(Ti_1-xHo_x)O₃（简称BHTH）陶瓷. 通过X射线衍射（XRD）、电子顺磁共振（EPR）和介电温谱技术研究了BHTH陶瓷的结构、位占据和介电性质. 结果表明：Ho³⁺离子在BaTiO₃陶瓷中能够形成自补偿模式,且具有轻微的Ba位占据倾向. 在BHTH陶瓷中,固溶度为x = 0.03. BHTH陶瓷的介电行为表现出一个反常现象：随着x从0.01增至0.03,居里温度TC向高温移动,即T_C从128℃升到131℃. BHTH晶体结构的四方度（c/a）随着x增加是T_C向高温移动的主要原因.