三种不同SrCO3粉料对空气中一次烧成SrTiO3GBBLC的性能影响

借助XRD、SEM、粒度分析仪，研究了三种常用的不同SrCO3粉料对空气中一次烧成晶界层电容器（GBBLC）性能的影响。研究结果表明，当SrCO3中含有多量的受主杂质离子（如Ca^2 等）或／和呈严重颗粒团聚状态，阻止GBBLC陶瓷的半导化，大而影响其介电性能。     

n型半导化TiO2压敏陶瓷的导电机制

分析了n型半导化TiO2压敏陶瓷中晶粒间界处的受主态性质，得出为晶界受主态的能级是多级化的；利用晶界平衡热电子发射势垒模型，合理地解释了该材料的I－V非线性特征；从理论上推导出了非线性系数α正比于晶界电压，且与晶界受主态的分布函数有密切关系。     

镁在钙钛矿型氧敏材料中的作用

讨论了添加剂镁（Mg)在钙钛矿型氧敏陶瓷中的作用和影响．利用固相合成法制备了不同Mg含量的样品,并在不同的温度、不同的氧分压下进行了阻温特性、氧敏特性的测量和TPD测量．研究表明,在SrTiO₃中Mg²⁺替位Ti⁴⁺可使SrTiO₃实现p型掺杂;适量的Mg掺杂,可使p型区向低氧分压方向扩展;受主掺杂促进了氧空位的产生,提高了杂质的固熔限;Mg掺杂促进环境氧与晶格氧的交换,提高了氧灵敏度;高于20mol%的Mg掺杂可产生Sr₂TiO₄,提高了材料的电阻率．     

Ta^5＋掺杂的SrTiO3系复合功能陶瓷的半导化和晶界层的研究

采用一次烧在法制备了Ｔａ＾５＋掺杂的ＳｒＴｉＯ３系复合功能陶瓷，测试了样品的介电性能，分析了晶粒的半导化机理，并讨论了晶界层对样品复合功能效应的影响。     

SiC复合(Ba,Pb)TiO3系PTC热敏陶瓷的研究

以（Ba,Pb)TiO3为主要原料，适当引入半导化施主元素，用SiC进行复合制备样品。研究烧成条件对产物的影响，讨论每种掺杂剂对材料的PTC热敏特性及微观形貌的影响，确定每种掺杂剂的最佳掺量，并对其半导机理进行分析。     

钇掺杂BaTiO_3半导体陶瓷的制备

以BaCO3和TiO2为原料,采用固相反应法制备了钇(Y)掺杂的BaTiO3半导体陶瓷。并且结合XRD分析的结果,讨论了不同煅烧温度对陶瓷半导化的影响和样品的室温电阻率与施主Y的摩尔分数的关系;提出了煅烧温度的选取原则。研究结果表明,随着煅烧温度的升高,材料半导化程度先增加后减小,最佳的煅烧温度为1 200℃。随着Y摩尔分数的增加室温电阻率先增加后减小。当Y摩尔分数为0.6%时在1 200℃煅烧2h获得的材料的室温电阻率最低为31.80Ω·cm。     

Nb掺杂浓度对BaTiO3陶瓷半导化的影响

本文就Nb掺杂BaTiO_3陶瓷中电阻率分布不均匀现象进行了实验研究,结果表明在掺杂量处在半导化组分附近的样品中电阻率分布存在有规律的分层现象,在此基础上对施主掺杂BaTiO_3陶瓷的室温电阻率随掺杂量的变化规律作出了新解释,并对分层现象形成的原因作了初步探讨。     

影响BaTiO3基PTC陶瓷材料性能因素的分析

在BaTiO3基质中用15mol% Pb作移峰剂,以此为基础配料制备了Bi和V分别取代部分Pb的PTC陶瓷及BaTiO3-钛酸钡钠(NBT)陶瓷,采用SEM、EDS等方法对其性能进行了测试,并分析研究了烧成制度对显微结构的影响以及晶界重氧化对材料电性能和PTC效应的影响.结果表明:Bi3 取代微量Pb2 可以使BaTiO3半导化,且具有PTC效应,但是室温下其电阻较大;用V5 取代微量Pb2 ,不能实现BaTiO3的半导化;NBT-BaTiO3陶瓷在还原气氛下烧结,半导化效果良好,但没有PTC效应,经重氧化试样的室温电阻增加,具有PTC效应.     

Ta~（5＋）掺杂的SrTiO_3系复合功能陶瓷的半导化和晶界层的研究

采用一次烧成法制备了Ｔａ５＋掺杂的ＳｒＴｉＯ３系复合功能陶瓷，测试了样品的介电性能，分析了晶粒的半导化机理，并讨论了晶界层对样品复合功能效应的影响。     

AlN陶瓷中的晶格缺陷

用透射电镜观察了不同热导率的ＡｌＮ陶瓷中存在晶格缺陷，这类缺争主要以位错或线形式呈现，分布不均匀，大多集中大晶界处，一些晶粒中存在反相畴界，热导率不同的试样共缺陷密度明显不同，氧杂质进入ＡｌＮ晶格并形成铝空位是产生晶格缺陷的主要原因，也对晶格参数有显著影响，分析了抑制晶格缺陷形成，提高热导率的工艺措施。     

(Ba,Eu)TiO_3细晶粒陶瓷制备中的影响因素

采用冷压陶瓷技术,分别在1 400℃和1 300℃制备了具有四方结构的(Ba_(1-x)Eu_x)TiO_3和(Ba_(1-x)Eu_x)Ti_(1-x/8)O_3陶瓷.应用X射线衍射(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究Eu含量、Ti空位缺陷和陶瓷化烧结温度的变化对制备(Ba,Eu)TiO_3细晶粒陶瓷的影响因素.结果表明:当x=0.05时,1 300℃制备的(Ba_(1-x)Eu_x)Ti_(1-x/8)O_3陶瓷细化到平均晶粒尺寸小于1μm,1 400℃制备的(Ba_(1-x)Eu_x)TiO_3陶瓷却畸变生长到5μm.而x=0.03时,(Ba_(1-x)Eu_x)TiO_3陶瓷仍能细化到1μm.说明较高的陶瓷化烧结温度并不是晶粒生长的主要原因,Ti空位的存在起到抑制晶粒生长的作用.x≥0.07时,(Ba_(1-x)Eu_x)TiO_3陶瓷为大于5μm的粗晶粒陶瓷,说明Eu含量的继续增加不能抑制晶粒生长.     

Effects of Excess Barium on the Structure and Electrical Properties of(Ba,Ca)TiO_3 Piezoelectric Ceramics with High Mechanical Quality Factors

Manganese-doped Ba_(0.925)Ca_(0.075)TiO_3 lead-free piezoelectric ceramics(abbreviated as BCT)with high mechanical quality factor were synthesized by conventional solid-state reaction method.The effects of excess Ba on the crystal structure,microstructure,and electrical properties of the ceramics were systematically investigated.X-ray diffraction and Raman spectra revealed that Ca~(2+)ions were pushed from Ba sites to Ti sites of BCT when 1.5 mol%extra Ba~(2+)ions were added after sintering.The grain size of the ceramics was decreased by adding extra Ba~(2+)ions.The mechanical quality factor and resistivity of the ceramics decreased dramatically when the excess Ba was more than 1.5 mol%.High piezoelectric coefficients(d_(33)=150-190 pC/N)and high mechanical quality factors(Q_m=1 000-1 200)were obtained in the ceramics when the excess of Ba was between 0.5 mol%and 1 mol%.These results indicated that the properties of BCT ceramics could be tailored by adjusting the content of Ba.     

（Ba,Pb）TiO3陶瓷湿敏特性的研究

介绍对(Ba,Pb)TiO_3陶瓷的湿敏特性的研究结果,从表面电导及表面势垒的观点出发,分析其吸湿特性,并给出定性解释。     

拉曼光谱在Ba(Ti_(1-x)Fe_x)O_(3-δ)陶瓷中的“电荷效应”湮灭

采用冷压陶瓷技术制备具有六方钙钛矿结构的Ba(Ti1-xFex)O3-δ(x=0.05,0.08)陶瓷.由拉曼光谱(RS)技术研究Ba(Ti1-xFex)O3-δ陶瓷在840 cm-1处的"电荷效应".实验观察到代表电荷效应的840 cm-1带消失,其原因最可能是:Fe3+相对于Ti4+具有更小的离子半径、Fe3+-Vo-Fe3+缺陷复合体的形成以及具有低对称性晶格点阵的六方畸变导致电荷效应湮灭.     

Effect of Pb Substitution on the Microstructure and Ferroelectric Properties of Ba0.7Sr0.3TiO3 Ceramic

Ferroelectric Ba0.7Sr0.3TiO3(BST) and partially Pb2+ substituted for Ba2+ ceramics (Bao.7-xPbx)Sr0.3TiO3 (x=0.1-0.4,BPST) were prepared by using conventional solid-reaction method.XRD analysis shows that the samples microstructure changes from cubic phase to tetragonal one with the Pb2+ content increasing.ESEM analysis shows that the Pb2+ substituted samples have a denser and more uniform surface morphology than that of pure BST.Measured electrical properties suggest that the Pb2+ substitution for Ba2+ in the BST system enhances the ferroelectric performance obviously when x=0.2.In addition,the substitution increases the samples Curie temperature (Tc).(Ba0.5Pb0.2)Sr0.3TiO3 ceramic has good ferroelectric properties measured at a maximal electric field of 30 kV/cm under the condition of room temperature.The corresponding saturated polarization (Ps),remnant polarization (Pr) and coercive field (Ec) is respectively 15.687 μC/cm2,8.100μ C/cm2 and 6.611 kV/cm.The measured Tc of (Ba0.5Pb0.2)Sr0.3TiO3 is 117 ℃.     

Ba_(0.98)Bi_(0.02)(Ti_(0.9)Zr_(0.1))_(1-x)Co_xO_3陶瓷的介电性能及弛豫特性研究

采用固相反应法通过施受主共掺的方式制备Ba0.98Bi0.02(Ti0.9Zr0.1)1-xCoxO3(x=0.005,0.01,0.015,0.02)陶瓷,通过XRD和LCR表征样品的相结构和介电性能。结果表明:在所掺杂溶度范围内,陶瓷样品未出现第二相;x=0.02时样品仅表现出弥散相变铁电体的特征,晶体中缺陷偶极子以[Bi·Ba-Co'Ti/Zr]为主,晶体中缺陷偶极子的存在形式与介电弛豫程度相关;样品结晶化学特性说明B位离子键价与其介电常数存在反比例关系。     

STUDY ON COMPLEX IMPEDANCE SPECTROSCOPY OF CU-IMPLANTED SEMICONDUCTING (BaO.72PbO.28)TiO3 CERAMICS

The ac impedance of Nb-doped semicon-ducting (Bao.72Pbo.28)TiO3 ceramics implanted with copper ions(200keV,6X1015 and 1X1017 ions/cm2) in the temperature range 25-320C and the frequency range 10 Hz -13MHz was measured. According to the change of impedance spectroscopy and the equivalent circuit model of semiconducting(Ba, Pb)TiO3 ceramics, the dependence of resistance of bulk and grain-boundary on temperature was analyzed. The results show that relatively low dose must be used to increase the magnitude of the positive temperature coeffieient of resistance(PTCR)effects in the cermmics. In addition,the effects of Cu ion implantation on the PTCR behavior of the ceramics was studied by raststance-tempera-ture measurement.     

Influence of Excessive SiO2 or TiO2 on the Electric Properties of

The dependence of electrical properties of Ba0.92Ca0.08TiO3 PTCceramics on the SiO2 or TiO2 content was studied. The dependence of room temperature resistivity on the SiO2 content was determined by the variation of the microstructure of Ba0.92Ca0.08TiO3 PTC ceramics. It was shown that a small amount of excessive TiO2 (2mol%) added could increase the dielectric constant of materials, and it results in a reducing of the potential height (e*φ) of grain boundary. Thus, samples with particularly low room temperature resistivity were obtained. The relationship of PTC effect with the TiO2 content was also discussed by using the chemistry defect theory. The inferior PTC effect caused by excessive TiO2 may be concerned with the behavior of oxygen vacancies in the grains of ceramics.     

单相BaCeO_3陶瓷的制备研究

采用冷压陶瓷技术在不同烧结温度下制备BaCeO3陶瓷.利用X射线衍射(XRD)和拉曼光谱(RS)研究烧结温度对CeO2在BaCeO3陶瓷形成中的固溶性及单相陶瓷形成的影响.研究表明:在1100～1450℃范围内,XRD和RS观测都证实了少量CeO2的残存.当烧结温度增加到1480℃并保持长时间烧结时,CeO2能够完全固溶,以CeO2位于33.07°的(200)XRD峰和460 cm-1处拉曼带的消失为标志,形成具有Pnma正交钙钛矿结构的单相BaCeO3陶瓷.Ba蒸发效应被讨论,Ba位不足由极少量的Ce3B a+-Ce3T i+形成来自补偿.     

施主掺杂BaTiO_3陶瓷的正电子湮没和顺磁共振研究

本文用正电子湮没和电子顺磁共振相结合的方法对施主掺杂BaTiO_3陶瓷的缺陷进行了研究。正电子湮没寿命测量说明与Ba/Ti=1的样品相比Ba过量或Ti过量都会引起材料中的空位增加。顺磁共振图谱表明,g=1.997峰的强度在铁电相变为顺电相后,强度有很大的增长(约20倍)。该峰强度随Ba/Ti的变化与正电子捕获率随Ba/Ti的变化相同。因此该峰是由阳离子空位(V_(Ba)和V_(Ti))引起的。它实质上是由O~-产生的,随施主掺量的增加g=1.997峰急剧增强,这很可能是由于施主增加引起V_(Ti)大量生成的缘故。