Nb2O5掺杂高温无铅(Ba,Bi,Na)TiO3基PTCR陶瓷结构与电性能研究

采用固相反应法制备了施主掺杂浓度不同的Nb₂O₅（分别为0.1mol%、 0.3mol%、 0.5mol%、 0.7mol%）掺杂(Ba, Bi,Na)TiO₃基PTCR陶瓷. 对其微观结构及电性能进行研究发现：随着Nb₂O₅掺杂浓度的增加,陶瓷晶粒尺寸先变大后变小,室温电阻率也随之先减小后增大,说明Nb₂O₅的掺杂量存在一个临界施主掺杂浓度. 当Nb₂O₅施主掺杂量为临界施主掺杂浓度0.5mol%时,获得了居里温度T_c为 183℃、室温电阻率ρ为1.06×10³Ω·cm、升阻比ρ_max/ρ_min为1.0×10⁴的高温无铅PTCR陶瓷. 通过交流复阻抗谱分析,探讨了Nb₂O₅施主掺杂在该PTCR陶瓷中的作用机理.     

Effect of Isovalent Ba-Site Substitutions on the Properties of (Ba1 – x – y M y Y x )TiO3(M = Ca, Sr, Pb) PTCR Ceramics

An approach is proposed for fabricating fine-grained, low-resistivity BaTiO₃-based PTCR ceramics via partial isovalent substitutions on the Ba site. The grain size of the ceramics thus prepared is shown to decrease as the ratio of ionic radii r(Ba²⁺)/r(M²⁺) (M = Ca, Sr, Pb) increases. Isovalent substitutions on the Ba site narrow down the range of donor dopant (yttrium) concentrations in which PTCR materials can be prepared. The experimental results agree well with thermodynamic calculations under the assumption that the materials contain the Y³⁺Ti³⁺O₃ phase, as suggested by ESR data, which point to the presence of Y³⁺–Ti³⁺ associates. Partial calcium, strontium, and lead substitutions on the Ba site reduce the average grain size of PTCR ceramics, which is probably due to the lattice strain arising from the isovalent substitution. Partial replacement of Ba²⁺ with mixtures of different isovalent elements (e.g., Sr²⁺ and Pb²⁺) offers the possibility of obtaining fine-grained, low-resistivity PTCR ceramics, without changing the phase transition temperature.     

Effect of potato-starch on the microstructure and PTCR characteristics of (Ba,Sr)TiO3

Porous semiconducting (Ba, Sr)TiO₃ ceramics were fabricated by the addition of potato-starch to the (Ba, Sr)TiO₃ powders. The effects of potato-starch on the microstructure and PTCR characteristics of the porous (Ba, Sr)TiO₃ ceramics have been investigated. The porosity largely increased and the grain size slightly decreased with increasing potato-starch content. The crystalline structure of (Ba, Sr)TiO₃ ceramics was independent of the potato-starch content. The (Ba, Sr)TiO₃ ceramics containing potato-starch showed higher PTCR (10⁶) characteristics than that of the (Ba, Sr)TiO₃ ceramics without potato-starch. It was found that the development of PTCR characteristic in the porous (Ba, Sr)TiO₃ ceramics containing various amounts of potato-starch, in the same way as normal BaTiO₃ ceramics without potato-starch, is associated with grain boundaries, from the impedance analysis.     

Mn掺杂BaTiO_3基PTCR陶瓷相变的EPR研究

为了探索利用ＥＰＲ谱线对ＰＴＣＲ陶瓷的相变及ＰＴＣ效应的机制研究的可能性,本文对接 Ｍｎ的 ＢａＴｉＯ３基正温度系数热敏电阻（简称ＰＴＣＲ）陶瓷在 １２０～４５０Ｋ温度范围内的电子顺磁共振谱进行了研究．得出了 Ｍｎ２＋离子 ＥＰＲ信号强度、 ｇ因子值和超精细耦合常数｜Ａ｜值的温度分布,发现ＥＰＲ参数与ＰＴＣＲ陶瓷相变有明显的对应关系,并给出微观结构上的初步解释．研究表明ＥＰＲ谱线以及精细结构的分析可以为ＰＴＣＲ陶瓷的相变机制以及ＰＴＣ效应的机制研究提供新的途径．     

PTCR properties of Sb2O3-doped (Ba,Sr)TiO3

Perovskite barium–strontium titanate, (Ba,Sr)TiO₃ was prepared and effects of Sb₂O₃ additives on its PTCR properties were investigated. The (Ba,Sr)TiO₃ with 0.05∼0.25 mol% Sb₂O₃ showed semiconducting PTCR behavior and anomalous grain growth was also observed when sintered at 1360 °C. It was considered that charge compensation by doping Sb₂O₃ as well as anomalous grain growth by sintering leads to resistivity reduction from insulating to semiconducting transition.     

Effect of partially oxidized Ti powders on the microstructure and PTCR characteristics of (Ba,Sr)TiO3

Rutile TiO₂ (a=4.594 å and c=2.958 å) phase was formed on the outer region of Ti powders after oxidation at 600 °C for 1–300 h. Porous (Ba,Sr)TiO₃ ceramics were fabricated by adding partially oxidized Ti powders (4–8 vol %) into (Ba,Sr)TiO₃ powders, and showed excellent positive temperature coefficient of resistivity (PTCR) characteristics after paste-baking treatment at 580 °C in air. The PTCR characteristics of the porous ceramics were mainly attributed to the adsorption of oxygen at the grain boundaries. The microstructure and electrical properties of the porous (Ba,Sr)TiO₃ ceramics containing the partially oxidized Ti powders oxidized at 600 °C for different oxidation times (1–300 h) were investigated.     

不同掺杂对Yb半导的（Ba,Sr）TiO3系PTCR材料性能的影响

研究了不同掺杂方式对ＰＴＣＲ材料电学性能的影响,结果表明,Ｙｂ一次掺杂ＢａＴｉＯ３电阻变化“Ｕ”型曲线,低阻区为０．１ｍｏｌ％～０．３ｍｏｌ％,其移峰效率为３～５℃／ｍｏｌ。二次单一掺杂Ｙｂ提高电阻率,降低对升阻比,二次单一掺杂Ｍｎ提高电阻率与升阻经,二次Ｙｂ,Ｍｎ共掺杂可降低电阻率,提高升阻比,并探讨了二者配合作用的机理,Ｙｂ：Ｍｎ＝１：１效果最佳。     

Mn掺杂BaTiO3基PTCR陶瓷相变的EPR研究

为了探索利用EPR谱线对PTCR陶瓷相变及PTC效应的机制研究的可能性,本文对掺Mn的BaTiO3基正温度系数热敏电阻（简称PTCR）陶瓷在120-450K温度范围内的电子顺磁共振谱进行了研究。得于了Mn^2 离子EPR信号强度、g因子值和超精细耦合常数|A|值的温度分布,发现EPR参数与PTCR陶瓷相变有明显的对应关系,并给出微观结构上的初步解释。研究表明EPR谱线以及精细结构的分析可以为PTCR陶瓷的相变机制以及上的初步解释。研究表明EPR谱线以及精细结构的分析可以为PTCR陶瓷的相变机制以及PTC效应的机制研究提供新的途径。     

La2O3、Y2O3掺杂对(Na0.5Bi0.5)0.94Ba0.06TiO3无铅压电陶瓷性能的影响

以(Na0.5Bi0.5)0.94Ba0.06TiO3为基体,研究了单、双组分掺杂La2O3、Y2O3对BNBT6陶瓷的压电和介电性能及微观结构的影响。XRD分析表明:掺杂La2O3、Y2O3均得到钙钛矿结构。SEM分析表明,分别掺杂0.2%La2O3和0.2%Y2O3使得陶瓷晶粒增大,压电常数提高,双组分掺杂La2O3、Y2O3在掺杂量0.12%La2O3+0.08%Y2O3时,压电常数d33增大到最大值144.6×10-12C/N,介质损耗降低到最小值0.039。     

高容量SiO2掺杂的（Ba,Pb）TiO3基高居里温度PTCR陶瓷

在制备高质量的（Ｂａ，Ｐｂ）ＴｉＯ＿３基高居里温度ＰＴＣＲ陶瓷时，一般采用铅气氛烧结方法。但是，这种烧结工艺制成的产品的相对成本是高的。作者的实验表明，高容量ＳｉＯ＿２掺杂烧结方法也可以用于制备高质量的（Ｂａ，Ｐｂ）ＴｉＯ＿３基高居里温度ＰＴＣＲ陶瓷。本文主要报道高容量ＳｉＯ＿２对（Ｂａ，Ｐｂ）ＴｉＯ＿３基高居里温度ＰＴＣＲ陶瓷烧结工艺和电特性的影响。     

Y2O3掺杂(Bi0.5 Na0.5)0.94 Ba0.06 TiO3无铅压电陶瓷的研究

采用固相合成法制备了Y2O3掺杂(Bi0.5 Na0.5)0.94 Ba0.06 TiO3无铅压电陶瓷.研究了Y2O3掺杂对(Bi0.5 Na0.5)0.94Ba0.06 TiO3陶瓷晶体结构、介电与压电性能的影响.XRD分析表明,在所研究的组成范围内陶瓷均能够形成纯钙钛矿固溶体.介电常数-温度曲线显示陶瓷具有弛豫铁电体特征,陶瓷的弛豫特征随掺杂的增加更为明显.在Y2O3掺杂量为0.5%时陶瓷的压电常数d33分别为137 pC/N,为所研究组成中的最大值,掺杂量为0.1%时,机电耦合系数kp与kt最大值为0.30,0.47.     

Y半导（Ba,Sr）TiO3系PTCR陶瓷Nb,Mn二次掺杂效果

研究了Ｙ半导（Ｂａ，Ｓｒ）ＴｉＯ２）系ＰＴＣＲ陶瓷Ｎｂ，Ｍｎ二次掺杂的电学性能及显微结构。探讨了施主与受主的掺杂效果。     

(Sr,Ca)TiO3陶瓷材料的结构与介电性能

研究(Sr,Ca)TiO₃系统陶瓷材料的组成、结构与介电性能关系.当ST/CT比值约为7:3时,主晶相(Sr_0.7Ca_0.3)TiO₃形成完全互溶钙钛矿型固溶体,具有立方顺电相结构;系统中微量钨青铜型新化合物铌酸钛钡BTN对主晶相(Sr_0.7Ca_0.3)TiO₃的介电性能起进一步的改善作用.获得具有理想介电性能(ε_(20℃1MHZ)>250,α_{c(-55～+125℃)}=-1150ppm/℃,tgδ_(20℃1MHZ)<5×10^-4,ρ_{v(20℃100VDC)}>10¹³Ω·cm)、不含Pb、Bi的Q组MLC瓷料.     

无铅Ba(Ce,Ti)O_3陶瓷的电卡效应

本文使用标准固相烧结法制备了Ba(Ti_(1-x)Ce_x)O_3(x=0.10,0.15,0.20)陶瓷,通过XRD分析发现这些陶瓷中除了Ba(Ti_(1-x)Ce_x)O_3主相外,还存在少量的杂相。利用Rietveld拟合的方法,获得了Ba(Ti_(1-x)Ce_x)O_3主相中的Ce/Ti实际比例。介电温谱表明这些陶瓷均存在一个明显的介电峰,且随着x的增加,峰值温度下降,介电峰宽展宽。利用不同温度下的电滞迴线,给出了不同温度和电场强度下的极化值,通过间接法获得了这些陶瓷的电卡效应。结果表明,BaTi_(0.9)Ce_(0.1)O_3的电卡效应最强,其DT值在403K和40kV/cm的电场下达到最大值,为0.48K,电卡强度为0.12×10~(-6)K·m/V。     

放电等离子烧结与传统烧结法制备（Ba，Sr）TiO3陶瓷的性能比较

研究分别采用了放电等离子烧结方法(Spark Plasma Sintering,SPS)和普通烧结方法,对(Ba,Sr)TiO3陶瓷进行不同温度下的烧结(1200～1300℃),进而研究了放电等离子烧结对(Ba,Sr)TiO3陶瓷性质的改良能力.实验表明,同温度下SPS法烧结的(Ba,Sr)TiO3陶瓷具有更大的相对介电常数,更低的电流损耗.同时,从SEM照片中观测到SPS烧结法可以较好的改进陶瓷的表面致密度.另外,1240℃下用SPS方法烧结的(Ba,Sr)TiO3陶瓷有着最优良的性质.     

Ba(Ti0.96Sn0.04)O3陶瓷的物性研究

采用传统固相反应法制备了Ba(Ti_0.96Sn_0.04)O₃无铅压电陶瓷, 对其压电性能、介电性能、铁电性能和微观结构等进行了研究。研究发现, 原料以及制备工艺对Ba(Ti_0.96Sn_0.04)O₃陶瓷的压电性质具有较大的影响。与BaTiO₃陶瓷相比, Ba(Ti_0.96Sn_0.04)O₃陶瓷的正交-四方相变温度T_O-T得到了一定的提高, 并且T_O-T附近的热滞只有1.8℃。陶瓷的微观形貌呈现出较为复杂的畴结构, 主要以90°平行带状畴为主, 偶尔有少量不同构型的180°畴。电滞回线呈现为理想的近似矩形饱和形状的曲线, 剩余极化强度P_r为18.9 μC/cm², 矫顽场E_c为 2.5 kV/cm。此外, 非180°畴的翻转是引起陶瓷逆压电常数d₃₃^*的主要因素, 其值可达550 pm/V。     

Ba0.04Bi0.48Na0.48TiO3-SrTiO3陶瓷微结构和储能性能

采用传统固相反应法制备了一种无铅储能铁电陶瓷(1-x)Ba0.04Bi0.48Na0.48TiO3-xSrTiO3 (x=0.27、0.28、0.30、0.32、0.34、0.36),研究了该陶瓷体系的微观结构、铁电、介电和电导率特征.所有陶瓷均形成了钙钛矿结构固溶体,晶粒尺寸均匀且致密.各陶瓷所得铁电曲线趋于双电滞回线,呈现反铁电特征,剩余极化强度较小,击穿强度高.当x=0.34时,可获得0.977J/cm3的较优储能值,陶瓷弥散程度高,表现为典型的弛豫特性.此含量对应低频下陶瓷的离子电导率为2.4×10-8 S/cm,电子电导率为6.02×10-13 S/cm,表明离子电导居于主导地位.     

掺锰PMW-PT陶瓷的制备及其介电性能研究

采用半化学法制备了掺锰的0.5Pb(Mg1/2W1/2)O3-0.5PbTiO3(PMW-PT)陶瓷.掺锰PMW-PT反应前驱体是以醋酸镁和硝酸锰分别代替传统化物法中的MgO和MnO2制得的.通过XRD和SEM对掺锰PMW-PT陶瓷样品进行了表征,并测试了陶瓷的介电性能.主要讨论了烧结温度和掺锰对PMW-PT陶瓷介电性能的影响.研究结果表明:半化学法能够制得掺锰均匀且为纯钙钛矿相的PMW-PT陶瓷,掺锰抑制陶瓷的晶粒长大,从而提高了PMW-PT陶瓷的烧结温度;掺锰明显降低了陶瓷的介电损耗,同时提高了陶瓷的介电常数,但随掺锰量的增加,陶瓷的介电常数减小.PMW-PT陶瓷的合适掺锰量为0.25mol%,烧结条件为1050℃/2h,最大介电常数为9230,介电损耗低于0.04.