PZT压电陶瓷液相低温烧结技术的研究进展

阐述了PZF压电陶瓷烧结过程中的液相传质机理及实现液相烧结的主要途径.综述了PZY压电陶瓷材料的液相低温烧结研究方向与进展.     

烧结助剂对氧化铝陶瓷低温烧结的影响

氧化铝(Al_2O_3)陶瓷烧结温度较高,通过添加烧结助剂可以实现Al_2O_3陶瓷的低温烧结。对比分析了不同含量的CuO-TiO_2和MnO_2-TiO_2-MgO复合烧结助剂在不同的烧结温度下对Al_2O_3烧结性能的影响,得到了烧结助剂含量和烧结温度对Al_2O_3陶瓷体积收缩率、体积密度以及内部显微结构的影响规律。实验分析表明,在1 350℃的烧结温度下,添加4%(质量分数) CuO-TiO_2和MnO_2-TiO_2-MgO的烧结助剂,Al_2O_3陶瓷分别能获得高达3. 67 g/mm~3和3. 76 g/mm~3的体积密度,并且在扫描电子显微镜下观察到良好的显微结构。     

水热法制备锆钛酸铅纳米粉体

以Ｐｂ（ＮＯ３）２、ＺｒＯＣｌ２．８Ｈ２Ｏ和Ｔｉ（ＯＣ４Ｈ９）４为前驱物,在温和水热条件下合成了制得了单一物相的压电陶瓷瓷锆钛酸铅纳米粉体。了前驱物配比、反应温度、反应时间和矿化剂浓度对合成粉体的影响。在Ｐｂ／（Ｚｒ＋Ｔｉ）＝１．７,Ｚｒ／Ｔｉ＝０．５２／０．４８,ＮａＯＨ的浓度为３ｍｏｌ／Ｌ,反应温度为２００℃,反应时间为２小时的条件下,得到了较好晶形的单一相的ＰＺＴ粉体。     

PZT/SiO2透明纳米复合材料的低温荧光特征

采用改进的溶胶－凝胶工艺制备了锆钛酸铅（Pb(Zr0.52Ti0.48)O3-PZT)/二氧化硅透明纳米复合材料。在740－800℃温度下热处理可得到PZT纳米微晶。X射线衍射分析表明，PZT为钙钛矿结构，而二氧化硅基体为非晶态。从10K至室温对样品进行了荧光分析，纯的二氧化硅基体在3.2eV处出现一较强的发光峰，在2.65eV处出现一较弱的发光峰。PZT微晶掺入后此两峰受到抑制，新的发光峰出现在2.3eV处，该峰随微晶尺寸的减小具有蓝移特征，表明铁电纳米粒子掺杂的纳米复合材料所产生的荧光峰强烈地依赖于微晶尺寸。     

分布式PZT片驱动性能的实验研究

通过将整块压电陶瓷PZT片分成小片用作驱动元件的实验，研究了PZT片大小对其驱动能力的影响，结果表明，减小PZT片的面积既能提高PZT的驱动能力，同时还能降低结构的破坏程度；另外，极化后的PZT片压电效应具有明显的非线性特性。     

水热条件下易烧结PZT粉体合成的影响

用水热法合成了低温烧结用ＰＸＴ「Ｐｂ（Ｚｒ０．５３ＴｉＯ０．４７）Ｏ３」粉体。探讨了水热条件下对合成粉体性能的影响。合成时添加了有助于烧结的Ｆｅ＾２＋,Ｂｉ＾３＋,Ｃｕ＾２＋等离子化合物,经Ｘ－ｒａｙ,ＳＥＭ,ＴＧ－ＤＴＡ及比表面积的测定。表明：当反应介质为４ｍｏｌ／Ｌ ＮａＯＨ,时间２ｈ,反应温度２００℃时合成后的粉体有良好的烧结性,。粉体中外加了微量ＢＣＷ「Ｂａ（ＣＸｕ０．５Ｗ０．５）Ｏ３」,     

先驱体法生成PZT固溶体反应机理的研究

借助X光衍射的方法研究了反应煅烧法生成PZT固溶体的反应机理。研究表明，Zr0.5Ti0.5O2与PbO反应过程中没有中间相的生成，反应的快慢由Pb^2 在生成PZT中扩散的快慢控制，反应过程中生成的钙钛矿PZT的A位是Pb缺位。     

水热条件对易烧结PZT粉体合成的影响

用水热法合成了低温烧结用PZT[Pb(Zr0 .5 3 TiO0 .47)O3]粉体。探讨了水热条件对合成粉体性能的影响。合成时添加了有助于烧结的Fe2 + ,Bi3 + ,Cu2 + 等离子化合物 ,经X ray,SEM ,TG DTA及比表面积的测定 ,表明 :当反应介质为 4mol/LNaOH ,时间 2h ,反应温度 2 0 0℃时合成后的粉体有良好的烧结性。粉体中外加了微量BCW[Ba(Cu0 .5 W0 .5 )O3] ,使PZT陶瓷在 850℃温度下即可烧成 ,密度可达理论值 98%。     

PZT及掺La^3＋,Nb^5＋PZT的性能初探和态密度计算

用固相化学反应陶瓷烧结法制备了ＰＺＴ及掺Ｌａ＾３＋，Ｎｂ＾５＋的ＰＺＴ压电陶瓷片，利用ＸＲＤ，ＸＰＳ现代测试手段分析了样品的结构和性能，并测试了其压电性能，从理论上阐述了掺杂Ｌａ＾３＋，Ｎｂ＾５＋离子对ＰＺＴ样品的性能影响，用量子化学计算方法计算了样品的电子态密度，并将计算结果与ＸＰＳ测试结果作比较。     

Synthesis of PZT power by wet-dry method and its structure

To prepare PZT powder at lower temperature, lead zirconate titanate (PZT) powder (x(Zr)/x(Ti)=56?44) was prepared by wet-dry method. Glycol was used as the solvent, and zirconium oxychloride was used as zirconium source. The properties and structure of the powder were analyzed by XRD, SEM and Sedimentograph. The effects of sintering parameter such as sintering temperature, keeping time and heating-up velocity on structure of PZT power were investigated. The results show that homogeneous PZT with single-phase perovskite structure can be obtained after sintering at 730 ℃ for 2 h, and the average size of PZT powder is about 113 nm.     

烧结Al2O3陶瓷在海水中的耐腐蚀性能研究

通过对SEM、孔径分布、孔隙率、弯曲强度等多项性能的测试,研究了由两性氧化物氧化铝烧结而成的陶瓷材料在海水中腐蚀的可能性. 研究结果表明,烧结氧化铝陶瓷在海水中浸泡一年后未发生腐蚀反应.     

烧结温度对BaTiO3多孔陶瓷性能的影响

采用水基冷冻浇注法制备了具有层状结构的BaTiO3多孔陶瓷,研究了烧结温度对多孔陶瓷微观形貌、收缩率、孔隙率及介电性能的影响,并探讨了高岭土悬浮剂在烧结过程中所起的作用.研究结果表明:高岭土含量4wt%的样品收缩率从1 200℃时的27%升高到1 220℃时的56%,同时孔隙率从78%下降到56%,高岭土含量8wt%的样品收缩率从1 200℃时的30%升高到1 220℃时的61%,同时孔隙率从72%下降到39%;高岭土在烧结过程中起到烧结助剂的作用;烧结温度升高会使孔径变小并导致孔隙排列由有序结构向无序结构转变.高岭土含量为8wt%,烧结温度1 200℃时,可以得到分布均匀的层状结构多孔陶瓷;高岭土含量为4wt%,烧结温度1 220℃时可得到介电常数130的多孔陶瓷.     

Effects of sintering additives on preparation of CaF2 transparent ceramics

The effects of different sintering addictives on the preparation of CaF2 transparent ceramics were studied. Transparent CaF2 ceramics were fabricated by vacuum sintering and hot isostatic pressing (HIP) method, using CaF2 nanopowders synthesized by chemical precipitation method as raw materials. The nanopowders and transparent ceramics were studied using X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and spectrophotometer. The experimental results indicated that the obtained nanopowders presented normal distribution with grain size about 30 nm; transmittance of CaF2 transparent ceramics was 39% and 26% at 1100 nm for LiF and NaF as sintering addictives, respectively, with corresponding mean grain size 188 μm and 44 μm. Loss of transmission could be attributed to the residual closed porosity. Sintering mechanism was liquid-phase sintering at pre-stage, then solid-phase sintering at later stage, as well as solid solution of lithium ions and sodium ions in the CaF2 lattice structure.     

(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.     

（Ba，Eu）Ti03细晶粒陶瓷制备中的影响因素

采用冷压陶瓷技术,分别在1400℃和1300℃制备了具有四方结构的（Ba1-xEu）TiO3和（Ba1-xEu）Ti1-x／80,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、n空位缺陷和陶瓷化烧结温度的变化对制备（Ba,Eu）TiO,细晶粒陶瓷的影响因素．结果表明：当z=0．05时,1300＇1：制备的（Ba1-xEu）Ti,-x／80,陶瓷细化到平均晶粒尺寸小于1μm,1400℃制备的（BahEu,）Ti03陶瓷却畸变生长到5斗m．而x=0．03时,（Ba1-xEu）TiO,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,（Ba1-xEu）TiO,陶瓷为大于5斗m的粗晶粒陶瓷,说明Eu含量的继续增加不能抑制晶粒生长．     

Spark plasma sintering of undoped SnO<Subscript>2</Subscript> ceramics

Various parameters in spark plasma sintering(SPS),such as sintering temperature,holding time,heating rate,and pressure,were adopted to investigate their effects on the densification of pure SnO2 power.The obtained experimental data show that the SPS process enhances densification.The high-density undoped SnO2 ceramics (96.6% of theoretical) was obtained at much lower temperature (1000℃),within a much shorter time,compared to the conventional sintering process.The high-density undoped SnO2 ceramics (96.6% of theoretical) were obtained by SPS,under the condition of temperature:1000℃,pressure:40MPa,heating-rate:200℃/min,and holding time:3min     

Fe离子注入Al_2O_3陶瓷改变其表面电阻率的研究

本文研究了Fe离子注入Al_2O_3陶瓷的注入射程、纵向浓度分布和注入层结构,测定了注入层中的载流子浓度和迁移率,讨论了Al_2O_3陶瓷注入Fe离子其表面层的导电机理。其结论是:注入的Fe~(2-)离子进入Al_2O_3晶格,替代了Al~(3-)离子形成替位杂质。这样注入离子与原有晶格比较呈现一个有效负电荷,形成负电中心。它可以把一个空穴束缚在它的周围,在禁带引入受主能级。     

Effect of nucleating agent on the crystallization of tailings glass ceramics prepared by one-time sintering

Glass ceramics was made by the one-time sintering method using the main raw material of iron tailings. On the basis of quaternary system of CaO-MgO-Al₂O₃-SiO₂, using DTA, XRD and SEM, the effects of different nucleating agents and mixing amounts as well as heat treatment on the crystallization of tailings glass ceramics were studied. The experimental results show that, nucleating agent and heat treatment are two necessary conditions for one-time sintering preparation of tailings glass ceramics namely, only adding nucleating agent or experiencing heat treatment, the quaternary system can not crystallize. The composite nucleating agent consisting of Cr₂O₃ and TiO₂ can further lead to the crystallization of the CaO-MgO-Al₂O₃-SiO₂ quaternary system at the lower temperature, with the major phase of diopside. In the range of mass content, 0%–4%, crystal intensity and crystal content grow. But when mass content is more than 4%, the crystal size will become coarser and the crystal distribution will be less regular. Different heat treatment regimes do not change the composition of the crystalline major phase in the glass ceramics crystallization of CaO-MgO-Al₂O₃-SiO₂ system. In the range of 30–60 minutes, with the extension of nucleation and crystallization, crystallization degree enhanced, but if the holding time surpasses 60 minutes, the crystallization is worse. Funded by The National Key Technology R & D Program of China for the 11^th Five-Year Plan(2006BAJ04A04)     

Effect of Cu~(2+) concentration on hydrogen fermentation

0　INTRODUCTIONHydrogenisconsideredtobeanidealsourceofener gyforthefuturebecauseitiseasilyconvertedtoelectricityandiscleanlycombustible .Whetherfromeconomicoren vironmentalstandpoints ,biologicalhydrogenproductionwasmostpromising .Biologicalhydrogenproductionhasbeenwidelyin vestigated .Microorganismsforhydrogenproductioncanbedividedintotwogroups :photosyntheticanaerobicbacteriaandanaerobicfermentativebacteria[1] .Thelatterdiges tiononlyrequiresalowenergyanddoesnotrequirephotoenergy .Ther…