Sr掺杂BNT-BT压电陶瓷结构与性能研究

采用传统的电子陶瓷制备工艺制备了一系列0.93Bi0.5Na0.5TiO3-0.07(Ba1-xSrx)TiO3(简写为BNBST100x;x=0.02,0.04,0.06,0.08,0.10)陶瓷,研究了陶瓷的结构、介电、压电性能变化特征.XRD分析表明,陶瓷样品均形成了单一的钙钛矿结构固溶体.陶瓷的介电、压电性能受Sr含量的影响显著.所有陶瓷样品表现出弥散相变特征.BNBST陶瓷的压电常数随着Sr含量的增加表现出先增大后减少的趋势.同时,当Sr含量为4 mol%时,压电常数(d33达到最大,分别为139.8 pC/N.     

Ca含量对(Ba1-xCax)(Ti0.9Zr0.1)O3无铅压电陶瓷性能的影响

采用传统的固相法制备(Ba1-xCax)(Ti0.9Zr0.1)O3(简称BCTZ)无铅压电陶瓷.借助扫描电镜(SEM)和X射线衍射仪(XRD)等测试方法研究了Ca含量对所制备BCTZ无铅压电陶瓷显微结构和压电介电性能的影响.结果表明:随着Ca含量的增加,(Ba1-xCax)(Ti0.9Zr0.1)O3无铅压电陶瓷的晶粒尺寸先增大后减小,所制备的BCTZ陶瓷的物相都是钙钛矿结构,没有杂相;随着Ca含量的增加,BCTZ陶瓷压电常数(d33),介电常数(εr),机电耦合系数(kp)分别先增加后降低,而介质损耗(tanδ)先减小后增大.当Ca含量(x)为0.15mol时,在1450℃烧结制得的(Ba1-xCax)(Ti0.9Zr0.1)O3无铅压电陶瓷性能最佳:压电常数(d33)为363pC/N,机电耦合系数(kp)为39.63％,介电常数(εr)为4184,介质损耗(tanδ)为1.08％.     

锰掺杂无铅压电陶瓷(Bi_(0.5)Na_(0.5))_0.9Ba_(0.07)Sr_(0.03)TiO_3的结构和电学性能(英文)

采用传统陶瓷工艺制备掺MnO2的(Bi0.5Na0.5)0.9Ba0.07Sr0.03TiO3(BNBST)无铅压电陶瓷。锰掺杂(MnO2摩尔掺量x=0～1.25%)可以提高陶瓷的烧结性能,在1150℃烧结,可以得到致密陶瓷和纯的钙钛矿相。X射线衍射显示:室温、0.20x0.75时,形成四方相与三方相共存的准同型相界(morphotropic phase boundary,MPB),且x=0.25时,锰掺杂的BNBST陶瓷表现出优良的性能,其中压电常数d33=157pC/N,平面机电耦合系数kp=33%,机械品质因数Qm=364,相对介电常数εr=843,介电损耗tanδ=2%。这些结果确认了MPB组成与x之间的相互关系,并为设计新型压电材料提供方法。     

La置换Pb对Sb掺杂PZT压电陶瓷介电和压电性能的影响

研究了Pb1–xLax(Zr1–yTiy)1–x/4O3+1.5%(质量分数)Sb2O5陶瓷(PLSZT)的介电、压电性能及其微观结构,获得了高压电性能、小晶粒尺寸的压电陶瓷材料。结果显示:x≤5%时,晶体结构为纯钙钛矿相;x>5%时,为钙钛矿和焦绿石两相混和物。随着x的增大,介电常数和压电常数均呈现先增大后减小的趋势。介电常数在x=6%、y=0.45时最大,最大介电常数εmax≈3900,介电损耗tgδ≈1.8%;压电性能在x=4%、y=0.45时最强,压电应变常数d33≈600pC/N,径向机电耦合系数kp≈0.7,厚度机电耦合系数kt≈0.51,此时的平均晶粒尺寸约为2μm。     

Sr、Mn离子掺杂PMS-PZT压电陶瓷相组成与性能研究

针对聚焦超声换能器用压电陶瓷,采用传统的固相法制备Pb1.04(Mn1/3 Sb2/3)0.05 Zr0.47 Ti0.48 O3+x％SrCO3+y％MnO2(x+y=0.3)(PMS-PZT)三元系压电陶瓷.使用正交实验分析方法研究添加不同比例的Sr、Mn离子后PMS-PZT压电陶瓷电学性能的变化.讨论了在准同型相界(MPB)随着掺杂元素相对含量的改变对压电陶瓷的相对介电常数εr、机电耦合系数kp、机械品质因数Qm和压电常数d33的影响.通过研究发现:在900℃煅烧,1180℃烧结保温2 h,当x=0.15时,三方相和四方相共存且三方度最大,得到综合性能优良的压电陶瓷材料:密度 ρ=7.84 g/cm3、压电常数d33=336 pC/N、机械品质因数Qm=1889、机电耦合系数kp=0.63、相对介电常数εr=1479,采用此工艺制备的压电陶瓷完全满足高强度超声换能器用的压电材料.     

Li含量对KNNLTSBZ无铅压电陶瓷性能的影响

采用传统固相法制备了(K0.49Na0.51)1-x Lix(Nb0.77Ta0.18Sb0.05)O3-0.005BaZrO3(x=0.02~0.06,KNNLTSBZx)无铅压电陶瓷。用X射线衍射、扫描电子显微镜及精密阻抗分析仪分析了Li含量(x)对样品的晶相组成、显微结构、压电及介电性能的影响。发现:所研究的组成范围内,陶瓷样品均具有纯的钙钛矿晶体结构;随着Li含量(x)的增加,室温样品的晶体结构由正交相逐渐向四方相转变,Curie温度(TC)向高温方向移动,而正交-四方相变温度(To-t)则向低温方向变化,且当x≥0.04时,To-t已经移到室温以下,0.04≤x≤0.06范围为陶瓷的正交-四方共存的多型相转变组成,当x=0.04时,陶瓷具有最佳的压电、介电性能:压电常数d33=240pC/N,平面机电耦合系数kp=44.7%,相对介电常数εT33/ε0=2 090,介电损耗tanδ=2.7%。     

高压电活性PNN–PZN–PBSZT陶瓷的结构及性能

采用铌铁矿预合成及固相法制备xPb(Ni_(1/3)Nb_(2/3))O_3–0.01Pb(Zn_(1/3)Nb_(2/3))O_3–(0.99–x)Pb_(0.82)Ba_(0.08)Sr_(0.10)Zr_(0.56)Ti_(0.44)O_3(x PNN–PZN–PBSZT)压电陶瓷。研究了不同铌酸镍NiNb_2O_6含量(x=0、0.01、0.015、0.02)对x PNN–PZN–PBSZT压电陶瓷的晶相结构以及压电和介电等性能的影响。结果表明:制备的压电陶瓷均为钙钛矿结构,处在准同型相界处,且随着x的增大,晶体结构逐渐向四方相转变。PNN的引入可以提高x PNN–PZN–PBSZT陶瓷的压电、机电和介电性能,当x=0.015时,样品的综合性能最佳,压电性能和室温介电性能达到最大,d33和εr分别达到998 pC/N和5 498,此时的机电转换因子k_p为74.61%,Curie温度TC为140℃,kp的最大值出现在x=0.02处,为76.26%。     

BNBMT无铅压电陶瓷的制备及性能研究

本文采用新型溶胶-凝胶制粉技术和传统陶瓷生产工艺制备了0.93Bi0.5Na0.5TiO3-0.07Ba1-xMgxTiO3（简称BNBMT100x）体系无铅压电陶瓷,并对BNBMT陶瓷的晶相特征及其介电和压电性能进行了讨论。XRD分析表明,陶瓷样品均形成了单一的钙钛矿结构固溶体;Mg的加入对陶瓷的介电、压电性能有显著影响;陶瓷的铁电-顺电相变峰显著降低、展宽;介电损耗在室温至200℃范围内较平缓。当x=0.04时,机电耦合系数kp和kt最大,分别为16%和19%,压电常数d33值为111pC/N。     

(K_(0.485)Na_(0.485)Li_(0.03))NbO_3-Pb(Zr_(0.53)Ti_(0.47))O_3压电陶瓷的压电性能与微观结构

采用传统电子陶瓷制备技术和工业原料制备了新型(1-x)(K0.485Na0.485>Li0.03)NbO3-Pb(Zr0.53Ti0.47)O3少铅压电陶瓷,研究了该体系陶瓷的压电性能及微观结构.X射线衍射分析表明:在1250℃烧结3h的条件下,所有陶瓷样品都具有纯的钙钛矿结构和高致密性,并且在室温下形成了正交相和四方相共存的结构.x=0.75时,陶瓷的压电性能达到最佳:压电常数d33=363 pC/N,机电耦合系数kp=63%,相对介电常数εr=1 590,介质损耗tanδ=1.70%.     

碱式碳酸钴掺杂量对BCZT无铅压电陶瓷性能和结构的影响

采用传统固相法制备了碱式碳酸钴掺杂不同量的Ba0.85Ca0.15Ti0.9Zr0.1O3(简称BCZT)系列无铅压电陶瓷,借助扫描电镜(SEM)和X射线衍射仪(XRD)等研究了不同碱式碳酸钴掺杂量(x=0,0.55,0.89,1.3,1.8 wt.％)对BCZT无铅压电陶瓷的物相组成、显微结构及压电性能和介电性能的影响.结果表明:碱式碳酸钴的加入并没有改变所制备陶瓷的相结构,仍为单一斜方相钙钛矿,当x=1.8wt.％时,出现杂相.随着碱式碳酸钴掺杂量(x)的增大,BCZT无铅压电陶瓷的压电系数(d33)、平面机电耦合系数(kp)先增大后减小,介质损耗(tan δ)先减小后增大,而相对介电常数(εr)一直增大.当碱式碳酸钴(x)为1.3wt.％时,BCZT无铅压电陶瓷的综合性能最佳:d33=135 pC/N,εr=3399,kp=0.38,tanδ =0.029.     

钛酸铋钠钾锂无铅陶瓷的柠檬酸制备技术

以钠、钾、锂的碳酸盐为原料，采用柠檬酸盐-凝胶法制备了Biol5（Na1-x-y，LixKy）0.5TiO3无铅压电陶瓷，研究了影响凝胶合成的各种工艺条件，利用TG-DTA，SEM，XRD，纳米粒度分析等技术分析了凝胶预烧温度及预烧粉体的粒度分布。研究结果表明：柠檬酸与金属离子的物质的量比、溶液浓度、pH是影响前驱液与凝胶形成的主要因素；用柠檬酸盐一凝胶法合成的Bi0.5（Na1-x-y，LixKy）TiO3粉体粒度细小均匀，合成温度低；陶瓷的压电常数d33可达138pC／N，其平面机电耦合系数kp为0．30。     

黏结剂对柴油车用V_2O_5-WO_3/TiO_2催化剂选择性催化还原性能的影响

采用偏NH_4VO_3和TiO_2为前驱体制备选择性催化还原(SCR)催化剂涂层所需浆料,将浆料浸涂在蜂窝陶瓷载体上,得到整体涂覆式SCR催化剂。研究了SiO_2溶胶、H_3PO_4及H_3NO_3对催化剂涂层耐久性及活性的影响。在模拟评价装置上对催化剂活性进行了评价。结果表明,SiO_2溶胶和H_3PO_4对催化剂涂层耐久性具有明显改善作用,质量分数8%的SiO_2溶胶和4%的H_3PO_4使催化剂涂层脱落率从32.71%降至4.08%和17.89%;V_2O_5-WO_3/TiO_2-4%SiO_2溶胶催化剂表现出较高的活性和选择性,新鲜催化剂NO的起燃温度(T_(50))为205℃,随着H_3PO_4添加量的增加,催化剂低温活性逐渐降低,高H_3PO_4添加量时,催化剂表面被H_3PO_4覆盖,大部分与钛及钒键连接的羟基基团被P—OH所取代,催化剂SCR活性降低。     

Critical review of the impact of tortuosity on diffusion

Most of the present formulations for the mass conservation of species do not correctly represent changes in the time scale of diffusion as a function of porosity in a system of porous media. In sediments, or in any porous system, the presence of solid particles causes the diffusion paths of species to deviate from straight lines. To represent the role of porosity on diffusion, the diffusion coefficient must be scaled with tortuosity. In this paper we present a review of the available formulations for the scaled diffusion coefficient with tortuosity, sensitivity tests with analytical solutions, and calibration of these formulations with respect to measured data.     

天然气基乙炔工艺 分析与改进

This article presents an acetylene production process by partial oxidation/combustion of natural gas. The thermodynamic performance and exergy analysis in the process are investigated using the flow-sheeting program Aspen Plus. The results indicate that the most important destruction of exergy is found to occur in the reactor and water quenching scrubber, amounting to 8.23% and 10.39%, respectively, of the entire system. Based on the results of thermodynamic and exergy analysis, the acetylene reactor has been retrofitted. The improvement ratios of molar 02 to CH4 and molar CO to CN4 are 0.65 and 0.20, respectively. An improvement of the acetylene production system is proposed. Adopting the improvement operation conditions and using oil to realize the reaction heat recovery, the feedstock of natural gas is reduced by 9.88% and the exergy loss in the retrofitting process is decreased by 19.71% compared to the original process.     

RK-05催化剂在新能凤凰公司的应用

介绍了RK-05催化剂在新能凤凰公司二期续建工程年产360kt甲醇装置中的应用情况,并针对存在的问题进行了改造,提高了合成气体中的氢含量,有利于保护催化剂,减少了副产物的生成,延长了催化剂的使用寿命。     

Effects of sintering temperature on properties of Na0·5K0·5NbO3-LiSbO3-BiFeO3 lead free ceramics

Abstract

Abstract

Lead free 0·95K_0·5Na_0·5NbO₃-0·05LiSbO₃ (KNN-LS) ceramics doped with 0·4?mol.-% BiFeO₃ (BF) have been prepared by the conventional mixed oxide method with sintering temperature at 1065-1135°C in this paper. The samples are characterised by X-ray diffraction analysis and scanning electron microscopy. The dielectric and piezoelectric properties are also investigated. The results present that initially the increase in the sintering temperature is very effective in improving the density and electric properties. However, the properties of the samples would be deteriorated as they are sintered over the optimum temperature. The KNN-LS (doped with 0·4%BF) ceramics shows excellent properties with sintering temperature at 1100°C.     

2-氰基丙烯酸酯类新化合物杀菌活性筛选研究

继2-氰基丙烯酸酯类杀菌剂氰烯菌酯(JS399-19)研发后,又发现该类化合物对小麦白粉病、小麦纹枯病具有高活性。新化合物JS399E12对小麦白粉病EC50值为1.3397mg/L,新化合物JS399F05在50mg/L的剂量下对小麦纹枯病的防效达90%以上。实验室条件下,JS399-19对小麦赤霉病高效,但对小麦白粉病和小麦纹枯病无效。本研究为该类化合物的研发提供了参考。     

QDB-05型CO耐硫变换催化剂在水煤浆气化制甲醇装置中的应用

总结了QDB-05型低水气比CO耐硫变换催化剂在水煤浆气化制甲醇装置中的工业应用情况。实际运行情况表明,该催化剂具有较高的变换活性和抗甲烷化副反应的性能,能适应较高一氧化碳含量、较高压力和低水气比的变换工况条件,无甲烷化副反应发生。     

油田本源微生物胞外聚合物产生菌AD-05发酵条件的实验室评估

对一株筛选自辽河油田油水样的生物聚合物产生菌AD-05进行了发酵条件的室内评估。结果表明:菌株AD-05为一株革兰氏阴性杆菌,菌落数、发酵液黏度及多糖产量具有很好的相关性。菌株在pH=8.0下,培养27 h,多糖产量达到25.2 mg·m L-1,黏度为59.96 m Pa·s;能够耐受8%NaCl。发酵产物胞外多糖在80℃下放置30 h黏度变化不明显。菌株AD-05的发酵特性为其应用于油藏出油率低、地层条件复杂的采油矿场提供了可能性。     

Effects of rapid thermal annealing treatment on 0·95(Na0·5Bi0·5)TiO3-0·05BaTiO3 thin films

Abstract

Abstract

A 0·95(Na_0·5Bi_0·5)TiO₃-0·05BaTiO₃+1?wt-%Bi₂O₃ (NBT-BT3) ceramic was used as target to deposit the NBT-BT3 thin films. The excess 1?wt-%Bi₂O₃ was used to compensate the vapourisation of Bi₂O₃ during the depositing processes. The optimal deposition parameters were substrate temperature of 500°C, radio frequency power of 100?W, chamber pressure of 10?mtorr and oxygen concentration of 40%. Rapid thermal annealing treated processes were carried out on NBT-BT3 thin films from 600 to 800°C in ambient or in oxygen atmosphere for 1?min. The surface morphologies and thicknesses of NBT-BT3 thin films were characterised by field emission scanning electron microscopy, and the thickness was ～216?nm. It would be shown that the NBT-BT3 thin films annealed in oxygen atmosphere had the smaller grain size, larger memory window, smaller leakage current density, larger remanent and saturation polarisation and smaller coercive field than the NBT-BT3 thin films annealed in ambient atmosphere.