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反相微乳液法合成碘化铅纳米棒 总被引:1,自引:0,他引:1
用Pb(NO3)2和KI为反应物, 在水溶液/Triton X-100/正己醇/环己烷反相微乳液体系中制得了碘化铅纳米棒. 研究了ω0(水与表面活性剂的摩尔比)、反应物浓度、反应温度及陈化时间等因素对产物尺寸和形貌的影响, 并用TEM和XRD等技术对产品进行了表征. 相似文献
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Ho and Ti co-doped BiFe03 multiferroic ceramics with enhanced magnetization and ultrahigh electrical resistivity 下载免费PDF全文
Bio.9HOo.lFeo.9503 and Bio.9HOo.lFeo.9Tio.0503 ceramics were prepared and compared to reveal the effects of Ho and Ti codoping in BiFeO3. X-ray diffraction indicated that both ceramics had a high rhombohedral perovskite phase content, and microstructural analyses showed that the grains of the Bio.9HOo.lFeo.9Tio.0503 ceramics were much smaller than those of Bio.9HOo.lFeo.9503. An electrical resistivity of more than 1 × 1014.cm at room temperature, and a magnetic hysteresis loop with a remnant magnetization 2Mr of 0.485 emu/g were obtained for Bi0.9HO0.1Fe0.9Ti0.0503; both were much higher than those of Bio.9Hoo.1Feo.9503. Changes in the defect subsystem of BiFeO3 induced by Fe-deficiency and (Ho,Ti) codoping are proposed as being responsible for the improvement in the properties. 相似文献
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Ho and Ti co-doped BiFeO_3 multiferroic ceramics with enhanced magnetization and ultrahigh electrical resistivity 下载免费PDF全文
Bi0.9Ho0.1Fe0.95O3 and Bi0.9Ho0.1Fe0.9Ti0.05O3 ceramics were prepared and compared to reveal the effects of Ho and Ti codoping in BiFeO3. X-ray diffraction indicated that both ceramics had a high rhombohedral perovskite phase content, and microstructural analyses showed that the grains of the Bi0.9Ho0.1Fe0.9Ti0.05O3 ceramics were much smaller than those of Bi0.9Ho0.1Fe0.95O3. An electrical resistivity of more than 1 × 1014?·cm at room temperature, and a magnetic hysteresis loop with a remnant magnetization 2Mr of ~ 0.485 emu/g were obtained for Bi0.9Ho0.1Fe0.9Ti0.05O3; both were much higher than those of Bi0.9Ho0.1Fe0.95O3. Changes in the defect subsystem of BiFeO3 induced by Fe-deficiency and(Ho,Ti) codoping are proposed as being responsible for the improvement in the properties. 相似文献
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在氢氧化钡和氢氧化锶水溶液/Triton X-100/环己烷/正己醇四元W/O型反相微乳液中制备了钛酸锶钡纳米棒, 研究了ω0值(水与表面活性剂Triton X-100的物质的量之比)、反应物浓度、陈化时间对产品形貌和尺寸的影响, 用TEM, SAED, SEM, EDS和XRD等技术对产品进行了表征. 结果表明, 所得Ba0.7Sr0.3TiO3纳米棒长约500~1200 nm、直径约为50~120 nm; 具有立方相单晶结构. 产品中钡、锶、钛的物质的量之比约为0.7∶0.3∶1. 相似文献
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Water-Induced Degradation in Lead Zinc Niobate-Lead Zirconate Titanate Soft Piezoelectric Ceramics 下载免费PDF全文
Water-induced degradation of lead zinc niobate-lead zirconate titanate (Pb(Zn1/3Nb2/3)O3-Pb(ZrTi)O3) soft piezoelectric ceramics is studied using electrochemical hydrogen charging, in which the silver electrodes of the piezoelectric ceramics constitute a cathode in 0.01-M NaOH solution to evolve hydrogen by electrolysis of water.It is found that with the increasing hydrogen charging time, the resonance impedance increases, the difference between the resonance frequency and the anti-resonance frequency decreases, the spontaneous polarization, the remanent polarization and the piezoelectric coefficient d33 decrease. The degradation behaviour of the soft piezoelectric ceramics can be explained to hydrogen incorporating into the lattice and forming hydroxy (OH^-) bonds in the perovskite structure, which prevents the Ti ions from switching and increases the coercive field Ec.The degradation characteristics of the soft piezoelectric ceramics are quite different from that of lead zirconate titanate hard piezoelectric ceramics. 相似文献
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随着新课改的不断深入,“知识与技能、过程与方法、情感态度和价值观”三维一体的教学目标已被广大中学物理教师熟悉和接受.但是,由于在长期的传统教学过程中大部分中学物理教师已经习惯于“知识本位”的教学目标,当面对新课改所提倡的这样一个“学生本位”的教学目标时,他们感到困惑和茫然,不知道到底该如何教了.于是在教学中就出现了两种极端现象:一种是教师不求甚解、流于形式地去追求新课改提倡的教学目标,以迎合新课改;一种是教师干脆放弃新课改提倡的教学目标回到传统教学目标上去,以抵制新课改.这两种现象也是新课改面临的两个新问题.这两个问题无论哪个解决不好都会影响新课改的顺利进行,甚至会导致新课改的最终失败. 相似文献
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采用溶胶-凝胶法和浸渍法制备了Li+掺杂纳米TiO2光催化剂,并用XRD和TEM等技术进行了表征;用pH值漂移法测量了催化剂的零电位pH值(pHpzc).结果表明,500℃煅烧制得的催化剂均为锐钛矿相;Li+的掺杂抑制了TiO2粒子的生长,提高了催化剂的分散性;催化剂的零电位pH值为6.6—8.1,其值取决于Li+的浓度和掺杂方式.分别以紫外光和太阳光为光源,孔雀石绿和甲基橙为降解物评价了催化剂的光催化活性;并用气相色谱测试了污染物降解产生的CO2的含量.结果显示,对孔雀石绿的降解,浸渍法和溶胶-凝胶法掺Li+都能有效提高TiO2的光催化活性,但浸渍法比溶胶-凝胶法效果更好,催化活性最高的为浸渍法制备的5%(摩尔分数)Li+掺杂TiO2,其在紫外光和太阳光下的光催化活性分别比纯TiO2提高了6—8倍和9—10倍;对甲基橙的降解,除溶胶-凝胶法制备的3%(摩尔分数)Li+掺杂TiO2能稍提高光催化活性外,其它Li+的掺杂都不同程度降低了TiO2的光催化活性;随污染物降解率的增加,最终降解产物CO2的含量增加.实验结果表明,Li+掺杂改变了催化剂表面的电荷状态从而改变了催化剂的零电位pH值是造成催化剂降解不同污染物具有不同催化活性的主要原因. 相似文献
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材料化学是材料学与化学等学科交叉、渗透下产生的一门新兴交叉学科,其学科内容还没有得到一致的认同,对应材料化学课程的内容往往与材料化学专业开设的其他课程内容出现重叠.本文通过对材料化学专业要求、核心知识领域以及材料化学学科概念的分析,对材料化学课程内容和材料化学专业课程体系的设置作了初步的探讨. 相似文献