排序方式: 共有46条查询结果,搜索用时 15 毫秒
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Ba0.6Sr0.4TiO3 thin films were deposited on Pt/SiO2/Si substrate by radio frequency magnetron sputtering. High-resolution transmission electron microscopy (HRTEM) observation shows that there is a transition layer at BST/Pt interface, and the layer is about 7-8 nm thickness. It is found that the transition layer was diminished to about 2-3 nm thickness by reducing the initial RF sputtering power. X-ray photoelectron spectroscopy (XPS) depth profiles show that high Ti atomic concentration results in a thick interfacial transition layer. Moreover, the symmetry ν of ?r-V curve of BST thin film is enhanced from 52.37 to 95.98%. Meanwhile, the tunability, difference of negative and positive remanent polarization (Pr), and that of coercive field (EC) are remarkably improved. 相似文献
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B4C作碳源高压合成金刚石的EPR谱特性 总被引:2,自引:2,他引:0
与传统用石墨作碳源不同,首次用B4C作碳源,在高温高压与过渡金属合金触媒作用下,合成出高含硼黑色金刚石。这种金刚石的EPR谱不再具有由孤立替位氮引起的三共振峰,而是一条线宽为7×10-4特斯拉、g=2.0023、浓度约为2×1018自旋数/厘米3的罗伦兹型单峰。分析表明:这可能是金刚石中硼杂质引起的受主中心,抵消了氮原子的未偶电子顺磁性后,所产生的共振现象。由于B4C分离出碳原子少,金刚石生长速度较慢,金刚石中铁磁杂质含量低,因此,它们引起的共振现象不明显。 相似文献
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以高活性的2-甲氧/乙氧羰基-4-(4-氟苯基)-1,5-苯并硫氮杂A和B为模型化合物,设计合成了11个含氟杂衍生物3a~3k,考察了它们对白色念珠菌和新生隐球菌的抑菌活性.研究结果表明,2-甲氧/乙氧羰基-4-(2-氟苯基)/(3-氟苯基)/(2,4-二氟苯基)-1,5-苯并硫氮杂3a,3b,3d~3f对新生隐球菌有很强的抑菌活性,3c的活性中等,而7位氯代杂3g~3k基本无活性;上述杂对白色念珠菌均无活性.在此基础上,进一步测试了高活性杂3a,3b,3d~3f对新生隐球菌的抑菌浓度梯度、最小抑菌浓度(MIC)和最小杀菌浓度(MFC),发现其MIC和MFC均远低于对照药氟康唑.为了考察杂3a~3f的药效基团,又设计合成了4类杂衍生物4a~4f,5a~5f,6a~6f和7a~7c,通过对其抑菌活性的评价,发现分子中2-甲氧/乙氧羰基和亚胺官能团对杂3a~3f的抑真菌(新生隐球菌)活性起关键作用,硫原子被氧原子或氮原子代替后原杂的活性降低. 相似文献
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