Oxidative coupling of methane(OCM) was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values(X = 6–10). The aim is to investigate the effect of p H...Oxidative coupling of methane(OCM) was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values(X = 6–10). The aim is to investigate the effect of p H values on the catalytic activity of La AlO3 catalysts in this reaction. The results showed that the co-precipitation pH value affected greatly on the formation of chemical species of precipitate precursors in the co-precipitation step, leading to different phases of the finally obtained LaAlO3 catalysts.When the co-precipitation pH value increased up to 8, the lanthanum-related phases such as La2 O3 and La(OH)3 were gradually formed as by-products, preventing the formation of LaAlO3 perovskite crystalline structure and facilitating the formation of oxygen vacancies on catalyst surface. However, at pH value of9 or higher, the lanthanum content in the precipitate precursor was increased greatly. Not LaAlO3 perovskite but lanthanum-related phases were developed as main phases, reducing their catalytic activities in this reaction. Among LaAlO3 catalysts, the one prepared at pH = 8 showed the highest C2 yield due to its well-developed oxygen vacancies and electrophilic lattice oxygen. Therefore, the co-precipitation pH value strongly affected the LaAlO3 catalyst activity in OCM reaction. A precious pH control should be required to prepare various perovskite catalysts for the OCM.展开更多
We have studied the interracial reactions between amorphous LaAlO3 thin films and Si substrates, using high- resolution transmission electron microscopy and x-ray photoelectron spectroscopy. It has been shown that the...We have studied the interracial reactions between amorphous LaAlO3 thin films and Si substrates, using high- resolution transmission electron microscopy and x-ray photoelectron spectroscopy. It has been shown that the interracial layer between LaAlO3 film and Si substrate chemical states show that the ratio of La 4d3/2 to Al 2p is SiLaxAlyOz. The depth distributions of La, Si and Al of the interfacial layer remains unchanged with the depth compared to that of the LaAlO3 film. Moreover, the Si content, in the interracial layer gradually decreases with increasing thickness of the interracial layer. These results strongly suggest that the Al element is not deficient in the interracial layer, as previously believed, and the formation of a SiLaxAlyOz interracial layer is mainly due to the diffusion of Si from the substrate during the LaAlO3 film deposition. With the understanding of the interracial layer formation, ones can control the interface characteristics to ensure the desired performances of devices using high-k oxides as gate dielectrics.展开更多
N 类型 LaAlO3？薄电影取向附生地在 p 类型 Si 底层上被种。一只改进模式地效果晶体管与氧被构造缺乏的 LaAlO3 吗？作为来源和排水管， p 类型 Si 作为半导体的隧道，和 SiO2 作为门绝缘体分别地。有地效果晶体管特征的典型当前电压...N 类型 LaAlO3？薄电影取向附生地在 p 类型 Si 底层上被种。一只改进模式地效果晶体管与氧被构造缺乏的 LaAlO3 吗？作为来源和排水管， p 类型 Si 作为半导体的隧道，和 SiO2 作为门绝缘体分别地。有地效果晶体管特征的典型当前电压的行为被观察。开／关比率在 10V 的门电压到达 14，地效果活动性是 10 厘米 2/V 吗？？展开更多
Well-cubic perovskite lanthanum aluminate (LaAl03) film on (110) silicon substrate was fabricated by sol-gel method with corresponding inorganic salts. Lanthanum acetate and aluminum acetate glacial acetic acid soluti...Well-cubic perovskite lanthanum aluminate (LaAl03) film on (110) silicon substrate was fabricated by sol-gel method with corresponding inorganic salts. Lanthanum acetate and aluminum acetate glacial acetic acid solutions were prepared via ligand exchange starting from lanthanum nitrate hexahydrate and aluminum nitrate hexahydrate after being refluxed. (CH3CO)2O removed nitrates and the crystallized H2O completely, acetylacetone (AcAc) was partially bidentated with metallic ion of the metallic acetates and formed La(OAc)3-x(AcAc)x, which were hydrolyzed into La(AcAc)3-x(OH)x by adding 10 ml 0.4% methyl cellulose (MCL) solution. The La(AcAc)3-x(OH)x, polymerizing and combining with MCL,formed the LaA1O3 sol precursor with heteropolymeric structure and formed film easily. The epitaxial LaA1O3 film on Si(110) substrate was crystallized after being annealed in thermal annealing furnace for 650-750 ℃/30 min. The morphologies and microstructures were characterized. The refractive index of the LAO film was 1.942 to 2.007; the dielectric constant and the dissipation factors were estimated to be 23-26 and 2.1×10^-4-2.4x10^-4 respectively.展开更多
基金supported by C1 Gas Refinery Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT&Future Planning(2015M3D3A1A01064908)
文摘Oxidative coupling of methane(OCM) was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values(X = 6–10). The aim is to investigate the effect of p H values on the catalytic activity of La AlO3 catalysts in this reaction. The results showed that the co-precipitation pH value affected greatly on the formation of chemical species of precipitate precursors in the co-precipitation step, leading to different phases of the finally obtained LaAlO3 catalysts.When the co-precipitation pH value increased up to 8, the lanthanum-related phases such as La2 O3 and La(OH)3 were gradually formed as by-products, preventing the formation of LaAlO3 perovskite crystalline structure and facilitating the formation of oxygen vacancies on catalyst surface. However, at pH value of9 or higher, the lanthanum content in the precipitate precursor was increased greatly. Not LaAlO3 perovskite but lanthanum-related phases were developed as main phases, reducing their catalytic activities in this reaction. Among LaAlO3 catalysts, the one prepared at pH = 8 showed the highest C2 yield due to its well-developed oxygen vacancies and electrophilic lattice oxygen. Therefore, the co-precipitation pH value strongly affected the LaAlO3 catalyst activity in OCM reaction. A precious pH control should be required to prepare various perovskite catalysts for the OCM.
文摘We have studied the interracial reactions between amorphous LaAlO3 thin films and Si substrates, using high- resolution transmission electron microscopy and x-ray photoelectron spectroscopy. It has been shown that the interracial layer between LaAlO3 film and Si substrate chemical states show that the ratio of La 4d3/2 to Al 2p is SiLaxAlyOz. The depth distributions of La, Si and Al of the interfacial layer remains unchanged with the depth compared to that of the LaAlO3 film. Moreover, the Si content, in the interracial layer gradually decreases with increasing thickness of the interracial layer. These results strongly suggest that the Al element is not deficient in the interracial layer, as previously believed, and the formation of a SiLaxAlyOz interracial layer is mainly due to the diffusion of Si from the substrate during the LaAlO3 film deposition. With the understanding of the interracial layer formation, ones can control the interface characteristics to ensure the desired performances of devices using high-k oxides as gate dielectrics.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10334070 and 60576015, and the National Basic Research Programme of China under Grant No 2004CB619004.
文摘一系列非结晶、单人赛水晶的 LaAlO3 (老挝人) 薄榆树被激光制作在免职的各种各样的条件下面的 Si 底层上的分子横梁的取向附生技术。老挝人的电影的结构稳定性在高温度退火了，各种各样的 ambients 被 X 光衍射以及高分辨率的传播选举显微镜学学习。结果证明取向附生的老挝人的电影有很好的稳定性，并且非结晶的老挝人的薄电影的结构强烈取决于免职退火 andpost 的条件。结果表明老挝人的作文的形成为老挝人的薄榆树的结构稳定性在免职期间是很重要的。
文摘Well-cubic perovskite lanthanum aluminate (LaAl03) film on (110) silicon substrate was fabricated by sol-gel method with corresponding inorganic salts. Lanthanum acetate and aluminum acetate glacial acetic acid solutions were prepared via ligand exchange starting from lanthanum nitrate hexahydrate and aluminum nitrate hexahydrate after being refluxed. (CH3CO)2O removed nitrates and the crystallized H2O completely, acetylacetone (AcAc) was partially bidentated with metallic ion of the metallic acetates and formed La(OAc)3-x(AcAc)x, which were hydrolyzed into La(AcAc)3-x(OH)x by adding 10 ml 0.4% methyl cellulose (MCL) solution. The La(AcAc)3-x(OH)x, polymerizing and combining with MCL,formed the LaA1O3 sol precursor with heteropolymeric structure and formed film easily. The epitaxial LaA1O3 film on Si(110) substrate was crystallized after being annealed in thermal annealing furnace for 650-750 ℃/30 min. The morphologies and microstructures were characterized. The refractive index of the LAO film was 1.942 to 2.007; the dielectric constant and the dissipation factors were estimated to be 23-26 and 2.1×10^-4-2.4x10^-4 respectively.
