用正电子湮没谱学研究氯化稀土在NaY沸石上的分散

用正电子湮没谱学研究氯化富铈稀土与NaY沸石机械混合形成的稀土NaY沸石(RE-NaY)中,氯化稀土在NaY中的分散．分别测量不同质量比的RE-NaY(1％-20％)经500℃烘烤1h,RE-NaY(5％)经过不同温度烘烤1h,以及RE-NaY(5％)经500℃烘烤不同时间后的正电子寿命谱．所有寿命谱都出现了5个寿命分量,其中第3,4,5寿命分别与β笼、超笼及沸石微粒界面空洞的大小和数量相关．实验表明了正电子湮没谱学能敏感地表征氯化稀土在NaY中的分散．     

正电子湮没与沸石内静电场

本文测定了不同类型沸石的正电子寿命谱。发现o-Ps的湮没寿命, 与沸石静电场之间有良好的对应关系, 静电场愈强, 湮没寿命愈短。根据正电子寿命谱结果。含不同阳离子的Y沸石的静电场强弱次序为KY相似文献   

用正电子谱学研究USY沸石中二次孔的脱水

超稳Ｙ型沸石（ＵＳＹ）分子筛是石油催化裂化中的优异催化剂,它是由ＨＹ型沸石经高温水热处理制备的,它的特点之一是具有良好的热稳定性．因而,对ＵＳＹ的改性研究一直受到关注［１-５］,尤其是在制备ＵＳＹ过程中由于水热处理所产生大量二次孔,它与ＵＳＹ的结构与?..     

微波法高度分散CuCl2-β沸石上CO吸附的IR光谱研究

近年来, 人们发现含铜沸石对NO和CO等有害气体的直接分解具有较高的活性和较好的稳定性[1～3]. 催化剂的活性与其铜含量密切相关, 而由传统离子交换法制得的沸石催化剂中铜含量较低, 且受沸石骨架中铝含量的限制[4]. 直接固态离子交换法是将金属离子引入沸石中的有效途径[5～7]. 本文采用微波法制备了CuCl2高度分散的β沸石, 用XRD和29Si MAS NMR对催化剂进行了表征, 并以CO吸附IR光谱法考察了CuCl2在β沸石中的扩散机理.     

CuCl2/NaY体系表面分散态研究

铜负载分子筛作为催化剂或吸附剂，在石油化工、环境保护等方面有许多用途[1，2]．已有研究发现，铜交换的Y型分子筛对NO分解等反应具有较高活性及稳定性［3-5］．因此研究铜负载Y型分子筛对有关吸附剂和催化剂的制备有重要意义．我们实验室在研究活性组分在载体表面分散现象时     

正电子湮没谱研究聚烯烃聚氨酯的自由体积、微观结构和溶剂的扩散行为

用正电子湮没技术(PAS)结合示差扫描量热法(DSC)研究了聚烯烃聚氨酯的自由体积特征和微相分离结构的关系.结果表明,硬段含量增加,自由体积孔洞平均半径和自由体积分数减小;丁腈聚氨酯相分离程度小,相应自由体积孔洞平均半径和自由体积分数小,而丁羟聚氨酯的情况正好相反.石英弹簧法对苯和乙醇蒸气的溶解和扩散行为的研究表明,聚烯烃聚氨酯的自由体积孔洞平均半径和自由体积分数与苯和乙醇溶剂蒸气的无限稀释扩散系数呈正相关,但它们的无限稀释扩散系数和自由体积分数关系无法用Fujita的自由体积模型描述,可能归因于它们对聚烯烃聚氨酯复杂的溶胀行为.     

6H-SiC缺陷的慢正电子研究

The defect formation and annealing behavior in as-grown and electron-irradiated 6H-SiC wafers were investi-gated by variable-energy slow positron beam. For the n-type as-grown samples, it was found that annealing decreased the defect concentration due to recombination with interstitial, and when it was annealed at 1400 ±C for 30 min in vacuum, a 20 nm thick Si layer was found on the top of SiC substrate, which is a direct proof of the Si atom diffusing to the surface when annealed at the high temperature stages. During the high temperature annealing stage, we found an obvious surface effect occurred that induced the higher S parameter close to the surface. This may be caused by the diffusion of the Si atoms to the surface during annealing. After 10 MeV electron irradiation of the n-type 6H-SiC, the positron effective diffusion length decreased from 86.2 nm to 39.1 nm. This shows that there are some defects created in n-type 6H-SiC. But in the p-type 6H-SiC irradiated by 10 MeV electrons, the change is very small. This may be because of the opposite charge of the vacancy defects. The same annealing behavior as that of as-grown 6H-SiC samples was also observed for the 1.8 MeV electron-irradiated 6H-SiC samples except that after being annealed at 300 ±C, its defect concentration increased. This may be explained as the generation of carbon vacancies, due to either the recombination between divacancies and silicon interstitial, or the charge of the charge states.     

正电子湮没技术（PAT）在高分子材料中的应用（上）

本文引用７０多篇文献，综述了正电子湮没技术（主要是正电子湮没寿命技术）近１０年来在高分子材料各个领域中的应用。     

用正电子湮没寿命谱法研究铝阳极氧化膜

退火纯铝(99.99%)在15%H_2SO_4中于不同电解条件下进行阳极氧化, 然后测其正电子湮没寿命谱, 寿命谱拟合为三个寿命成份, 指认第二寿命成分为e~+在氧化膜中的湮没。从I_2随电解条件的变化推知膜厚与槽压近似成正比, 在恒温和固定槽压条件下, 膜厚只能达到某极限值。根据τ_2的变化推断出, 使用较高槽压或延长电解时间均使膜的结晶度提高, 它诱发了裂缝或微洞的形成, 导致膜体松散。根据上述结论进一步分析提高膜机械性能的可能途径。     

用正电子湮没技术研究稀土对16Mn钢回复过程的影响

应用正电子湮没多普勒展宽技术研究了含不同稀土量的16Mn钢的回复过程。实验结果表明,稀土元素的存在使S参数迅速下降,这可能是由于稀土元素对间隙杂质原子的吸引减少了杂质原子对位错的封锁以及稀土对钢质的净化作用所致。在再结晶温度下,湮没特征表现为连续回复过程。     

预吸附微波合成纳米NaY沸石晶种制备NaY型分子筛膜

在常压回流的微波加热体系中成功地合成出纳米尺寸的NaY分子筛,XRD和SEM等表征结果表明,分子筛具有40nm左右的平均晶粒尺寸.以其为晶种,预吸附在多孔氧化铝载体上,结合原位水热法进行二次晶化,制备出较为致密的NaY分子筛膜,该膜主要以孪生聚晶的形式存在.CO₂/N₂气体分离测试结果显示,随着温度的升高,分子筛膜的气体分离能力呈上升趋势,在140℃时真实选择分离系数达到最大值4.0.     

侧链型丙烯酸酯共聚物相变的正电子湮没谱研究

利用正电子湮没技术对侧链型热致高分子液晶丙烯酸酯共聚物进行了变温相变研究．除实验标识出样品的相变温度点外，根据试样中自由体积随温度的变化关系，对高分子液晶材料内部立链、侧链以及介晶基元的相变行为特点进行了探讨，并就与小分子液晶变化特点的一些不同做了解释．     

MoNiP/Al2O3加氢脱氮催化剂的研究:金属分散状态对催化剂活性的影响

采用ＰＡＳＣ Ａ，ＸＰＳ，ＳＴＥＭ和微型反应色谱等技术，研究了一系列ＭｏＮｉＰ／Ａｌ２Ｏ３催化剂表面活性组分的分散状态及其对催化剂ＨＤＮ反应活性的影响。     

An IR Study on Adsorption of CO and NO on Copper Ion-exchanged Zeolite Beta

Thee adsorption of CO and NO on copper ion-exchanged zeolite Beta was investigated using IR method.It was found that the thermalvacuum pretreatment procedure could result in the reduction of Cu2 ions in zeolite Beta.The adsorption of CO on Cu sites in zeolite Beta closely follows Langmuir isotherm.Another Cu species may form during the reaction between water and CO.The catalytic decomposition of NO on the zeolite was observed at room temperature,indicating that the decomposition reaction may occur between two coordinated NO ligands of the same dinitrosyhc complex.Furthermore,the appearance of two series of NO adsorption bands reveals that copper ions existing at different cation sites may have different effect on the adsorption and decomposition of NO molecules.     

Intercalation of xylenol orange, morin and calmagite into NaY zeolite and their application in dye/zeolite modified electrode

The intercalation of xylenol orange, morin and Calmaigite into NiaY zeolite were studied by XRD, TGA, and BET and diffuse reflectance. These dye incorporated into NaY zeolite by ion exchange in aqueous phase. Results show that xylenol orange can be intercalating better into zeolite. The dye molecules are strongly retained in the channels of zeolites. The prepared intercalated dye/zeolite, for the first time, was used as the modifier for carbon past electrode. The dye/zeolite modified carbon paste electrode was developed for the voltammetric determination of Cu(II). Copper(II) was selectively preconcentrated. Results shows the peak current intensity increased in order of calmagite > xylenol orange > morin dyes intercalated in zeolite. The results agree with complex formation of those dyes as chelating agents with Copper(II).