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1.
钛酸铝陶瓷粉体的制备研究   总被引:3,自引:0,他引:3  
以NH4HCO3作沉淀剂的共沉淀法制备了钛酸铝(Al2TiO5)陶瓷粉体.实验发现,此反应体系的pH值对钛、铝元素的沉淀量有重要的影响,只有在pH6.0~6.5左右极小范围内能保证钛、铝完全沉淀.采用FT-IR、XRD、DTA-TG等分析手段确定了前驱体的组成.通过XRD、DTA-TG等分析表明,前驱体在热处理形成Al2TiO5的过程中,物相的变化情况是:碳酸铝铵→无定形Al2O3→α-Al2O3;无定形TiO2→锐钛型TiO2→金红石型TiO2;在1000℃左右α-A12O3和金红石TiO2开始形成Al2TiO5,然后在1350℃完全形成Al2TiO5.同时,TEM分析显示Al2TiO5粉体的形貌为球形,粒径为70~100nm.  相似文献   

2.
溶胶凝胶法合成TiO_2纳米粉体及光催化活性研究   总被引:1,自引:0,他引:1  
肖文胜  李文洪 《河南科学》2006,24(5):648-651
利用简便的溶胶凝胶法合成了锐钛型纳米TiO2粉体,对合成的TiO2粉体进行了XRD,SEM,TEM分析,利用对锐钛型纳米TiO2粉体形成过程进行了分析,并对合成的纳米TiO2粉体的光催化性能进行了研究,表明其对罗丹明B的光催化降解在1h内可达98%以上.  相似文献   

3.
MnOx/TiO2催化剂的制备及其低温NH3选择性催化还原NO性能   总被引:2,自引:0,他引:2  
为了研究MnOx/TiO2催化剂的低温催化还原NO性能,采用微乳液法在不同的煅烧温度下制备了不同晶相的纳米TiO2,并以此为载体,利用浸渍法制备了一系列MnOx/TiO2催化剂.然后,利用BET,XRD,HRTEM,H2-TPR等方法研究了载体和催化剂的微观结构、分散状态和氧化还原性质.实验结果表明:随着煅烧温度的增加,纳米TiO2从锐钛型逐渐向金红石型转变,700℃煅烧得到的纳米TiO2呈混晶相,800℃煅烧得到的纳米TiO2则为纯金红石型;锐钛型及混晶相TiO2载体与活性氧化物MnOx之间的相互作用较为强烈,当纳米TiO2中金红石型与锐钛型并存时,MnOx优先与锐钛型纳米TiO2作用;纯金红石型纳米TiO2与MnOx之间的相互作用较弱.模拟NH3选择性催化还原NO的反应活性测试结果表明,500℃煅烧得到的MnOx/TiO2催化剂表现出较高的低温活性.  相似文献   

4.
加热处理纳米锐钛TiO2使其发生转晶,因而得到一种利用可见光激发的光催化剂,并对此催化剂用x射线衍射,红外吸收,紫外可见吸收等方法进行了表征.用该方法得到的TiO2为催化剂,进行可见光催化降解酸性红B的研究.结果表明,随着加热温度的升高,TiO2转晶比例逐渐增大,温度升到1000℃,全部锐钛型转变成金红石型TiO2,但TiO2在500℃下加热30min催化活性最高,酸性红B的光降解效果明显优于单独使用纳米锐钛型、纳米金红石型TiO2和按照转晶的比率混合的锐钛型和金红石型TiO2.这种显著提高的光催化作用归因于加热所形成的特殊锐钛-金红石界面耦合状态,导致光生电子从金红石相转移到锐钛相,避免了电子-空穴对的复合.  相似文献   

5.
低压下利用四异丙醇钛水解法制备了TiO2薄膜,将TiO2固定化并尽可能保留其尺寸效应 .联系制膜条件和膜的表性,研究了TiO2薄膜的光催化活性.利用Raman、XRD、AFM和UV -vis等手段探讨了不同膜厚、晶型、衬底对膜催化活性的影响.结果表明,随着衬底温度的升高,TiO2由非晶型转变为锐钛矿,光催化活性提高;随着TiO2薄膜厚度的增加,催化活性降低.在玻片、Si、SnO2、Al为基片所制TiO2薄膜中,以Al为基片的TiO2薄膜的光催化活性最好.  相似文献   

6.
钛表面制备多孔氧化膜的研究   总被引:5,自引:0,他引:5  
以硫酸和磷酸为电解液,工业纯钛为阳极,不锈钢为阴极,恒电流阳极氧化的方式在钛表面直接获得TiO2多孔氧化膜,经过500℃热处理,促进氧化膜由非晶体向晶体的转变.采用扫描电镜和X射线衍射对阳极氧化膜的形貌和结构进行了分析,研究了电流密度、电解液种类以及浓度对TiO2多孔氧化膜形态和晶型的影响,并探讨了其形成机理.结果表明,以磷酸为电解液时钛表面仅生成锐钛矿相的TiO2,而以硫酸为电解液时钛表面生成锐钛矿和金红石两种晶相的TiO2.  相似文献   

7.
用部分中和法制备超细二氧化钛粉体   总被引:2,自引:0,他引:2  
采用部分中和法制备超细TiO2粉体,通过TEM、XRD和TG-DTA对产品进行了表征,指出水合TiO2在煅烧过程中逐步失去游离水和化合水,再形成TiO2结晶,且随着煅烧温度的上升,颗粒的粒度迅速增大.在600℃以下煅烧时所形成的TiO2颗粒为锐钛型,在800*!℃时完全转化为金红石型.  相似文献   

8.
SnO2@TiO2纳米粒子的光催化性能   总被引:5,自引:0,他引:5  
以纳米SnO2·nH2O胶体粒子为基质,采用活性层包覆法制备出复合光催化剂SnO2@TiO2.用其对有机磷农药DDVP的稀释液进行降解,并用SEM、TEM、XRD、BET和XPS等手段进行了表征.结果表明:SnO2@TiO2粒径在12nm左右,比表面积为72.27m2g,由锐钛型TiO2与金红石型SnO2组成,光催化活性明显优于单一的SnO2、TiO2.其最佳用量为3.0gL,并且可重复使用.添加剂H2O2、Fe3+的最佳浓度分别为1.65mmolL和0.5mmolL.  相似文献   

9.
以钛酸四丁酯为前驱体、聚乙二醇(PEG)为模板剂,通过调节加入溶胶中模板剂的相对分子质量实现TiO2膜微观形貌的调控。X线衍射(XRD)结果表明制备的DENSE、PEG-600和PEG-1000 3种膜均为TiO2锐钛晶型。通过场发射扫描电子显微镜(FESEM)及N2吸附-脱附表征发现:无模板剂加入的TiO2膜呈现平整致密形貌,加入平均相对分子质量为600及1 000的聚乙二醇后,制备的TiO2膜分别呈现规则纳米颗粒及纳米介孔结构表面。将3种TiO2膜固定化葡萄糖氧化酶并制备成电极后,无需加入氧化还原媒介体,均可对溶液中葡萄糖产生直接电化学响应。葡萄糖传感测试发现具有介孔结构的TiO2膜电极具有较好的灵敏度(5.95 mA·L/(mol·cm2))及电活性蛋白密度(1.63×10-11mol/cm2),具有纳米颗粒结构TiO2膜电极的葡萄糖传感性能次之,表明TiO2材料的微观形貌对葡萄糖传感性能影响显著,具有介孔结构的TiO2膜在生物传感领域具有潜在的应用价值。  相似文献   

10.
采用阳极氧化法在钛金属表面制备出致密有序的TiO2纳米管膜层.利用FESEM、XRD方法研究了不同阳极氧化时间、电解液组成以及退火对TiO2纳米管形貌的影响.讨论了TiO2纳米管的形成机制.  相似文献   

11.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

12.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

13.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

14.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

15.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

16.
17.
The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.  相似文献   

18.
R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).  相似文献   

19.
The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.  相似文献   

20.
Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.  相似文献   

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