首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
用哌嗪和丙胺作模板剂在水热条件下合成了微孔材料NH4[Ni(H2O)2Al2(PO4)3];单晶解析表明该结构与以往的金属磷酸铝大有不同,结构中的镍原子是八配位的,且与铝的位置区别明显;单晶结构数据,元素分析,拉曼光谱表明NH4[Ni(H2O)2Al2(PO4)3]材料的八元环孔道中只含有NH4 离子;热重分析和焙烧后的XRD图谱显示,该材料在350℃和空气条件下焙烧2 h,仍然保持其原来的骨架结构;若焙烧温度为550℃,则结构被破坏.  相似文献   

2.
采用正交实验设计,以Ca(OH)2,ZnO和H3PO4为原料,通过水热法合成出超细磷酸锌钙粉体.借助于动态光散射粒度分析仪、扫描电镜对产物的粒度和形貌进行分析表征,通过XRD图谱对反应机理进行研究,同时通过TG图谱对产物失水过程进行分析.实验结果表明:最佳反应条件是:Ca与Zn摩尔比n(Ca)∶n(Zn)=1∶2,反应温度为80℃,反应时间为12h,OP-10为表面活性剂:得到的产物颗粒大小均匀,粒度为1~2μm;最终产物CaZn2(PO4)2·2H2O是通过中间产物Ca[Zn(OH)3]2·2H2O与磷酸反应而生成的.CaZn2(PO4)2·2H2O分子的失水过程分为2个阶段,第1阶段失水温度为95~393℃,第2阶段失水温度为403~553℃.  相似文献   

3.
本文采用x-射线衍射和差热分析法,研究了P_4O_(10)-Al(OH)_3-H_2O混合体系中生成的磷酸铝种类和生成量与摩尔比P_2O_5/Al(OH)_3(R)、P_4O_(10)的吸水量、加热温度和加热时间的关系。得出了本体系各磷酸铝的生成最佳条件以及在各温度下的热变化情况,弄清了五氧化二磷和氢氧化铝的反应过程。  相似文献   

4.
希夫碱钛配合物/三异丁基铝催化MMA本体聚合   总被引:1,自引:1,他引:0  
经希夫碱缩合反应,制得水杨醛亚胺配体(1),其Na盐分别与TiCl4和CpTi-Cl3反应合成了新型希夫碱钛配合物{3,5-di-Br-2-(O)C6H2CHN[2(O)C6H4]}TiCl2(2);{3,5-di-Br-2-(O)C6H2CHN[2(O)C6H4]}[TiCl(C5H5)](3).以GC-MS,1HNMR和元素分析对中间产物及配合物进行了表征.以Al(i-Bu)3为助催化剂,详细考察了聚合时间、温度、Al/Cat和MMA/Cat的摩尔比对催化MMA本体聚合的影响.两个催化体系的聚合转化率均可以达到62%左右.2/Al(i-Bu)3(A)催化体系在聚合条件MMA/Cat(摩尔比)=2 000,Al/Cat(摩尔比)=20,T=60℃,t=15 h下,Mη可以达到3.6×105,相对分子质量分布2.14;3/Al(i-Bu)3(B)催化体系在相同聚合条件下,Mη可以达到4.3×105,相对分子质量分布2.44.红外光谱分析表明,A,B两个催化体系所得的PMMA的间同含量分别为85%和86%左右.  相似文献   

5.
利用循环流化床锅炉粉煤灰在n(SiO2)/n(Al2O3)≈3.3、Na2O/SiO2为1.2~L 5、H2O/Na2O为40~70、凝胶温度和时间分别为60-70℃、时间2 h、晶化反应温度在90-95℃,晶化时间为4-6 h的条件下可以合成出较高结晶度的分子筛,通过XRD表征发现,产品具有良好的P型分子筛特征峰,其相对结晶度为53%.热重分析可知其具有好的稳定性.  相似文献   

6.
利用水热合成方法制备了新颖的基于{Na[Mo6O12)(OH4)3(HPO4)(H2PO4))3]2}3-构筑单元的一维链状杂多化合物[DETA]4NaH2{Na[Mo6O12(OH)3(HPO4)(H2PO4)3]2}·8H2O(DETA=diethylenetriamine), 并用元素分析、IR、UV、TG及X-射线单晶衍射对其进行了表征. 该化合物属于三斜晶系, P-ī空间群, a=12.421 2(4)nm, b=12.5911(4) nm, c=13.078 2(4) nm, α=85.411 0(10)°, β=73.313 0(10)°, γ=82.276 0(10)°, V=1 939.63(11) nm3, Z=2, R1= 0.024 4. 杂多阴离子{Na[Mo6O12(OH12(OH)3(HPO4)(H2PO4)3]2}3-具有夹心结构, Na离子位于2个半单元[Mo6O12(OH)3(HPO4)(H2PO4)3]2-中心. 夹心型阴离子之间又以Na离子为桥形成了一维链, 并通过氢键作用形成了三维网状结构. 半单元[Mo6O12(OH)3(HPO4)(H2PO4)3]2-中, 6个MoO6八面体通过共边连接形成一个Mo6环,4个PO4四面体位于环的一侧.  相似文献   

7.
水滑石与氢氧化镁纳米晶的液相法制备及其生成机制   总被引:4,自引:0,他引:4  
研究了纳米晶镁铝水滑石Mg6Al2(OH)16CO3·4H2O与 Mg(OH)2 的液相法制备及其物相变化.X射线衍射(XRD)和透射电镜(TEM)分析表明,在制备温度分别为30 ℃的低温和190 ℃的高温,可获得纯度大于99%的氢氧化镁针状纳米晶,在45~150 ℃的中间温度范围,可获得纯度大于 99%的镁铝水滑石针状纳米晶.合成温度由35 ℃提高到45 ℃时,生成物相由氢氧化镁变成镁铝水滑石相;合成温度由 170 ℃提高到190 ℃时,生成物相由镁铝水滑石相变成氢氧化镁相.提出低温时生成物的变化与瞬间生成无定形态的Mg(OH)2 有关,无定形态的Mg(OH)2 沉淀为Al13(OH)7 32 中铝离子以及CO2-3 扩散进入Mg(OH)2提供了更为有利的条件.高温时生成物的变化,是由于温度的升高,使含结晶水的镁铝水滑石纳米晶中间层中的高极性水分子堆积所要求的一定的物理条件受到破坏所致.  相似文献   

8.
运用XRD、TEM等测试手段,对硫铁矿烧渣水热法合成的纺锤形α- Fe2O3的工艺进行了研究.结果表明以Fe(OH)3为前驱体水热合成纺锤形α-Fe2O3的适宜条件是搅拌速率500 r/min,升温速率2.5 ℃/min,加热到(170±2) ℃水热反应1.5 h,快速冷却.反应系统中NaH2PO4的加入量对产物的α-Fe2O3轴比有显著影响.NaH2PO4对α-Fe2O3形貌的影响机理为NaH2PO4与水热反应的前驱体Fe(OH)3、中间体α-FeOOH和产物α-Fe2O3的络合作用,抑制了α-Fe2O3晶核的成核速率并控制了α-Fe2O3在不同晶面的生长速率.  相似文献   

9.
碳化法从菱镁矿中提取高纯氧化镁的研究   总被引:1,自引:0,他引:1  
采用碳化法,对低品位菱镁矿进行磨矿、浸出,可获得MgO含量大于99%的高纯(4MgCO3·Mg(OH)24H2O)产品,MgO回收率大于85%。其最佳工艺条件如下:煅烧时间为60min,煅烧温度为800℃,磨矿时间为3min,浸出温度为22℃,浸出压强为3kPa,搅拌排气量为0.6m3/h,液固比为50∶1。  相似文献   

10.
对锐钛矿型Ti O2在高钙体系下的反应进行了热力学和动力学分析,确定了理论上能发生的反应,计算了活化能和反应级数并判断出反应控制类型.通过实验研究了锐钛矿型Ti O2在Ti O2-Ca O-Na Al O2体系下的反应行为.结果表明,在Ti O2与Ca O物质量的比为1,反应1 h,铝酸钠溶液中Na2O的质量浓度为220 g/L,Na2O与Al2O3物质量的比为3.1的条件下,随着温度的升高,首先Ti O2与Na OH反应生成Na2Ti O3,Ca(OH)2和Na Al(OH)4反应生成3Ca O·Al2O3·6H2O,反应产物3Ca O·Al2O3·6H2O与Na2Ti O3反应最终可以得到稳定的Ca Ti O3.锐钛矿型Ti O2可在220℃以上完全转型为Ca Ti O3,升高温度能促进钛向最终物相Ca Ti O3的转型.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

18.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

19.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

20.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号