S.K.Durrani
,
J.Akhtar
,
M.Ahmad
,
M.J.Moughal
材料科学技术（英文）
Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate (SAPO) microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer (PSA) and scanning electron microscope (SEM). The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test (F-test) methods were performed for the significance of results by the analysis of variance (ANONA) and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett & Teller (BET) volumetric technique and v-αs plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.
关键词:
Synthesis
,
null
,
null
,
null
Zhiqiang ZHANG
,
Ren HE
,
Peng LEI
,
Yan GAO
,
Haijun CHI
,
Zhizhi HU
材料科学技术（英文）
The incorporation of the imidazole nucleus is an important strategy in pharmaceuticals, chemiluminescence and electroluminescence. A facile synthesis of some aryl substituted imidazole derivatives from substituted benzils and substituted benzaldehydes via Debus reaction is described. Their structures were identified by IR, MS, NMR and their characteristics were evaluated by UV-visible and fluorescence spectroscopy.
关键词:
Synthesis
,
null
,
null
Shixi ZHAO
,
Hanxing LIU
,
Qiang LI
,
Shixi OUYANG
材料科学技术（英文）
Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to α-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.
关键词:
Orthorhombic LiMnO2
,
null
,
null
,
null
Guoqing CHEN
,
Kaifeng ZHANG
,
Wenbo HAN
,
Junting LUO
材料科学技术（英文）
A series of alumina-zirconia composites with various grain sizes were prepared from the nano-sized powders with different agglomerations. Microstructural analysis of the sintered compacts indicates that the as-sintered material is a typical intra/inter granular nanocomposite with uniform distribution of the zirconia grains in the alumina matrix. Superplastic deep drawing test under different conditions demonstrates that dense Al2O3/ZrO2 samples with average grain size of 230 nm can be elongated to a dome height of at least 12 mm at the punch rate of 0.6 mm•min-1 at 1400℃. Further drawing tests show that for the composites with larger grain size, such elongation cannot be achieved at such a strain rate.
关键词:
Nanocomposite
,
null
,
null
,
null
M.H.Khedr
,
A.A.Farghali
材料科学技术（英文）
Copper ferrite, CuFe2O4, one of the important ferrites due to its interesting electrical, magnetic and structural properties, is obtained by a novel self flash combustion of a homogeneous mixture of one mole copper acetate monohydrate, Cu(CH3COO)2•H2O, and two moles of iron (III) acetate basic, Fe(CHCOO)2•OH. Nanocrystalite (89 nm) copper ferrite (less than 100%) is obtained at lower temperatures, whereas 100% copper ferrite is obtained after calcination at 1000℃. Thermal analysis (TG and DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photo microscopy, magnetic and porosity measurements have been carried out for the specimens obtained after calcinations at 700, 800, 900 and 1000℃ to characterize the conversion efficiency of the powder precursors to copper ferrite. It was found that increasing temperature leads to great improvement in the magnetic properties. By increasing calcination temperature from 700～1000℃ saturation magnetic flux density (Bs) increased from 17.8 to 40.8 emu/g, while remnant magnetic flux density (Br) increased from 10.1 to 17.11 emu/g.
关键词:
Copper ferrite
,
null
,
null
,
null
,
null
,
null
Peter J.Majewski
,
Tobias M.Fuchs
,
Shashi Prakash
,
Laure Tribalat
材料科学技术（英文）
The synthesis of organic self-assembled monolayers (SAMs) with –CH3, -SH, -SO3H, -CH3CO2, -NH, -NHCl, and -CN functionality onto silica particles and their properties has been studied and characterised by infrared spectroscopy and measurement of the zeta-potential of the resulting powder, respectively. The infrared measurements of the samples clearly show the presence of CH2-goups and the various functionalised head groups of the SAMs in the samples indicating a successful deposition of the SAMs onto the silica particles. The measurements of the zeta-potential of the samples show clear variations of their zeta-potential depending on the type of SAM compared to the zeta-potential of the pure silica powder used in this study. Even positive zeta-potential could be measured for silica powder coated with –NH2, -NHCl, and CN-SAM. After immersing into manganese chloride solutions, the presence of manganese oxide on the SAMs coated silica particles could be observed. This phenomenon is believed to be caused by precipitation of manganese oxide particles out of the solution onto the SAMs.
关键词:
Self-assembled monolayers
,
null
,
null
任慧
,
康飞宇
,
焦清介
,
沈万慈
新型炭材料
doi:10.1016/S1872-5805(08)60032-3
研究了熔融盐状态下金属氯化物-石墨层间化合物的合成判据.根据插层反应热动力学及化学键理论,选取元素的电负性和离子势作为键参数,并设计键参数函数λ为客体材料的遴选判据.基于键参数函数图对金属氯化物发生插层反应的难易程度和产物稳定性进行理论预估.研究结果表明:键参数函数图中λ≤1.2区域内的金属氯化物在700℃以下即可发生插层反应,且所得产物较为稳定;在1.2≤λ≤1.8区域内相应的客体材料在低温下很难单独插入石墨层间,常与低熔点氯化物形成共熔体后一起插入石墨层间;在λ≥1.8区域内大多为碱金属氯化物和碱土金属氯化物,理论分析认为这类物质的插层反应不适宜采用熔盐法.
关键词:
石墨层间化合物
,
合成
,
键参数
,
熔盐法
宋燕
,
乔文明
,
尹圣昊
,
持田勲
新型炭材料
doi:10.3969/j.issn.1007-8827.2006.01.006
通过采用不同金属催化剂进行乙烯催化裂解制备了具有不同微观结构的纳米炭纤维.利用纳米二氧化硅负载的铁、镍以及铁镍合金催化剂在适当的反应条件下分别制备了管状、实心鱼骨状以及空心鱼骨状的纳米炭纤维.由于金属催化剂与纳米二氧化硅间的强相互作用导致在低反应温度下也能达到高的反应活性,所以能够合成出高收率、小直径而且分布均匀的纳米炭纤维.不同结构的纳米炭纤维归因于金属催化剂的不同分散性以及不同的生长机理.通常利用铁催化剂进行乙烯裂解制备纳米炭纤维需要高于650℃,但是在我们的实验中发现500℃低温下利用纳米二氧化硅负载的铁催化剂进行乙烯裂解就能够合成出管状纳米炭纤维.
关键词:
纳米炭纤维
,
催化剂载体
,
气相化学沉积
,
控制合成
吕华
,
单晓辉
,
陈娇
,
蒋瑀涵
,
陈建秋
,
严拯宇
新型炭材料
以木炭为碳源,分别采用回流、微波及超声等不同方法制备碳量子点(Carbon quantum dots,CQDs).比较不同方法的优劣并优化反应条件、考察不同因素对其荧光量子产率的影响.得到最佳制备方法,制得粒径较小的荧光CQDs,用钝化剂PEG2000修饰后,提高其荧光寿命和量子产率.将修饰后的CQDs应用于与牛血清白蛋白(Bovine serum albumin,BSA)的相互作用,采用紫外吸收光谱法和荧光光谱法探讨其相互作用机理.结果表明,经回流法所制CQDs的荧光量子产率最高,其与BSA之间的荧光猝灭为静态猝灭过程.
关键词:
碳量子点
,
制备
,
荧光
,
牛血清白蛋白
