Enhancing energetic performance of metal-organic complex-based metastable energetic nanocomposites by spray crystallization

Energetic metal-organic complexes have been involved in nanothermites as novel oxidants.However,the existing preparation methods often lead to mixing inhomogeneity and small contact area of ingredients,the reactivity and functionality of the novel energetic nanocomposites are still limited.In this work,spray crystallization(SC)method was used to prepare novel energetic nanocomposites,the high-energy metal-organic complex[Ni(CHZ)_(3)](ClO_(4))_(2)(CHZ=1,3-diaminourea)was composited with nanoaluminum(n-Al).Results showed that n-Al/[Ni(CH_(2))_(3)](ClO_(4))_(2)energetic nanocomposites prepared by SC method increased heat release to 2977.6 J/g and peak pressure to 3.91 MPa with higher pressurization rate(1324.06 MPa/s),decreased sensitivity thresholds(>100 mJ)to electrostatic discharge(ESD)and enhanced detonation ability compared with[Ni(CHZ)_(3)](ClO_(4))_(2)alone and physically mixed(PM)n-Al/[Ni(CHZ)_(3)](ClO_(4))_(2).These results proved that it is significant to introduce energetic metal-organic complexes with inherent high energy in new-concept n-Al/energetic metal-organic complexes nanocomposites through SC method for a better performance of its application.

喷雾-反溶剂结晶法制备掺杂铝粉的复合微球

纳米铝粉作为高能添加剂广泛应用于含能复合材料领域。然而,制备高球形度铝粉掺杂的复合微球却面临着一系列挑战。采用喷雾与反溶剂结晶相结合的方法,探索了一种制备纳米铝粉与有机分子形成复合功能微球的喷射-结晶途径。通过自主设计的内混三流式空气雾化喷嘴,将前驱液雾化成液滴,反溶剂接收浴接收后,溶剂与反溶剂发生快速的相互扩散和传质过程,含能分子模拟物蔗糖八乙酸酯(SOA)在液滴内部析出,将铝粉包裹在内,洗涤干燥后得到铝粉掺杂的复合微球。通过调控合适的雾化、溶剂与反溶剂、添加剂等条件,成功解决了干燥后复合微球球形度低、微球之间相互团聚等现象,最终制备出粒径分布窄、形貌均一、分散性较好、球形度和密实度较高的掺杂铝粉的微球复合材料。

PLA/nano-CaCO_(3)复合材料的制备与性能

采用熔融共混法制备了聚乳酸(PLA)/纳米碳酸钙(nano-CaCO_(3))复合材料,利用X射线衍射仪、差示扫描量热仪(DSC)、万能拉力机和摆锤冲击试验机等研究了PLA/nano-CaCO_(3)复合材料的结晶性能和力学性能。结果表明:nano-CaCO_(3)粒径及用量、表面处理剂种类及用量均会对PLA/nano-CaCO_(3)复合材料的结晶行为产生一定影响。当硬脂酸钠用量为3.5%(质量分数)时,与纯PLA相比,随着nano-CaCO_(3)用量的增加,PLA/nano-CaCO_(3)复合材料的拉伸强度逐渐下降,断裂伸长率和缺口冲击强度均逐渐升高。

A METHOD OF PREPARING SPHERICAL NANO-CRYSTAL CELLULOSE WITH MIXED CRYSTALLINE FORMS OF CELLULOSE Ⅰ AND Ⅱ

A new kind of nano-crysta cellulose (NCC) prepared from natural cotton fiber has been obtained by the method ofacid hydrolysis. Compared to most other nanophase materials that derive from inorganic materials, our products are preparedfrom natural cotton fibers. The products are of spherical shape with mixed crystal forms of cellulose I and II. The preparationconditions determine the properties of the products. Prior treatment is a critical procedure. The properties of the products arealso strongly affected by such conditions as the kinds of acids used, the ratio of the acid mixture, the acid concentration, theultrasonic agitation time and hydrolysis temperature. The number average molecular weight of NCC is determined by gelpermeation chromatography (GPC). The particle size and shape were determined by transmission electron microscopy(TEM). X-ray diffraction was used to detect the crystallinity and average crystallite size of the panicle.

Effect of Oleic Acid-modified Nano-CaCO3 on the Crystallization Behavior and Mechanical Properties of Polypropylene

Oleic acid (OA)-modified CaCO3 nanoparticles were prepared using surface modification method. Infrared spectroscopy (IR) was used to investigate the structure of the modified CaCO3 nanoparticles, and the result showed that OA attached to the surface of CaCO3 nanoparticles with the ionic bond. Effect of OA concentration on the dispersion stability of CaCO3 in heptane was also studied, and the result indicated that modified CaCO3 nanoparticles dispersed in heptane more stably than unmodified ones. The optimal proportion of OA to CaCO3 was established. The effect of modified CaCO3 nanoparticles on crystallization behavior of polypropylene (PP) was studied by means of DSC. It was found that CaCO3 significantly increased the crystallization temperature, crystallization degree and crystallization rate of PP, and the addition of modified CaCO3 nanoparticles can lead to the formation of β-crystal PP. Effect of the modified CaCO3 content on mechanical properties of PP/CaCO3 nanocomposites was also studied. The results showed that the modified CaCO3 can effectively improve the mechanical properties of PP. In comparison with PP, the impact strength of PP/CaCO3 nanocomposites increased by about 65% and the flexural strength increased by about 20%.

Modified Scherrer Equation to Estimate More Accurately Nano-Crystallite Size Using XRD

Scherrer Equation, L=Kλ/β.cosθ, was developed in 1918, to calculate the nano crystallite size (L) by XRD radiation of wavelength λ (nm) from measuring full width at half maximum of peaks (β) in radian located at any 2θ in the pattern. Shape factor of K can be 0.62 - 2.08 and is usually taken as about 0.89. But, if all of the peaks of a pattern are going to give a similar value of L, then β.cosθ must be identical. This means that for a typical 5nm crystallite size and λ Cukα1 = 0.15405 nm the peak at 2θ = 170° must be more than ten times wide with respect to the peak at 2θ = 10°, which is never observed. The purpose of modified Scherrer equation given in this paper is to provide a new approach to the kind of using Scherrer equation, so that a least squares technique can be applied to minimize the sources of errors. Modified Scherrer equation plots lnβ against ln(1/cosθ) and obtains the intercept of a least squares line regression, ln=Kλ/L, from which a single value of L is obtained through all of the available peaks. This novel technique is used for a natural Hydroxyapatite (HA) of bovine bone fired at 600°C, 700°C, 900°C and 1100°C from which nano crystallite sizes of 22.8, 35.5, 37.3 and 38.1 nm were respectively obtained and 900°C was selected for biomaterials purposes. These results show that modified Scherrer equation method is promising in nano materials applications and can distinguish between 37.3 and 38.1 nm by using the data from all of the available peaks.

Preparation and thermal decomposition mechanism of Mg,Al-hydrotalcite nano-crystals with titania doping

The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD, TEM, IR and DSC. Moreover, based on the DSC test results, the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.

晶种辅助预晶化法合成纳米ZSM-5分子筛及其在丙烷芳构化反应中的应用

在丙烷芳构化反应中,常规分子筛催化剂易积炭失活,导致催化性能及使用寿命均不理想。采用全硅分子筛Silicalite-1(S-1)作为晶种,结合晶种法和预晶化法合成了纳米ZSM-5分子筛(ZSM-5-Nano)。采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和N2物理吸/脱附表征了ZSM-5-Nano的结构。结果表明,ZSM-5-Nano是由粒径为50 nm左右的小颗粒堆积而成的,其比表面积高达395 m^(2)/g,同时富含晶间介孔。将ZSM-5-Nano负载Zn后得到催化剂Zn-ZSM-5-Nano,然后在固定床反应器中评价了该催化剂在丙烷芳构化反应(n(N_(2)):n(C_(3)H_(8))=7:3、空速为3000 h^(-1)、反应温度为550℃)中的催化性能。结果表明,Zn/ZSM-5-Nano拥有相对温和的酸性质,在丙烷芳构化反应中表现出了良好的催化性能,5 h内的丙烷转化率和轻芳烃(苯、甲苯和二甲苯)选择性分别高达88.4%和86.7%,且在5 h内基本不失活,催化性能优于微米ZSM-5分子筛(水热法)负载Zn催化剂和纳米ZSM-5分子筛(预晶化法)负载Zn催化剂。构效分析结果表明,Zn/ZSM-5-Nano的形貌和酸性共同作用提升了其催化性能,更短的扩散距离和更温和的酸性有效延缓了积炭的生成。

Krypton ion irradiation-induced amorphization and nano-crystal formation in pyrochlore Lu_2Ti_2O_7 at room temperature

Polycrystalline pyrochlore Lu2Ti2O7 pellets are irradiated with 600-keV Kr^3＋ions up to a fluence of 1.45 ×10^16Kr^3＋/cm^2. Irradiation induced structural modifications are examined by using grazing incidence x-ray diffraction（GIXRD） and cross-sectional transmission electron microscopy（TEM）. The GIXRD reveals that amorphous fraction increases with the increase of fluences up to 2 × 10^15Kr^3＋/cm^2, and the results are explained with a direct-impact model.However, when the irradiation fluence is higher than 2 × 10^15Kr^3＋/cm^2, the amorphous fraction reaches a saturation of-80%. Further TEM observations imply that nano-crystal is formed with a diameter of -10 nm within the irradiation layer at a fluence of 4 × 10^15Kr^3＋/cm^2. No full amorphization is achieved even at the highest fluence of 1.45 × 10^16Kr^3＋/cm^2（-36 displacement per atom）. The high irradiation resistance of pyrochlore Lu2Ti2O7 at higher fluence is explained on the basis of enhanced radiation tolerance of nano-crystal structure.

Growth Pattern and Its Indication of Spheroidal Nano-Micro Crystal Aggregates of Pyrite in the Baiyunpu Pb-Zn Polymetallic Deposit, Central Hunan

The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle Devonian, and its geological occurrence is consistent with the wall rocks. A large number of spheroidal pyrite aggregates are found unevenly distributed in the ores. The spheroidal aggregates are made up of kernels and concentric rings. The kernels are composed of approximately epigranular pyrite nanocrystals, while the rings are composed of accumulated pyrite microcrystals growing along the radial direction. The spheroidal pyrite aggregate and its outer zones can be divided into five areas（A–E）. The results of electron probe micro analysis（EPMA） show that from the zone A1 to B, Co/Ni 〈1, the sum of Co and Ni is 0.08%–0.26%, S/Fe increases from 2.06 to 2.15. While from the zone C to E, Ni cannot be detected and S/Fe decreases from 2.22 to 2.08. Powder X-ray diffraction（XRD） analysis in the micro zone shows obvious crystalline characteristics in the aggregates. Moving from the inside outwards, the maximum diffraction peak intensity of the（111） and（220） crystal planes of pyrite increases, and the crystallinity improves. The degree of change in the（111） plane is the most prominent. Considering the theory of crystal growth along with the geologic features of the depositional environment where the spheroidal pyrite aggregates developed, we confirm that the spheroidal aggregates are the result of nano-micro crystalline gathering and growth occurring by the following sequence of processes：nano-crystalline nucleation and growth, gathering into a ball, oriented growth of microcrystals, continuous accumulation, and adjustment of grain boundaries. The formation of the spheroidal pyrite aggregates in the late Qiziqiao Formation of the Middle Devonian occurred in a neutral to weak alkaline and reductive sedimentary environment in the normal oxygen-rich shallowwater carbonate platform edge. The variations in the S/Fe ratio and crystallisation characteristics indicate that during pyrite crystal growth, the sulphur fugacity was high locally and rose constantly, the degree of supersaturation decreased locally and the growth environment was stable relatively.

Effect of Anion Surface Active Agent on the Preparation of SrTiO_3 Nano-Crystals

SrTiO_3 nano-crystal samples with floccule or flake crystal morphology,which were indexed as a perovskite-type crystal structure based on the results of XRD and TEM,were successfully prepared by one-step liquid reaction method.And the growth mechanism of the SrTiO_3 nano-crystals under the liquid condition with/without adding the surface active agent was investigated.It was found that adding the surface active agent contributes to the processing in which the ions gathering bodies transit to a more stable phase through the chemical reaction and form the flake SrTiO_3 nano-crystals.

Up-conversion luminescence properties and energy transfer of Er^(3+)/Yb^(3+)co-doped oxyfluoride glass ceramic containing CaF_2 nano-crystals

The Er^3＋/yb^3＋ co-doped transparent oxyfluoride glass-ceramics containing CaF2 nano-crystals were successfully prepared. After heat treatments, transmission electron microscopy （TEM） images showed that CaF2 nano-crystals of 20-30 nm in diameter precipitated uniformly in the glass matrix. luminescence of Er^3＋ at 540 nm and 658 nm was observed in Comparing with the host glass, high efficiency upconversion the glass ceramics under the excitation of 980 nm. Moreover, the size of the precipitated nano-crystals can be controlled by heat-treatment temperature and time. With the increase of the nano-crystal size, the intensity of the red emission increased more rapidly than that of the green emission. The energy transfer process of Er^3＋ and Yb^3＋ was convinced and the possible mechanism of Er^3＋ up-conversion was discussed.

Effect of Oleic Acid-modified Nano-CaCO_3 on the Crystallization Behavior and Mechanical Properties of Polypropylene

Oleic acid OA-modified CaCO3 nanoparticles were prepared using surface modification method. In- frared spectroscopy IR was used to investigate the structure of the modified CaCO3 nanoparticles, and the result showed that OA attached to the surface of CaCO3 nanoparticles with the ionic bond. Effect of OA concentration on the dispersion stability of CaCO3 in heptane was also studied, and the result indicated that modified CaCO3 nanoparticles dispersed in heptane more stably than unmodified ones. The optimal proportion of OA to CaCO3 was established. The effect of modified CaCO3 nanoparticles on crystallization behavior of polypropylene PP was studied by means of DSC. It was found that CaCO3 significantly increased the crystallization temperature, crystal- lization degree and crystallization rate of PP, and the addition of modified CaCO3 nanoparticles can lead to the for- mation of β-crystal PP. Effect of the modified CaCO3 content on mechanical properties of PPCaCO3 nanocompo- sites was also studied. The results showed that the modified CaCO3 can effectively improve the mechanical proper- ties of PP. In comparison with PP, the impact strength of PPCaCO3 nanocomposites increased by about 65% and the flexural strength increased by about 20%.

Nano-CaCO_(3)晶体规整度对PET复合材料性能的影响

采用碳酸化工艺,合成了一系列具有不同晶体规整度的纳米碳酸钙(nano-CaCO_(3)),研究了其晶体规整度对聚对苯二甲酸乙二醇酯(PET)复合材料结晶性能、流变性能和力学性能的影响。结果表明:nano-CaCO_(3)的晶体规整度越高,PET复合材料的剪切变稀性能越好,越有利于PET成核结晶,使其力学性能更好。

纳米薄片状高硅ZSM-5分子筛的制备及其甲苯脱除性能研究

以四丙基氢氧化铵(TPAOH)为模板剂、NH4F为矿化剂,运用水热晶化法制备厚度为10~100 nm的纳米薄片状高硅ZSM-5分子筛,考察TPAOH/SiO_(2)摩尔比、晶化温度对纳米薄片状高硅ZSM-5分子筛制备的影响,并对其甲苯动态吸附性能进行评价。结果表明,晶化温度为90℃时,随着TPAOH/SiO_(2)摩尔比的增加,纳米薄片状高硅ZSM-5分子筛的尺寸与厚度减小,孔容与平均孔径增大。TPAOH/SiO_(2)摩尔比为0.35时,晶化温度的升高不影响纳米薄片状高硅ZSM-5分子筛的形貌、结晶度与孔结构。相比市售高硅ZSM-5分子筛,厚度10~20 nm、SiO_(2)/Al_(2)O_(3)摩尔比为305的纳米薄片状高硅ZSM-5分子筛对甲苯的动态穿透吸附容量增加约22.5%、饱和吸附容量增加约26.8%,且吸附曲线符合Yoon-Nelson模型。经20次重复再生后,该纳米薄片状高硅ZSM-5分子筛的甲苯吸附容量衰减低于0.5%,展现出良好的再生使用性能。

Asymmetric Synthesis and Crystal Structure of (-)-N-[(3R)-3-Cyclohexyl]-3-phenylpropananoyl]bornane-10,2-sultam

The title compound （-）-N-[（3R）-3-cyclohexyl]-3-phenylpropananoyl]bornane-10,2sultam （C 25 H 35 NO 3 S,M r=429.60）,a derivative of camphorsultam,crystallizes in the monoclinic space group P2 1 /c with a=10.3301（7）,b=19.4040（13）,c=11.8106（8）,β=100.5580（10）°,V=2327.3（3） 3,Z=4,D c=1.226 g/cm 3,λ=0.71073,μ（MoKα）=0.165 mm-1 and F（000）=928.X-ray diffraction analysis reveals that the six-membered ring of sultam shows a boat form （Fig.1）.The planes constructed by （C（4）,C（5）,C（6）,C（7）） and （C（7）,C（8）,C（9）,C（4）） form a dihedral angle of 69.5°.The C（1）-C（2）-C（3） plane forms dihedral angles to the aforementioned planes of 89.8（1） and 85.9（3）°,respectively.And molecules are linked via hydrogen bonding （C-H···N/O） interactions.

多级孔纳米SAPO-34分子筛制备及甲醇制烯烃性能研究

为缩短SAPO-34分子筛的高温晶化时间,提高其在甲醇制烯烃(MTO)反应中的寿命和选择性,以三乙胺和四乙基氢氧化铵作为双模板剂,采用分步晶化法快速制备了粒径为300~500 nm的纳米SAPO-34分子筛,同时添加表面活性剂十六烷基三甲基溴化铵(CTAB)进一步对分子筛进行改性,得到多级孔纳米SAPO-34分子筛(C-ST1T2)。对制备的所有样品进行理化性质表征,并应用于甲醇制烯烃的催化反应,考察了其在一定条件下的催化性能。表征结果显示,分步晶化法可以有效缩短分子筛的晶化时间,并且得到纳米级SAPO-34分子筛。用CTAB改性后得到的多级孔纳米SAPO-34分子筛晶型完整,具有多级孔道结构和适中的酸强度。催化性能测试表明,CST1T2的甲醇转化率能够达到100%,并且催化寿命可以达到690 min,较单模板剂合成的分子筛有较大提升,同时低碳烯烃的选择性稳定在89%以上。研究结果表明,利用CTAB对纳米分子筛的多级孔改性,有利于分子筛的MTO反应性能进一步提升。

The Transmission Modes and Losses of the Poled Nano-crystal and Polymer Composite PbTiO_3 / PEK-c Thin-film Waveguides

Composite thin films of PbTiO3 nano-crystals and high transparency polymer polyetherketone （PEK-c） for application of non-linear optical devices were prepared by spin coating. The size of PbTiO3 nano-crystals was estimated to be 30-40 nm using a transmission electron microscope. The refractive index and the mode propagation losses at 633 nm were measured using the prism coupling technique and improved photographic technique respectively. They were found to be 1.6545 and 2.00 dB cm^-1 （fundamental mode）,respectively. Moreover, it is observed that this loss is increased at higher mode indices.

Predictive model based on artificial neural net for purity of perovskite-type SrTiO_3 nanocrystalline

A three-layer structure back-propagation network model based on the non-linear relationship between the purity of the perovskite-type SrTiO3 nano-crystal samples and the technology factors, such as reaction time, reaction temperature, raw material adding amount of NaOH and SrCl2, and the rate of TiCl4/Hl, was established. The input variables were pretreated by using the main component analysis firstly. Moreover, the momentum terms were introduced so as to accelerate the converging rate and avoid the non-converging situation. At the same time, the variable learning speed was adopted. The results show that the improved back propagation neural network model is very efficient for the prediction of the perovskite-type SrTiO3 nano-crystal sample purity.

Atomic simulation on evolution of nano-crystallizaion in amorphous metals

The deformation-induced nano-crystallization behavior of amorphous pure Ni was investigated by using a molecular dynamics simulation. The microevolution mechanism of the nano-crystallization, the crystallization process in the multicomponent amorphous Ni-Pd alloys and the temperature effect on the nano-crystallization behavior in amorphous metals were studied. The results show that the small nano-crystalline grain will nucleate and grow during the compression deformation. The deformation induces the growth of the ordered clusters in the amorphous metals and the nano-crystalline grain grows under the shearing combination and shearing deposition. The nano-crystalline grain will nucleate in a lower strain under a higher temperature. The combining severe plastic deformation with thermal annealing treatments presents a new opportunity for developing bulk nano-crystalline materials with controlled microstructures.