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101.
通过连续多步自组装的方式分别将三唑亚铁(SCO1)和氨基三唑亚铁(SCO2)自旋转换纳米材料生长于氧化铝模板(AAO)的孔道内和表面上。利用扫描电镜(SEM)、红外光谱(IR)、粉末X射线衍射(PXRD)、拉曼光谱(Raman)等手段对SCO1-1D+2D和SCO2-1D+2D纳米材料进行表征,SEM表明随着自组装时间的增加,球状的SCO纳米颗粒生长于AAO孔道内,并逐渐形成1D的纳米结构,而在AAO表面则形成致密均匀的SCO-2D薄膜。两种SCO-1D+2D纳米粒子都具有两步自旋行为(SCO1-1D+2D:Tc1↑=319 K,Tc1↓=313 K,Tc2↑=381 K,Tc2↓=340 K;SCO2-1D+2D:Tc1↑=181 K,Tc1↓=155 K,Tc2↑=246 K,Tc2↓=233 K)。对相应的SCO-1D和SCO-2D磁性结果表明,两步自旋转换行为的产生是由于SCO组装体形貌的差异。其中,低温区的自旋转换行为是由生长于AAO表面的SCO-2D自旋转换性能所致,而发生在更高温度的第二阶段的自旋转换行为则归因于生长于AAO孔道内的SCO-1D的自旋转换性能。 相似文献
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以PEG-2000、柠檬酸和甘氨酸为表面活性剂,采用水热法制备出扁平纳米棒、纳米花和纳米片状的GdF3:Eu3+发光材料,并对其结构和性能进行了表征.XRD结果表明,所得样品均为正交晶系.FESEM照片表明,使用不同表面活性剂所制备的产物形貌不同.研究了以PEG-2000为表面活性剂时反应物浓度对产物形貌的影响,并对其... 相似文献
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M. Bystrzejewski 《Journal of solid state chemistry》2011,184(6):1492-1498
The encapsulation of iron nanoparticles in protective carbon cages leads to unique hybrid core-shell nanomaterials. Recent literature reports suggest that such nanocomposites can be obtained in a relatively simple process involving the solid state carbothermal reduction of iron oxide nanoparticles. This approach is very attractive because it does not require advanced equipment and consumes less energy in comparison to widely used plasma methods. The presented more-in-depth study shows that the carbothermal approach is sensitive to temperature and the process yield strongly depends on the morphology and crystallinity of the carbon material used as a reductant. 相似文献
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Nanocelluloses: a new family of nature-based materials 总被引:2,自引:0,他引:2
Klemm D Kramer F Moritz S Lindström T Ankerfors M Gray D Dorris A 《Angewandte Chemie (International ed. in English)》2011,50(24):5438-5466
Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants. 相似文献
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Anatase TiO2 nanosheets (TiO2 NS) with dominant (001) facets and TiO2 nanoparticles (TiO2 NP) with dominant (101) facets are fabricated by hydrothermal hydrolysis of Ti(OC4H9)4 in the presence and absence of hydrogen fluoride (HF), respectively. Adsorption of N719 onto the as‐prepared samples from ethanol solutions is investigated and discussed. The adsorption kinetic data are modeled using the pseudo‐first‐order, pseudo‐second‐order, and intraparticle diffusion kinetics equations, and indicate that the pseudo‐second‐order kinetic equation and intraparticle diffusion model can better describe the adsorption kinetics. Furthermore, adsorption equilibrium data of N719 on the as‐prepared samples are analyzed by Langmuir and Freundlich models; this suggests that the Langmuir model provides a better correlation of the experimental data. The adsorption capacities (qmax) of N719 on TiO2 NS at various temperatures, determined using the Langmuir equation, are 65.2 (30 °C), 68.2 (40 °C), and 76.6 (50 °C) mg g−1, which are smaller than those on TiO2 NP, 92.4 (30 °C), 100.0 (40 °C), and 108.2 (50 °C) mg g−1, respectively. The larger adsorption capacities of N719 for TiO2 NP versus NS are attributed to its higher specific surface areas. However, the specific adsorption capacities (qmax/SBET) at various temperatures are 1.5 (30 °C), 1.6 (40 °C), and 1.7 (50 °C) mg m−2 for TiO2 NS, which are otherwise higher than those for NP, 0.9 (30 °C), 1.0 (40 °C), and 1.1 (50 °C) mg m−2, respectively. The larger specific adsorption capacities of N719 for TiO2 NS versus NP are because the (001) surface is more reactive for dissociative adsorption of reactant molecules compared with (101) facets. Notably, the qmax and qmax/SBET for both TiO2 samples increase with increasing temperature, suggesting that adsorption of N719 on the TiO2 surface is an endothermic process, which is further confirmed by the calculated thermodynamic parameters including free energy, enthalpy, and entropy of adsorption process. The present work will provide a new understanding on the adsorption process and mechanism of N719 molecules onto TiO2 NS and NP, and this should be of great importance for enhancing the performance of dye‐sensitized solar cells. 相似文献