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121.
Ali Saberi Zahra Negahdari Sofiane Bouazza Monika Willert-Porada 《Journal of fluorine chemistry》2010,131(12):1353-1355
Nanosized MgF2 was synthesized by precipitation in microemulsions of water in cyclohexane stabilized by polyethylene glycol tert-octylphenyl ether. The synthesized MgF2 powder was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), BET specific surface area, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD). The results showed that the synthesized powder was a MgF2 powder with a crystallite size in the range of 9-11 nm and a specific surface area of 190 m2/g. 相似文献
122.
The luminescent nanocrystalline Yb3+ and Er3+ codoped KLa(WO4)2 has been prepared by Pechini method. X-ray diffraction and transmission electron microscope were used to study the structure of the obtained samples. The average grain size of these samples depended on the annealing temperature, increasing with the increase of the temperature. The cell parameters and the crystallite size of KYbxEr0.02La0.98−x(WO4)2 nanocrystalline decreased with the increase of x value. Luminescence studies showed that the intensity of upconversion emission of the Yb3+ and Er3+ codoped samples was much stronger than that of the Er3+ single doped samples (pumped by 980 nm LD). The upconversion emission mechanisms suggested that all the three bands of upconversion emissions were two-photon process. 相似文献
123.
Ag2Se, CuSe and PbSe were prepared by irradiating the mixtures of AgNO3, CuI or PbCl2 with selenium in ethylenediamine (en) with ultrasound at 18 kHz, using a commercial ultrasonic cleaner, respectively. X-ray powder diffraction (XRD) patterns and transmission electron microscope (TEM) images show that the products are orthorhombic Ag2Se, hexagonal CuSe and cubic PbSe, respectively, and all are well crystallized in nanometers. 相似文献
124.
The soft magnetic nanocrystalline/amorphous FeSiB flakes were fabricated by the ball-milling method and evaluations were made of the composition, microstructure, magnetic and microwave properties in the milling process. An investigation of the relationship between microstructure and magnetic/microwave properties showed that the electromagnetic characteristics were attributed to the changes of nanograin size, crystal and amorphous content corresponding to the composition variation. The replacing of Fe atoms by Si in α-Fe crystal caused the decrease of grain size, saturation magnetization and coercivity, while B content devoted to amorphous phase and decreased the permittivity. Consequently, it was observed that the optimum composition for microwave performance is Fe82Si5B13. 相似文献
125.
R.K. Murakami H.R. Rechenberg A.C. Neiva F.P. Missell V. Villas-Boas 《Journal of magnetism and magnetic materials》2008,320(14):e65-e68
Effects of titanium carbide (TiC) addition on structural and magnetic properties of isotropic (Pr,Nd)–Fe-B nanocrystalline magnetic materials have been investigated. In this work, we investigate the effect of TiC addition on a (Pr,Nd)-poor and B-rich composition, as well as on a B-poor and (Nd,Pr)-rich composition. Rapidly solidified (Pr,Nd)–Fe–B alloys were prepared by melt-spinning. The compositions studied were (Pr1−xNdx)4Fe78B18 (x=0, 0.5, and 1) with addition of 3 at% TiC. Unlike the (PrxNd1−x)9.5Fe84.5B6 materials that present excellent values for coercive field and energy product, the (Pr,Nd)-poor and B-rich composition alloys with TiC addition present lower values. Rietveld analysis of X-ray data and Mössbauer spectroscopy revealed that samples are predominantly composed of Fe3B and -Fe. For the RE-rich compositions (PrxNd1−x)9.5Fe84.5B6 (x=0.1, 0.25, 0.5, 0.75, and 1) with the addition of 3 at% TiC, the highest coercive field and energy product (8.4 kOe and 14.4 MGOe, respectively) were obtained for the composition Pr9.5Fe84.5B6. 相似文献
126.
Er2O3纳米晶光伏特性及谱带解析 总被引:1,自引:0,他引:1
纳米做教是介于体相材料和分子或原子之间的新型材料,表现出许多超常的电、热、光、磁及催化的特性,因此引起人们高度的重视[1,2].目前对其光学、磁学、力学和比热等研究已有大量的报导[3].但是,对于稀土氧化物纳米材料的合成及性质的研究,尤其对它们的电学性质、电子输运方式和光电行为报导较少.本文利用表面光电压谱(SPS)技术对不同粒径的Er2O3纳米晶进行了表面光伏特性的研究,并结合漫反射吸收光谱对其谱带进行了解析,发现,除f→f跃迁外,在300~550nm区间有一定吸收边带,此带可归属于O2p→Er4f电荷转移跃迁.随着样品… 相似文献
127.
128.
Mona Mouallem-Bahout Sarah Bertrand Octavio Peña 《Journal of solid state chemistry》2005,178(4):1080-1086
Nanocrystalline single-phase samples of Zn1−xNixFe2O4 ferrites (0<x<1) have been obtained via a soft-chemistry method based on citrate-ethylene glycol precursors, at a relatively low temperature (650 °C). The influence of the nickel and zinc contents as well as that of heat treatments were investigated by means of X-ray powder diffraction, Brunauer-Emmett-Teller (BET) surface area, scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy. Higher Ni content increases the surface areas, the largest one (∼20 m2/g) being obtained for NiFe2O4 annealed at 650 °C for 15 h. For all compositions, the surface area decreases for prolonged annealing at 650 °C and for higher annealing temperatures. Those results were correlated to the particle size evolution; the smallest particles (∼50 nm) observed in the NiFe2O4 sample (650 °C, 15 h) steadily increase as Ni ions were replaced by Zn, reaching ∼100 nm in the ZnFe2O4 sample (650 °C, 15 h). For all the Zn1−xNixFe2O4 samples and, whatever the heat treatments was, the FTIR spectra show two fundamental absorption bands in the range 650-400 cm−1, characteristics of metal vibrations, without any superstructure stating for cation ordering. The highest ν1-tetrahedral stretching, observed at ∼615 cm−1 in NiFe2O4, shifts towards lower values with increasing Zn, whereas the ν2-octahedral vibration, observed at 408 cm−1 in NiFe2O4, moves towards higher wavenumbers, reaching 453 cm−1 in ZnFe2O4. 相似文献
129.
Jun Zhang Yongdong Yang Baolong Xu Feihong Jiang Jianping Li 《Journal of Crystal Growth》2005,280(3-4):509-515
A simple efficient thermal evaporation technique, oxidizing zinc foils and in situ evaporating at 700 °C in air without the presence of catalyst and carrier gas, was developed to control the growth of the different morphologies of ZnO nano- and micro-structures. Porous membrane, nanowires (or nanorods), nanobelts, nanoneedles, and tetrapods have been achieved through tuning the heating rates in a tube furnace. The morphologies and microstructures of samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Our deterministic growth of different shapes of ZnO crystals offers ideal model system to study the physical properties. 相似文献
130.
机械合金化Mg/MmNi5-x(CoAlMn)x复合储氢合金的组织结构与吸氢特性 总被引:6,自引:0,他引:6
运用X射线衍射、扫描电及粒度分析等方法表征了机械合金化制备Mg/MnNi5-x(CoAlMn)x复合储氢合金的结构,通过PCT曲线研究了基储氢性能。结果表明,在适当的球磨条件下能够获得纳米晶结构的Mg/MnNi5-x(CoAlMn)x复合储氢合金,MmNi5-x(CoAlMn)x合金相彘,复合储氢合金的活化性能及储氢量有明显提高。此外,还考察了Mg含量对复合储氢合金的组织结构及储氢性能的影响。 相似文献