共查询到20条相似文献,搜索用时 93 毫秒
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采用溶胶-凝胶法制备氧化铝掺杂纳米钴锌铁氧体.通过X射线衍射(XRD)与透射电子显微镜(TEM)等测试手段对材料的形貌和结构进行了表征.结果表明产物有超纳米晶态出现. 相似文献
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以硝酸溶解废旧碱性锌锰电池所得的溶液为原料,在溶胶-凝胶法的基础上,与水热方法耦合,制备出了具有尖晶石结构的锰锌铁氧体.经IR、XRD对所得锰锌铁氧体的结构进行了确证,利用VSM测试了材料的磁性能,探讨了不同制备条件对材料结构和性能的影响.结果表明,制备锰锌铁氧体的最适宜条件为:干凝胶自蔓延燃烧后维持200℃温度0.5h后,在200℃条件下水热反应4h,在该条件下,制备的锰锌铁氧体的磁性能参数为饱和磁化强度为58.490 emμ/g,7.8311 emμ/g,矫顽力为69.559 Oe,具有较为优良的磁性能. 相似文献
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采用溶胶-凝胶法制备锌铁氧体和钡铁氧体,并研究其对雷达波的吸收性能。结果表明,在800℃煅烧1h,得到了锌铁氧体;在900℃煅烧1h,得到了钡铁氧体。钡铁氧体对雷达波的吸波性能较强,其在频率10GHz、11GHz的反射损耗分别为11.27dB和12.01dB。 相似文献
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机械力化学合成CaTiO_3纳米晶的研究 总被引:1,自引:0,他引:1
研究了采用高能球磨机混合粉磨CaO ,TiO2 的机械力化学变化过程 .发现在一定操作参数 (行星磨公转转速 30 0r/min ,自转 2 0 0r/min)条件下 ,粉磨初期 ( 2h)为无定形形成期 ,混合物颗粒粒度减小 ,晶格畸变 ,转变为无定形 ,并形成CaTiO3 晶核 ;粉磨中期 ( 2~ 10h)为晶粒生长期 ,CaTiO3 晶粒长大 ;粉磨后期 ( 10h以后 )为动态平衡期 ,晶粒生长与粉磨引起的晶粒减小处于动态平衡 ,锐钛矿型TiO2 能够转变为金红石型TiO2 ,具有较好的反应活性 .XRD ,TEM ,FT -IR研究表明 :混合粉磨CaO ,TiO2 可机械力化学合成CaTiO3 纳米晶体 ,晶粒尺寸为 2 0~ 30nm 相似文献
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A Espíndola-Gonzalez AL Martínez-Hernández C Angeles-Chávez VM Castaño C Velasco-Santos 《Nanoscale research letters》2010,5(9):1408-1417
The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost
with annelids (Eisenia foetida) is reported. The product (humus) is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD), transmission electron microscopy
(TEM), high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS) show that the biotransformation
allows creating specific crystalline phases, since equivalent particles synthesized without biotransformation are bigger and
with different crystalline structure. 相似文献
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Boehmite (γ-AlOOH) nanoparticles were successfully synthesized by the two-reverse emulsion technique at 90°±1°C under constant agitation with varying Al3+ concentrations in the aqueous solution. A mixture of cyclohexane and the surfactant, sorbitan monooleate (Span 80), constituted the support solvent in the reverse emulsions. The synthesized particles were characterized by thermogravimetry, differential thermal analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), particle size analysis, and transmission electron microscopy (TEM). XRD and FTIR results confirmed crystalline boehmite formation at 90°±1°C. The average particle size of boehmite was found to be 10 nm. The spherical morphology of the boehmite nanoparticles was confirmed by TEM. 相似文献
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Dianying Chen Eric H. Jordan Maurice Gell 《Journal of the American Ceramic Society》2008,91(8):2759-2762
Yttrium aluminum garnet (Y3 Al5 O12 , YAG) nanocrystalline powders were synthesized by a novel sol–gel combustion process. Yttrium acetate and aluminum sec-butoxide were used as the precursors and triethanolamine was used as the chelating agent and fuel. Thermal and crystallization behaviors of the YAG precursor powders were investigated by thermal gravimetric differential thermal analysis (DTA), Fourier transform infrared spectrum, and X-ray diffraction. The combustion-synthesized powders are amorphous and transform to a pure YAG crystalline phase at 900°C. The crystallization activation energy of amorphous YAG precursor was investigated by variable heating rate DTA. The calculated activation energy is 58.9 KJ/mol. The average crystalline size of heat-treated YAG powders at 900°C is ∼20 nm. 相似文献
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含2种介晶基元的液晶弹性体合成与性能研究 总被引:1,自引:0,他引:1
合成了一种向列液晶单体(M1)和一种新型手液晶交联单体(M2),与含氢聚硅氧烷(PM-HS)接枝共聚。交联剂的摩尔分数从0-20%,得到了一系列侧链液晶弹性体P1-P7。通过差式扫描量热仪(DSC)、偏光显微镜(POM)和X-射线分析等手段对聚合物的结构、液晶性能及热性能进行了表征。结果表明,聚合物P1为向列液晶聚合物,P2-P6为胆甾液晶弹性体,P7没有液晶性。随着交联单体M2摩尔分数在体系中的增加,聚合物的玻璃化转变温度(Tg)、清亮点(Ti)和介晶范围逐渐降低。 相似文献
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We report a method for synthesizing quasi-single crystalline porous ZnO nanostructures containing a single large cavity. The microwave-assisted route consists of a short (about 2 min) temperature ramping stage (from room temperature to 120 °C) and a stage in which the temperature is maintained at 120 °C for 2 h. The structures produced by this route were 200-480 nm in diameter. The morphological yields of this method were very high. The temperature- and time-dependent evolution of the synthesized powders and the effects of an additive, vitamin C, were studied. Spherical amorphous/polycrystalline structures (70-170 nm in diameter), which appeared transitorily, may play a key role in the formation of the single crystalline porous hollow ZnO nanostructures. Studies and characterization of the nanostructures suggested a possible mechanism for formation of the quasi-single crystalline porous ZnO nanostructures with an interior space. 相似文献