共查询到20条相似文献,搜索用时 245 毫秒
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采用化学共沉淀法成功地制备出适用于彩电显象管内荧光体着色的CoxR1-xAl2O4(R=Zn、 Mg, x=0.8~1.0)钴蓝颜料: 450nm波长处反射率最大提高18.2%, 600nm处反射率最大降低5%。通过对该颜料反射率的影响因素,如掺杂离子类型、掺杂浓度和Co2+离子浓度的探讨,结论如下:Zn2+、Mg2+改变钴蓝颜料反射性能的作用机理为晶格畸变引起Co2+3d轨道电子能级分裂程度的变化;对于掺杂离子Zn2+、Mg2+,x下限值分别约为0.85和0.8. 相似文献
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非均相沉淀法制备Al2O3-YAG复相陶瓷 总被引:1,自引:0,他引:1
本文测量了YAG粉体的ξ电位,通过调节pH值获得均匀分散的YAG水悬浮液.采用非均相沉淀方法获得YAG分布均匀的Al2O3-YAG复合粉体.通过热压烧结得到致密烧结体,YAG的加入对烧结温度的影响不大.Al2O3-5vol%YAG复相陶瓷的抗弯强度为485MPa,断裂韧性为4.2MPa·m1/2,均高于单相Al2O3陶瓷,数据的重复性好于球磨混合所制备的样品.通过TEM观察,YAG颗粒均匀分布于整个样品中,表明通过非均相沉淀制粉可以获得YAG颗粒分布均匀的Al2O3-YAG复相陶瓷. 相似文献
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Huanping Wang Qinghua Yang Denghao Li Lihui Huang Shilong Zhao Shiqing Xu 《材料科学技术学报》2012,28(8):751-755
The B2O3-doped MgTiO3 powders and ceramics have been prepared by sol-gel method using Mg(NO3)2·6H2O, Ti(C4H9O)4 and H3BO3 as the starting materials. The sintering behavior and microwave dielectric properties of ceramics prepared from powders with different particle sizes were investigated. The gels were calcined at 650, 700, 750, 800, 850 and 900 C and the derived particle sizes of powders were 20-30 nm, 30-40 nm, 40-60 nm, 60-90 nm, 90-120 nm and 120-150 nm, respectively. The nanoparticles with the size of 30-60 nm benefited the sintering process with high surface energy whereas nanoparticles with the size of 20-30 nm damaged the microwave dielectric properties due to the pores in the ceramics. The addition of B2O3 used as a liquid sintering aid reduced the sintering temperature of MgTiO3 ceramic, which was supposed to enter the MgTiO3 lattice and resulted in the formation of (MgTi)2(BO3)O phase. The B2O3-doped MgTiO3 ceramic sintered at 1100 C and prepared from the nanoparticles of 40-60 nm had compact structure and exhibited good microwave dielectric properties: εr=17.63, Q × f=33,768 GHz and τ f= 48×10 6 C 1. 相似文献
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Yang H Huang D Wang X Gu X Wang F Xie S Yao X 《Journal of nanoscience and nanotechnology》2005,5(10):1737-1740
III-V semiconductor nanocrystals rarely exist as spherical inclusions inside glasses, due to difficulties during their preparation, such as high toxic reagents or fast oxidation under usual glass technology temperatures. In this letter a sol-gel method for synthesis of InP nanocrystals embedded in silica glasses was described. Gels were synthesized by hydrolysis of a complex solution of Si(OC2H5)4, InCl3.4H2O, and PO(OC2H5)3. Then, the gels were heated at 600 degrees C in the presence of H2 gas to form fine cubic InP crystallites. Raman spectrum showed an InP longitudinal-optic mode (342 cm(-1)) and a transverse-optic mode (303 cm(-1)). The size of InP nanocrystals was found to be from 2 to 8 nm in diameter by transmission electron microscopy. A strong photoluminescence with a peak at 856 nm was observed from InP nanocrystals embedded in silica glasses. The results suggest that it might be possible to synthesize other III-V semiconductor nanocrystals embedded in silica glasses through the sol-gel process. 相似文献
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Yang H Yao X Huang D Wang X Shi HZ Zhang B Liu S Fang Y 《Journal of nanoscience and nanotechnology》2005,5(5):786-789
III-V semiconductor nanocrystals rarely exist as spherical inclusions inside glasses, due to the difficulties during their preparation, such as high toxic reagents or fast oxidation under usual glass technology temperatures. In this paper a sol-gel method for synthesis of InAs nanocrystals embedded in silica glasses was described. Gels were synthesized by the hydrolysis of a complex solution of Si(OC2H5)4, InCl3 x 4H2O, and As2O3. The gels were then heated at 200-450 degrees C in the presence of H2 gas to form fine cubic InAs crystallites. The X-ray diffraction patterns showed four strong peaks from InAs. The Raman spectrum showed InAs longitudinal-optic (233 cm(-1)) and transverseoptic modes (215 cm-(-1)). The size of InAs nanocrystals was found to be from 5 to 30 nm in diameter by transmission electron microscopy. A strong room temperature photoluminescence with peaks at 601 and 697 nm was observed from InAs nanocrystals embedded in silica glasses. The results suggest that it might be possible to synthesize other III-V semiconductor nanocrystals embedded in silica glasses through the sol-gel process. 相似文献
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NiFe2O4纳米晶的制备及表面效应对其比饱和磁化强度的影响 总被引:3,自引:1,他引:2
以FeSO4*7H2O和NiSO4*7H2O为原料,首先制备出颗粒细小的碱式碳酸盐前驱体,在300~700℃焙烧1h后,制备出铁酸镍纳米晶,粒径为8~54nm,粒度均匀。通过测量它的比饱和磁化强度σs与比表面积Sa,得出经验公式σs(Sa)=σs(∞)(1-aSa),运用非共线磁结构理论很好地解释了上述经验公式,并得到纳米晶的非共线表面层的厚度。,A basic carbonate precursor with very fine particles was synthesied by using FeSO4*7H2O and NiSO4*7H2O, and NiFe2O4 nanocrystallites were then obtained by calcining the precursor. The results of XRD and TEM analysis show the NiFe2O4 nanocrystallites with spherical shape are even, and their average diameters increase from 8nm to 54nm when the precursor is calcined at 300—700℃ for 1h. Their specific saturation magnetization σs and specific surface area Sa were measured. A empirical formula σs(Sa)=σs(∞)(1-aSa)was obtained which can be interpreted very well by a noncollinear magnetic structure model, and the value of the canted-layer thickness was deduced. 相似文献
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以FeSO4(NH4)2SO4、6H2O、CoCl2·6H2O、C6H5Na3O7·2H2O为前驱物,采用水热法合成了钴铁氧体CoFe2O4。用XRD、TEM、VSM分别测试了CoFe2O4颗粒大小、形貌、饱和磁化强度和矫顽力,探讨了反应时间、温度、溶质浓度、酸碱环境对颗粒粒径大小、形貌及其磁性能的影响。结果表明,适度的减短反应时间、降低温度、选取合适的溶质浓度和NaOH溶液浓度,可以得到粒径小、形貌统一的纳米颗粒,并且有助于增大CoFe2O4颗粒的饱和磁化强度。 相似文献
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Highly selective and sensitive detection of trimethylamine (TMA) was achieved by the decoration of discrete p-type Cr(2)O(3) nanoparticles on n-type ZnO nanowire (NW) networks. Semielliptical Cr(2)O(3) nanoparticles with lateral widths of 3-8 nm were deposited on ZnO NWs by the thermal evaporation of CrCl(2) at 630 °C, while a continuous Cr(2)O(3) shell layer with a thickness of 30-40 nm was uniformly coated on ZnO NWs at 670 °C. The response (R(a)/R(g): R(a), resistance in air; R(g), resistance in gas) to 5 ppm TMA of Cr(2)O(3)-decorated ZnO NWs was 17.8 at 400 °C, which was 2.4 times higher than that to 5 ppm C(2)H(5)OH and 4.3-8.4 times higher than those to 5 ppm p-xylene, NH(3), benzene, C(3)H(8), toluene, CO, and H(2). In contrast, both pristine ZnO and ZnO (core)-Cr(2)O(3) (shell) nanocables (NCs) showed comparable responses to the different gases. The highly selective and sensitive detection of TMA that was achieved by the deposition of semielliptical Cr(2)O(3) nanoparticles on ZnO NW networks was explained by the catalytic effect of Cr(2)O(3) and the extension of the electron depletion layer via the formation of p-n junctions. 相似文献
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采用改良的溶胶-凝胶法制备系列的As2O3纳米粒,用透射电镜、扫描电镜、能谱仪、图像分析系统等进行表征及特性检测.应用MTT法研究As2O3纳米粒体外对细胞的增殖抑制作用;用流式细胞仪测定As2O3纳米粒及亚砷酸诱导细胞的凋亡率;用免疫组织化学半定量法检测As2O3纳米粒及亚砷酸处理细胞后Bcl-2、Bax、CD44v6和P53基因的表达改变.研究结果表明,制备的As2O3纳米粒在电镜下呈圆形或椭圆形,分散性较好,平均直径约为80nm、110nm、130nm、150nm和450nm;体外细胞实验证实As2O3纳米粒抗肺癌A-549细胞的效应强于亚砷酸溶液;免疫组织化学半定量法显示As2O3纳米粒有较强的诱导肺癌细胞凋亡的作用,可能与其改变Bcl-2和Bax基因表达(Bcl-2/Bax比值降低)及促进P53基因的表达、抑制CD44v6基因表达有关. 相似文献
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采用改进的聚丙烯酰胺凝胶法合成了YMn2O5纳米颗粒.XRD分析结果表明,合成的纳米颗粒主要为正交YMn2O5相,兼有少许的六方YMn2O5相,无其它杂质相存在.SEM观察显示,制得的YMn2O5纳米颗粒粒度均匀、形貌规整、呈类球形,平均颗粒尺寸约为45nm.利用紫外—可见光漫反射光谱研究了YMn2O5纳米颗粒的光吸收特性及带隙,获得的光学带隙值为1.21eV.以一种典型的偶氮染料甲基红为目标降解物,研究了YMn2O5纳米颗粒的光催化活性.结果表明,在紫外光和可见光辐照下纳米颗粒均表现出了良好的光催化活性.实验确定了光催化降解率的最佳条件:甲基红的初始浓度为~15mg/L,催化剂的加载量为~1.2g/L. 相似文献
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Stoichiometric MgAl2O4 spinel nanoparticles were synthesized by microwave assisted combustion reaction from aluminium nitrate nanohydrate(Al(NO3)3.9H2O) and Sol-Gel prepared magnesium hydroxide(Mg(OH)2) in the presence of urea((NH2)2CO) as a fuel,in about 20 min of irradiation.X-ray diffraction(XRD) studies reveal that mi-crowave assisted combustion synthesis route yields single-phase spinel nanoparticles with larger crystalline size(around 75 nm) than other conventional heating methods.Scanning electronic microscope(SEM) images show nanoparticles with spherical shape and homogenous morphology.The surface area measurements(SBET) show crystals with 2.11 m2/g and 0.0033 mL/g pore volume. 相似文献