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共沉淀法制备纳米Fe3O4及其对橙黄Ⅱ的降解 总被引:1,自引:0,他引:1
通过共沉淀法制备Fe3O4纳米颗粒,采用X射线衍射(XRD)、扫描电子显微镜(SEM)和比表面孔隙分析(BET)对样品进行表征。以合成的纳米Fe3O4催化H2O2氧化降解橙黄Ⅱ,考察了共沉淀法制备过程中的Fe2+/Fe3+的摩尔比、反应温度、pH值、Fe离子浓度等因素对Fe3O4催化性能的影响。结果表明在Fe2+/Fe3+的摩尔比为3∶4、反应温度80℃、pH值为10、Fe离子浓度为0.1mol·L-1的条件下制备出的Fe3O4纳米颗粒催化活性最高,其粒径为20nm左右。并且未干燥的磁流体对橙黄Ⅱ的降解效率明显高于Fe3O4粉体。 相似文献
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磁场诱导自蔓延高温合成钡铁氧体 总被引:1,自引:0,他引:1
本文采用外加磁场诱导自蔓延高温合成钡铁氧体,试验用的电磁场强度最高可达1.3T,对无磁场和不同磁场强度下合成的铁氧体的形貌、相组成和磁性能分别进行了表征.研究结果表明:外加磁场对燃烧温度有影响,燃烧温度影响产物转换,燃烧温度较低时,产物为BaFe2O4与BaFe12O19相共存;本试验条件下,磁场强度为0.86T时,合成为M型的钡铁氧体(BaFe12O19),产物结晶完整,有六角片状的钡铁氧体,且性能达到了最佳,矫顽力达到1083(4π)-1·kA·m-1,比剩余磁化强度为16.16 A·m2/kg,比不加磁场条件下分别提高50%和提高32%,说明适当的磁场强度诱导自蔓延高温合成可以改善BaFe12O19的磁性能. 相似文献
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以硝酸钡、硝酸铁和柠檬酸为原料,采用溶胶-凝胶法制备了单相钡铁氧体(BaFe12O19)纳米粉体,并进一步研究了n(Fe)/n(Ba)、热处理温度对产物组成、形貌以及磁性能的影响。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和振动样品磁强计(VSM)分别对样品的组成、形貌和磁性能进行了表征。实验结果表明,当煅烧温度不变时,样品的晶粒尺寸随着n(Fe)/n(Ba)的增大而变大,磁性能随n(Fe)/n(Ba)的增大而增强;当n(Fe)/n(Ba)不变时,样品的晶粒尺寸随着煅烧温度的升高而变大。当n(Fe)/n(Ba)=12时,在800℃煅烧2h得到单一晶型的钡铁氧体粉体。1000℃时样品的磁性能最佳,饱和磁化强度(Ms)为70.88A.m2/kg,矫顽力(Hc)为372.89kA/m。 相似文献
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用水热法在不同温度下制备结晶性较好、颗粒均一的CoFe2O4纳米颗粒,无需进一步煅烧。利用X射线衍射仪(XRD)、场发射扫描电镜(SEM)、穆斯堡尔谱仪和综合物性测量系统(PPMS)对不同温度下合成的样品进行表征。结果表明,随着合成温度的升高,CoFe2O4纳米颗粒的结晶性增强,粒径逐渐增大,样品的饱和磁化强度逐渐增强。当合成温度为500℃时,CoFe2O4纳米颗粒的饱和磁化强度达到64.1A.m2/kg,与块体的CoFe2O4(72A.m2/kg)接近。穆斯堡尔谱分析表明,当晶粒粒径超过了超顺磁性的临界尺寸,样品的超顺磁性消失,随着合成温度的升高,B位上Fe3+离子的比例增高,磁性能增强。 相似文献
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新型中温固体氧化物燃料电池阴极材料Ba0.5Sr0.5Co0.8Fe0.2O3-δ的制备 总被引:1,自引:1,他引:0
碳酸共沉淀法合成了新型中温固体氧化物燃料电池(ITSOFC)阴极材料Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF).利用XRD、DSC、TG、SEM和EDX等手段研究了不同煅烧温度对产物相结构、形貌和成分的影响.结果表明,前驱体经过1000℃煅烧2h后,产物形成了钙钛矿结构,但存在少量BaO或SrO杂相.随着煅烧温度提高,产物中的杂相逐渐消失,产物的晶体结构在1180℃条件下转变为单一的立方型钙钛矿结构,其化学组成为Ba0.51Sr0.49Co0.72Fe0.19O3-δ,而且颗粒均匀,基本在10 μm以下. 相似文献
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利用溶胶-凝胶法,在室温条件下,以钛酸四丁酯、硝酸镧为主要原料,无水乙醇为溶剂,冰醋酸为抑制剂,浓硝酸为催化剂制得稳定的掺La3+TiO2溶胶,陈化后的凝胶经不同温度煅烧3h后制得不同掺La3+量的TiO2。通过XRD对不同煅烧温度及不同掺La3+量的TiO2进行了表征;以紫外光为光源,研究了掺La3+-TiO2对甲基橙溶液的光降解效果。用化学共沉淀法制备了具有强磁性的Fe3O4水基磁流体,再与La3+掺杂TiO2进行复合,制备了Fe3O4负载量不同的磁性La3+掺杂TiO2,研究了Fe3O4负载量不同的La3+掺杂TiO2对甲基橙的光催化降解效果、磁分离回收率的影响。结果表明,掺La3+量及煅烧温度对TiO2的晶型、各晶型TiO2的相对含量及对甲基橙的光降解效果均有影响。La3+掺杂TiO2比纯TiO2显示出更强的光催化性能,掺La3+量2%,热处理温度450℃的La3+掺杂TiO2光催化活性最高。Fe3O4负载量为10%的Fe3O4/La3+-TiO2对甲基橙的降解率8h时为99.4%;磁分离回收率达97.39%。 相似文献
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针对两种新型稀土型储氢合金La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2的储氢特性进行研究分析。实验表明,相同温度下,La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的PCT曲线基本重合,且都具有优良的吸氢动力学性能;相比之下,后者的滞后系数要小于前者,吸氢量较大,吸氢速率也较快,故其储氢性能较优。300次吸放氢循环实验结果表明,La0.5Y0.5Ni4.8Al0.2合金的吸氢动力学性能虽然略有下降,但抗粉化性能较好。 相似文献
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Quanmin YANG Yongquan LEI+ Changpin CHEN Jing WU Qidong WANG Dept. of Mater. Sci. Eng. Zhejiang Univresity Hangzhou China 《材料科学技术学报》1993,9(2):125-128
The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed. 相似文献
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Experimental studies and analysis of acousto-optic diffraction in alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are given. Ultrasonic wave velocity, elastic compliance and stiffness coefficients, and piezo-optic and photoelastic coefficients of alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are determined. The acousto-optic figure of merit has been estimated for different possible geometries of acousto-optic interaction. It is shown that the acousto-optic figures of merit for alpha-BaB(2)O(4) crystals reach the value M(2)=(270 +/- 70) x 10(-15) s(3)/kg for the case of interaction with the slowest ultrasonic wave. The directions of propagation and polarization of those acoustic waves are obtained on the basis of construction of acoustic slowness surfaces. The acousto-optic diffraction is experimentally studied for alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals. 相似文献
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Nanomechanical characterization of one-step combustion-synthesized Al(4)B(2)O(9) and Al(18)B(4)O(33) nanowires 总被引:1,自引:0,他引:1
Two kinds of aluminum borate nanowires, Al(4)B(2)O(9) and Al(18)B(4)O(33), were successfully synthesized by a one-step combustion method through control of the Al:B atomic ratio and synthesis temperature. Both nanowires are single crystalline but have distinguishing growth habits. Nanoindentation tests were performed directly on individual nanowires to reveal their mechanical properties. A 70% reduction in elastic modulus was found in Al(18)B(4)O(33) nanowires compared with their bulk counterpart. Al(18)B(4)O(33) nanowires exhibited higher hardness and elastic modulus than Al(4)B(2)O(9) nanowires. 相似文献
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Natural Passivity of Amorphous Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 Alloys
The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis. 相似文献
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B.M.P. Ferreira L.M.P. Pinheiro P.A.P. Nascente M.J. Ferreira E.A.R. Duek 《Materials science & engineering. C, Materials for biological applications》2009,29(3):806-813
The surfaces of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) were modified by oxygen and nitrogen plasma treatments. The physical and chemical surface characteristics were evaluated by contact angle tests, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The plasma treatments caused an increase in both contact angle and roughening, altered the surface morphology, inserted polar groups, and, consequently, enhanced the hydrophilicity for both PLLA and PHBV polymers. 相似文献
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Junming LIU 《材料科学技术学报》1998,14(3):193-199
Phase decomposition in amorphous Cu12.5Ni10Zr411Ti14Be22.5 alloy as annealed in the super-cooled liquid range was studied by applying small angle neutron scattering (SANS). As annealed between 600 K and 700 K, the alloy was observed to decompose into two new amorphous phases,with the second phase precipitates embedded in the matrix of the first. Long time annealing of the alloy results in crystallization in addition to evolution of the decomposed microstructure.The kinetic diagram of the decomposition and crystallization for this alloy is given. The second phase precipitates have several nanometers in size and occupy a quite low volume fraction. The decomposition of the supercooled liquid in overall temperature range exhibits the features of spinodal reaction. 相似文献