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γ-AlOOH作为液相法合成γ-Al2O3的前驱体,其形貌与最终产物的性能密切相关。 本文采用水热法合成γ-AlOOH纳米棒,通过改变Al3+浓度和沉淀剂的种类调控γ-AlOOH纳米棒的长径比,利用X射线衍射仪(XRD)和透射电子显微镜(TEM)表征产物的晶体结构和形貌。 结果表明,随Al3+浓度增大可得到长径比在5.9~8.0的γ-AlOOH纳米棒,而改变沉淀剂的种类可进一步将长径比增大到8.0~10.0。 通过对产物结晶过程的分析,发现增大Al3+浓度和增强沉淀剂碱性均可以促进铝离子与羟基的配合。 提高反应体系中Al(OH)3浓度,有利于γ-AlOOH晶粒的成核,促进了晶核之间的定向接触,从而提高了纳米棒的长径比。 长径比为10.0的γ-AlOOH纳米棒烧结所得纳米γ-Al2O3改性变压器油(体积分数为0.1%)的正冲击击穿强度较纯油提高9.9%. 相似文献
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γ-AlOOH作为液相法合成γ-Al_2O_3的前驱体,其形貌与最终产物的性能密切相关。本文采用水热法合成γ-AlOOH纳米棒,通过改变Al3+浓度和沉淀剂的种类调控γ-AlOOH纳米棒的长径比,利用X射线衍射仪(XRD)和透射电子显微镜(TEM)表征产物的晶体结构和形貌。结果表明,随Al3+浓度增大可得到长径比在5.9~8.0的γ-AlOOH纳米棒,而改变沉淀剂的种类可进一步将长径比增大到8.0~10.0。通过对产物结晶过程的分析,发现增大Al3+浓度和增强沉淀剂碱性均可以促进铝离子与羟基的配合。提高反应体系中Al(OH)3浓度,有利于γ-AlOOH晶粒的成核,促进了晶核之间的定向接触,从而提高了纳米棒的长径比。长径比为10.0的γ-AlOOH纳米棒烧结所得纳米γ-Al_2O_3改性变压器油(体积分数为0.1%)的正冲击击穿强度较纯油提高9.9%. 相似文献
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A novel compound of 1,2-dis(1,3-diphenylpropan-2-yl)disulfane(C30H30S2,Mr=454.27)was synthesized in ethanol with 1,3-diphenyl-2-propanone as raw materials,giving high yield of product(90%).Its structure was determined by IR,1H NMR,MS,elemental analysis and X-ray diffraction.The crystal belongs to monoclinic,space group C2 with a=18.727(3),b=6.5179(9),c=13.7576(18),β=131.0610(10)o,V=1266.2(3)3,Z=2,Dc=2.136 g/cm3,μ=1.078 mm-1,F(000)=843,R=0.0490 and wR=0.1247 for 3211 observed reflections with I>2(I).X-ray analysis reveals that the molecule is not symmetrical.There exist no classical hydrogen bonds andπ-πstacking interactions.Moreover,the thermal stability of compound 3 was investigated. 相似文献
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The title compound of Cu(C14H9O3)2(C5H5N)2(C2H5OH)2(1) was synthesized via the hy- drothermal reaction of CuCl2·2H2O and 9-hydroxy-fluorene-9-carboxylic acid(HHF) with pyridine, and characterized by elemental analysis and infrared spectra. The crystal belongs to triclinic, space group P1 with a = 8.8302(12), b = 10.1625(14), c = 12.2708(17), α = 86.207(2), β = 69.562(2), γ = 64.932(2)o, V = 930.3(2) 3, Z = 1, Mr = 764.30, Dc = 1.364 g/cm3, F(000) = 399, S = 1.059 and μ(MoKα) = 0.644 mm-1. The final R = 0.0459 and wR = 0.1274 for 3414 observed reflections with I 2σ(I). The copper atom is six-coordinated by two oxygen atoms from two different 9-hydroxy-fluorene-9-carboxylate ligands, two pyridine nitrogen atoms and two ethanol oxygen atoms, forming a distorted octahedral coordination geometry. The extensive O–H···O hydrogen bonding connects the molecules to form a one-dimensional chain structure. Between adjacent one-dimensional chains, a two-dimensional layered structure was formed by fluorene ring π-π packing interaction. Between the layers, a three-dimensional structure was formed through the π-π packing interaction of the pyridine ring. Moreover, the thermal stability and photoluminescent property of the complex has been investigated. 相似文献
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题 1 (湖北襄樊市 2 0 0 2年 5月高三质量检测题 )已知二次函数 f ( x) =ax2 ( 2 a -1 ) x 1在区间 [- 32 ,2 ]上的最大值为 3,求参数 a的值 .命题溯源 此题与 2 0 0 1年湖北荆州市高中毕业班质量检查题第 1 9题、2 0 0 1年湖北黄冈市高三第二次模拟考试第 2 1题类似 .二次函数在某区间上的最值问题是高考命题中经久不衰的“热点”,是考查学生能力和数学素养的一个好素材 .原解思路 ( 1 )当 a >0时 ,由于二次函数图像开口向上 ,则最大值只能在 [- 32 ,2 ]的端点处取得 .1若 f( - 32 ) =3,则得 a =- 23,与 a >0矛盾 ,舍去 .2若 f( 2… 相似文献
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