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1.
用循环伏安和红外光谱法对α-Fe2O3在室温LiOH溶液中的锂化行为进行研究,采用X射线衍射(XRD)、电感偶合等离子体光源的原子发射光谱(ICP)对α-Fe2O3电极在第一、二次循环中不同时段进行了跟踪分析测量。实验结果揭示:α-Fe2O3能进行少量锂化;大量的α-Fe2O3在第一次放电和充电后反应生成Fe3O4;之后,Fe3O4的锂化行不可避免地为Fe的析出,氧化反应所限制,但在用KOH作电解  相似文献   

2.
固溶体α-(Fe_(1-x)Sb_x)_2O_3(0≤x≤0.2)气敏材料   总被引:1,自引:2,他引:1  
用化学共沉淀法在a-Fe_2O_3,中掺入锑离子,X-射线衍射(XRD)分析证实,锑离子可固溶于n型半导体a-Fe_2O_3中形成a-(Fe_1-xSb_x)_2O_3(0《x《0.2)固溶体。由于锑离子(Sb ̄5+)部分取代a-Fe_2O_3晶格中Fe ̄3+的格位,使得该系列材料的电导值增大一个数量级以上,气敏性能明显改善。  相似文献   

3.
Fe/ZrO2催化剂的Mossbauer谱及XAFS表征   总被引:3,自引:0,他引:3  
索掌怀  寇元  王弘立 《催化学报》2000,21(6):586-590
考察了经不同温度还原的Fe/ZrO2催化剂在CO2加氢制低碳烃反应中的催化活性,最佳结果为CO2转化率27.0%,对C2+烃的选择性56.7%,采用XRD,^57FeMossbauer谱,Fe-K-吸收边的X射线吸收近边结构(XANES)及扩展X射线吸收精细结构(EXAFS)等表征方法研究了催化剂的表面结构。结果表明,在ZrO2表面上主要存在α-Fe及配位不饱和的Fe^3+两种物种。催化剂表面明显呈氧缺位,零价铁相对富集的状态,还原温度对表面结构有显著的影响,最佳还原温度与表面Fe-O键的键长有关,结合这种催化剂在CO2加氢制低碳烃反应中的催化活性,认为α-Fe与配位不饱和的Fe^3+物种的协同作用是其具有较高催化活性的重要原因。  相似文献   

4.
刘强  邓勃 《分析化学》1993,21(11):1258-1262
本文应用X-射线衍射,X-射线光电子能谱,俄歇电子能谱和其它一些实验,考察石墨炉升温过程中氟化锗,锗酸钠在石墨探针表面上的形态变化,阐明了它们的原子化机理:GeF2与Na2GeO3首先分解为GeO2,GeO2还原为GeO,后者在>2400K热分解产生自由态的锗原子,GeF2和Na2GeO3的原子化均源于GeO(g)的气相分解。原子化的升温过程中,在1400-2400K GeF2和Na2GeO3都产  相似文献   

5.
ANOVELREACTIONBETWEENGe-GeANDFe-FeBONDSINCOMPLEX(Me_2GeGeMe_2)[(η~5-C_5H_4)Fe(CO)]_2(μ-CO)_2ANDCRYSTALSTRUCTUREOFTHEPRODUCT¥XiuT?..  相似文献   

6.
用循环伏安和红外光谱法对α-Fe_2O_3在室温LiOH溶液中的锂化行为进行研究.采用X射线衍射(XRD)、电感偶合等离子体光源的原子发射光谱(ICP)对α-Fe_2O_3电极在第一、二次循环中不同时段进行了跟踪分析测量.实验结果揭示: α-Fe_2O_3能进行少量锂化;大量的α-Fe_2O_3在第一次放电和充电后反应生成Fe_3O_4;之后,Fe_3O_4的锂化行为不可避免地为Fe的析出、氧化反应所限制,但在用KOH作电解质溶液的对比实验时发现:α-Fe_2O_3在LiOH溶液中的充放电行为与它在KOH溶液中是不同的,主要表现为,1)在LiOH溶液中,锂化和Fe析出、氧化反应协调的结果是其充放电曲线平台高度比在同碱度 KOH溶液中降低了 100 mV左右, 2)与 K~(+)对比, Li~(+)的插入反应促进了α-Fe_2O_3到Fe_3O_4的转化.  相似文献   

7.
采用扫描电镜、俄歇探针、X射线衍射、热磁分析、热磁分析等方法深入研究了Nd34Fe60O6合金的显微组织。发现合金的平衡组织由Nd2Fe17主相、含氧的富钕相和一个Nd-Fe-O三元铁磁性相(记为T1相)组成。该相在840℃通过Nd2Fe17相与富Nd液相的包晶反应形成。它的成分约为Nd34Fe50O10,居里温度为180℃。其X射线衍射峰可用点阵常数α=0.771nm、c=2.228nm的四方晶  相似文献   

8.
在240℃水热体系中首次合成出系列纳米晶固溶体(CeO2)1-x(BiO1.5)x(x=0.0 ̄0.50)。产物采用X射线衍射,扫描电子显微镜和X射线光电子能谱仪进行表征。Bi2O3在CeO2中的固溶限约为50%。所有固溶体结晶属立方萤石结构,粒度范围为10 ̄18nm。当Bi2O3掺杂量小于固溶限时,于800℃烧结不会导致结构转变。而对于(CeO2)0.5(BiO1.5)0.5,于800℃在空气中  相似文献   

9.
胡宗球 《结构化学》1999,18(3):159-162
通过电荷自洽叠代的EHMO量子化学计算,求得Fe(CO)5,PX5(X=F,Cl)及Fe(CO)4H2分子的键能EAB并分析它与键强度的关系,解释了Fe(CO)5分子中键长长的Fe-C键其键强度反而比键长短的Fe-C键强,Fe(CO)5和Fe(CO)4H2中C-O键键长相等,但键强度又不一样的“反常”现象  相似文献   

10.
合成了{[(n-Bu)2Sn(4-Fc-C6H4COO)]2O}2(1)和{[n-Oct)2Sn(4-Fc-C6H4COO)]2O}2(2)(Fc=ferroenyl两组新的配合物,对其进行了元素分析,并用IR,NMR(^1H,^13C,^119Sn)进行了谱学表征,单晶X射线衍射法测定表明,配合物1的晶体属单斜晶系,P21/c空间群,晶胞参数a=1.2988(1)nm,b=2.655(1)nm,  相似文献   

11.
钡铁氧体纳米复合材料的制备及其微波吸收性能   总被引:28,自引:0,他引:28  
采用聚乙二醇(PEG)凝胶法制备了Ba(Zn1-xCox)2Fe16O27复合氧化物纳米材料,用X射线衍射分析对产物进行了表征.将制得的材料与传统的微波吸收剂铁粉结合起来,制成双层复合的吸波涂层,进行测试.实验结果表明,所制材料对微波具有良好的吸收性能.并进一步对纳米复合材料的吸波机理进行了探讨.  相似文献   

12.
Dong X  Zhang Y  Liu B  Zhen Y  Hu H  Xue G 《Inorganic chemistry》2012,51(4):2318-2324
A double sandwich polyoxometalate and its Fe(III) substituted derivative, [As(2)Fe(5)Mo(21)O(82)](17-) (1) and [As(2)Fe(6)Mo(20)O(80)(H(2)O)(2)](16-) (2), were synthesized and characterized by single-crystal X-ray diffraction, infrared spectroscopy, fluorescent spectroscopy, UV spectra, thermogravimetry-differential scanning calorimetry analyses, electrospray ionization mass spectrometry, and magnetism measurements. The polyoxoanion is composed of a central fragment FeMo(7)O(28) for 1 (Fe(2)Mo(6)O(26)(H(2)O)(2) for 2) and two external AsMo(7)O(27) fragments linked together by two distinct edge-sharing dimeric clusters Fe(2)O(10) to lead to a C(2v) molecular symmetry. The central FeMo(7)O(28) fragment and external AsMo(7)O(27) fragment have a similar structure, and both of them can be viewed as a monocapped hexavacant α-Keggin subunit with a central FeO(4) group or a central AsO(3) group. Both of the polyoxoanions contain a oxo-bridged Fe(III)(5) magnetic core with the angles of Fe-O-Fe in the range of 96.4(4)-125.7(5)°, and magnetism measurements show an overall ferromagnetic interactions among the five-nuclearity cluster Fe(5) with the spin ground state S = 15/2.  相似文献   

13.
Nagaoka MH  Maitani T 《The Analyst》2000,125(11):1962-1965
Serum transferrin (Tf) is an iron-binding glycoprotein. Aluminium in the blood is bound to the transferrin. In the present study, the chemical forms of co-existing Al and Fe bound to human serum Tf were studied by combined on-line HPLC and high-resolution ICP-MS (HPLC-HR-ICP-MS). Samples were subjected to HPLC equipped with an anion-exchange column. The levels of 27Al, 56Fe and 32S, which are interfered with by polyatomic ions such as 13C14N+, 12C15N+ and 12C14N1H+, 40Ar16O+ and 40Ca16O+, and 16O2+, respectively, when using quadrupole ICP-MS, were monitored simultaneously by HR-ICP-MS at a resolution of m/delta m = 3000. Al added to apo-Tf as Al-citrate was preferentially bound to the N-lobe site almost selectively. Al in serum from a healthy person without any in vitro Al spike was present both as AlN-Tf and AlN,FeC-Tf. The chemical states were reproduced in the apo-Tf solution supplemented with Fe (Fe/Tf ratio = 0.6) and Al (Al/Tf ratio = 1) successively. The 32S level was useful for monitoring the protein levels in the HPLC eluate. The clean-up column procedures employed reduced the detection limit for 27Al to 0.1 microgram l-1 (3SB) at the middle resolution.  相似文献   

14.
硝酸铁,硝酸铈,邻菲咯啉(phen)和钛铁试剂(Tiron)通过水热方法合成了一种d-f异双核配合物[Fe(phen)3]2[FeCe(tiron)3]·6H2O,tiron=C6H2O8S2。X-射线单晶衍射分析表明,晶体属立方晶系,P213空间群,晶胞参数为:a=2.19409(4)nm,V=10.5624(3)nm3,Z=4,F(000)=4648,R1=0.0451,wR2=0.1077,S=1.072。在具有C3对称性的[FeCe(tiron)3]6-单元中,Fe髥与6个酚氧配位形成一个反三棱柱配位多面体,Ce髥则与3个桥联的酚氧μ2-O和3个磺酸基的氧形成另一个与FeO6共用底面的反三棱柱配位多面体CeO6。配阳离子通过phen-phen之间的π-π相互作用和与配阴离子间的静电引力等作用组装成一种三角梅状准主/客体型的超分子。在2~300K温度范围内测试了配合物的变温磁化率,结果表明,Ce髥-Fe髥之间存在典型的反铁磁性相互作用。  相似文献   

15.
Two cyanide bridged trinuclear compounds [Fe(bpy)2(CN)2]·[Cu(Cyclam)]2(ClO4)4·DMF 1 and [Fe(Phen)2(CN)2]·[Cu(Cyclam)]2(ClO4)4·2CH3CN·4H2O 2 (Bpy = 2,2'- bipyridine, Phen = 1,10-phenanthroline, Cyclam = 1,4,8,11-tetraaza-cyclotetradecane, and DMF = N,N-dimethylformamide) have been synthesized by using mononuclear [Fe(Phen)2(CN)2]·2H2O and [Fe(bpy)2(CN)2]·3H2O as precursors. These two complexes crystallize in monoclinic space groups P21/c and C2/c, respectively. For 1, a = 25.164(2), b = 12.0405(11), c = 20.4433(15) A, β = 91.948(3)°, V = 6190.5(9) A^3, Z = 4, Mr = 1418.90, Dc = 1.522 g/cm^3, F(000) = 2936, μ = 1.161 mm^-1, the final R = 0.0722 and wR = 0.2011 for 10779 observed reflections (I 〉 2σ(I)). For 2, a = 43.5945(0), b = 11.8447(0), c = 29.5637(2)A, β = 120.430(11)o, V = 13162.76(9) A^3, Z = 8, Mr = 1518.48, Dc = 1.533 g/cm^3, F(000) = 6288, μ = 1.101 mm^-1, the final R = 0.0711 and wR = 0.1783 for 11262 observed reflections (I 〉 2σ(I)).  相似文献   

16.
用浸渍法制得一系列不同铁负载量的Fe2O3/ZrO2催化剂,应用催化反应评价结合穆斯堡尔谱对催化剂的CO加氢反应性能、催化剂活性相结构及催化剂铁物种在合成气反应过程中的物相变化进行了研究.结果表明,铁负载量的大小对于Fe2O3/ZrO2催化剂的F-T反应催化性能有很大影响,铁负载量适当时,Fe2O3/ZrO2催化剂铁锆间适当的强相互作用使得催化剂在保持较高催化活性的同时高选择性地生成低碳烯烃,产物分布偏离Schulz-Flory分布规律.  相似文献   

17.
Zhang W  Zhao F  Liu T  Yuan M  Wang ZM  Gao S 《Inorganic chemistry》2007,46(7):2541-2555
2-(2H-Tetrazol-5-yl)-1,10-phenanthroline (HL0), its alkyl-substituted derivatives (Ln, where n = 1-8, 10, 12, 14, and 16, denoting the carbon atom number of the alkyl chain) at the 2H position of the tetrazole ring, and their iron(II) complexes (a for [Fe(L0)2], na for [Fe(Ln)2](ClO4)2, and nb for [Fe(Ln)2](BF4)2) were synthesized and characterized. The crystal structures of a, a.CH3OH, 1a.CH3OH, 1b.CH3OH.CH3CN, 2a.H2O, 2b.H2O, 4b.CH3OH, 5a.H2O, 5b.H2O, 6a, 6b, 7a, 7b, and 16a are described, along with thermal analyses. a undergoes an abrupt spin crossover (SCO) at 255 K with a hysteresis loop of 6 K. a.CH3OH, 2a.H2O, and 2b.H2O exhibit irreversible SCO behaviors due to the loss of solvent molecules upon heating. 3a, 3b, 4a, and 5a.H2O show simple spin transitions above 350 K. The desolvated samples of 4b.CH3OH and 5b.H2O undergo two-step spin transitions. 16a exhibits a two-step SCO behavior between 100 and 300 K, corresponding to sequential phase transitions from the low-spin (LS) phase to the intermediate phase and then to the high-spin phase, respectively, proved by crystal structure analysis and 57Fe M?ssbauer spectroscopy. 1a.CH3OH, 10a, 10b, 12a, 12b, 14a, 14b, and 16b show gradual and incomplete SCO behaviors after cooling down from 400 K. 1b.CH3OH.CH3CN, 6a, 6b, 7a, 7b, 8a, and 8b remain in the LS state even at 400 K. This proves that the alkyl side chains, together with the solvent molecules and anions, play a crucial role in the complicated SCO behaviors in this system.  相似文献   

18.
在水和乙醇溶剂中,通过Cu(Ⅱ),Fe(Ⅲ)和Fe(Ⅱ)与2,2'-联咪唑协同作用,构筑了四种新的超分子配合物[Cu(H2biim)(gly)(H2O)]Cl·H2O(1),[Cu(H2biim)(C3H2O4)(H2O)]·1.5H2O(2),[Fe2(μ-O)(H2biim)4(H2O)2](NO3)4·C2H5OH(3)和[Fe(H2biim)3]SO4(4)(H2biim=2,2'-联咪唑;gly-=甘氨酸根;C3H2O24-=丙二酸根).并通过元素分析,红外光谱和X射线单晶衍射对其组成、结构和谱学性质进行研究.H2biim配体,丙二酸根和甘氨酸根三种配体都采用了双齿螯合方式与金属离子配位.配合物1~4中,通过H2biim配体的N-H键与阴离子、水分子和溶剂分子形成多种氢键,如R12(7),R22(9)和R12(4)等,以及H2biim配体之间的π-π堆积,阳离子不对称单元构筑了多维结构的超分子配合物.  相似文献   

19.
The effects of reaction temperature and pO2 were investigated on a series of (Ba,Ca,Nd)FeO3-delta perovskite systems in order to isolate phases containing ordered arrangements of the distinct vacancy and cation ordering patterns identified in less compositionally complex iron oxide systems. Initial synthesis in air at high temperature yields cubic perovskite phases (I) with average iron oxidation states higher than 3; selected area electron diffraction together with diffuse features observed in the synchrotron X-ray diffraction (SXRD) patterns of these materials show evidence of small domains of short-range cation and vacancy order. Annealing these materials in nitrogen or in a sealed tube in the presence of an NiO/Ni buffer yielded the Fe(3+) phase Ca2Ba2Nd2Fe6O16 (II), closely related to Sr2LaFe3O8 but with partial cation order as well as anion order present the larger Ba cations are largely present in the 12-coordinate site between the octahedral iron layers, and Ca is largely present in 10-coordinate sites between octahedral and tetrahedral sites. Further reduction of Ca2Ba2Nd2Fe6O16 using a Zr getter yields the mixed-valence phase Ca2Ba2Nd2Fe6O15.6 (III). The structure of III was solved by maximum entropy analysis of XRD data coupled with analysis of high-temperature neutron diffraction data and refined against combined SXRD and high-Q ambient-temperature neutron data. This material crystallizes in a 20-fold perovskite super cell (Imma, a approximately square root(2 x a(p), b approximately 10 x a(p), c approximately square root(x 2a(p)) and can be visualized as an intergrowth between brownmillerite (Ca2Fe2O5) and the YBa2Fe3O8 structure. There are three distinct iron coordination environments, octahedral (O), square-pyramidal (Sp), and trigonal planar (Tp, formed by distorting the tetrahedral site in brownmillerite), which form a Sp-O-Tp-O-Sp repeat. Bond valence calculations indicate that Tp is an Fe(2+) site, while the O and Sp sites are Fe(3+). The A-site cations are also partially ordered over three distinct sites: 8-coordinate between the Sp layers, 10-coordinate between Tp and O layers, and 12-coordinate between Sp and O layers. Mossbauer spectroscopy, magnetometry, and variable-temperature neutron diffraction show that the material undergoes two magnetic transitions at approximately 700 and 255 K.  相似文献   

20.
K2O-Fe2O3系催化剂的穆斯堡尔谱研究   总被引:1,自引:0,他引:1  
利用穆斯堡尔谱在K2 O Fe2 O3催化剂中检出了α Fe2 O3(大晶粒及微晶 )、KFeO2 、K1 XFe11O17、α FeOOH和γ FeOOH等物相 ,它们的相对含量取决于催化剂的含钾量及煅烧温度 ,相对含量的改变导致样品的穆斯堡尔谱图出现了复杂的变化 .与XRD相比 ,穆斯堡尔谱可对钾与氧化铁的相互作用进行更有效的表征 ,穆斯堡尔谱和TPR研究都表明钾可延缓催化剂中Fe(III)的被还原 .  相似文献   

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