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41.
The reactivity of a Cr‐Te multilayer film consisting of 326 Cr/Te double‐layers with about 88(3) at% Te was investigated with in‐situ X‐ray diffraction. The occurrence of a superstructure reflection caused by the multilayer system is observed. During the annealing procedure between 80 and 90 °C the layer‐by‐layer arrangement is destroyed and elemental Te crystallizes. After 6 h isothermal annealing at 140 °C CrTe3 starts to crystallize. The amount and the crystal size of CrTe3 increase with raising temperature and Te is consumed during the growth process. At 220 °C the formation of crystalline Cr2Te3 is observed and between 220 and 260 °C CrTe3 is completely decomposed into Cr2Te3. The two Cr tellurides grow as highly textured materials. The size of CrTe3 crystals is significantly larger than that of Cr2Te3. For a co‐deposited Cr‐Te film with composition 77(3) at% Te the tri‐telluride and elemental Te crystallize simultaneously. The texture of CrTe3 is less pronounced and different reflections of the tri‐telluride occur besides the (h00)‐reflections. Up to 160 °C a pronounced increase of the crystallite size is observed and the crystals are significantly larger than those obtained with the multifilm sample. At 130 °C the crystallization kinetics seem to be controlled by nucleation. 相似文献
42.
合成和表征了4种以四溴代邻苯二甲酸根阴离子(4Br-PHTH)桥联、以1,10-菲咯啉(phen),5-硝基-1,10-菲咯啉(NO_2-phen),2,2′-联吡啶(bpy)和4,4′-二甲基-2,2′-联吡啶(Me_2bpy)端接的双核钴(Ⅱ)配合物[Co_2(4Br-PHTH)(L)_4](ClO_4)(L=phen(l),NO_2-phen(2),bpy(3),Me_2bpy(4))。基于IR光谱、元素分析、电导测量等方法推定配合物具有四溴代邻苯二甲酸根桥联结构和Co(Ⅱ)离子具有畸变的八面体配位环境。进行了配合物变温磁化率(75~300K)的测定,其数据已用从自旋哈密顿符导出的磁方程拟合,求得交换参数J=-0.87cm~(-1)(1),-0.84cm~(-1)(2),-0.82cm~(-1)(3),-0.85cm~(-1)(4),表明金属离子间有弱的反铁磁性自旋交换相互作用。 相似文献
43.
44.
通过X射线衍射分析和超导量子干涉磁强计(SQUID)磁性测量,研究了Co替代Fe含量对居里温度在室温以上的磁制冷材料La(Fe1-xCox)11.7Al1.3(x=0.072,0.081)磁结构和磁性能的影响。La(Fe1-xCox)11.7Al1.3材料的居里温度随Co的含量增加而增加,La(Fe0.919Co0.081)11.7Al1.3的居里温度为311 K。当外场变化为1.9 T时磁熵变达到3.6 J·kg^-1·K^-1,RCP值为168.6 J·kg^-1,虽然它的磁熵变小于具有巨磁熵变的磁制冷材料,但是它在磁场为1.9 T时的制冷能力与这些材料相当。 相似文献
45.
Silica gel impregnated with poly(ethylene glycol) of different molecular mass (400, 1000, 1540, 4000, and 5500) was investigated for salting-out thin-layer chromatography of 15 mixed aminocarboxylato Co(III) complexes using eight ammonium sulphate solutions as mobile phases. Regularities established earlier for non-impregnated adsorbents are also valid in this work. Poly(ethylene glycol) of high molecular mass increases the hydrophobicity of the adsorbent. Positive linear dependence of RM values and of salting-out efficiency on average poly(ethylene glycol) molecular mass was usually observed. In contrast with non-impregnated silica gel, separation was achieved between complexes with the smallest hydrocarbon groups. 相似文献
46.
The determination of nickel in various silicate rocks and glasses by photon activation analysis with a linear electron accelerator is described. Simultaneous irradiation of the sample and comparative standards produces the 58Ni(γ, n)57Ni reaction, and a post-irradiation chemical separation is used in conjunction with Ge(Li) γ-spectrometry. Nickel abundances for ten standard silicate rocks and two elementally doped glasses are presented and compared with the data previously published. The method is quite simple and gives good reproducible results for nickel down to sub-p.p.m. levels. 相似文献
47.
S. Colonna S. De Rossi M. Faticanti I. Pettiti P. Porta 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):161-168
ZrO2-supported La, Co oxide catalysts with different La, Co loading (2, 6, 8, 12 and 16 wt.% as LaCoO3) were prepared by impregnation of tetragonal ZrO2 with equimolar amounts of La and Co citrate precursors and calcination at 1073 K. The catalysts were characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and BET specific surface area determination. Catalytic CO oxidation was performed at 298–800 K. XRD revealed the presence of tetragonal zirconia with traces of the monoclinic phase. LaCoO3 perovskite was also detected for loading higher than 6%. XAS experiments suggested that at high loading LaCoO3 and Co3O4 were formed, while at low loading, La, Co oxide species interacting with support, and hard to be structurally defined, prevailed. The catalysis study evidenced that the catalytic activity was due to segregated and highly dispersed cobalt oxide species. 相似文献
48.
Pb2(OH)2[p‐O2C‐C6H4‐CO2]: Synthesis and Crystal Structure Single crystals of Pb2(OH)2[p‐O2C‐C6H4‐CO2] ( 1 ) were obtained by hydrothermal reaction of terephthalic acid and PbCO3 at 180 °C (10 days). 1 crystallizes in the monoclinic space group P21/c with Z = 2 (a = 1115.6(2) pm, b = 380.10(4) pm, c = 1141.3(2) pm, β = 93.39(1)°, V = 0.4831(1) nm3). The crystal structure is characterized by ladder‐type Pb(OH)3/3 double chains, which are connected to a three‐dimensional framework by terephthalate dianions. 相似文献
49.
Czakis-Sulikowska D. Malinowska A. Łuczak A. 《Journal of Thermal Analysis and Calorimetry》2004,78(2):461-471
Two lactates and four new mixed ligand complexes with formulae Co(lact)2·2H2O, Ni(lact)2·3H2O, Co(4-bpy)(lact)2, Co(2,4'-bpy)2(lact)2, Ni(4-bpy)(lact)2·2H2O and Ni(2,4'-bpy)2(lact)2 (where 4-bpy=4,4'-bipyridine, 2,4'-bpy=2,4'-bipyridine, lact=CH3CH(OH)COO-) were isolated and investigated. The thermal behaviour of compounds was studied by thermal analysis (TG, DTG, DTA). In the
case of hydrated complexes thermal decomposition starts with the release of water molecules. The compounds decompose at high
temperature to metal(II) oxides in air. A coupled TG-MS system was used to analyse the principal volatile products of thermolysis
and fragmentation processes of obtained complexes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
50.
The solid–liquid equilibria of the ternary system H2O–Fe(NO3)3–Co(NO3)2 were studied by using a synthetic method based on conductivity measurements.
Two isotherms were established at 0 and 15 °C, and the stable solid phases which appear are the iron nitrate nonahydrate (Fe(NO3)3·9H2O), the iron nitrate hexahydrate (Fe(NO3)3·6H2O), the cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and the cobalt nitrate trihydrate (Co(NO3)2·3H2O). 相似文献