镍锌铁氧体/膨胀石墨/聚苯胺复合物的电磁损耗性能

用化学共沉淀法和原位乳液聚合法分别制备了镍锌铁氧体(NixZn1-xFe2O4)、Ni0.7Zn0.3Fe2O4/膨胀石墨(NZF/EG)二元复合物及其聚苯胺(PANI)包覆的三元复合物(NZF/EG/PANI)。用现代测试技术表征了样品的组成、结构、形貌和电磁性能。结果表明,NZF粒子较好地嵌入到EG的层间,PANI对NZF/EG的包覆效果良好;三元复合物的磁性能随磁性组分含量的减小而减弱,而电导率与EG和PANI的导电性及其相对含量相关联;复合物的电磁损耗性能优良,其中三元复合物优于二元复合物。含PANI70wt%的NZF/EG/PANI三元复合物,制样厚度分别为1.5、2.0和2.5 mm时,其反射损耗峰值(有效带宽)分别为-19.99 d B(5.82GHz),-20.33 d B(4.08 GHz)和-25.28 d B(3.67 GHz),具有优良的电磁波吸收效果。     

NZFO-PZT磁电复合纳米纤维的制备及其吸波性能

采用静电纺丝法制备(1-x)Ni_0.5Zn_0.5Fe₂O₄-(x)Pb(Zr_0.52Ti_0.48)O₃(简称为(1-x)NZFO-(x)PZT, x=0.1、0.2、0.3、0.4、0.5)磁电复合纳米纤维, 研究了PZT含量对复合纳米纤维结构、电磁特性及微波吸收性能的影响。所有样品均由尖晶石结构NZFO和钙钛矿结构PZT两相所组成。由于NZFO磁损耗与PZT介电损耗的协同效应及界面效应的加强, 适量PZT相的引入可改善复合纳米纤维吸波涂层的电磁阻抗匹配和衰减特性, 提高微波吸收性能。x=0.3和0.4的复合纳米纤维分别在低频和高频范围表现出最强的微波吸收能力。当涂层厚度为2.5~5.0 mm时, x=0.3样品的最小反射损耗在6.1 GHz处达-77.2 dB, 反射损耗小于-10 dB的有效吸收带宽为11.2 GHz(2.8~12.9和16.9~18 GHz);x=0.4样品的最小反射损耗位于18 GHz处为-37.6 dB, 有效吸收带宽达到12.5 GHz(3.3~12.5和14.7~18 GHz)。     

NZFO-PZT磁电复合纳米纤维的制备及其吸波性能

采用静电纺丝法制备(1-x)Ni_0.5Zn_0.5Fe₂O₄-(x)Pb(Zr_0.52Ti_0.48)O₃(简称为(1-x)NZFO-(x)PZT, x=0.1、0.2、0.3、0.4、0.5)磁电复合纳米纤维, 研究了PZT含量对复合纳米纤维结构、电磁特性及微波吸收性能的影响。所有样品均由尖晶石结构NZFO和钙钛矿结构PZT两相所组成。由于NZFO磁损耗与PZT介电损耗的协同效应及界面效应的加强, 适量PZT相的引入可改善复合纳米纤维吸波涂层的电磁阻抗匹配和衰减特性, 提高微波吸收性能。x=0.3和0.4的复合纳米纤维分别在低频和高频范围表现出最强的微波吸收能力。当涂层厚度为2.5~5.0 mm时, x=0.3样品的最小反射损耗在6.1 GHz处达-77.2 dB, 反射损耗小于-10 dB的有效吸收带宽为11.2 GHz(2.8~12.9和16.9~18 GHz);x=0.4样品的最小反射损耗位于18 GHz处为-37.6 dB, 有效吸收带宽达到12.5 GHz(3.3~12.5和14.7~18 GHz)。     

纳米Fe3O4及Ni2 掺杂Fe3O4的制备、表征及吸附Pb(Ⅱ)的特性

采用一种改进的共沉淀法制备了纳米磁铁矿(Fe₃O₄)及Ni²⁺掺杂磁铁矿(Ni_xFe_3-xO₄,x=0.1,0.3,0.6),用X-射线衍射(XRD)、扫描电镜(SEM)、氮气物理性吸附、酸碱滴定等手段对产物进行了表征,用平衡吸附法研究了4种样品对Pb(Ⅱ)离子的吸附容量及吸附模型。结果表明,Fe₃O₄和3种Ni_xFe_3-xO₄均为近似球形的单相晶质纳米颗粒;与Fe₃O₄比较,Ni_xFe_3-xO₄的颗粒尺寸变小、表面电荷零点和pH＝5.0时的表面正电荷量降低;样品的孔体积、比表面积和表面分形度以及表面羟基含量都随产物中Ni²⁺掺杂量的增加而升高。4种样品对Pb(Ⅱ)的等温吸附数据均适合用Langmuir模型拟合(R²=0.9942~0.9858),其相关系数的大小表现为：Fe₃O₄>Ni_0.1Fe_2.9O₄>Ni_0.3Fe_2.7O₄=Ni_0.6Fe_2.4O₄;Freundlich模型对样品等温吸附Pb(Ⅱ)的实验数据拟合度较低(R²=0.981 3~0.947 7),4种样品的Freundlich相关系数的大小关系与Langmuir相关系数相反。初始pH=5.0时,Fe₃O₄,Ni_0.1Fe_2.9O₄,Ni_0.3Fe_2.7O₄和Ni_0.6Fe_2.4O₄对Pb(Ⅱ)的最大吸附容量分别为6.02,6.68,7.29和8.34 mg·g^-1。可见,Ni_xFe_3-xO₄(尤其是Ni²⁺掺杂量较高的产物)对水环境中重金属Pb(Ⅱ)的去除能力明显高于Fe₃O₄。     

纳米Fe3O4及Ni2+掺杂Fe3O4的制备、表征及吸附Pb(Ⅱ)的特性

采用一种改进的共沉淀法制备了纳米磁铁矿(Fe₃O₄)及Ni²⁺掺杂磁铁矿(Ni_xFe_3-xO₄,x=0.1,0.3,0.6),用X-射线衍射(XRD)、扫描电镜(SEM)、氮气物理性吸附、酸碱滴定等手段对产物进行了表征,用平衡吸附法研究了4种样品对Pb(Ⅱ)离子的吸附容量及吸附模型。结果表明,Fe₃O₄和3种Ni_xFe_3-xO₄均为近似球形的单相晶质纳米颗粒;与Fe₃O₄比较,Ni_xFe_3-xO₄的颗粒尺寸变小、表面电荷零点和pH＝5.0时的表面正电荷量降低;样品的孔体积、比表面积和表面分形度以及表面羟基含量都随产物中Ni²⁺掺杂量的增加而升高。4种样品对Pb(Ⅱ)的等温吸附数据均适合用Langmuir模型拟合(R₂=0.9942~0.9858),其相关系数的大小表现为:Fe₃O₄>Ni_0.1Fe_2.9O₄>Ni_0.3Fe_2.7O₄=Ni_0.6Fe_2.4O₄;Freundlich模型对样品等温吸附Pb(Ⅱ)的实验数据拟合度较低(R²=0.9813~0.9477),4种样品的Freundlich相关系数的大小关系与Langmuir相关系数相反。初始pH=5.0时,Fe₃O₄,Ni_0.1Fe_2.9O₄,Ni_0.3Fe_2.7O₄和Ni_0.6Fe_2.4O₄对Pb(Ⅱ)的最大吸附容量分别为6.02,6.68,7.29和8.34mg·g^-1。可见,Ni_xFe_3-xO₄(尤其是Ni²⁺掺杂量较高的产物)对水环境中重金属Pb(Ⅱ)的去除能力明显高于Fe₃O₄。     

Zn0.4Ni0.6Cr0.5LaxFe1.5－xO4铁氧体纳米粉晶的制备及磁性

用柠檬酸盐前驱物-溶胶凝胶法制备了Zn_0.4Ni_0.6Cr_0.5La_xFe_1.5－xO₄ (x＝0～0.10)纳米粉晶. 用DSC-TG分析了前驱物转变为粉晶的热分解过程, 通过粉末X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)等表征了产物的结构、形貌和磁性能. 结果表明, 不同温度和不同的La掺杂量对样品的晶粒尺寸、晶胞参数和形貌均产生了明显的影响, 且通过改变La含量能起到调控样品磁性能的作用.     

AxMn1-xFe2O4铁氧体(A=Zn,Ni)中阳离子的占位有序化行为研究

基于尖晶石晶体结构信息,本文采用热力学三亚晶格模型,将材料热力学计算和第一性原理计算相结合,研究了Zn_xMn_1-x Fe₂O₄和Ni_xMn_1-xFe₂O₄立方相中的Zn²⁺、Ni²⁺、Mn²⁺以及Fe³⁺在8a和16d亚晶格上的占位有序化行为。结果表明:在锰铁氧体中,室温下Mn²⁺完全占据在8a亚晶格上,Fe³⁺完全占据在16d亚晶格上,属于正尖晶石结构;随着热处理温度升高,在1 273 K达到热处理平衡时的占位构型为(Fe_0.09³⁺Mn_0.91²⁺)[Fe_1.91³⁺Mn_0.09²⁺]O₄,在热处理温度升至1 473 K时,达到热处理平衡时的占位构型为(Fe_0.11³⁺ Mn_0.89²⁺)[Fe_1.89³⁺Mn_0.11²⁺]O₄,均与实验结果符合较好。在锌铁氧体中,室温下Zn²⁺完全占据在8a亚晶格上,Fe³⁺完全占据在16d亚晶格上,属于正尖晶石结构;在热处理温度较高时,Zn²⁺和Fe³⁺发生部分置换,符合实验结果。在镍铁氧体中,半数的Fe³⁺在室温下占据在8a亚晶格上,Ni²⁺与剩下另一半的Fe³⁺共同占据在16d亚晶格上,仅在热处理温度较高的时候发生微弱变化,亦与已有的实验结果吻合。在此基础上,本文进一步通过热力学预测建立了立方相尖晶石结构的Zn_xMn_1-xFe₂O₄、Ni_xMn_1-xFe₂O₄复合体系中阳离子占位行为与热处理温度对占位的影响。     

Fe-Co-Ni合金纳米粒子镶嵌的碳纳米纤维的简单制备及其吸波性能

通过在氩气中碳化含有乙酰丙酮金属盐的电纺聚丙烯腈纳米纤维合成了镶嵌（Fe_1-xCo_x）_0.8Ni_0.2（x=0.25,0.50,0.75）合金纳米粒子的碳纳米纤维,用X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、振动样品磁强计（VSM）和矢量网络分析仪（VNA）等对其物相、形貌、微观结构、静磁及电磁特性进行表征和分析,并根据传输线理论模拟计算了2~18 GHz频率范围内的微波吸收性能。结果表明：所制备的复合纳米纤维具有典型的铁磁特征,由无定形碳、石墨和面心立方结构Fe-Co-Ni合金三相组成,原位形成的合金纳米粒子沿纤维轴向均匀分布,且被有序石墨层所包覆。磁损耗和介电损耗间的协同作用及特殊的核/壳微观结构使仅含5%（w/w）的（Fe_1-xCo_x）_0.8Ni_0.2/C复合纳米纤维的硅胶基吸波涂层表现出优异的微波吸收性能。当涂层厚度为1.1~5.0 mm时,x=0.25、0.50和0.75的样品最小反射损耗分别达到-78.5、-80.2和-63.4 dB,反射损耗在-20 dB以下的吸收带宽分别为14.9、14.8和14.5 GHz,几乎覆盖整个S波段至Ku波段。通过调节合金的组成可对材料的电磁特性及微波吸收性能进行一定程度的控制。     

FexOy/SBA-15介孔分子筛的合成以及性能研究

在酸性溶液中利用溶胶凝胶-pH值控制两步法直接合成Fe_xO_y/SBA-15介孔分子筛，同时利用场发射扫描电子显微镜(FESEM)、小角度X射线衍射(Low-angle XRD)、透射电子显微镜(TEM)以及振动样品磁强计(VSM)对制备的各种SBA-15介孔分子筛进行结构以及性能的测试、表征。结果显示Fe_xO_y均匀地分散在SBA-15的骨架中，而且会对SBA-15介孔分子筛起钉轧作用。而后着重研究了Fe_xO_y的加入对SBA-15介孔分子筛的热稳定性、催化特性以及磁学性能的影响。Fe_xO_y的引入可以增加制备的SBA-15介孔分子筛的热稳定性;Fe_xO_y的引入可以改善SBA-15介孔分子筛的催化活性，得到了开口的、石墨化程度较好的纳米碳管。Fe_xO_y的引入使SBA-15介孔分子筛具有明显的铁磁性。     

纳米镍钴铁氧体空心微球的制备与性能

以乙二醇为溶剂,氯化铁、氯化钴、氯化镍和醋酸铵为反应试剂,采用溶剂热法制备纳米Ni_xCo_1-xFe₂O₄(x=0、0.3、0.5、0.7、1)铁氧体空心微球,研究镍含量对铁氧体空心球的磁性与吸波性能的影响。借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、振动样品磁强计(VSM)和网络分析仪对试样的物相组成、微观形貌和电磁特性进行表征。结果表明制备的镍钴铁氧体为尖晶石结构,且形貌为空心球,粒径在200nm左右。当x=0时,镍钴铁氧体空心球饱和磁化强度最大为81.7emu·g^-1,反射损耗在1658.8MHz有最小值为-16.9dB。     

Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Simultaneous propane dehydrogenation andco2hydrogenation overCrOx/SiO2catalyst

Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO₂(DH-CO₂) reactions in the presence and absence of the CrO_x/SiO₂ catalyst have been studied between 673 and 873 K. It was found that the CrO_x/SiO₂ catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the dehydrogenation of propane to propene in the presence of CO₂on CrO_x/SiO₂can be facilitated by the RWGS reaction.</o:p>     

Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes

Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/₂, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of⁹⁹Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/₃, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material.     

Direct synthesis of dimethyl carbonate ?from CH3OH AND CO2 by H3PW12O40/CexTi1-xO2 catalyst

Summary Ce_xTi_1-xO₂ and H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ showed a better catalytic performance than the corresponding Ce_xTi_1-xO₂, due to the bifunctional catalysis of Br?nsted acid sites (provided by H₃PW₁₂O₄₀) and base sites (provided by Ce_xTi_1-xO₂). H₃PW₁₂O₄₀/Ce_0.1Ti_0.9O₂ showed the highest catalytic performance among the H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts.     

An investigation of the promotional effect of propylene or propane traces on the activity of sulfatedPt/g-Al2O3andPt-Sn/g-Al2O3inCH4combustion

Summary A strong promoting effect of the presence of C₃H₈or C₃H₆was determined for the combustion of CH₄in excess oxygen, over pre-sulfated 1%Pt/g-Al₂O₃and pre-sulfated 1%Pt-2%Sn/g-Al₂O₃catalysts.</o:p>     

Crystal structure of Na3PO4 · 12H2O

The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is $\text{C2}\text{c}$ and a unit cell contains eight formula units. The unit cell dimensions of $\text{Na}{}_3\text{PO}{}_4\text{·}\text{1}\text{2}\text{H}{}_2\text{O}$ are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO₆ octahedra. The hydrogen bonding scheme is given.     

LixNi0.8-yCo0.2ZnyOp的合成及电化学性能研究

A series of single-phase Li_xNi_0.8-yCo_0.2Zn_yO_p(0.96 ≤x≤ 1.10， 0 ≤y≤ 0.05， 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method， in which LiOH·H₂O， Zn-doped spherical Ni(OH)₂ and Co₂O₃ were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD， SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine， narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity， but also a better cycling stability characterization than the un-doped one. The Li_1.06Ni_0.75Co_0.22Zn_0.03O_2.03 material has an initial reversible capacity as high as 160.5mAh·g^-1; and a first discharge efficiency 89.2%， and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles.     

Visible light-sensitive yellow TiO2−xNx and Fe-N co-doped Ti1−yFeyO2−xNx anatase photocatalysts

Nitrogen substituted yellow colored anatase TiO_2−xN_x and Fe-N co-doped Ti_1−yFe_yO_2−xN_x have been easily synthesized by novel hydrazine method. White anatase TiO_2−δ and N/Fe-N-doped samples are semiconducting and the presence of ESR signals at g ∼1.994-2.0025 supports the oxygen vacancy and g∼4.3 indicates Fe³⁺ in the lattice. TiO_2−xN_x has higher conductivity than TiO_2−x and Fe/Fe-N-doped anatase and the UV absorption edge of white TiO_2−x extends in the visible region in N, Fe and Fe-N co-doped TiO₂, which show, respectively, two band gaps at ∼3.25/2.63, ∼3.31/2.44 and 2.8/2.44 eV. An activation energy of ∼1.8 eV is observed in Arrhenius log resistivity vs. 1/T plots for all samples. All TiO₂ and Fe-doped TiO₂ show low 2-propanol photodegradation activity but have significant NO photodestruction capability, both in UV and visible regions, while standard Degussa P-25 is incapable in destroying NO in the visible region The mid-gap levels that these N and Fe-N-doped TiO₂ consist may cause this discrepancy in their photocatalytic activities.     

Synthesis and characterization of Ti1−2xNbxNixO2−x/2 solid solutions

Doped-rutile has been traditionally used in ceramic pigments for its intense optical properties. In this paper, we compare the classical ceramic synthesis of Ti_1−2xNb_xNi_xO_2−x/2 system with the sol-gel methodology, which allows a reduction of the anatase-rutile transformation temperature. The composition was optimised in order to obtain a unique rutile phase with the minimum amount of pollutant Ni(II) and enhanced chromatic coordinates. Incorporation of the doping ions in the rutile structure was corroborated by XRD and Rietveld refinements. The species responsible for the colour mechanism were studied by different techniques. UV-VIS spectroscopy showed the characteristic features of Ni²⁺ ions, whose existence was corroborated by EPR and magnetic measurements. From these results, (Ni,Nb)doped-TiO₂ powder samples can be now shaped as thin films, monoliths, etc. by using sol-gel methodology without modifying their properties. This study introduces new possibilities of coloured TiO₂-based solid solutions in new combined advanced applications (colouring agent and photocatalyst, etc.).     

Carbon black and propylene oxidation over Ru/CoxMgyAl2Oz catalysts

The effects of Co_xMg_yAl₂O_z mixed oxides composition and ruthenium addition on the oxidation of propylene and carbon black (CB) were investigated. Different reactive cobalt and ruthenium oxide species were formed following calcination at 600 °C. The addition of ruthenium was beneficial for the CB oxidation under “loose contact” conditions and for propylene oxidation when the cobalt content was intermediate to low. The calculated activation energy for CB oxidation was decreased from 151 kJ mol⁻¹ for the uncatalyzed reaction to 111 kJ mol⁻¹ over the best catalyst.