添加铝对纳米合金Nd10.5Fe78-xCo5ZrxB6.5（x=0～5）的微观结构与磁性能的影响

研究了Zr元素对Nd10.5Fe78-xCo5ZrxB6.5(x=0，2，4，5)纳米晶双相永磁材料的磁性能与结构的影响。结果表明：适量地添加2％的Zr可以显著增强合金的内禀矫顽力，而且可以有效抑制α—Fe和Nd2Fe14B晶粒的长大，细化晶粒，改善结构。在Nd10.5Fe76Co5Zr2B6.5(x=2)合金中可以获得分布更加均匀、晶粒尺寸约为20nm的微观结构。     

ICP-发射光谱测定镁钇合金中稀土和非稀土元素

本文研究了ICP-AES测定镁钇合金中17种稀土和非稀土元素的方法。选择了合适的分析线及ICP操作参数。探讨了酸度,载气和基体的变化对被测元素谱线强度的影响,不用化学分离,可同时测定镁钇合金中Y,La,Ce,Pr,Nd,Gd,Tm, Dy,Lu,Ho,Er,Yb和Mo,Ni,Cu,Al,Fe。测定范围分别为(％):Y_(1-40);La,Er0.048—3.2;Tm,Yb,Lu,Dy0.019—1.28;Ho0.0384—2.56;Ce0.0288—1.92;Fe,Ni,Mo,Al,Pr,Nd,Gd0.024-1.6;Cu0.012—0.8。相对标准偏差为1.1—5.3％。回收率为90～115％。方法简单、快速、再现性好、准确度高。     

混合稀土对共晶Al-2％Fe合金组织形态的影响

研究了富La混合稀土对共晶Al-2％Fe合金组织形态的影响。当混合稀土加入量较少时，合金中的α—Al相为明显的胞状枝晶；随着混合稀土加入量的增加，α-Al枝晶优先形核生长得到抑制，共晶Al3Fe相得到细化；当稀土加入量增至0．6％(质量分数)共晶Al3Fe相尺寸逐渐增大。并对混合稀土对共晶Al-2％Fe合金组织形态的影响机制进行了探讨。     

添加铌对铜模吸铸Nd9Fe81-x-yTi4C2BxNby（x=11,13,15;y=0,4）合金铸态组织及其晶化行为的影响

采用铜模吸铸制备了厚度为0.8 mm,成分为Nd9Fe81-x-yTi4C2BxNby(x=11,13,15;y=0,4)的Nd2Fe14B/Fe3B型纳米复合永磁合金块体样品,研究了添加Nb对合金铸态组织及其晶化行为的影响,并测试了其磁性能。结果表明:在合金中添加4%(原子分数)Nb元素,不仅能抑制吸铸样品表面Nd2Fe23B3软磁性相、Nd1.1Fe4B4非磁性相和未知相的形成,导致Nd2Fe14B,Fe3B和α-Fe相的相对量增加,而且促使样品内部在非晶基体上形成了少量的Nd2Fe14B和α-Fe,Fe3B纳米晶。添加了Nb的合金吸铸样品表现出一定的硬磁性,其中Nd9Fe66Ti4C2B15Nb4吸铸样品具有最高的矫顽力(Hci=116.66 k A·m-1);添加4%(原子分数)Nb使得合金在晶化过程中由原来的异相同温一步晶化转变为两步晶化,且初始晶化温度Tx均明显降低,两个放热峰的ΔTpx均增大。     

添加镝的Nd-Fe-B纳米晶单相合金的微结构与磁性能研究

采用单辊快淬法制备了Nd12.3-xDyxFe79.7Zr0.8Nb0.8Cu0.4B6.0(x=0,0.5,1.5,2.5)合金纳米晶单相永磁薄带,研究了合金薄带晶化处理后,成分、组织结构与磁性能之间的关系.X射线衍射分析(XRD)表明,淬态合金主要由非晶相和Nd2Fe14B相组成,完全晶化后由Nd2Fe14B相和少量α-Fe组成.高分辨透射电镜(HRTEM)分析表明,经充分退火后,Nd2Fe14B晶体完整,晶粒间几乎没有边界相.随着Dy含量增加,晶粒尺寸细化,矫顽力大幅提高.x=0.5合金综合磁性能最佳,经过700℃晶化处理10min后,其磁性能为Jr=1.09 T,Hci=1048kA·m-1,(BH)max=169.5 kJ·m-3.     

Nd-(Fe,Co,Zr)-B纳米复合磁体的研究

利用XRD,TEM和DTA研究了不同淬火辊速度、晶化处理温度与时间对α-Fe／Nd2Fe14B型Nd10.5Fe78.8-xCo5.0ZrxB5.7纳米晶复合磁体结构和磁性能的影响规律。冷却辊速为25m·s^-1的Nd10.5Fe78.8-xCo5.0ZrxB5.7快淬态条屑具有纳米晶复合磁体结构,不经晶化处理就可获得较好的永磁性能。研究了Zr的添加和晶粒尺寸对性能的影响规律。添加0．5％（原子分数）Zr的合金进行700℃×10min的晶化处理后可获得较好的永磁性能。分析了微观结构和性能变化的机制。     

Nd60Fe20Al8Co10B2大块非晶合金晶化过程中的结构及磁性能变化

利用吸铸的方法制备了Nd60Fe20Al8Co10B2大块非晶合金。采用示差扫描量热法(DSC)，X射线衍射(XRD)，扫描电子显微镜(SEM)和振动样品磁强计(VSM)研究了Nd60Fe20Al8Co10B2大块非晶合金在晶化过程中的微观结构及磁性能的变化情况。Nd60Fe20Al8Co10B2大块非晶合金在低于723K退火时，富Nd相和富Fe相的析出对于合金的矫顽力影响不大。但是，富Fe相的长大使合金的饱和磁化强度和剩磁下降明显。合金完全晶化后，硬磁性迅速消失。     

富铁稀土金属间化合物永磁材料的研究进展

富铁ThMn₁₂型R(Fe, M)₁₂(R=稀土,M=其他元素)和Th₂Ni₁₇/Th₂Zn₁₇型R₂Fe₁₇金属间化合物通常被命名为1-12和2-17型化合物;它们已被开发成为稀土基磁性合金中重要的系列化合物。随着以Sm₂Fe₁₇N_x和R(Fe, M)₁₂N_x(R=Pr, Nd)等氮化物为代表的“间隙原子效应”的发现,以及稀土资源的绿色开采和综合利用的发展,对富铁稀土-过渡金属间化合物的研究成为热点。其中,Sm(Fe, Co)₁₂化合物和间隙原子调制的R(Fe, M)₁₂N(R=Pr, Nd), Sm₂(Fe, M)₁₇N_x等富铁材料的内禀磁性能与作为当前主流应用的高性能永磁材料Nd_2...     

Nd2Fe17-xSbx的化学合成

Nd2Fe14B稀土永磁材料的发现[1,2]促使人们对稀土铁合金的结构和性能进行深入地研究,近年来发现Ln2Fe17金属间化合物中的Fe可以被其他主族或过渡元素部分取代,形成的Ln2Fe17-xMx的磁性质受取代元素的种类和含量的影响很大.一般认为当部分取代使稀土-铁金属间化合物的晶胞体积增加时,材料的内禀磁性可以得到改善,这是因为材料中Fe-Fe距离增加使铁之间的反铁磁相互作用减小造成的.     

纳米晶稀土永磁材料的制备和磁性

介绍了纳米晶稀土永磁材料的制备和磁性方面的有关研究工作, 主要内容有: 低钕快淬Fe3B基钕铁硼新型纳米晶复合稀土永磁材料的相结构与磁性, 快淬Pr2Fe14B/α-Fe型纳米复合稀土永磁材料的微结构与永磁性, 快淬Sm-Co基稀土永磁材料的织构与磁各向异性的关系, 以及纳米晶稀土永磁材料的矫顽力机制和模拟计算研究等.     

火焰原子吸收法测定固氮酶活性中心模拟物中钼和铁含量的研究

本文报导了用空气-乙炔火焰原子吸收法,采用钼的灵敏线、铁的次灵敏线,在同一溶样中连续测定固氮酶活性中心模拟物中钼和铁含量的研究。     

掺铁碳化硅陶瓷的制备及其吸波性能

将羰基铁和液态聚碳硅烷(LPCS)反应生成的铁(Fe)溶胶与固态聚碳硅烷(PCS)混合,合成出不同Fe质量分数的PCS先驱体,然后经氧化交联和高温热解制备了不同Fe质量分数的磁性碳化硅陶瓷(Fe/SiC),系统地研究了Fe元素的引入对SiC陶瓷的组成、结构、磁性能和介电性能的影响规律。 研究发现,当Fe质量分数小于8.94%时,在热解过程中,Fe元素可以显著促进SiC_xO_y的分解,生成β-SiC,且随着Fe质量分数的增加,β-SiC的结晶峰越来越强;但随着Fe质量分数继续增加,达11.78%时,则主要生成Fe₃Si;Fe/SiC陶瓷均呈铁磁性,其饱和磁化强度随着Fe质量分数的增加而呈指数形式增加;当Fe质量分数为4.19%时Fe/SiC陶瓷在12.4 GHz具有最小的反射损耗,为-9.4 dB,同时低于-5 dB的带宽为2.4 GHz,Fe质量分数为8.94%时,低于-5 dB的带宽则为3.7 GHz,可用作良好的微波吸收材料。     

ICP–AES法测定金属钼中微量Fe,Ni

采用ICP–AES法测定金属钼中Fe,Ni含量,以盐酸–硝酸–氢氟酸溶解样品,试验了基体元素和共存元素对Fe,Ni的光谱干扰,Fe,Ni的分析谱线分别为238.204 nm,341.477 nm。测定Fe,Ni的线性范围均为0.001%~0.01%,线性相关系数分别为0.999 4,0 999 8,检出限分别为0.000 01%,0.000 04%。方法的加标回收率为95.7%~115.0%,测定结果的相对标准偏差为2.36%~17.82%(n=8)。该方法快速、简便,能够满足金属钼中含量范围为0.001%~0.01%的Fe,Ni元素的检测要求。     

Determination of synthetic ferric chelates used as fertilizers by liquid chromatography-electrospray/mass spectrometry in agricultural matrices

A high-performance liquid chromatography-electrospray ionization/mass spectrometry (time of flight) method has been developed for the simultaneous determination of synthetic Fe(III)-chelates used as fertilizers. Analytes included the seven major Fe(III)-chelates used in agriculture, Fe(III)-EDTA, Fe(III)-DTPA, Fe(III)-HEDTA, Fe(III)-CDTA, Fe(III)-o,oEDDHA, Fe(III)-o,pEDDHA, and Fe(III)-EDDHMA, and the method was validated using isotope labeled (57)Fe(III)-chelates as internal standards. Calibration curves had R values in the range 0.9962-0.9997. Limits of detection and quantification were in the ranges 3-164 and 14-945 pmol, respectively. Analyte concentrations could be determined between the limits of quantification and 25 muM (racemic and meso Fe(III)-o,oEDDHA and Fe(III)-EDDHMA) or 50 muM (Fe(III)-EDTA, Fe(III)-HEDTA, Fe(III)-DTPA, Fe(III)-CDTA and Fe(III)-o,pEDDHA). The average intraday repeatability values were approximately 0.5 and 5% for retention time and peak area, respectively, whereas the interday repeatability values were approximately 0.7 and 8% for retention time and peak area, respectively. The method was validated using four different agricultural matrices, including nutrient solution, irrigation water, soil solution, and plant xylem exudates, spiked with Fe(III)-chelate standards and their stable isotope-labeled corresponding chelates. Analyte recoveries found were in the ranges 92-101% (nutrient solution), 89-102% (irrigation water), 82-100% (soil solution), and 70-111% (plant xylem exudates). Recoveries depended on the analyte, with Fe(III)-EDTA and Fe(III)-DTPA showing the lowest recoveries (average values of 87 and 88%, respectively, for all agricultural matrices used), whereas for other analytes recoveries were between 91 and 101%. The method was also used to determine the real concentrations of Fe(III)-chelates in commercial fertilizers. Furthermore, the method is also capable of resolving two more synthetic Fe(III)-chelates, Fe(III)-EDDHSA and Fe(III)-EDDCHA, whose exact quantification is not currently possible because of lack of commercial standards.     

Flow-injection manifold for the simultaneous spectrophotometric determination of Fe(II) and Fe(III) using 2,2''-dipyridyl-2-pyridylhydrazone and a single-line double injection approach

A simple and rapid flow-injection (FI) method is reported for the simultaneous spectrophotometric determination of Fe(II) and Fe(III) in pharmaceutical products. The method is based on the reaction of Fe(II) with 2,2'-dipyridyl-2-pyridylhydrazone (DPPH) in acidic medium to form a water-soluble reddish complex (lambdamax=535 nm). Fe(III) reacts with DPPH under flow conditions only after its on-line reduction by ascorbic acid (AsA). Both analytes were determined in the same run via a double-injection valve, which enabled the simultaneous injection of two sample volumes in the same carrier stream (,,single-line double-injection" approach). The two well-defined peaks produced corresponded to total iron [Fe(II)+Fe(III)] and Fe(II). Speciation of the analytes in their mixtures was achieved by multiple regression analysis. The calibration curves obtained were linear over the ranges 0-30 and 0-50 mg L(-1) for Fe(II) and Fe(II), respectively, and the precision [s(r)=1.0% for Fe(II) and 1.5% for Fe(III)] was satisfactory. The method proved to be selective and adequately sensitive (cL=0.25 and 0.17 mg L(-1) for Fe(III) and Fe(II), respectively, in mixtures). Application of the method to the analysis of pharmaceutical samples resulted in excellent accuracy; the percent mean recoveries were in the range 99.0-102.0% for both Fe(II) and Fe(III) and the mean relative error was e(r)=1.0%.     

磁性聚苯胺纳米微球的合成与表征

报道了具有核壳结构的Fe3O4-聚苯胺磁性纳米微球的合成方法和表征结果.微球同时具有导电性和磁性能.在优化的实验条件下,可得到饱和磁化强度Ms为55.4 emu/g,矫顽力Hc为62 Oe的磁性微球.微球的导电性随着微球中Fe含量的增加而下降.微球的磁性能则随着Fe含量的增加而增大.Fe3O4磁流体的粒径和磁性聚苯胺微球的粒径均在纳米量级.纳米Fe3O4粒子能够提高复合物的热性能.实验表明,磁流体和聚苯胺之间可能存在着一定的相互作用,但这种相互作用较为复杂,难于研究     

石墨管原子吸收法测定原子簇化合物中钼铁含量

不久前,我们研究了火焰原子吸收测定Mo-Fe-S原子簇化合物中钼铁元素的方法,收到了较好的效果^[1]。但待测液中铁的含量小于20μg/ml时,铁对钼测定所产生的正干扰消除得不理想。并且当钼、铁浓度小于10μg/ml时,测量的准确度较差.为了克服以上不足,我们研究了石墨管原子吸收法测定低含量钼、铁元素的方法,取得了满意的结果.     

负载型金基催化剂Au/Fe(OH)3催化苯乙烯环氧化反应

用共沉淀法制备了Au/Fe(OH)3催化剂, 以叔丁基过氧化氢为氧化剂, 考察焙烧温度和金担载量等对苯乙烯环氧化反应的影响. 结果表明, 催化剂的焙烧温度、金担载量对苯乙烯环氧化反应有较大影响. 在室温下直接合成的质量分数为4.67%的Au/Fe(OH)3催化剂对苯乙烯环氧化反应显示了很好的催化活性, 于80 ℃反应3 h苯乙烯的转化率达到84.1%, 环氧苯乙烷的选择性达到71.5%. 通过X射线粉末衍射(XRD)、X射线光电子能谱(XPS)和Mössbauer分析, 发现催化剂的催化活性与金的价态及铁的化学存在状态有很大关系. 离子态Au3+与载体Fe(OH)3的协同作用对苯乙烯环氧化反应显示出很好的催化活性.     

磁性Fe_3O_4-聚吡咯纳米微球的合成与表征

报道了具有核壳结构的Fe3O4 聚吡咯磁性纳米微球的合成方法和表征结果 .微球同时具有导电性和磁性能 .在优化的实验条件下 ,可得到饱和磁化强度为 2 3 4emu g ,矫顽力为 45 2Oe的磁性微球 .微球的导电性随着微球中Fe3O4含量的增加而下降 .微球的磁性能则随着Fe3O4含量的增加而增大 .Fe3O4磁流体的粒径和磁性聚吡咯微球的粒径均在纳米量级 .纳米Fe3O4粒子能够提高复合物的热性能 .实验表明 ,磁流体和聚吡咯之间存在着一定的相互作用 ,正是这种相互作用使磁性聚吡咯纳米微球的热稳定性提高 .     

Absolute measurements and certified reference material for iron isotopes using multiple-collector inductively coupled mass spectrometry

Two enriched isotopes, 99.94 at.% 56Fe and 99.90 at.% 54Fe, were blended under gravimetric control to prepare ten synthetic isotope samples whose 56Fe isotope abundances ranged from 95% to 20%. For multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) measurements typical polyatomic interferences were removed by using Ar and H2 as collision gas and operating the MC-ICP-MS system in soft mode. Thus high-precision measurements of the Fe isotope abundance ratios were accomplished. Based on the measurement of the synthetic isotope abundance ratios by MC-ICP-MS, the correction factor for mass discrimination was calculated and the results were in agreement with results from IRMM014. The precision of all ten correction factors was 0.044%, indicating a good linearity of the MC-ICP-MS method for different isotope abundance ratio values. An isotopic reference material was certified under the same conditions as the instrument was calibrated. The uncertainties of ten correction factors K were calculated and the final extended uncertainties of the isotopic certified Fe reference material were 5.8363(37) at.% 54Fe, 91.7621(51) at.% 56Fe, 2.1219(23) at.% 57Fe, and 0.2797(32) at.% 58Fe.