Sol-hydrothermally derived gadolinium oxide (Gd2O3) nanorods and tamarind-like shape evolution under 80 MeV C6+ ion impact

The present work highlights swift heavy ion irradiation-induced shape evolution of gadolinium oxide (Gd₂O₃) nanorods synthesized via a sol-hydrothermal route. Upon dispersing Gd₂O₃ nanorods in the polyvinyl alcohol matrix, thin solid films were cast on borosilicate glass substrates. The films were then exposed to 80?MeV carbon-ion irradiation, while fluence was varied in the range of 1×10¹¹–3×10¹²?ions/cm². The post analyses were carried out by using X-ray diffraction, high resolution transmission electron microscopy (TEM) and Raman spectroscopy studies. An apparently observable shortening of length (L) and diameter (D) of the nanorods can be revealed through the TEM imaging analyses. Moreover, while exhibiting an aspect ratio (L/D) between 3.3 and 4.7, the nanorods were found to exist in the form of bunching at higher fluences. The irradiation-induced tamarind-like shape evolution at higher fluences was attributed to the overlapping of ion impacts on certain regions of the nanorods. The most intense Raman active peak of the pristine sample located at ～360?cm^?1 was seen to experience blue-shifting (～375?cm^?1) when irradiated at the highest fluence (～3×10¹²?ions/cm²). An altered shape evolution of a thermally and mechanically stable oxide system by the energetic ion impact would bring in new insights as regards construction of surface patterns and their potential use in miniaturized devices.     

Er~(3+)/Tm~(3+)/Yb~(3+)共掺杂BaGa2ZnO5粉末的上转换发光

对Er~(3+)/Tm~(3+)/Yb~(3+)共掺杂BaGa_2ZnO5粉末的上转换发光特性进行了研究。首先,通过不同的制备工艺研究了BaGa2ZnO5粉末的生成条件。XRD分析表明,由于ZnO的高温分解,必须密封烧结并增加ZnO用量才能制备出BaGa2ZnO5。其次,测量了Er~(3+)/Tm~(3+)/Yb~(3+)共掺杂BaGa2ZnO5粉末在980nmLD激发下的上转换发射光谱,发现存在8个较强上转换发射峰,其中480nm和798nm对应于Tm~(3+)离子能级跃迁,其他上转换峰对应于Er~(3+)离子能级跃迁。另外,测量了980nmLD不同激发功率对应的上转换发射峰强度,并根据激发功率-上转换强度曲线拟合得到了各发射峰对应的多光子吸收过程。最后,根据上转换发射光谱和CIE1931标准数据计算了样品粉末的色坐标为(x=0.4151,y=0.4794) ,比较接近白光色坐标,说明所制备的粉末样品具有产生上转换白光的前景。     

Influence of rare-earth metal doping on the catalytic performance of CuO-CeO2 for the preferential oxidation of CO in excess hydrogen

Doping of different rare-earth metals （Pr, Nd, Y and La） had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation （PROX） of CO in excess hydrogen. As for Pr, the doping enhanced the catalytic activity of CuO-CeO2 for PROX. For example, the CO conversion over the above catalyst for PROX was higher than 99% at 120 °C. Especially, the doping of Pr widened the temperature window by 20 °C over CuO-CeO2 with 99% CO conversion. For Nd, Y, and La, the doping depressed the catalytic activity of CuO-CeO2 for PROX. However, the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.     

连铸结晶器喂稀土处理的碳锰钢夹杂物研究

为研究钢中添加稀土带来的夹杂物问题,采用金相夹杂物评级、电解夹杂分析以及电子探针和扫描电镜观察分析,对经稀土处理的微合金化碳锰钢夹杂物进行了研究.结果表明,采用铝脱氧和RH真空充分脱气的微合金化碳锰钢,经连铸结晶器喂稀土处理后,钢中的A,B,C,D类夹杂物分别不大于1.0级、1.5级、0.5级、1.5级,氧化物夹杂总量约为0.0030%.试验钢中主要形成球状稀土硫化物,同时还形成有链状"稀土硫化物包围氧化铝"的复合夹杂物,而稀土氧化物难以生成.     

铈铽共惨杂氟化镧纳米晶体的快速合成和荧光特性

用一种简单的方法快速合成了水溶性铈铽共惨杂氟化镧纳米晶体。这种荧光纳米晶体直径只有14 nm,具有很好的生物相容性,并且在活体干细胞中显示出很强的荧光。结果表明这种铈铽共惨杂氟化镧纳米晶体可作为一种有效的生物荧光标记材料。     

内蒙古中部渣尔泰山群微量元素地球化学特征

通过对内蒙古中部渣尔泰山群各层位岩石采样,对该山群中共43个微量元素（含稀土元素）与地壳丰度进行了对比分析,总结了该山群微量元素的地球化学特征。研究表明,该山群富集W、Re、Cu、Pb、Co等元素,而In、V、Cr、Ni等元素亏损较严重;微量元素在板岩和云母石英片岩中相对含量较高,在灰岩中相对贫化;此外,该山群稀土元素地球化学特征表现为轻稀土富集,重稀土亏损;具有明显的Eu的负异常,Ce的弱正异常。     

五个无心四元硫化物AlxLn3（SiyAl1-y）S7（Ln=Y,Gd,Dy）和In0.33Sm3SiS7的合成、结构及性质

使用一种新的高温固相反应方法合成得到了五个新的异质同构的四元稀土硫化物.它们结晶于六方晶系的手性空间群P63,属于ALn3EQ7（A：碱金属或货币金属 Ln：稀土元素 E：第IVA族元素 E：硫属元素）结构类型,晶胞参数为a=9.621（1）～10.038（2）A,c=5.672（2）～5.939（1）A,V=476.1（1）～494.9（2）A^3,Z=2.它们的晶体结构可以描述为：LnS8双帽三棱柱之间相互连接成三维框架结构,而A位和E位原子分别占据所形成的八面体和四面体空隙.化合物4的光学和磁性质的研究表明：它是光学带隙为2.34eV的半导体,并表现出类似于反铁磁相互作用的磁行为.     

Synthesis,structures and magnetic properties of Pr-lean Pr2Fe14B/Fe3B nanocomposite alloys

The lean rare-earth Pr_4.5Fe_77−xTi_xB_18.5 (x=0, 1, 4, 5) nanocomposite alloys were prepared by melt spinning method and subsequent thermal annealing. The effect of Ti content and annealing temperature on the magnetic properties and the microstructure of these magnets were investigated. The enhancing coercivity H_c from 211.4 to 338.2 kA/m has been observed at the optimal annealing temperature of 700 °C by the addition of 5 at% Ti in Pr₂Fe₁₄B/Fe₃B alloys. It was also found that increasing Ti content leads to marked grain refinement in the annealed alloys, resulting in strong exchange-coupling interaction between the hard and the soft phases in these ribbons. In addition, the magnetization reversal behaviors of Pr₂Fe₁₄B/Fe₃B nanocomposites were discussed in detail.     

通过氢键构筑的含3-硝基邻苯二甲酸的层状超分子化合物

合成了含大量氢键的层状超分子化合物[C₄H₁₂N₂](HL)₂ (I)和[YL(HL)(H₂O)₃]₂•2H₂O (II) (H₂L＝O₂NC₆H₃- (CO₂H)₂, 3-硝基邻苯二甲酸), 并通过元素分析、红外分析和单晶X衍射表征了组成与结构. 化合物I为双质子化哌嗪阳离子和3-硝基邻苯二甲酸氢根阴离子组成的加合物, 阴离子之间靠强烈的O—H…O氢键形成无限链状结构, 同时阴离子链通过N—H…O氢键与阳离子扩展成网状结构, 相邻的网状结构再由分子间弱作用力构筑成层状超分子. 化合物II则是在双核稀土配合物结构单元通过O—H…O氢键构成的网状结构基础上再进一步由层间弱作用力构筑成的层状超分子化合物. 化合物II的网格结构中, 菱形单元空隙里填充的两个结晶水通过氢键将结点上的双核单元更牢固地结合在一起. 化合物I为单斜晶系, P2₁/c空间群, a＝1.3176(3) nm, b＝1.1096(2) nm, c＝0.75950(15) nm, b＝97.14(3)°, V＝1.1017(4) nm³, Z＝4, μ＝0.129 mm^－1, D_c＝1.533 Mg/m³. 化合物II为三斜晶系, P-1空间群, a＝0.81262(16) nm, b＝0.86942(18) nm, c＝1.5011(3) nm, α＝99.84(3)°, β＝91.26(3)°, γ＝104.55(3)°, V＝1.0091(4) nm³, Z＝1, μ＝2.983 mm^－1, D_c＝1.910 Mg/m³.