镧、钇对90W-Ni-Fe合金显微结构及性能的影响

以喷雾干燥 H2还原法制备的纳米级90W 7Ni 3Fe复合粉末为原料,针对不同稀土元素La,La Y,Y含量对90W Ni Fe合金性能和显微结构的影响进行了研究。结果表明:当添加La,La Y,Y在0～0.8%(质量分数)范围时,试样相对密度均在0.4%稀土时出现极大值,分别为99.3%,99.4%,99.6%。添加0.4%的La或La Y时,试样抗拉强度出现极大值,分别是906和983.5MPa,而当添加0.6%Y时,试样抗拉强度出现极大值1078MPa。添加0.2%La和Y时,试样延伸率出现极大值分别为17%和19.5%。添加La对W晶粒的抑制作用不明显,添加0.4%Y后对W晶粒长大的抑制作用较为明显,W晶粒尺寸从原来的15～20μm减少到10～15μm,W晶粒由不加稀土时的球形变为近球形或多边形,且随稀土含量的增加其影响作用更明显。La,La Y,Y同W,Ni,Fe3种元素在晶界上分别形成了W12.95Ni3.42Fe1.93La27.51,W13.61Ni2.61Fe1.07Y20.52La25.27,W13.07Ni2.96Fe1.52Y23.65(摩尔比)的中间相。添加稀土元素后,使得W在粘结相中的溶解度明显下降,由58.65%下降为添加0.4%La Y时的29.86%。当添加相同含量的稀土元素时,对合金性能影响程度的大小顺序是Y>La Y(混合稀土)>La。     

基于核酸酶安培型电化学生物传感器的示差脉冲伏安法测定纺织品中的铅

建立基于核酸酶安培型电化学生物传感器的示差脉冲伏安法测定纺织品中铅的含量。信号探针集成的核酸酶17E DNAzyme铅离子识别体系组装在金纳米粒子修饰的金基底电极上,同时作为生物识别元件和信号元件。采用三电极体系,以0.1 mol/kg的NaClO_4溶液为电解质溶液。调整时间为50 ms,间隔时间为0.5 s,调制振幅为50mV,阶跃电势为5 mV,扫描范围为0.15～0.55 V,采用示差脉冲伏安法测定铅离子。铅离子的质量浓度c在0.020～2.0μg/kg范围内,其对数lgc与电极峰电流信号的变化率(I_0–I)/I_0呈良好的线性关系,线性相关系数为0.992 4,方法检出限(S/N=3)为1.3μg/kg。测定结果的相对标准偏差为2.5%～4.0%(n=6),加标回收率为91.4%～105.3%。该方法与国标法的测定结果无显著性差异。该传感器对铅离子的检测具有良好的选择性,实现了对溶液中铅离子的无试剂化检测。该方法操作简便,准确度高,可用于纺织品铅含量的检测。     

微波消解–分光光度法测定陶瓷原料中二氧化钛

采用微波消解–二安替比林甲烷分光光度法测定陶瓷原料中二氧化钛的含量。探讨了样品消解用酸的种类、检测波长、显色时间和显色剂用量对测定结果的影响。试验结果表明,以HNO_3–HF–H_2O_2溶解样品,395 nm为检测波长,显色20 min,显色液用量为12 m L时测试结果满意。测定钛的线性范围为0~2.0μg/m L,线性相关系数r~2=0.999 5,方法检出限为0.56μg/g。用该法对4种标准物质进行分析验证,测定结果与推荐值相符,测定结果的相对标准偏差为0.64%~2.28%(n=6),加标回收率为95.3%~104%。用该方法和国标方法对乐山和眉山地区陶瓷原料样品进行分析比对,经t检验证明,两种方法测定结果无显著性差异。该方法快速、准确,适合陶瓷原料中二氧化钛的检测。     

醇盐法制备稀土化合物超微粉末

稀土元素具有广泛的用途,在大多数的应用中其效果都与原料的纯度、粒度、粒经分布范围等因素有关。由于超微粉末的比表面积大、化学活性高,因此可以预料,若将稀土化合物制成超微粉末,会使它的催化性能及在各种材料中的性能有明显的改变,也可使稀土有新的、更高的应用价值。     

Thermal Stability of 4-chloro-2-nitro- and 4-chloro-3-nitrobenzoates of Rare Earth Elements: Influence of substituent positions

The physico-chemical properties and thermal stability in air of rare earth element 4-chloro-2-nitro- and 4-chloro-3-nitrobenzoates of the general formulae Ln(C₇H₃NO₄Cl)₃2H₂O were compared and the influence of the position of the Cl and NO₂ substituents on their thermal stabilities was investigated. The complexes of both series are crystalline, hydrated salts with colours typical of Ln³⁺. The carboxylate group in these complexes is a bidentate, chelating ligand. The NO₂ group in the chloronitro complexes does not undergo isomerization. The thermal stabilities of the 4-chloro-3-nitrobenzoates of rare earth elements were studied in the temperature range 293–1173 K, but those of 4-chloro-2-nitrobenzoates of those elements were studied only at 293–523 K because they decompose explosively above 523 K. The positions of the Cl and NO₂ substituents on the benzene ring influence the thermal properties of the complexes and their decomposition mechanisms. The different thermal stabilities of the complexes are connected with various inductive and mesomeric effects of the Cl and NO₂ substituents on the electron density in benzene ring.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermal Stability of 4-Chloro-3-Nitro- and 5-Chloro-2-Nitrobenzoates of Rare Earth Elements

The physico-chemical properties and thermal stabilities in air of rare earth element 4-chloro-3-nitrobenzoates and 5-chloro-2-nitrobenzoates were compared and the influence of the positions of the Cl and NO₂ substituents on their thermal stabilities was investigated. The complexes of both series are crystalline, hydrated or anhydrous salts with colours typical of Ln³⁺. The carboxylate group in these complexes is a bidentate, chelating ligand. The NO₂ group in the chloronitro complexes does not undergo isomerization. The thermal stabilities of the 4-chloro-3-nitrobenzoates of Y and the lanthanides were studied in the temperature range 273-1173 K, but those of the 5-chloro-2-nitrobenzoates of these elements were studied only at 273-523 K, because they decompose explosively above 523 K. The positions of the Cl and NO₂ substituents on the benzene ring influence the thermal properties of the complexes and their decomposition mechanisms. The different thermal stabilities of the complexes are connected with various inductive and mesomeric effects of the Cl and NO₂ substituents on the electron density in the benzene ring. This revised version was published online in July 2006 with corrections to the Cover Date.     

稀土的毒理学效应

综述了稀土的毒理学效应，包括：稀土的急性毒性，稀土的慢性毒性，稀土的日允许摄入量和稀土的毒性分类。     

我国稀土化学的进展

建国以来我国稀土化学研究取得了重要进展,本文概述了我国50年来,特别是近20年来在稀土的固体化学、稀土的生物无机化学、稀土的萃化学和稀土的配位化学领域取得的一些代表性成果。     

稀土离子特性与稀土功能材料研究进展

稀土元素是一个包含了由钪、钇与镧系共17种元素的系列统称,它们既具有本质上的物理化学相似性,也具有各自独特和多样的电子结构。 从化学水平上讲,稀土离子的特性决定了稀土永磁、磁致冷、超导、热释电、光学制冷、非线性光学、催化等高新技术应用的本质;从材料水平上讲,稀土功能材料是实现这些技术应用的基础。 从科技发展要求来讲,稀土功能材料的研发是实现稀土资源高质量发展的最重要途径。 本文从稀土离子特性出发,利用轨道杂化模型构建稀土离子与稀土功能材料之间的基本关系,总结了近年来不同应用领域中稀土离子在稀土功能材料的组成设计与性能优化方面的研究进展。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定镧玻璃废粉中稀土元素总量及配分量

建立了电感耦合等离子体原子发射光谱(ICP-AES)法测定镧玻璃废粉中稀土元素总量和配分量的分析方法。样品经碱熔融后分离硅、铝等元素及钠盐,用硝酸和高氯酸破坏滤纸和溶解沉淀,用ICP-AES法测定稀土元素总量和配分量。讨论了溶解样品条件、共存元素干扰等影响测定的各种因素。实际样品的稀土总量与草酸盐重量法测定结果一致,配分量与X-射线荧光光谱(XRF)法、电感耦合等离子体质谱(ICP-MS)法测定结果一致。RSD(n=11)在0.15%~1.1%,加标回收率为97%~105%。测定范围为:La_2O_3/REO(80%~98%);CeO_2/REO(2%~20%);REO(16%~70%)。方法能快速准确地测定镧玻璃废粉中稀土元素总量及配分量。     

希土季铵盐配合物的研究——Ⅴ.[(n-C_4H_9)_4N]_3Nd(NCS)_6的晶体结构研究

合成了硫氰酸合希土酸四丁基季铵盐配合物,测定了它们的远红外光谱及部分配合物的中红外光谱,结果表明,配合物中的NCS~-是以氮原子与Ln~(3+)配位。用X射线单晶衍射法测定了[(n-C_4H_9)_4N]_3Nd(NCS)_6晶体的结构,结果表明,该晶体属单斜晶系,C_c空间群,晶胞参数为:a=25.188(8)(?),b=13.320(6)(?),c=25.322(8)(?),β=121.30(2)°,晶胞体积V=7258.9(?)~3,每一晶胞中有四个配合物分子,中心离子Nd~(3+)与六个来自NCS~-的氮原子配位,这六个氮位于配位正八面体的六个顶角上,构成配阴离子Nd(NCS)_6~(3-),它与三个[(n-C_4H_9)_4N]~+以静电引力结合成中心分子,所以晶体为离子型晶体。     

Die chemische Zersetzung von Seltenerd-Nitraten: Eine neue Methode zur Anreicherung schwerer Yttererdnitrate im kg-Maßstab

Summary On addition of oxidizable organic substances to molten rare earth nitrates reaction takes place with evolution of nitric oxides and formation of basic nitrates, the two-step hydrolysis of which results in effective enrichment of heavy yttrium earths (YE) from rare earth mixtures in kg-quantities. Using methanol as reducing agent the reaction takes place at 160°C, much lower than using the method of purely thermal decomposition. In both methods after the first hydrolysis step a productYE(OH)_1.5(NO₃)_1.5·H₂O can be isolated.