Lamellar structures in neodymium borides

Samples with the nominal composition Nd₂B₅ contain strongly disordered crystals composed of nanosized (100) lamellae. Most commonly, a polysynthetic twinning based on a fourfold rotation separates the lamellae at coherent boundaries. The structure of the twin interface contains a pseudo fourfold arrangement of B atoms as derived from electron microscopy techniques. Such pseudo-symmetry serves for a rationalization of the twinning. Additionally, a chemical intergrowth of Nd₂B₅ and NdB₄ lamellae based on related structural building units can be observed. Further HRTEM examinations allow the identification of a new structural variant of neodymium borides.     

铕和铽与3,4-呋喃二甲酸双核配合物的合成、表征及其晶体结构

本文首次合成了铕(Ⅲ)和铽(Ⅲ)与3,4-呋喃二甲酸配合物,研究了它们的IR、DTA、TG、DTG和荧光光谱等性质,并完成了单晶的晶体分析。结果表明,配合物为〔Ln·HL_2(H_2O)_2〕_2·2H_2O(Ln=Eu(Ⅲ),Tb(Ⅲ);H_2L=3,4-呋喃二甲酸),属单斜晶系,P2/c空间群,Z=2,晶胞参数对铕和铽配合物分别为α=10.842(1),10.801(4);b=8.725(2),8.664(2);c=16.366(4),16.308(6)A;β=93.50(1),93.67(3)°;V=1545.3(5),1523.0(8)A~3。     

稀土对高铬铸铁碳化物形态及相变动力学的影响

研究了稀土元素对高铬铸铁中碳化物的影响，并对加稀土、不加稀土的高铬铸铁试样的连续冷却转变（ＣＣＴ）曲线进行了测定。结果表明，稀土元素能破碎高铬铸铁中的碳化物，使碳化物由网状、长条状向岛状、块状过渡。同时，稀土元素提高了高铬铸铁的固态相变温度并缩短了贝氏体的孕育期。     

Nd2O3改性PbTiO3陶瓷性能的研究

通过添加少量的Ｎｄ２Ｏ３可以改善ＰｂＴｉＯ３陶瓷的性能。这种性能的改善是与用Ｎｄ２Ｏ３改性的ＰｂＴｉＯ３陶瓷的显微结构物导电机制密切相关的。本文研究了Ｎｄ２Ｏ３改性的ＰｂＴｉＯ３陶瓷的性能参数。     

Uncertainty propagation through correction methodology for the determination of rare earth elements by quadrupole based inductively coupled plasma mass spectrometry

Determination of rare earth elements by quadrupole based inductively coupled plasma mass spectrometry (ICP-QMS) shows several spectroscopic overlaps from M⁺, MO⁺ and MOH⁺ ions. Especially, the spectroscopic interferences are observed from the atomic and molecular species of lighter rare earth elements including Ba during the determination of Eu, Gd and Tb. Mathematical correction methods, knowing the at.% abundances of different interfering isotopes, and the extent of formation of molecular species determined experimentally, have been used to account for various spectroscopic interferences. However, the uncertainty propagated through the mathematical correction limits its applicability. The uncertainty propagation increases with the increase in contribution from interfering species. However, for the same extent of total contribution, the overall error decreases when the interfering species are more than one. In this work, chondrite as well as a few geological reference materials containing different proportions of various rare earth elements have been used to study the contributions of different interfering species and the corresponding uncertainty in determining the concentrations of rare earth elements. A number of high abundant isotopes are proposed for determining the concentrations of various rare earth elements. The proposed isotopes are tested experimentally for determining the concentrations of different rare earth elements in two USGS reference materials AGV-1 and G-2. The interferences over those isotopes are corrected mathematically and the uncertainties propagated due to correction methodology are determined for those isotopes. The uncertainties in the determined concentrations of rare earth elements due to interference correction using the proposed isotopes are found to be comparable with those obtained by the commonly used isotopes for various rare earth elements.     

Selective preconcentration of rare earth elements by substoichiometric precipitation of calcium oxalate and its application to the neutron activation analysis of biological material

A preconcentration method for trace amounts of rare earth elements (REs) based on the substoichiometric precipitation of calcium oxalate was developed. RE(III) was quantitatively coprecipitated with calcium oxalate which had been precipitated from the calcium of a macrocomponent in a biological sample by addition of a substoichiometric amount of oxalate. In this way high selectivity for RE(III) from other elements was achieved. The method was applied to the neutron activation analysis of a biological sample (NBS SRM 1572 Citrus Leaves), and Sc, La, Ce, Pf, Nd, Sm, Eu, Th, Dy, Ho, Yb and Lu were determined with a relative standard deviation of less than 5%.     

铽锰基化合物TbMn6Sn6的结构和磁性

研究了重稀土金属化合物ＴｂＭｎ６Ｓｎ６的晶体结构、内禀磁性及其矫顽力随和外场变化的规律。ＴｂＭｎ６Ｓｎ６为ＨｆＦｅ６Ｇｅ６型六角型结构，晶格常数为：ａ＝０．５５６１ｎｍ，ｃ＝０．９０４７７ｎｍ，单胞体积为０．２４１ｎｍ＾３，居里温度ＴＣ＝４２１Ｋ。ＴＭｎ６Ｓｎ６化合物在外场较弱时，热磁曲线呈亚铁磁性；当外场较强时，则表现出铁磁行为，具有变磁性，ＴｂＭｎ６Ｓｎ６的矫顽力随温度变化，当温度Ｔ＝２００Ｋ     

稀土（Ⅲ）—三溴偶氮胂络合物极谱吸附波的研究

在PH9.0的氨水-氯化铵缓冲溶液中,稀土(Ⅲ)与三溴偶氮胂在-0.69V(vs.SCE)处产生一灵敏的极谱波,二次导数峰高与稀土浓度在3.O×10~(-8)～9.0×10~(-7)mol·L~(-1)范围内呈线性关系,检出限为2.O×10~(-8)mol·L~(-1).探讨了该极谱波的性质和电极反应机理.用此法测定了球墨铸铁中的稀土总量,结果满意.     

超低硫微合金钢中稀土元素的作用

稀土在超低硫（Ｓ〈０．００３％）铌钛微合金风中仍然有净化钢质、变质夹杂的作用。钢中ＣＲＥ／ＣＯ＋Ｓ控制在４左右，可获得最佳效果。超低硫钢中稀土固溶量可达到１０＾－５－－１０＾－４数量级，显著减少晶界Ｓ、Ｐ的偏聚，推迟钢的动态再结晶，细化晶粒和沉淀相，促进铌钛碳氮化物析出。稀土在钢中还有微合化的作用。     

稀土的电分析化学

本文介绍了稀土元素的电分析化学，举例简述三大类染料及一些有机试剂与稀封土离子的络合吸附波、络合物组成、电还原机理及其在稀土农用中的分析应用，具有我国对稀土电分析化学研究的特点。