ICP-AES法测定铸铁中的镧、铈、镨、钕、钐

应用ICP-AES法测定铸铁中稀土元素镧、铈、镨、钕、钐可优化ICP的工作参数,选择合适的分析谱线,精密度良好,相对标准偏差＜5%,回收率在95%～101%之间.     

ICP-AES法测定钢中微量La、Ce、Pr、Nd和Sm

采用ICP-AES测定钢中微量La、Ce、Pr、Nd、Sm,试验了元素的干扰情况,优化了仪器工作条件,选择了元素最佳分析谱线。方法准确、快速、简便。     

ICP-AES法测定钢中稀土夹杂物La,Ce,Pr,Nd,Sm含量

采用ICP-AES测定钢中稀土夹杂物La,Ce,Pr,Nd,Sm含量.确定了电解制度、优化了仪器工作条件、选择了元素最佳分析谱线.方法准确、快速、简便.     

ICP-AES法测定镁合金中的La、Ce、Pr、Nd

采用ICP-AES法代替传统的化学分析方法，不仅实现了对镁合金中的La、Ce、Pr、Nd元素的同时快速测定，而且测试数据的准确度和精度很高。     

La、Ce、Pr、Nd四组份串级萃取Ce/Pr分离系数的研究及其在工艺设计中的应用

本文研究了La、Ce、Pr、Nd四组份串级萃取Ce/Pr分离时有效分离系数在槽体中的变化规律,推导了该类体系有效分离系数的函数表达式,提出了四组份两出口工艺设计的有效分离系数模型。该模型简化并优化了多组份稀土萃取的理论设计,克服了多组份体系各参量变化时进行工艺设计的盲目性,从本质上符合了串级分馏萃取体系的实际。生产实践表明,该模型设计的工艺参数可靠、优化,指导工艺参数调整,同样的萃取设备,处理能力提高了57.82%,酸、氨耗分别下降了47.44%和38.79%,结果令人满意。     

P204萃取分离ICP-AES法测定CeO_2标准物质中La,Pr,Nd,Sm,Gd和Y

采用ＨＮＯ_３和Ｈ_２Ｏ_２一溶解试样,在８ｍｏｌ／ＬＨＮＯ_３介质中,以溴酸钾将Ｃｅ（Ⅲ）氧化成Ｃｅ（Ⅳ）,继以Ｐ２０４／ＣＣｌ_４萃取Ｃｅ（Ⅳ）,将三价稀土元素与四价体分离,用ＩＣＰ—ＡＥＳ法测定ＣｅＯ_２标准物质中Ｌａ,Ｐｒ．Ｎｄ,Ｓｍ,Ｇｄ和Ｙ,分析结果均落在标准值的置信区问内,ＲＳＤ＜６％．     

La0.65RE0.10Mg0.25Ni3.5Si0.15(RE=La,Ce,Pr,Nd,Sm)储氢合金的电化学性能及EIS分析

通过感应熔炼制备La0.65RE0.10Mg0.25Ni3.55i0.15(RE =La,Ce,Pr,Nd,Sm)合金.采用X射线衍射方法分析了合金的相结构,研究了其电化学性能,并采用电化学阻抗谱分析了合金电极的放氢动力学特性.研究结果表明,合金是以LaNi5、LaNi3为主相的多相结构,同时合金中少量的Si元素与Mg和Ni元素形成了少量的Mg2 Si相和Ni2Si相.Ce,Pr,Nd,Sm部分替代La以后,合金的放电容量下降,Ce的替代使合金容量大幅度降低.对于本系列合金,La被其他稀土元素部分替代后,合金经过100次循环后的容量保持率略有下降,但除了Pr元素以外,变化值均较小.合金电极的电化学阻抗谱分析表明,中低频区的容抗弧半径依次为Ce ＞La＞ Nd ＞Sm ＞Pr,这表明采用Nd、Sm、Pr替代La后合金电极在碱液中放电过程电荷传递电阻Rct减小,即合金表面活性增加,但Ce替代却导致Ret急剧增大,这可能与Ce在碱液中易形成氧化物降低了合金的表面活性有关.     

Structural and optoelectronic properties of CsLnZnTe3(Ln=La,Pr,Nd and Sm)

Zinc telluride is a versatile wide band gap semiconductor used in many applications.But it has certain limitations like large dimensions and large band gaps.Introducing alkali metal to its bulk lattice(3D) can reduce its dimensions and lanthanide can produce a red shift in the energy gap by converting it into quaternary compounds.The alkali and lanthanide incorporated quaternary zinc tellurides CsLnZnTe₃(Ln =La,Pr,Nd and Sm) form layered crystal structure in which_∞²     

Thermochemical Properties of the Complexes RE(HSal)3·2H2O (RE=La, Ce, Pr, Nd, Sm)

Five solid rare earth salicylate complexes were synthesized by low hydrated lathanide chloride and salicylic acid. The complexes in this experiment were identified as the general formula RE(Hsal)3·2H2O(RE=La, Ce, Pr, Nd, Sm) by elemental analysis and EDTA volumetric analysis. IR spectra of the complexes show that carboxyl of salicylic acid coordinates to RE3 ions. Electrochemical behaviors of the complexes on the glass-carbon electrode were researched with cyclic voltammetry (CV). It is indicated that the electrochemical process of the complexes is a one-electron redox process and the electrochemical reversibility of complexes is less than that of the lanthanide chlorides. The constant-volume combustion energies of complexes, ΔcU, were determined with a precise rotating-bomb calorimeter at 298.15 K. Their standard molar enthalpies of combustion, ΔcHθm, and standard molar enthalpies of formation, ΔfHθm, were calculated.     

金属钕及镨中钕,镨和钐的ICP测定

采用ＩＣＰ发射光谱研究了稀土钕和镨样品中钕、镨和钐三个元素的分析。通过采用内参比法补偿非光谱干扰、Ｋ系数法和逐步逼近法扣除光谱干扰,测定了稀土主含量、次含量和杂质,主含量的变异系数小于０．５％,次含量的变异系数小于４％。将本方法同Ｘ荧光光谱法对比,结果吻合很好。     

Calculation of RECl_3-CaCl_2-LiCl Phase Diagrams(RE=La, Ce, Pr, Nd)

ＣａｌｃｕｌａｔｉｏｎｏｆＲＥＣｌ_３－ＣａＣｌ_２－ＬｉＣｌＰｈａｓｅＤｉａｇｒａｍｓ（ＲＥ＝Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ）ＱｉａｏＺｈｉ－Ｙｕ（乔芝郁）；ＸｉｎｇＸｉａｎ－Ｒａｎ（邢献然），ＤｕａｎＳｈｕ－Ｚｈｅｎ（段淑贞）（ＤｅｐａｒｔｍｅｎｔｏｆＰｈ...     

Determination of La,Pr,Nd,Sm,Gd and Y in CeO2 Certified Reference Materials by ICP-AES

A method for the determination of trace La,Pr,Nd,Sm,Gd and Y in CeO₂by ICP-AES after P204/CCl₄extraction separation is described.The limit of determination of impurities in CeO₂ is in the range of 0.05×10^-6-0.24×10-6.The RSD is less than 6%.The proposed method provides excellent and accurate analytical results for the CeO₂ samples prepared as certified reference materials.     

Thermodynamics of cadmium- and zinc-rich alloys in the Cd−La,Cd−Ce,Cd−Pr,Zn−La,Zn−Ce and Zn−Pr systems

The thermodynamics of the cadmium- and zinc-rich alloys in the Cd?La, Cd?Ce, Cd?Pr, Zn?La, Zn?Ce, and Zn?Pr systems have been studied with a high-temperature galvanic cell method. The values of the standard free energy of formation (kcal per mole) of the intermetallic compounds are given by the equations: $$\begin{gathered} (LaCd_{11} ), \Delta Gf^ \circ = - 72.3 + 43.6 \times 10^{ - 3} T (670^ \circ to 804^ \circ K) \hfill \\ (CeCd_{11} ), \Delta Gf^ \circ = - 70.5 + 44.6 \times 10^{ - 3} T (638^ \circ to 884^ \circ K) \hfill \\ (PrCd_{11} ), \Delta Gf^ \circ = - 69.1 + 44.8 \times 10^{ - 3} T (635^ \circ to 825^ \circ K) \hfill \\ (LaZn_{11} ), \Delta Gf^ \circ = - 92.6 + 48.0 \times 10^{ - 3} T (705^ \circ to 793^ \circ K) \hfill \\ (CeZn_{11} ), \Delta Gf^ \circ = - 87.9 + 45.0 \times 10^{ - 3} T (710^ \circ to 1018^ \circ K) \hfill \\ (PrZn_{11} ), \Delta Gf^ \circ = - 85.3 + 42.7 \times 10^{ - 3} T (696^ \circ to 875^ \circ K) \hfill \\ \end{gathered} $$ Equations are also given for the partial molar excess free energies of the lanthanide in dilute solutions of the lanthanide in liquid cadmium or zinc. The enthalpy of formation of the intermetallic compounds is discussed in terms of the crystalline structure of these intermetallic compounds. It is shown that the enthalpy of formation is a linear function of the ration/V _c , wheren is the number of zinc or cadmium atoms which are near-neighbors of the lanthanide atom andV _c is the volume of the cage formed by the near-neighbor cadmium or zinc atoms. A linear dependence of the enthalpy of formation onn/V _c is also found for the intermetallic compounds in several other binary systems. These empirical correlations are discussed in terms of a model which involves localized bonds between the lanthanide and zinc or cadmium atoms.     

(Nd,Pr,Ce)-Fe-B磁体的组织与磁学性能

为开发低成本烧结钕铁硼磁体,用30% Ce替代(Nd_0.75Pr_0.25)_32.69Fe_66.25B_1.06磁体中的Nd和Pr,研究了磁体在烧结及回火过程中的组织结构和磁学性能变化.结果表明,取向压坯在1030~1080℃烧结2 h后,随烧结温度升高,磁学性能下降,烧结温度为1030℃时综合磁学性能均最好.烧结态Ce替代磁体的综合磁学性能优于未替代磁体.一级回火后,相组成和晶粒尺寸基本不变,边界结构也未发生明显变化,磁体性能基本不变,或有少量下降.二级回火后,晶界明显改善,获得较清晰且平直的晶界,磁体矫顽力均得到大幅提高.Ce替代磁体的剩磁、矫顽力和磁能积均稍低于未替代磁体.     

铈、镧、钕和硫在铸铁中行为的研究

研究了不同含硫量和不同冷却速度下铈、镧和钕对铸铁石墨形态和基体组织的影响。试验表明，不同的稀土元素在铸铁中的行为是不一样的。同时，硫和冷却速度对稀土元素的作用有重要的影响。     

Preparation and Structure of Mg2-xRExNi （RE = La, Ce, Pr, Nd, Y） Ternary Alloys

A series of Mg2-xNdxNi (x =0.05, 0.1, 0.2, 0.3) alloys and Mg1.95RE0.05Ni (RE= La, Ce, Pr, Nd, Y)ternary alloys were prepared by ball milling of mixted powder of Mg, Ni, RE and sintering under the protection of argon. XRD analysis shows that Mg2-xNdxNi (x = 0.05, 0.1 ) and Mg1.95RE0.05Ni consist of single phase with the same crystal structure as Mg2Ni. While three-phase alloys including Mg2Ni, NdNi and NdMgNi4 were formed in Mg1.8Nd0.2Ni and Mg1.7Nd0.3Ni alloys respectively. The lattice constants of Mg2Ni in those ternary alloys were calculated. The decomposition of Mg2Ni occurs in the milling process of Mg2Ni and Mg1.95RE0.05Ni alloys respectively. For the latter, another earlier reaction occurs in milling process, which means that atoms of RE are separated from crystal structure of Mg2Ni and form relevant oxides by combination with oxygen existed in argon atmosphere.