稀土矿区茶叶中稀土元素ICP-AES测定

本文用ＩＣＰ－ＡＥＳ测定稀土矿区茶叶中稀土元素，并用干扰系数法校正茶叶中的无机元素及其他稀土元素对待测稀土元素的光谱干扰。在最佳工作条件下，测定了茶叶样品中的稀土元素含量。     

ICP—AES法同时测定岩石,矿物,土壤等样品中十五种稀土元素的方法研究

本文应用强酸Ｉ号离子交换树脂将稀土元素与基体元素分离，待测液直接用ＩＣＰ－ＡＥＳ同时测定１５种稀土元素，测定中采用干扰等效浓度法，消除稀土元素之间和残余基体元素产生的光谱干扰，方法具有较高的准确度和精密度，是目前较理想的测定岩石等样品中微量稀土元素的方法。     

ICP－AES法同时测定岩石、矿物、土壤等样品中十五种稀土元素的方法研究

本文应用强酸Ｉ号离子交换树脂将稀土元素与基体元素分离，待测液直接用ＩＣＰ－ＡＥＳ同时测定１５种稀土元素，测定中采用干扰等效浓度法，消除稀土元素之间和残余基体元素产生的光谱干扰，方法具有较高的准确度和精密度，是目前较理想的测定岩石等样品中微量稀土元素的方法。     

电感耦合等离子体法测定高纯氧化铕中14个稀土和20个非稀土杂质

本文提出了用ICP-AES直接同时测定高纯氧化铕中14个稀土和20个非稀土杂质元素的分析方法。着重考察了铕基体对分析元素的基体效应,谱线干扰及背景影响等情况,同时对仪器的工作条件进行了优化。在标准溶液中改变了以往对高纯物质进行分析时常常忽略基准物质中的含量,而用标准加入法测出氧化铕基准中的各稀土微量杂质元素的含量作为低标值,有效的消除了由于忽略基准中的杂质元素的含量给分析测定带来的误差。在本工作所选定的条件下,各稀土元素、非稀土元素的回收率在90％-112％之间,稀土元素的精密度实验显示相对标准偏差为1.12％-9.5％。对不同稀土分离厂家的样品进行了检测,结果令人满意。     

微波消解-电感耦合等离子体-原子发射光谱法测定茶叶中的稀土元素

采用HNO3-HClO4-HF消解体系对茶叶进行湿法消解和微波消解,去除有机成分,保留待测元素.用电感耦合等离子-原子发射光谱法测定茶叶中15种稀土元素Sc、Dy、Er、Eu、Gd、Ho、La、Lu、Nd、Pr、Sm、Tb、Tm、Y、Yb的含量.稀土元素加标回收率为90.2%-102.1%,检出限在0.0009-0.0...     

发射光谱法测定茶叶中的痕量铅、铬、镍和铜

茶是人们喜爱的主要饮料之一。茶叶中总是含有不同的痕量重金属元素,当其含量超过一定限最时,就影响茶叶的质量和危害人体健康。因此,测定茶叶中重金属元素的含量,具有重要意义。茶叶中重金属含量的测定,已报导的有     

ICP-AES直接测定氯化稀土和轻稀土中稀土元素

以电荷耦合器件为检测器的ICP-AES光谱仪直接测定混合稀土中的十五种稀土元素.考察十五种稀土元素的五十余条灵敏线的谱图,分析稀土元素之间的光谱干扰并利用多组分谱图拟合方法扣除空白及元素间的干扰.研究溶液酸度及仪器工作参数的影响,方法回收率为98.4%～101.7%,相对标准偏差小于2%.     

ICP-MS法测定茶叶及其多糖提取物中的降血糖相关性元素

采用微波溶样ICP-MS法测定了江西婺源绿茶茶叶、茶叶温水及热水浸提液和茶多糖中降血糖相关性元素(ERBS)的含量,探讨了ERBS含量与茶叶品质老嫩以及茶多糖中ERBS含量与茶叶中ERBS总量的关系.结果表明,茶叶品质老嫩不同,茶叶以及茶多糖中各ERBS含量存在一定差异,由品质差的茶叶提取得到的茶多糖中的ERBS的量较高.茶叶中结合于多糖中的各ERBS占相应ERBS总量的比例在0.03%～9.57%之间,与元素种类、茶叶品质有关.结合于多糖中的ERBS占茶叶ERBS总量的比例,鄣山特级和五级茶分别为1.11%和2.10%,对孤山老叶茶,为0.85%.测定结果可以作为选择提取茶多糖茶叶原料的依据,也可为研究茶多糖可能的降血糖机理提供可靠的无机元素方面的数据.     

共沉淀分离-ICP-OES测定含铁溶液中稀土元素

研究了含铁砂土样品中稀土元素的ICP-OES测量技术。采用草酸盐沉淀或氟化物沉淀与草酸盐沉淀的组合去除样品中Fe和大量岩石基体元素的光谱干扰。结果表明:分析溶液中Fe的浓度小于110μg·mL~(-1),可忽略对样品中稀土元素的ICP-OES光谱测定干扰。不同稀土元素之间沉淀的不同步性小于3%,若以测定稀土元素相邻近的一种稀土元素作内标,则可提高沉淀过程回收率的测定精度。     

茶叶等植物体中稀土元素的光谱测定

本文究了干法灰化样品,以直流粉末法对茶叶等植物体中稀土元素进行光谱测定。工作中以无机盐制配“人工模拟基体”,用其配制标准试样,对茶叶及铁花所作的分析其精密度与准确度都得到较满意的结果。     

应用ICP-AES法研究云南普洱茶稀土含量

应用电感耦合等离子体发射光谱法(ICP-AES)对云南省普洱茶主产地采集的150份普洱茶样品的稀土含量进行检测研究.检测样品中稀土的含量在0.26～4.07 mg·kg-1范围.依据国家标准GB 2762-2005<食品中污染物限量>中稀土限量标准2 mg·kg-1考核,43%的普洱茶样品被检出稀土含量超标.云南普洱熟茶和生茶不同的生产工艺会造成普洱茶稀土含量的差异,并影响产品质量.云南普洱茶不同主产地区之间的稀土含量存在差异,个别地区的普洱茶稀土质量安全控制情况不容乐观.     

铸造锌铝合金稀土变质机理的电子理论研究

根据分子动力学理论建立了液态锌铝合金ZA27的模型，结合计算机编程构造出了ZA27合金α 相与液相共存时的原子结构模型，利用递归方法计算了稀土固溶于晶粒内和富集于结晶前沿 时的电子结构.由此得出：稀土处于相界区比在晶内更稳定，从而解释了稀土在α相内溶解 度很小，结晶时富集于结晶前沿液体中的事实；稀土处于液态和晶态的结构能差相对于铝较 大解释了稀土在相界前的富集使α晶枝产生熔断、游离、增殖的观点.原子间的键级积分计 算也表明，稀土处于结晶前沿液体中与铝相比不容易结晶到晶体表面，起到阻碍晶粒长大， 细化晶粒的作用，这就从电子层次解释了稀土的变质机理. 关键词： 电子结构 液固相界原子结构模型 稀土变质机理     

稀土元素的价电子结构和熔点、结合能的关联性

稀土是重要的战略物资资源,有一些已形成产业,在永磁、发光、催化和储氢等方面有着重要的作用. 对稀土及其化合物的研究一直是国内外研究的热点.对稀土原子结构和价电子结构的研究有助于对其的更深刻的理解. 依据固体与分子经验电子理论,对镧系稀土和Sc, Y的价电子结构进行系统地研究, 并以此为基础,对它们的熔点和结合能做进一步分析,分析结果和实验值相符. 研究结果表明:稀土金属的结构与晶格电子和共价电子密切相关,随着晶格电子向共价电子的转换, 稀土金属的熔点趋于增加.稀土的价态变化也是影响电子分布和性能的主因, 如: Sm和Eu的熔点与电子结构的关系不同于其他稀土,外壳层的共价电子之间的转化是其熔点与其他元素之间差别较大的主要原因.稀土的4f电子对结合能的影响大,这是源于其4f电子引发的收缩效应. 此结果揭示了决定稀土熔点和结合能的主要因素是稀土的价电子结构的变化.     

Coriolis attenuation in the rare earth region

It is shown that the observed rotational band structure in a number of odd-proton and odd-neutron nuclei situated in the rare earth region, can be reproduced in the particle-rotor model without any ad hoc reduction of the Coriolis matrix elements if a value of the pairing gap parameter, which is about 30–40% of that deduced from the corresponding odd-even mass difference, is used. The importance of the proper choice of the pairing gap parameter in the study of the Coriolis attenuation problem is emphasised.     

A method for the determination of some rare earth elements and their correlation with thorium using X-ray fluorescence

This paper presents the results of a simultaneous determination of some rare earth elements and some accompanying elements of the rare-earth fields of Mongolia. Correlation connections of rare earth elements with thorium are established. Data from X-ray fluorescence, gamma activation, and classical chemical methods for analyzing mineral resources were used to find the correlation dependence between rare earth elements and thorium.     

X-ray isochromats of some rare earth elements

Recordings of the isochromat curves of the rare earth elements 64 Gd to 71 Lu have been made by means of a high vacuum spectrometer provided with a bent topaz crystal. The information concerning the density of statesN(E) near the Fermi limit is compared with that deduced from specific heat measurements. The results obtained from the isochromat curves are rather constant, which on account of the atomic configuration in these elements is expected. An observed anomaly in the band structure of Tb metal is discussed. The appearance of this anomaly indicates that a rigid band model is not applicable to some of the actual elements.     

Performance of lead iodide nuclear radiation detectors with the introduction of rare earth elements

Lead iodide has been recognized as a promising material for room temperature radiation detectors. It has a wide band-gap (∼ 2.3 eV), high atomic numbers (82, 53) and it is environmentally very stable compared to mercuric iodide. Electrical and optical properties of lead iodide grown crystals purified under the influence of selected rare earth elements have been investigated. Photo-luminescence and capacitance-voltage measurements have been performed using different rare earth elements.     

Intermediate valence in rare earth systems

The current status of the phenomenon of intermediate valence in rare earth systems is surveyed. Particular attention is paid to the merits and demerits of various experimental methods employed to obtain the value of the mean valence of the rare earth ion, followed by the discussion on the cerium problem.     

Raman spectra of soda-lime-silicate glass doped with rare earth

Soda-lime-silicate glasses doped with different rare earth oxides (La₂O₃, CeO₂, Nd₂O₃, Gd₂O₃ and Y₂O₃) of 1 mol% content were prepared by the traditional melting-quenching methods. In order to reveal the effects of rare earth elements on the behavior of soda-lime-silicate glass the structures of soda-lime-silicate glasses doped with different rare earth oxides were determined using an INVIA confocal microRaman spectrometer equipped with a CCD detector, and viscosities of glass melts were measured using a rotating crucible viscometer; the melting temperature of the studied glasses was derived on the basis of the Arrhenius equation. Three expressions of the fraction of non-bridging oxygen (NBO/NBO+BO), average number of non-bridging oxygen (NBO) per tetrahedron (NBO/tetrahedron) and average number of bridging corners per tetrahedron (bridges/tetrahedron) for investigated soda-lime-silicate glasses were given, and the effect of rare earth dopants on the structure of soda-lime-silicate was characterized by the Raman shift, variation of the [SiO₄] tetrahedron structural unit Qⁿ (n=1,2,3,4), fraction of non-bridging oxygen and the average number of bridging corners per tetrahedron. The effect of doping rare earth oxides into glass on the viscosity and melting temperature was interpreted by changes in structure of soda-lime-silicate glasses doped with rare earth oxides.     

Electrical transport in rare earth ortho-chromites, -manganites and -ferrites

Rare earth ortho-chromites, -manganites and -ferrites are p-type semiconductors with conductivities in the range 10⁻⁴–10⁻¹ ohm⁻¹ cm⁻¹. The conductivity in each series of perovskites decreases with the increasing atomic number of the rare earth. The ionic contribution to conductivity is small in all the three series of solids. None of these solids exhibits intrinsic behavior up to ∼1000°C. The conductivity behaviors of these rare earth compounds reflect the known crystallographic, dielectric and magnetic transitions in these materials. Seebeck coefficients in these compounds are large, typical of narrow-band materials; the Seebeck coefficients show marked changes at temperatures where magnetic and dielectric transitions occur. The electrical transport properties of all the three series of rare earth compounds are essentially controlled by the d-electrons of the transition elements which show localized behavior. This conclusion is in agreement with the results from optical spectra and the predictions of Goodenough. In all these compounds small polarons seem to be responsible for the conduction.