共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
以强酸型离子交换纤维柱分离富集高纯Yb2O3中La,Nd,Eu和Gd等痕量杂质元素,并用Optima 5300 DV ICP-AES测定分离富集后的这4种元素。供试纤维对Yb的动态吸附容量为134 mg·g-1,4.0 g纤维柱的分离条件为:pH 3.00的试液以1.0 mL·min-1流速上柱后,分离柱先以流速为1.5 mL·min-1的pH 3.00 HNO3溶液80 mL预淋洗,再以同样流速pH 5.00的0.01 mol·L-1 EDTA铵溶液淋洗。结果表明:10 mg Yb与各为0.100 μg的La,Nd,Eu和Gd能达到基线分离;分离含100 mg Yb的试液后,在杂质富集液中Yb的残留浓度仅为0.017 1 μg·mL-1。 研究显示,当待测试液中Yb2O3的浓度小于100 μg·mL-1(如Yb 87.8 μg·mL-1)时,它对测定La,Nd,Eu和Gd等杂质元素的基体干扰可以忽略不计。富集倍数分别为La2O3 3.68×105,Nd2O3 4.20×105,Eu2O3 3.82×105,Gd2O3 4.01×105。方法检出限分别为La2O3 0.005 0 pg·mL-1,Nd2O3 0.014 pg·mL-1,Eu2O3 0.001 8 pg·mL-1,Gd2O3 0.008 2 pg·mL-1。本方法已用于99.99% Yb2O3样品中4种稀土杂质的测定,标准加入的平均回收率分别为La2O3 94.2%,Nd2O3 107%,Eu2O3 97.8%,Gd2O3 102%,RSD (%, n=5)分别为La2O3 6.2,Nd2O3 5.9,Eu2O3 7.3,Gd2O3 2.5,校正曲线不需进行Yb的基体匹配,分析周期为4 h。 相似文献
3.
4.
测定了酸性水溶液中甘氨酸、丝氨酸和天冬氨酸稀土络合物(Ln=La、Pr、Nd、Eu、Tb、Dy、Ho、Er、Tm和Yb)的13C诱导位移。对位移试剂的分析指出,三种氨基酸通过α-羧基以双齿形式配位于稀土,配位键长为0.23nm~0.25nm,天冬氨酸的γ-羧基也是配位基团。由本文与文献中已报道的各种氨基酸稀土络合物的13C诱导位移的系统分析表明,配体13C超精细偶合常数A值和结构因子G值有如下规律:(1)│A(C0)│<│A(Cα)│;A(C0)为正,A(Cα)为负;(2)│G(C0)│>│G(Cα)│;配体碳核的G均为负值。 相似文献
5.
6.
7.
采用液相沉淀法合成了铽单掺杂,铕单掺杂,铽、铕双掺杂的硅酸锶发光材料。其结构经X-射线衍射表征。研究了合成样品的激发、发光光谱。研究结果表明:在254nm波长紫外光激发下,SrSiO3:0.04Eu3+的发光光谱中出现4个Eu3+的发光峰,分别为Eu3+的5D0→7F1(588、590nm)、5D0→F2(609nm)、5D0→7F3(626nm)、5D0→4F4(651nm)跃迁峰;SrSiO3:0.04Tb3+的发光光谱中出现4个Tb3+的发光峰,分别为Tb3+的5D4→F6(488nm)、5D4→7F5(541、548nm)、5D4→7F4(584nm)跃迁峰;SrSiO3:0.04Tb3+,0.04Eu3+发光体系中,Tb3+的共掺杂显著增强了Eu3+的特征发射,存在Tb3+→Eu3+的能量传递现象,结果表明有Eu3+和Tb3+两个发光中心。 相似文献
8.
在6—300K下,利用红外傅里叶光谱仪研究了400—4000cm-1间的硅、锗中氧的红外吸收。采用高分辨条件时,分辨率可达0.5cm-1。研究了在低温下利用硅的1106cm-1吸收峰和锗的855cm-1吸收峰探测硅和锗氧含量的探测限和误差。若样品厚度为2cm,估计在20K下,硅中氧含量探测限~9.6×1014氧原子·cm-3,锗中氧含量探测限~3.0×1014氧原子·cm-3。同时,对不同生长条件下直拉锗单晶的氧含量进行了研究,并与用锂沉淀法所求得的锗中氧含量加以比较。对不同氧含量的硅样品的1106cm-1吸收峰在6—300K的变化进行了观察和讨论。
关键词: 相似文献
9.
锂、硼、硅酸盐玻璃体系的11B核磁共振研究 总被引:1,自引:1,他引:0
利用11B的核磁共振谱研究了锂、硼、硅酸盐(Li2O·B2O3·SiO2)三元玻璃体系,测量并分析了BO4单元与对称和非对称的BO3单元的比例。分析结果表明,三元体系的结构单元亦可适用于锂、硼玻璃的二元体系的FDB模型说明,其差异在于前者中的Li2O由B2O3与SiO2按比例分享。 相似文献
10.
在乙醇溶液中以邻菲咯啉(phen)、2,2’-联吡啶(bipy)和对氨基马尿酸(PAH,HL)为配体与铽离子(Tb(Ⅲ))合成了二元和三元稀土配合物。通过元素分析、差热-热重分析、紫外光谱、红外光谱分析,确定了配合物的组成为TbL3(1)、TbL3·phen·H2O(2)和TbL3·bipy·H2O(3),并讨论了配合物1~3的谱学性质和荧光性能。推测出羧基中的氧原子以桥式双齿的形式与稀土离子配位。由红外光谱和热分析测试确定的配合物1及配合物2中的水分子未参与配位。研究表明,铽配合物在489,583和621 nm处出现发射峰,它们分别归属于5D4→7F6,5D4→7F5,5D4→7F4和5D4→7F3的跃迁。其中544 nm处5D4→7F5跃迁的强度最强,配体的共平面性和共轭性越大,配合物的荧光性能越高,三元配合物TbL3·phen·H2O和TbL3·bipy·H2O的荧光强度优于二元配合物TbL3的荧光强度。 相似文献
11.
Possible existence of bound states of a charmed baryon, Λ c , Σ c , Σ* c with a nucleon, N, as well as two charmed baryons, Λ c Λ c , etc., are examined in the meson exchange potential approach. The heavy quark spin symmetry induces a strong tensor coupling between Λ c N, Σ c N and Σ* c N states, which causes a bound state of Λ c N (J = 0+ and 1+) states. Such a bound state is also seen in the spin-singlet Λ c Λ c channel, which resembles the H dibaryon in the strange sector. 相似文献
12.
13.
14.
The temperature dependences of the elastic constants, c11, c33, c44, and c66, in KCP are described. In the temperature range 10–100 K softening is observed in c44, while c66 decreases almost linearly with decreasing temperature. These results indicate the presence of a new critical region. 相似文献
15.
The superconducting transition temperature, Tc, of the LaT4P12 compounds with T = Fe, Ru, or Os has been measured under hydrostatic pressure P up to 1.8 GPa. The T = Fe compound exhibits a substantial increase of Tc from Tc (P = 0) = 4.1 K at a rate (dTc/dP)P=0= +7.2 x 10-1 K/GPa. In contrast, the Ru and Os compounds exhibit only weak decreases of Tc from Tc (P = 0) = 7.2 K and 1.8 K with (dTc/dP)P=0= -1.6 x 10-1 K/GPa and -9.5 x 10-2 K/GPa, respectively. An analysis of this strikingly divergent behavior of Tc(P) in terms of the structural characteristics of the RT4X12 class of compounds where R = rare earth element, T = Fe, Ru, or Os, and X = P, As, or Sb suggests that Tc(P) for these materials consists of two competing contributions: a depression of Tc due to the compression of the lattice (i.e., decrease in volume), and an enhancement of Tc due to the effect of pressure on La itself. 相似文献
16.
Abstract We have studied the effects of fast neutron (E>0.1 MeV) irradiation at reactor (~ 360 K) and low (~ 20 K) temperatures on the superconducting properties of polycrystalline orthorhombic YBa2Cu3O7?y . Measurements were made on the superconducting critical temperature Tc , critical current Jc , Meissner effect and magnetic field dependence of Jc . The Tc drops by an irradiation at reactor temperature and Jc increases with increasing fluence. On the other hand with the irradiation at low temperature, Tc rises and Jc increases. Results of observation of Meissner effect and the magnetic field dependence of Jc are consistent with the behavior of Tc and Jc . 相似文献
17.
Alexander F. Izmailov Alexander R. Kessel 《International Journal of Theoretical Physics》1990,29(10):1073-1090
The exact calculation of the reduced BCS model quantum partition function (QPF) in the thermodynamic limit is carried out by the path integration method. The expression for the QPF and the phase transition temperatureT
c in the regular phase coincide with the results of Bogolyubov. In the nonregular phase a temperature singularity appears in the expression for the QPF: the QPF diverges in the region of temperaturesT
c which are smaller than some critical temperatureT
c
*
, and it turns out that in all casesT
c
*
>
T
c and the differenceT
c
*
–T
c is not small. The interpretation of the temperatureT
c
*
is given. 相似文献
18.
D. V. Shovkun M. R. Trunin A. A. Zhukov Yu. A. Nefyodov N. Bontemps H. Enríquez A. Buzdin M. Daumens T. Tamegai 《JETP Letters》2000,71(2):92-96
The c-axis penetration depth Δλc in Bi2Sr2CaCu2O8+δ (BSCCO) single crystals as a function of temperature has been determined using two techniques, namely, measurements of the ac-susceptibility at a frequency of 100 kHz and the surface impedance at 9.4 GHz. Both techniques yield an almost linear function Δλc(T)∝T in the temperature range T<0.5T c. Electrodynamic analysis of the impedance anisotropy has allowed us to estimate λc(0)≈50 µm in BSCCO crystals overdoped with oxygen (T c≈84 K) and λc(0)≈150 µm at the optimal doping level (T c≈90 K). 相似文献
19.
We review the recent BESIII measurement of e~+e~-→ππh_c in which its line shape is studied between the center-of-mass energies of 3.9 to 4.42 Ge V and an iso-vector charmonium-like state Z_c(4020) is observed in the invariant mass of πhc at the BESIII experiment. The charged Z_c(4020)~± is the second observed Z_c state following Z_c(3900), while the Z_c(4020)~0 is the first observed neutral Z_c state. The line shape of σ(e~+e~-→ππh_c) is also reanalyzed in view of searching for the Y state and the existence of the Y(4220) state is confirmed and compared with the previous work of the BESIII experiment. 相似文献