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1.
使用复杂晶体化学键理论计算了La0.5R0.5Ba2Cu3O7(R=Pr,Nd,Sm,Eu,Gd,Dy,Y,Ho,Er,Tm,Yb,Lu)(La-R123),Pr0.5R0.5Ba2Cu3O7(R=La,Nd,Sm,Eu,Gd,Dy,Ho,Y,Er,Tm,Yb,Lu)(Pr-R123)以及RBa2Cu3O7(R=La,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Y,Er,Tm)(R123)中Cu-O键的键共价性,结果表明Pr-R123,La-R123,以及R123都应具有超导性,而实验结果是La0.5Pr0.5Ba2Cu07,R0.5,Pr0.5Ba2Cu3O7(R=La,Nd,Sm,Eu,Gd)无超导性,产生这种矛盾的原因尚不明确,需要做进一步的研究。  相似文献   

2.
研究发现La^3+(Lu^3+,Y^3+)对Tb^3+均苯四甲酸(BTCA)体系具有强烈的共发荧光效应,在最佳条件下,共发光离子La^3+,Lu^3+,Y^3+可分别使Tb-BTCA体系的荧光增强312,133和100倍,介绍了Tb-La(Lu,Y)-BTCA共发荧光体系的荧光特点,形成条件和影响因素,利用La^3+(Lu^3+,Y^3+)的增敏效应,测定了合成稀土样品和包头稀土标准氧化物中的Tb  相似文献   

3.
吲哚-3-丙酸稀土二元配合物的合成表征和生物活性   总被引:7,自引:0,他引:7  
合成了15种稀土二元配合物.其组成为RE(IPA)3(RE=La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y;IPA=吲哚3丙酸根).通过化学分析、红外光谱、1HNMR谱、X射线粉末衍射和热谱等方法对新合成二元配合物的结构及性质进行了研究,并探讨了La(IPA)3·H2O对小麦幼苗根部生长的作用  相似文献   

4.
合成了双水杨醛缩乙二胺Schif碱(SALEN)与钴的配合物Co(SALEN)(NO3)2·3H2O及镧系-钴的异核配合物LnCo(SALEN)2(NO3)5·2H2O(Ln=La,Nd,Sm,Gd,Yb,Y).以紫外、红外光谱,特别是1HNMR及EPR波谱等方法研究了它们在组成、结构和配位等方面的异同.文中讨论了配合物EPR谱在不同溶剂中峰宽的相对关系、配合物晶体场强度及Gd3+周围局部对称性等问题.  相似文献   

5.
合成了双水杨醛缩乙二胺Schiff碱(SALEN)与钴的配合物Co(SALEN)(NO3)2.3H2O及镧系-钴的异核配合物LnCo(SALEN)2(NO3)5.2H2O(Ln=La,Nd,Sm,Gd,Yb,Y)以紫外红外光谱,特别是HNMR是EPR波谱等方法研究了它们在组成、结构和配位等方面的异同,中讨论了配合物EPR谱在不同溶剂中峰宽的相对关系,配合物在晶体场强度及Gd^3+周围局部对称性等  相似文献   

6.
La0.8Sr0.2MnO3和La0.8Sr0.2CoO3在γ—Al2O3上的载体效应研究   总被引:7,自引:1,他引:7  
薛屏  沈岳年 《分子催化》1998,12(6):424-428
一般认为La0.8Sr0.2MnO3和La0.8Sr0.2CoO3两种钱钛矿型复合氧化物是CO氧化、碳氢(HC)化合物完全氧化和NO,还原的良好氧化物催化剂,用复合硝酸功体,制取此类负载型催化剂,负载量15%,用二甲苯完全氧化反应作为“探针反应”,配合XRD分析、BETG只测定,发现resume  相似文献   

7.
稀土与氨基酸固体配合物的合成及生物活性的研究   总被引:17,自引:2,他引:17  
用稀土硝酸盐与γ-甲基-α氨基戊酸(白氨酸,C6H(13)NO2)制得了8种组成为RE(Leu)3(NO3)3·nH2O(RE=La、Ce、Pt、Nd、Sm、Eu、Yb、Y,n=1~3)的新固体配合物;与δ-胍基-α氨基戊酸(精氨酸,C6H(14)N4O2)制得了4种组成为RE(Arg)n(NO3)3.mH2O(RE=La、Pr、Nd、Sm,n=2~3,m=1~3)的新固体配合物。经元素分析、IR、摩尔电导及核磁共振时配合物进行厂表征。选用部分稀上盐,配合物及氨基酸分别对5种细菌、2种霉菌进行了生物活性试验,证明稀士氨基酸配合物均具有抑菌或杀菌作用。  相似文献   

8.
不经分离,高敏,连续光度滴定混合物中钕和铁   总被引:3,自引:0,他引:3  
提出以Fe(3+)(Nd(3+)-CAS-CPB-C2H5OH作为不经分离、高敏、连续光度配合滴定混合物中Fe(3+)和Nd(3+)的多元胶束配合指示体系。滴定Fe(3+)和Nd(3+)的适宜pH分别为2.3~3.2和6.0~8.6。用EDTA目视滴定Fe(3+)时,终点处由蓝紫变粉红色,对比度大(Δλ=130nm)、灵敏度高(配合物摩尔吸光系数ε(630)=1.14×105L·cm(-1)·mol(-1),至少可检测0.4μg/mL,滴定线性范围为0~2.8μg/mL。线性相关系数为0.9994;目视滴定Nd(3+)时,终点处由绿色变橙黄,Δλ>180nm,ε(630)=7.6×104,至少可检测1μg/mL,滴定线性范围0~3.7μg/mL,线性相关系数0.9994。对于铁钕硼混合物样品则不经分离在630nm处连续光度滴定,可更精密、高敏、准确地确定终点,变异系数1.76%~2.86%,标准加入回收率96%~104%,且简便、快速。  相似文献   

9.
本系统地研究了硫代苹果在络合滴定中的掩蔽性能,发现它在pH1.5~10可作为Sn^4+、Sb^3+、Tb^3+、Bi^3+、Cu^2+、Hg^2+和Ag^+等的掩蔽剂(在pH2~3.5还可掩蔽Fe^3+)。掩蔽上述离子后,可在pH2.5~3用Th^4+回滴EDTA,在pH5~6用EDTA滴定Zn^2+或Yb^3+等,或在pH10用EDTA滴定Mg^2+、Ca^2+、Mg^2++Ca^2+和Mn^  相似文献   

10.
在pH9.20的NH3.H2O-NH4Cl介质中,铍与均三溴偶氮胂(TBA)的形成配合物,于-0.55V(vs.SCE)处产生一灵敏的配合物吸附波,峰电流与Be浓度在8.0×10^-8~2.0×10^-6mol/L范围内呈线性关系。测得铍与均三溴偶氮胂的配合比为Be(Ⅱ):TBA=1:1,稳定常数β=3.0×10^,电子转移数n=2,峰电流由配合物中配位体TBA还原产生。可不经分离直接测定矿样中铍  相似文献   

11.
TTHA complexes with diamagnetic rare earth ions (La3+, Y3+ and Lu3+) were studied by 1H and 13C NMR spectroscopy. A symmetric structural model was suggested for La(TTHA) complex and an asymmetric model for Y(TTHA) and Lu(TTHA) complexes. The complex formation was dependent on the pH value of the solution. The interactions of La(TTHA) with the additional metal ions (La3+, Y3+ and Ca2+) were relatively weak, but relatively strong for that of Lu(TTHA) with the additional Lu3+.  相似文献   

12.
The formation and the mode of coordination of rare earth (Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) complexes with proline and hydroxyproline have been investigated by1H and13C NMR spectral techniques. It has been established that the nitrogen and the carboxyl group of the ligands are involved in complexation, and that the OH group of hydroxyproline does not participate in coordination.
1H und13C NMR Untersuchungen an Lanthanid-Komplexen mit Prolin und Hydroxyprolin
Zusammenfassung Die Bildung und die Koordination von seltenen Erden (Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) in Komplexen mit Prolin und Hydroxyprolin wurden mit Hilfe von1H- und13C-NMR-Spektroskopie untersucht. Es wurde festgestellt, daß in den Komplexen der Stickstoff und der Carboxylsauerstoff der Liganden koordinieren. Die OH-Gruppe von Hydroxyprolin nimmt keinen Anteil an der Koordinierung.
  相似文献   

13.
The luminescence of Ce3+ in perovskite (ABO3) hosts with nd0 B-site cations, specifically Ca(Hf,Zr)O3 and (La,Gd)ScO3, is investigated in this report. The energy position of the Ce3+ excitation and emission bands in these perovskites is compared to those of typical Al3+ perovskites; we find a Ce3+ 5d1 centroid shift and Stokes shift that are larger versus the corresponding values for the Al3+ perovskites. It is also shown that Ce3+ luminescence quenching is due to Ce3+ photoionization. The comparison between these perovskites shows reasonable correlations between Ce3+ luminescence quenching, the energy position of the Ce3+ 5d1 excited state with respect to the host conduction band, and the host composition.  相似文献   

14.
A coordination study of Lu(III) has been carried out for the nitrate and perchlorate salts in aqueous mixtures of acetone-d6 and Freon-12 by1H,15N and35Cl NMR spectroscopy. At temperatures lower than –90°C, proton and ligand exchange are slow enough to permit the direct observation of1H resonance signals for coordinated and free water molecules, leading to an accurate measure of the Lu(III) hydration number. In perchlorate solution, in the absence of inner-shell ion-pairing, Lu(III) exhibits a maximum coordination number of six over the allowable concentration range of study, contrasting markedly with the report of values of six to nine or greater as determined by a similar NMR method. The absence of contact ion-pairing was confirmed by35Cl NMR chemical shift and linewidth measurements. Extensive ion-pairing was observed in the nitrate solutions as reflected by the lower Lu(III) hydration numbers of two to three in these systems, the observation of two coordinated water signals, and15N NMR signals for two complexes. The1H and15N NMR spectra and the hydration number could be accounted for by the presence of (H2O)4Lu(NO3)2+ and (H2O)2Lu(NO3) 2 1+ .  相似文献   

15.
采用高温固相法合成了一系列的(Y0.95Ln0.01Ce0.04)3Al5O12(简称YAG∶Ce,Ln), 系统地研究了此体系中的Ln3+对Ce3+的发光强度的影响. 结果表明, 在YAG∶Ce的体系中, La3+, Gd3+, Lu3+等光学透明离子的少量掺杂对Ce3+的发光强度的影响不大; 掺入少量的Pr3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+等稀土离子, 由于它们的能级与Ce3+的能级有交叠, 使它们之间存在着竞争吸收或能量转移, 对Ce3+的发光有较明显的变化, 其中, Pr3+和Sm3+的掺入使其在红光区有发射峰, 可以增加YAG∶Ce的红色成分以提高显色性; Nd3+, Eu3+和Yb3+对Ce3+的发光有严重的猝灭作用.  相似文献   

16.
Whether La3+ can enter human peripheral blood lymphocytes by the Na+/Ca2+ exchanger or not and the effect of La3+on the Na+/Ca2+ exchanger activity are examined by fura-2 technique. And that whether La3+ is sequestered by intracellular organelles (mainly endoplasmic reticulum and mitochondria) is studied by this method. La3+uptake is obviously stimulated by pre-treating the cells with ouabain and by removing extracellular Na+, and intracellular La3+concentration ([La3+]i) is directly proportional to its extracellular concentration ([La3+]o). But when [La3+]o exceeds 0.4 mmol/L, the 340/380 nm ratio of fluorescence is no longer varied and the maximum [La3+], is 1.5×10-12 mol · L-1. The higher concentration of La3+ (0.1 mmol/L) increases Na+/Ca2+ exchange-mediated calcium influx, but lower concentration (10 μmol/L) appears to block calcium influx. The results also suggest that cytosolic La3+ is transported by the ATP-dependent Ca2+ pump. Intracellular Ca2+ stores are depleted by ionomycin, and then ion  相似文献   

17.
以CaCO3,CuO,TiO2,La2O3为反应物,NaCl,KCl为熔盐,通过熔盐法分别在700、750、800、850℃条件下合成Ca0.9La0.2/3Cu3Ti4O12陶瓷粉体。利用XRD和SEM分别对陶瓷粉体的物相结构和微观形貌进行了分析,并对其介电性能进行了测试。实验结果表明,随着合成温度的升高,陶瓷粉体的钙钛矿相含量逐渐增大,与传统固相法相比,熔盐法制备的粉体无团聚现象,耗时少。Ca0.9La0.2/3Cu3Ti4O12粉体制备的陶瓷在1 000℃烧结、测试频率在100 Hz~10 kHz时,获得优良的介电性能:介电常数大大超过104,介电损耗在0.1~0.47之间。  相似文献   

18.
Y2O3:Eu3+红色荧光粉由于色纯度高、化学性质稳定和量子效率接近100%而广泛用于荧光灯和投影电视等方面.近年来,Y2O3:Eu3+的大量研究工作主要集中于纳米粉末的制备方法及其与体相材料不同的发光特性[1~3].最近,有关Y2O3:Eu3+及其稀土化合物的纳米管、纳米线和纳米带一维材料的制备成为研究热点.Wu Changfeng等[4,5]利用表面活性剂合成了Y2O3 : Eu3+纳米管.激光格位选择激发测试结果表明,Eu3+在纳米管中占据3个不同的格位,其611 nm处的红色发光峰出现了宽化.He Yu等[6]采用水热法及退火处理制备出了Y2O3:Eu3+纳米带,发现Eu3+的发射峰不仅宽化,而且出现了625 nm的新峰.Li Yadong等[7~9]采用水热法制备了稀土氧化物、硫氧化物和氢氧化物等的纳米线和纳米管,并探索了其形成机理,同时发现Y2O3S : yb3+,Er3+具有上转换的性质.  相似文献   

19.
With extensive applications the rare earth elements to agriculture, medicine and animal husbandry, whether rare earth ions can cross cell membranes and participate in the metabolism of animals and plants is not clear until now. Otherwise, rare earth ions have different interaction fashions to different kinds of cells, therefore, in this study we determined whether La3+ enter human peripheral blood lymphocytes via Na+/Ca2+ exchanger (measured with fura-2).Relative sensitivity of fura-2 to Ca2+…  相似文献   

20.
Eu3+ luminescence is studied in apatite-related phosphate BiCa4(PO4)3O. Compositions of the formula Bi1−xEuxCa4(PO4)3O [x=0.05, 0.1, 0.3, 0.5, 0.8 and 1.0] are synthesized and they are isostructural with parent BiCa4(PO4)3O. Room temperature photoluminescence shows the various transitions 5D07FJ(=0,1,2) of Eu3+. The emission results of compositions with different Eu3+ content show the difference in site occupancy of Eu3+ in Bi1−xEuxCa4(PO4)3O. The intense 5D0-7F0 line at 574 nm for higher Eu3+ content is attributed to the presence of strongly covalent Eu-O bond that is possible by substituting Bi3+ in the Ca(2) site. This shows the preferential occupancy of Bi3+ in Ca(2) site and this has been attributed to the 6s2 lone pair electrons of Bi3+. This is further confirmed by comparing the emission results with La0.95Eu0.05Ca4(PO4)3O.  相似文献   

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