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1.
The title compound belongs to monoclinic,space group C2/c with a=5.2694(1),b=12.6659(4),c=19.4108(2) ,β=91.504(2)°,V=1295.06(5) 3,Z=4 and Dc=5.599 g/cm3. The structure of BaGd2(MoO4)4 contains a MoO4 tetrahedron,a distorted GdO8 polyhedron,and Ba2+ ions in a tenfold coordination. The GdO8 polyhedra are linked together through edge-sharing to give a two-dimensional Gd layer. The MoO4 tetrahedra connected to the Gd atoms are capped up and down the Gd layer through common oxygen apices,thus forming a new Gd-Mo layer. Finally,the Gd-Mo layers are held together through bridging BaO10 polyhedra to form a three-dimensional framework. Since the Ba-μ3-O bond has a large average distance of 2.888 ,this structural characteristic will result in a cleavage along the (001) plane.  相似文献   

2.
1 INTRODUCTION With the development of high power InGaAs laser diode (LD) as pump sources, the Yb3+-doped laser crystals have received much attention. Due to the simple energy level structure of the Yb3+ ions, the Yb3+-doped laser crystals have no concentration quenching, and have high quantum efficiency and low quantum defects even at high doping concentration of the Yb3+ ions[1, 2]. Therefore, the Yb3+-doped crystals are good candidates of media in the LD-pumped solid-state laser,…  相似文献   

3.
1 INTRODUCTION There has been an increasing interest in the re- search of diode-pumped solid-state lasers in recent years because of the rapid development of high power diode lasers. The absorption peak of Nd3 ions at about 800 nm corresponding to 4I9/2→ 2H9/2 tran- sition is suitable for commercial laser diode GaAlAs pumping[1]. KLa(MoO4)2 is a kind of disordered crystalline host for lasing rare-earth ions[2], and it belongs to Scheelite (CaWO4) structure[3]. The disorder derives…  相似文献   

4.
何翔  卢灿忠  张全争 《结构化学》2005,24(2):159-162
1 INTRODUCTION The design and synthesis of metal-organic frame-work structure have been studied widely during thepast decade not only because of their intriguing ar-chitectures but also their unexpected properties forpotential practical applications in a wide number offields, such as asymmetric catalysis, magnetism, pho-toluminescence and so on[1~3]. These novel struc-tures can be rapidly and efficiently synthesized fromsimple subunits, where the metal ions, bi- or multi-dentate organic l…  相似文献   

5.
6.
1 INTRODUCTION As one kind of compound with extensive phy- siological and pharmacology activities[1], 2-amino- pyridine is easy to form complexes, and some of which may catalyse hydrolysis of ester[2]. Acetyl- acetone is an useful intermediate in the synthesis of sulfanilamide, additive and catalyst[3]. Complexes containing acetylacetone take on excellent lumines- cent properties[4]. To be an active center of some sig- nificant enzymes[5, 6], zinc takes the form of its su- pramolecular co…  相似文献   

7.
IntroductionRecently,the molecular designs of polyox-ometalates( POM) with basic oxometal clusterbuilding blocks are of great interest[1,2 ] . Hy-drothermal synthesis,with the characteristic ofone- pot reaction,provides a convenient method toobtain novel structures of POM compounds[3— 6] . Inthe Ln/Mo/O system ( Ln=rare earth) ,somecompounds containing La and Mo elements havebeen reported[7— 17] . However,these compoundshave all been synthesized under the highly restrict-ed synthetic co…  相似文献   

8.
1 INTRODUCTION Salicylaldehyde salicyloylhydrazone (SHSH) and their deviatives show moderate fungicidal and anti- bacterial activities[1]. Rao has reported some novel lanthanoid complexes of salicylaldehydrazone. Va- rious polyhedral geometries such as distorted octa- hedron, pentagonal bipyramid and distorted square antiprism were tentatively proposed for the com- plexes used as excellent semi-conducting materials[2]. Tang has studied spectrofluorimetric determination of hydrogen perox…  相似文献   

9.
1 INTRODUCTION More than 200 known metalloenzymes of a wide variety of types have been shown to contain zinc centers at their active sites (such as hydrolases, ligases and anhydrases)[1~3]. The active zinc centers in biological systems are usually surro…  相似文献   

10.
1 INTRODUCTION In recent years, the rational design and synthesisof metal-directed supramolecular frameworks throughintermolecular hydrogen bonds, π-π stacking interac-tion or other weak interactions have received muchattention because of their interesting molecular topo-logies and various potential applications in catalysis,superconductor, magnetism, nonlinear optics, sen-sors and molecular recognition[1~4]. On the otherhand, the attachment of mono- or polypyridyl frag-ments to a ferr…  相似文献   

11.
采用溶胶凝胶/碳热还原法合成了锂离子电池正极材料Li3V2(PO4)3及其掺Ti化合物Li3-2x(V1-xTix)2-(PO4)3. 电化学测试结果表明, 经Ti4+离子掺杂后材料的充放电性能及循环性能明显提高. 与纯相Li3V2(PO4)3在3.58、3.67和4.08 V出现三个平台相比, 掺杂后材料的前两个平台发生简并且平台趋于模糊的倾斜状态. 这种趋势随掺杂量的增大而增强. 差热分析(DTA)表明掺杂生成了稳定的酌相产物. 采用X射线衍射和Rietveld方法表征了化合物的晶体结构, 结果表明, 三个不同位置Li的不完全占据导致晶体中产生阳离子空穴, 使材料在常温下的离子电导率提高了3个数量级. 锂离子混排提高了样品的电导率和充放电比容量.  相似文献   

12.
Nd^3 :GdAl3(BO3)4(NGAB) crystal with the size of 30 mm was grown from the solvent system of K2O-Gd2O3-MoO3-B2O3 by combining accelerated seed rotation technology with medium seeded solution growth (MSSG) method,and its crystal structure has been determined by X-ray powder diffraction.It crystallizes in the trigonal system,space group R32 with a=9.2743(2),c=7.2438(1)A,V=538A^3,Z=3and Dc=4.379g/cm^3,The absorption and emission spectra of NGAB in the function of σ and π polarizations at room temperature have been measured.UV generation tuneable in 378-382nm,green(531nm) generation and blue generation tuneable in 436-443 nm as well as red(669)nm generation by self-frequency changing were obtained with the oupput of 105, 119.5,445and 19μJ/pulse,respectively,when the crystal was pumped by a dye laser.  相似文献   

13.
The compound (SiCl3)2Fe(CO)4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287(2), b = 9.829(2), c = 9.042(2) A, β = 96.19(3)°, V= 732.2(3) A^3, C4Cl6FeO4Si2, Mr = 436.77, Z = 2, Dc = 1.981 g/cm^3, F(000) = 424, μ(MoKα) = 2.282 mm^-1, the final R = 0.048 and wR = 0.164 for 1109 observed reflections (I 〉 2σ(I)). The crystal structure of (SiCl3)2Fe(CO)4 reveals that the Si(l)- Fe-Si(l)^a sequence is linear and perpendicular to the Fe(CO)4 cross-shaped plane.  相似文献   

14.
采用水热合成技术成功制备了一种新型的上转换发光纳米晶体NaGd(MoO4)2:Yb3+,Er3+.采用X射线粉末衍射分析、透射电镜和光谱分析对不同条件下所得样品的结构和发光性能进行了表征.NaGd(MoO4)2:Yb3+,Er3+和NaGd(MoO4)2具有相同的晶体结构,属于四方晶系;透射电镜观察表明,所得晶体为直径约为20 nm的纳米棒;在980 nm红外激光器的激发下,观察到了3个明显的上转换发射峰,发光中心分别位于531,552和656 nm,分别对应于Er3+2H11/2→I15/2,4S3/2→I15/2和4F9/2→4I15/2的跃迁.  相似文献   

15.
In this work, we report on the Czochralski growth of Li2MoO4 crystals up to 230 g for heat-scintillation cryogenic bolometers likely to be used in astroparticle physics and neutron spectroscopy. Their transmission properties, radiopurity levels and detector behavior characterizations were carried out in order to validate the crystal growth process. The melting characteristics, the partition coefficients of a broad range of impurities, the thermal expansion (lattice parameters and dilatometry) and specific heat properties of the crystals were measured, over a broad temperature range for the last two, providing new data likely to be used in crystal growth process numerical simulations. We also investigated the crystal growth of Li4Mo5O17 and determined its melting behavior and specific heat. The physical properties directly relevant to heat-scintillation cryogenic bolometers of Li2MoO4 and Li4Mo5O17 are discussed in the context of the current materials developed for such applications.  相似文献   

16.
1 INTRODUCTION 3-Hydroxy-2-methyl-4-pyranone (maltol) and 3-hydroxy-2-ethyl-4-pyranone (ethylmaltol) are nontoxic compounds that have been applied to bio- inorganic chemistry over several decades[1, 2]. Their iron(III) complexes are relevant to the control of iron levels in the human body. Such complexes have been assessed for the amelioration of anaemia[3] and their respective ligands have been tested for the removal of excess burdens of iron in diseases such as siderosis, haemochroma…  相似文献   

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