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991.
Dr. Yingsheng Wang Dr. Peipei Dang Dr. Lei Qiu Dr. Guodong Zhang Dr. Dongjie Liu Dr. Yi Wei Prof. Hongzhou Lian Prof. Guogang Li Prof. Ziyong Cheng Prof. Jun Lin 《Angewandte Chemie (International ed. in English)》2023,62(45):e202311699
Lead-free halide double perovskites are currently gaining significant attention owing to their exceptional environmental friendliness, structural adjustability as well as self-trapped exciton emission. However, stable and efficient double perovskite with multimode luminescence and tunable spectra are still urgently needed for multifunctional photoelectric application. Herein, holmium based cryolite materials (Cs2NaHoCl6) with anti-thermal quenching and multimode photoluminescence were successfully synthesized. By the further alloying of Sb3+ (s-p transitions) and Yb3+ (f-f transitions) ions, its luminescence properties can be well modulated, originating from tailoring band gap structure and enriching electron transition channels. Upon Sb3+ substitution in Cs2NaHoCl6, additional absorption peaking at 334 nm results in the tremendous increase of photoluminescence quantum yield (PLQY). Meanwhile, not only the typical NIR emission around 980 nm of Ho3+ is enhanced, but also the red and NIR emissions show a diverse range of anti-thermal quenching photoluminescence behaviors. Furthermore, through designing Yb3+ doping, the up-conversion photoluminescence can be triggered by changing excitation laser power density (yellow-to-orange) and Yb3+ doping concentration (red-to-green). Through a combined experimental-theoretical approach, the related luminescence mechanism is revealed. In general, by alloying Sb3+/Yb3+ in Cs2NaHoCl6, abundant energy level ladders are constructed and more luminescence modes are derived, demonstrating great potential in multifunctional photoelectric applications. 相似文献
992.
Zhiang Lin James A. Kitts Haibin Yang J. Richard Harrison 《Computational & Mathematical Organization Theory》2008,14(3):175-208
In this study we describe a comprehensive computational model of network dynamics (COM-NeD) and demonstrate how it may help
us better understand and theorize the dynamics of strategic networks. Specifically, we model a population of firms characterized
by idiosyncratic resource needs and productive capacities, while having to respond to the demands of external events by establishing
ties and receiving needed resources from other firms. Through COM-NeD we investigate a set of established theoretical perspectives
that represent distinct strategies for seeking and establishing interfirm ties. Rigorous computational experiments demonstrate
the expected behavior of such a system under a broad range of assumptions. The results shed light on the complexity of strategic
network dynamics, demonstrating novel interactions of firms’ internal resource capacity, relational search approaches, and
external resource growth.
相似文献
J. Richard HarrisonEmail: |
993.
Glen B. Deacon Prof. Craig M. Forsyth Peter C. Junk Matthias Hilder Stuart G. Leary Claudia Bromant Ingo Pantenburg Gerd Meyer Brian W. Skelton Allan H. White 《无机化学与普通化学杂志》2008,634(1):91-97
Anhydrous rare earth tris(cinnamates) [RE(cinn)3] (RE = La–Lu, Y and Sc and cinnH = trans‐cinnamic acid) were prepared by metathesis in water and by direct reaction of the metal with cinnamic acid in a 1,2,4,5‐tetramethylbenzene flux at ca. 200 °C. X‐ray crystal structure determinations and X‐ray powder data show that, in the solid state, the larger lanthanoids (La–Dy) form an isomorphous polymeric series consisting of homoleptic nine‐coordinate metal centres bonded to three chelating and bridging tridentate cinnamates. The late REIII cinnamate (RE = Dy, Ho–Lu, Y) complexes also form linear one‐dimensional polymeric chains with all RE metal atoms being seven‐coordinate. The cinnamates are either bound tridentate bridging in a μ‐η2:η1 fashion, or μ‐η1:η1 syn‐syn bidentate bridging. A structural break occurs at dysprosium which has been characterised in both crystallographic forms, and gives solely the late RE form when precipitated at 80 °C. ScIII cinnamate was also isolated as an analytically pure precipitate which was, again, found to be anhydrous in nature. A structural change was identified by powder XRD between the late REIII cinnamates and ScIII cinnamate. 相似文献
994.
Wen‐Tong Chen Prof. Dr. Ya‐Ping Xu Qiu‐Yan Luo Xiao‐Niu Fang Hua‐Long Chen 《无机化学与普通化学杂志》2008,634(3):529-533
The first heterometallic 4f‐5d inorganic‐organic metal‐isonicotinic acid hybrid [{Er(NC5H4COOH)(H2O)2}2(H5O2)(HgCl5)(HgCl4)2(H2O)2]n ( 1 ) has been synthesized via hydrothermal reaction and structurally characterized. Complex 1 crystallizes in the space group C2/c of the monoclinic system with four formula units per unit cell: a = 24.194(3), b = 20.792(3), c = 15.289(4) Å, β = 128.39(2)°, V = 6028(2) Å3, C36H47Cl13Er2Hg3N6O20, Mr = 2280.94, Dc = 2.513 g/cm3, S = 0.929, μ(MoKα) = 11.017 mm?1, F(000) = 4248, R = 0.0425 and wR = 0.0739. The crystal structure analysis reveals that the title complex is characteristic of a one‐dimensional chain‐like structure. Photoluminescent investigation reveals that the title complex displays interesting emissions. Optical absorption spectra of 1 reveal the presence of an optical gap of 3.45 eV. The magnetic properties show that complex 1 exhibits antiferromagnetic interactions. 相似文献
995.
Synthesis of trisubstituted imidazoles was successfully accomplished using rare earth(III) perfluorooctanesulfonates (RE(OPf)3), RE = Sc, Y, La-Lu as catalysts in fluorous solvents. Ytterbium perfluorooctanesulfonates (Yb(OPf)3) catalyze the high efficient synthesis of trisubstituted imidazoles in fluorous solvents. By simple separation, fluorous phase containing only catalyst can be reused several times. 相似文献
996.
Philippe Gall 《Journal of solid state chemistry》2008,181(1):1-6
Polycrystalline samples and single crystals of the R4Mo4O11 compounds (R=Yb and Lu) were synthesized by solid-state reactions at high temperature in sealed Mo crucibles. The structure of Lu4Mo4O11 (a=10.5611(1), b=5.61930(5), c=15.6877 (2), β=99.5131(4) and Z=4) was determined by single crystal X-ray diffraction and refined by least squares on F2 converging to R1=0.0425, wR2=0.0980 for 3508 intensities. Contrary to the R4Mo4O11 compounds with lighter rare earths, which crystallize in the orthorhombic space group Pbam, the Yb and Lu compounds crystallize in the monoclinic space group P2/m. The R4Mo4O11 compounds contain distorted infinite oxide-molybdenum chains of trans-edge-sharing Mo6 octahedra diluted with the rare earths. Magnetic susceptibility measurements indicate that the oxidation state of the Yb atoms is +3, affording 14 metallic valence electrons per Mo4 fragment and, the absence of localized moments on the Mo network. Resistivity measurements on single crystals show that the Yb4Mo4O11 and Lu4Mo4O11 compounds are small band-gap semi-conductors. 相似文献
997.
The feasibility of utilizing Y2O3:Tb3+ and Y2O3:Eu3+ as radioluminescent nanophosphors under alpha-particle excitation is investigated. Materials synthesized by the urea homogeneous precipitation method were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The XRD analysis of as-produced precipitates and nanophosphors fired at temperatures ranging from 950 to 1100 °C indicated the presence of highly crystalline cubic Y2O3 with crystallite sizes of ∼40 nm. SEM and TEM analysis revealed that particles with average diameters of ∼200 nm and comprised of ∼40 nm grains were obtained. High-resolution radioluminescence and photoluminescence spectra were used to investigate the unwanted radioluminescence saturation effects associated with the high ionization rate of alpha-particles. Additionally, the radioluminescence intensity as a function of rare-earth ion dopant concentration is investigated for these materials under alpha-particle excitation. The prospect for utilizing these materials as intermediate absorbers in indirect-conversion radioisotope batteries is discussed. 相似文献
998.
Tetrahydrosalen ligand was employed in the synthesis of gadolinium complex. The ligand was deprotoned by LiBu, and the afforded lithium salt was reacted with anhydrous GdCl3 to produce the gadolinium complex through salt metathesis. This complex was successfully used to initiate the ring-opening polymerization of ε-caprolactone. The initiation conditions in different temperature, monomer-to-initiator ratio and time were investigated. Under the condition: [ε-caprolactone]: [catalyst]=600,56℃, toluene: 2ml, poly(ε-caprolactone) (PCL) with Mw=11,2782 and PDI=1.96 was achieved. 相似文献
999.
Tetrahydrosalen ligand was employed in the synthesis of gadolinium complex. The ligand was deprotoned by LiBu, and the afforded lithium salt was reacted with anhydrous GdCl3 to produce the gadolinium complex through salt metathesis. This complex was successfully used to initiate the ring-opening polymerization of ε-caprolactone. The initiation conditions in different temperature, monomer-to-initiator ratio and time were investigated. Under the condition: [ε-caprolactone]:[catalyst] = 600, 56 ℃, toluene: 2 ml, poly(ε-caprolactone) (PCL) with Mw = 11,2782 and PDI = 1.96 was achieved. 相似文献
1000.
采用1,2,3-三羧基-(1′,2′,3′-三羧基偶氮苯)-苯(H6TTAB)连接线性四核铕配位单元, 组装形成具有 {414·620·811}{43}2{45·6}拓扑结构的稀土金属-有机框架Eu-TTAB. Eu-TTAB具有高的热和溶剂稳定性, 在紫外光激发下具有发光性质, 且其发光性能可以被铽离子调控并被银离子大幅度提升. 相似文献