Institute of Chemistry
Changchun Institute of Applied Chemistry, Chinese Academy Of SciencesNot a member yet
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Assessment of LaM0.25Mn0.75O3-delta (M = Fe, Co, Ni, Cu) as promising cathode materials for intermediate-temperature solid oxide fuel cells
No full textA series of novel perovskites LaM0.25Mn0.75O3 delta (M = Fe, Co, Ni, Cu) are considered as promising cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Polycrystalline powders of LaM0.25Mn0.75O3 delta are synthesized by a modified Pechini method. Powder X-ray Rietveld refinements reveal that LaM0.25Mn0.75O3 delta series are in the orthorhombic perovskite structure within Pnma (no. 62) space group at room temperature. In situ high temperature X-ray diffractions indicate the existence of phase transformation from the orthorhombic Pnma phase to a higher symmetrical rhombohedral phase at elevated temperatures without any second phase formation for all these compounds. Multivalent states of M (Fe, Co, Ni and Cu) and Mn ions are testified by X-ray photoelectron spectroscopy measurement (XPS). The electrical conductivity are measured to be 39.6, 85.3 and 48.1, 99.4 S cm (1) for M = Fe, Co, Ni and Cu, respectively and the corresponding impedance are 0.131, 0.106, 0.107 and 0.0634 Omega cm(2) at 850 degrees C. Among these compounds, LaM0.25Mn0.75O3 delta exhibits the highest electrical conductivity and the lowest electrode polarization resistances, which is consistent with its calculated smallest band gap and lowest oxygen vacancy formation energy. Moreover, they all exhibit excellent chemical compatibility with prototypical electrolyte Ce0.8Sm0.2O2 delta (SDC). While the overall electrochemical properties of LaM0.25Mn0.75O3 delta (M = Fe, Co, Ni) are high enough to fulfill the practical applications. Thus, these LaM0.25Mn0.75O3 delta (M = Fe, Co, Ni, Cu) compounds are potential cathode materials for IT-SOFCs. (C) 2015 Elsevier Ltd. All rights reserved
Host-sensitized luminescence in LaNbO4:Ln(3+) (Ln(3+) = Eu3+/Tb3+/Dy3+) with different emission colors
No full textIn this work, a series of Eu3+, Tb3+, and Dy3+ singly-doped and co-doped LaNbO4 (LNO) phosphors have been synthesized by a high-temperature solid-state reaction route. X-ray diffraction (XRD) along with Rietveld refinement, diffuse reflection spectra, photoluminescence (PL) and cathodoluminescence (CL) properties, decay lifetimes, and PL quantum yields (QYs) were exploited to characterize the phosphors. Under UV excitation, energy transfer process from the host to the activators exists in the singlydoped samples, which leads to tunable emission color from blue to red for LNO: Eu3+, green for LNO: Tb3+, and yellow including white for LNO: Dy3+. In Eu3+ and Tb3+ co-doped phosphors, LNO: Eu3+, Tb3+, the energy transfers from the host to the activators and Tb3+ to Eu3+ ions have also been deduced from the PL spectra, resulting in tunable emission color from green to red by adjusting the concentration ratio of Eu3+ and Tb3+ ions. The decay times monitored at host emission and Tb3+ emission confirm the existence of energy transfer in the as-prepared samples. The best quantum efficiency can reach 43.2% for LNO: 0.01Tb(3+) among all the as-prepared phosphors. In addition, the CL spectra of LNO: Eu3+/Tb3+/Dy3+ are a little different from their PL spectra because another emission envelope around 530 nm appears in the samples, which is attributed to the bombardment of higher energy excitation source of low-voltage electron beam. However, the characteristic emissions similar to PL spectra were reserved. Moreover, the CL spectrum of LNO: 0.02Tb(3+) has stronger emission intensity than that of ZnO:Zn commercial product. These results from the PL and CL properties of LNO: Eu3+/Tb3+/Dy3+ suggest their potential in solid-state lighting and display fields
Magnetic-field-enabled resolution enhancement in super-resolution imaging
No full textA novel strategy for modulating the photophysics of organic dyes in super-resolution fluorescence imaging using an external magnetic field was reported. The magnetic field induced increase in fluorescence intensity, localization number of probe molecules, and the number of photons emitted per molecule as compared to those acquired without a magnetic field were experimentally confirmed. Improved dSTORM localization precision and imaging resolution were consequently achieved
Exploiting verdazyl radicals to assemble 2p-3d-4f one-dimensional chains
No full textA series of one dimensional chain complexes [Ln(hfac)(3)](2)center dot[Cu(hfac)(2)](2)center dot 4(3pyvd)center dot n-C7H16 (Ln = Gd(1), Tb(2), Dy(3)) containing 2p, 3d and 4f spin carriers have been successfully synthesized and magnetically characterized where the verdazyl radicals represent the bridge linking copper(II) and lanthanide(III) ions. Rough estimation of magnetic behaviors of complex 1 revealed that the coupling between a Gd(III) ion and a radical is weakly ferromagnetic, while alternating-current susceptibilities of complexes 2 and 3 suggest no slow magnetic relaxations exist at low temperature
Single molecular recognition force spectroscopy study of a DNA aptamer with the target epithelial cell adhesion molecule
No full textThe epithelial cell adhesion molecule (EpCAM) is a tumor-specific antigen for malignancies of the epithelialis lineage. In this study the interaction between the DNA-based EpCAM aptamer (SYL3C) and EpCAM was explored using single molecular recognition force spectroscopy (SMFS). The capability of aptamer SYL3C to recognize the EpCAM protein and the kinetic parameters were investigated
A dual-mode colorimetric and fluorometric "light on" sensor for thiocyanate based on fluorescent carbon dots and unmodified gold nanoparticles
No full textA novel, highly sensitive and selective dual-readout (colorimetric and fluorometric) sensor based on fluorescent carbon dots (CDs) and unmodified gold nanoparticles (AuNPs) for the detection of thiocyanate (SCN-) was proposed. Amino-functionalized CDs could be readily adsorbed onto the surface of citrate-stabilized AuNPs through Au-N interactions, leading to the aggregation of AuNPs and the nonfluorescent off-state of CDs arising from potential fluorescence resonance energy transfer (FRET). However, SCN- had a stronger affinity toward AuNPs and could compete with CDs to bind onto the surface of AuNPs in priority, which prevented the aggregation of AuNPs and fluorescence quenching of CDs. Correspondingly, both the colorimetric and fluorometric signals remained "light-on". The color of the sensing solution remained red and the fluorescence remained unquenched. A distinguishable change in the color was observed at a SCN- concentration of 1 mu M by the naked eye and a detection limit as low as 0.036 mu M was obtained by virtue of fluorescence spectroscopy. Both colorimetric and fluorometric sensors exhibited excellent selectivity toward SCN- over other common metallic ions and anions. In addition, such a sensing assay featured simplicity, rapidity, cost-effectiveness and ease of operation without further modification. The accuracy and precision were evaluated based on the quantitative detection of SCN- in tap water and saliva samples with satisfactory results
A tricarbocyanine near-infrared fluorescent probe for sulfide through a copper displacement mechanism
No full textA near-infrared fluorescent probe 1R806-DPAP was developed based on tricarbocyanine dyes. 1R806-DPAP functioned as an "on-off" sensor for Cu2+. The resulted Cu2+-IR806-DPAP complex selectively responded to S2- over other anions, functioning as an "off-on" sensor for S2- through a displacement mechanism. The detection limit of Cu2+-IR806-DPAP for S2- was 1.79 mu M. The applications of 1R806-DPAP and Cu2+-1R806-DPAP in living cells were also tested. (C) 2015 Elsevier By. All rights reserved
Novel Two-Step Topotactic Transformation Synthetic Route Towards Monodisperse LnOF:Re,(3+) (Ln = Y, Pr-Lu) Nanocrystals with Down/Upconversion Luminescence Properties
No full textA novel two-step topotactic transformation (TT) synthetic route, Y-2(OH)(5)NO3 center dot nH(2)O (LYH)Y(OH)(2.02)F0.98YOF, is first developed for the monodisperse YOF:Re3+ (Re = Eu, Tb, Yb/Er, and Yb/Tm) nanostructure with bundle, tube, and atomically thick sheet morphologies. The intermediate Y(OH)(2.02)F-0.98 precursor is synthesized from the starting point of the {0001} plane, which forms by a novel type of ion-exchange from the brucite-like LYH due to the structural similarity between the [Y-2(OH)(5)(H2O)(n)](+) unit layer and the Y(OH)(2.02)F-0.98 {0001} plane. Such ion-exchange behavior is different from the traditional case for LYH exchanging the intercalated anions. The detailed structural characterization reveals that the formation of YOF is attributed to an in situ TT with the structural matching of [0001]Y(OH)(2.02)F-0.98//[110]YOF. Moreover, this novel synthetic route can be also extended to other lanthanides oxyfluorides series (LnOF, Ln = Pr-Lu), and the as-prepared YOF:Re3+ products exhibit intense characteristic down/upconversion luminescence. Our synthetic strategy dovetails well with the green concept in the current nanoscience and nanotechnology, which may bring new opportunity to LRHs and open a new avenue in the synthetic methodology for micro/nanomaterials
Ultrahigh Color-Stable, Solution-Processed, White OLEDs Using a Dendritic Binary Host and Long-Wavelength Dopants with Different Charge Trapping Depths
No full textInvestigation on Luminescence Properties of a Long Afterglow Phosphor Ca2SnO4:Tm3+
No full textA series of new long afterglow phosphors Ca2SnO4:xTm(3+) were synthesized by using traditional solid-state reactions. XRD measurements and Rietveld refinement revealed that the incorporation of the Tm3+ dopants generated no second phase other than the original one of Ca2SnO4, which indicated that the dopants completely merged into the host. The corresponding optical properties were further systematically studied by photoluminescence, phosphorescence, and thermoluminescence (TL) spectroscopy. The results show that the Tm3+-related defects account for the bright bluish green afterglow emission from the characteristic f-f transitions of Tm3+ ions. The bluish green long-lasting phosphorescence could be observed for 5h by the naked eye in a dark environment after the end of UV irradiation. Two TL peaks at 325 and 349K from the TL curves were adopted to calculate the depth of the traps, which were 0.45 and 0.78eV, respectively. The mechanism of the long afterglow emission was also explored