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Pairs of Ln(Ⅲ)dopant ions in crystalline solid luminophores:an ab initio computational study

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Journal of Rare Earths 2016年第8期34卷 820-827页

作者： A.Shyichuk G.Meinrath S.Lis Department of Rare Earths Faculty of ChemistryAdam Mickiewicz UniversityUmultowska 89b61-614 PoznafiPoland Radioactivity Environment Remediation(RER)Consultants Fuchsbauerweg 5094036 PassauGermany

Formation of dopant ions clusters in solid （glass） luminophores may affect efficiency of non-radiative energy transfer proc- esses between dopant （photoactivator） ions via shortening of the effective distance between them. This study was based on the as- sumption that the distance between the dopant ions affects the energy of crystal volume at proximity. According to this idea, semi-empirical and ab initio density functional theory （DFT） calculations were performed on various supercells of YVO4：Eu3＋ as a model system. It was noted that a shorter Eu-Eu distance resulted in lower total energy of the system, compared to an analogous structure with distant Eu3＋ ions. As lower energy configurations are preferred, the observed phenomenon was considered to be related to dopant ions clusters formation. Additionally, the values of energies obtained from DFT calculations were used to estimate the per- centage of dopant ions occurring as pairs, for different dopant concentrations. The estimation agreed quite well with the available lit- erature data.

关键词： crystalline luminophore lanthanides Vanadate DFT dopant clustering rare earths

Photoluminescence enhancement of red-emitting GdVO_4:Eu and YVO_4:Eu phosphors by adding zinc

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Journal of Rare Earths 2013年第1期31卷 13-17页

作者： K.Park J.Kim K.Y.Kim J.Y.Kim Y.Kim S.J.Dhoble Faculty of Nanotechnology and Advanced Materials Engineering Sejong University Department of Advanced Materials Engineering Hoseo University Department of Chemistry and Institute of Basic Sciences Dankook University Department of Physics R.T.M. Nagpur University

We synthesized the rare-earth activated Ro.94_xEuo.06ZnxVO4 （R： Gd and Y; 0〈_x〈_0.08） phosphors with a spherical mor- phology and a smooth surface by the ultrasonic spray pyrolysis. The annealed Ro.94_xEuo.06ZnxVO4 crystallized in the tetragonal zircon type structure, belonging to the space group of I41/amd. The incorporation of a small amount of Zn to Ro.94Euo.06VO4 improved the emission characteristics. The emission intensities of the Gdo.88EUo.06Zno.06VO4 and Yo.9Euo.06Zno.04VO4 phosphors at 619 nm were 72% and 2 1% stronger than those of the Gdo,94Euo.06VO4 and Yo.94Euo.06VO4 phosphors, respectively. We demonstrated that the addi- tion of Zn to Ro.94Euo.06VO4 was quite effective for improving the photoluminescent properties.

关键词： rare earths photolurninescence Vanadate ultrasonic spray pyrolysis

A novel yellow emitting phosphor Dy^(3+),Bi^(3+) co-doped YVO_4 potentially for white light emitting diodes

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Chinese Physics B 2010年第5期19卷 571-576页

作者：慈志鹏王育华张加弛 Department of Material Science School of Physical Science and TechnologyLanzhou University Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou University

Novel Y1-x-yVO4：xDy3＋, yBi3＋（0.01 ≤ x ≤ 0.05,0 ≤ y ≤0.20） phosphors for light emitting diode （LED） were successfully synthesised by solid-state reaction. The calculation results of electronic structure show that YVO4 has a direct band gap with 3 eV at G. The top of the valence band is dominated by O 2p state and the bottom of the conduction band is mainly composed of O 2p and V 3d states. An efficient yellow emission under near-ultraviolet （365 nm） excitation is observed. Compared with the pure YVO4：Dy3＋ samples, the Dy3＋, Bi3＋ co-doped samples show a more intensive emission peak （at 574 nm） and a new broad emission band （450-770 nm）, due to the 4F9/2 - 6H13/2 transition of Dy3＋ and the emission of the VO43-Bi3＋ complex respectively. The optimum chromaticity index of Y1-x-yVO4：xDy3＋, yBi3＋（0.01 ≤ x ≤0.05,0 ≤y ≤ 0.20） is （0.447, 0.497）, which indicates that YVO4：Dy3＋, Bi3＋ has higher colour saturation than the commercial phosphor YAG： Ce3＋. The effects of concentration of Dy3＋, Bi3＋, electric states and the photoluminescence properties are discussed in details.

关键词： phosphor light-emitting diode Vanadate

Hierarchical growth of a novel Mn-Bi coupled BiVO4 arrays for enhanced photoelectrochemical water splitting

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Nano Research 2019年第3期12卷 575-580页

作者： Lu Wang Jinzhan Su Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School cf Energy & Power Engineering Xian Jiaotong University Xian 710049 China

Oxygen evolving catalyst (OEC) is a critical determinant for the efficiency of photoelectrochemical (PEC) water splitting. Here we report an approach to depositing a novel manganese borate (Mn-Bi) OER catalyst on BiVO4 nanocone photoanode by photodeposition in sodium borate buffer solution containing Mn(Ⅱ) ions. Due to the spontaneous photo-electric-field-enhancement effect at the vertically oriented BiVO4 nanocone structure, spherical Mn-Bi nanoparticle was selectively photodeposited at the apex of BiVO4 nanocone. Significant improvement of photocurrent was observed for the obtained hierarchical Mn-Bi/BiVO4 photoanode which could be ascribed to enhanced hole injection efficiency, especially in low bias region. It was observed that the injection efficiency of Mn-Bi/BiVO4 is 98% which gave a photocurrent of 0.94 mA/cm^2 at 1.5 V vs. RHE.

关键词： bismuth Vanadate photoelectrochemistry solar water splitting oxygen evolution

Recent perspectives into biochemistry of decaVanadate

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World Journal of Biological Chemistry 2011年第10期2卷 215-225页

作者： Manuel Aureliano FCT University of Algarve Gambelas 8005-139 Faro Portugal

The number of papers about decaVanadate has doubled in the past decade. In the present review, new insights into decaVanadate biochemistry, cell biology, and antidiabetic and antitumor activities are described. Decameric Vanadate species (V10) clearly differs from monomeric Vanadate (V1), and affects differently calcium pumps, and structure and function of myosin and actin. Only decaVanadate inhibits calcium accumulation by calcium pump ATPase, and strongly inhibits actomyosin ATPase activity (IC50 = 1.4 μmol/L, V10), whereas no such ef- fects are detected with V1 up to 150 μmol/L; prevents actin polymerization (IC50 of 68 μmol/L, whereas no effects detected with up to 2 mmol/L V1); and interacts with actin in a way that induces cysteine oxidation and Vanadate reduction to vanadyl. Moreover, in vivo decaVanadate toxicity studies have revealed that acute exposure to polyoxoVanadate induces different changes in antioxidant enzymes and oxidative stress parameters, in comparison with Vanadate. In vitro studies have clearly demonstrated that mitochondrial oxygen consumption is strongly affected by decaVanadate (IC50, 0.1 μmol/L); perhaps the most relevant biological effect. Finally, decaVanadate (100 μmol/L) increases rat adipocyte glucose accumulation more potently than several vanadium complexes. Preliminary studies sug- gest that decaVanadate does not have similar effects in human adipocytes. Although decaVanadate can be a useful biochemical tool, further studies must be carried out before it can be conf irmed that decaVanadate and its complexes can be used as anticancer or antidiabetic agents.

关键词： DecaVanadate Vanadate Calcium pump Myosin Actin Actin polymerization Insulin mimetic Antidiabetic agent Antitumor agent

Thermal and FT-IR Properties of Semiconducting SnO2-PbO-V2O5Glass System

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New Journal of Glass and Ceramics 2015年第3期5卷 53-58页

作者： Ponnada Tejeswara Rao Balireddy Vasundhara Department of Physics GITAM Institute of Technology GITAM University Visakhapatnam India

Melt quenched “SnO2(50-x)PbO:50V2O5” glass system containing x = 5, 10, 15 in molar ratio has been investigated. Effects of heating rate, glass transition, crystallization, melting temperature and infrared spectra of SnO2 substituted PbO-V2O5 glass system are reported. XRD results show that perfect vitrification has been achieved for all the glass samples after annealing at 150°C. DSC results have indicated that eutectic composition of the lead metaVanadate has been maintained for all the glass systems up to 15 mole% of substitution. IR spectra for a SnO2 substitution of 5 mole% V=O stretching frequency occur at 966 cm-1 without appearance of any additional peak. But for 10 mole% and 15 mole% SnO2 substituted samples, additional peaks appear at 1023 and 1005 cm-1 indicating the effect of SnO2 in the Vanadate crystalline matrix such that there is an elongation of V=O bond. Since the crystalline matrix is affected, we can expect similar effect in the glass matrix also.

关键词： DSC XRD FT-IR Lead Vanadate Glasses

Structure, valence state and magnetic properties of LnGa_(1-x)V_xO_3

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Chinese Science Bulletin 1995年第7期40卷 561-565页

作者：杨健美苏锵王鸿燕 Laboratory of Rare Earth Chemistry and Physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China

Recently considerable attention has been paid to the ABO3 type RE complexoxides since they have special electrical-magnetic properties, good catalytic behaviour andgas sensitive behaviour. One of them is ABO3 type RE ... 详细信息

关键词： RE compound gallate Vanadate valence state magnetic properties.