首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 171 毫秒
1.
In this study, Sr2+, Ca2+, Zn2+, and Mg2+ ions act to tune the emission band to the blue-cyan region in BaxSryB2O5:Ce3+ (BSBO), BaxCazB2O5:Ce3+ (BCBO), BaxZnuB2O5:Ce3+ (BZBO), and BaxMgvB2O5:Ce3+ (BMBO) phosphors. A red shift occurs with the increase of Sr2+, Ca2+, Zn2+, and Mg2+ concentration, and a blue shift occurs when the concentrations of Sr2+, Ca2+, Zn2+, and Mg2+ exceed the critical value. The emission color can be tuned from deep blue (0.15, 0.12) to cyan (0.16, 0.27) upon 365 nm UV lamp excitation due to the crystal field splitting and centroid shifts. The excitation band shift to long wavelength by introducing ions, so that the synthesized phosphor can be better matched with the n-UV chip. The emission intensity slowly decreases with the temperature increasing. Therefore, the BMBO:Ce3+, BZBO:Ce3+, BCBO:Ce3+, and BSBO:Ce3+ phosphors with relatively good thermal stability were synthesized, which could have potential applications in the n-UV white LEDs.  相似文献   

2.
A highly insoluble metalloporphyrin polymeric material was used as sorbent for the solid‐phase extraction of phenolic compounds. Substantial quantities of phenols (40 to 60 mg/g polymer) were absorbed from aqueous solution comparing satisfactorily with other extraction methods. The polymeric phase presented similar KSPE values for the hydrophobic compounds tested such as p‐chlorophenol, BPA, p‐nitrophenol, and a significant lower value for the more hydrophilic p‐aminophenol and cresol. Several metallic complexes of protoporphyrin IX (Co2+, Cu2+, Ni2+, Zn2+, and Fe3+) have been tested. The analytes were extracted with high recoveries at acid and neutral pH values, whereas at pH 10 low recoveries were obtained. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3038–3043, 2001  相似文献   

3.
We synthesized chitosan-based sorbents for the uptake of metal cations in acidic solutions. Chitosan was reacted with 2-formylbenzene sodium sulfonate and 4-formyl-1,3-benzene sodium disulfonate in the presence of NaCNBH3 to yield N-benzyl mono- and disulfonate derivatives of chitosan. IR and NMR spectra confirmed the presence of benzyl sulfonate groups. The degrees of substitution of the monosulfonate chitosan derivatives were in the range of 80%, while those of disulfonate derivatives were about 50%. These sulfonate derivatives of chitosan were tested on the sorption of heavy metals Cd2+, Zn2+, Ni2+, Pb2+, Cu2+, Fe3+, and Cr3+. The sorption capacities for disulfonate compounds were better than for monosulfonate compounds. This phenomenon was attributed to the amphoteric character of the monosulfonate derivatives. To improve the capacity of adsorption of monosulfonate compounds, the amino groups of these compounds were protected by the benzyloxycarbonyl groups. The protection of amino groups of disulfonate derivatives by benzyloxycarbonyl also improved their sorption capacity. The resulting protected polymers were tested for sorption of heavy metals. Both protected polymers were more efficient than are the parent nonprotected polymers. The synthesized sulfonate derivatives of chitosan are especially adapted to the sorption of heavy metals from the acidic industrial effluents. © 1996 John Wiley & Sons, Inc.  相似文献   

4.
《分离科学与技术》2012,47(15):3493-3501
Abstract

The synthesis of new N‐donor pyridylpyrazole ligands with a functionalized arm is described. The complexation capabilities of these compounds towards bivalent metal ions (Hg2+, Cd2+, Pb2+, Cu2+, and Zn2+) and alkali metal ions (K+, Na+, and Li+) were investigated using the liquid‐liquid extraction process. The percentage limits of extraction were determined by atomic absorption measurements.  相似文献   

5.
A series of LaCaGaO4:xBi3+,yEu3+ (x = 0.002–0.04, y = 0.02–0.45) phosphors with adjustable emission colors were synthesized by high-temperature solid-state reaction. The samples were identified as pure phases by X-ray diffraction and Rietveld refinement, and the crystal structures were analyzed in detail. The LaCaGaO4:xBi3+ phosphor shows an intense blue emission under near-ultraviolet excitation, originating from the 3P11S0 transition. The spectrum analysis reveals that the Bi3+ ions occupy two luminescence centers in the LaCaGaO4 host and that energy transfer can occur. A model of the energy transfer between the Bi3+ and Eu3+ ions was also created and studied in detail. As the Eu3+-concentration increased, the emission color of the LaCaGaO4:0.005Bi3+,yEu3+ phosphor changed from blue to pink to red. In addition, the fluorescence lifetime, quantum yield, thermal stability, and other properties of the phosphors were characterized and analyzed. Finally, two white light-emitting diode devices with Ra values of 96.6 and 95 and correlated color temperatures of 4578 and 3324 K were fabricated, indicating the potential of phosphors for warm white lighting applications.  相似文献   

6.
Larvae of the cabbage butterfly,Pieris rapae, refuse to feed on the wild mustard,Erysimum cheiranthoides, due to the presence of alcoholextractable deterrents. The active components were extracted inton-BuOH, and this extract was separated into four fractions (I–IV) by reverse-phase HPLC. Fractions III and IV retained the feeding deterrent activity. The activity of fraction III was found to be due to the cardenolide diglycosides 1 and 2, which were previously reported as oviposition deterrents for gravidP. rapae butterflies. Three active compounds were isolated from fraction IV by column chromatography on silica gel followed by reverse-phase HPLC. These compounds were identified as a monoglycoside, digitoxigenin 3-O--D-glucoside (4), and two diglycosides, glucodigigulomethyloside (5) and glucodigifucoside (6). An additional cardenolide isolated from fraction II was identified as cheirotoxin (7). All compounds were identified by UV, NMR (1H and13C), and mass spectrometry, as well as hydrolysis experiments. The feeding deterrent activity of these compounds was compared with that of related commercially available chemicals and other compounds isolated fromE. cheiranthoides.  相似文献   

7.
A series of blue electroluminescent polyfluorenes (PFs) containing triphenylamine and various alkyl moieties were synthesized using an Ni(0) mediated C?C Yamamoto coupling reaction assisted by microwaves. The synthesized PFs were characterized by various spectroscopic techniques. Their absorption and photoluminescence properties were investigated in solvent and found to possess characteristic electronic absorption and emission spectra. These PFs were found to emit in the blue region (407?415 nm) with high quantum yield in the range 0.41?0.73. Cyclic voltammetry studies of the PFs revealed that the compounds were stable under redox conditions with highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital in the range 5.24–5.29 eV and 1.98?2.01 eV, respectively. The EHOMO for the PFs was similar to the most widely used hole transporting materials N,N′‐Di(1‐naphthyl)‐N,N′‐diphenyl‐(1,1′‐biphenyl)‐4,4′‐diamine (NPD), N,N′‐Bis(3‐methylphenyl)‐N,N′‐diphenylbenzidine (TPD) and N2,N2,N2′,N2′,N7,N7,N7′,N7′‐octakis(4‐methoxyphenyl)‐9,9′‐spirobi[9H‐ fluorene]‐2,2′,7,7′‐tetramine, Spiro‐OMeTAD (spiro‐OMe‐TAD). The thermal stability observed for the PFs accounts for their use under ambient conditions. The electrochemical studies of the fabricated polymer light emitting diodes suggest that the PFs have potential to be used as hole transporting and blue electroluminescent materials for optoelectronic devices. © 2017 Society of Chemical Industry  相似文献   

8.
Ca9La(PO4)5(SiO4)F2:Tb3+,Dy3+ (CLPSF:Tb3+,Dy3+) phosphors were successfully prepared using the traditional solid-state technique. The crystal structure was refined and the luminescence properties have been examined in detail. The band gap and electronic structure of Ca9La(PO4)5(SiO4)F2 were performed by the periodic density functional theory (DFT) calculation. The spectral and fluorescence decay dynamics of CLPSF:Tb3+,Dy3+ show that the energy transfer behavior between Tb3+ and Dy3+ ions is observed. The CLPSF:Tb3+,Dy3+ phosphors can be efficiently excitable at the wavelengths range from 300 to 500 nm. The emission spectrum covers the whole visible part of the spectra with the sharp emission bands in red, green, and blue regions. The correlated color temperature (CCT) and color rendering index (CRI) of white light emission could be improved by the fine-tuning of the Tb3+ and Dy3+ ions ration in accordance with the energy transfer behavior. Thus, the CLPSF:Tb3+,Dy3+ phosphor could be used as a material for the near-ultraviolet (n-UV) and white light-emitting diodes (w-LEDs).  相似文献   

9.
The three‐step reactions of ethyl 4‐aminobenzoate, formic acid, and halohydrocarbons afforded 10 N‐substituted‐N,N′‐diaryl‐formamidine derivatives ( F1 – 10 ) as ultraviolet absorbers. These N‐substituted formamidines were characterized by 1H NMR, 13C NMR, FT‐IR, and ESI‐MS spectroscopies. The UV–vis absorbance and fluorescence properties of the compounds F1 – 10 were investigated in different solvents and in the presences of different metal ions. The effects of the amount of Al3+, Pb2+, Zr4+ ions on the UV–vis absorbance and fluorescence properties of compound F1 were also investigated. Moreover, the thermal stability of the compounds F1 – 10 was evaluated as well as the intermediate N,N′‐bis(4‐ethoxycarbonylphenyl)‐formamidine. J. VINYL ADDIT. TECHNOL., 25:E108–E113, 2019. © 2019 Society of Plastics Engineers  相似文献   

10.
Eu2+ and Mn2+ coactivated β–Ca3(PO4)2 (TCP) phosphors have been prepared by high‐temperature solid‐state reaction. The site occupation and photoluminescence properties of Eu2+ and Mn2+ have been identified and discussed in detail. The energy transfer from Eu2+ to Mn2+ in TCP: Eu2+, Mn2+ phosphors has been validated and demonstrated to be a resonant type via a dipole‐quadrupole mechanism, and the critical distance (RC) calculated by concentration quenching method is 21.76 Å. A color‐tunable emission from violet‐blue to red in TCP: Eu2+, Mn2+ phosphors can be realized via the energy transfer from Eu2+ to Mn2+ ions.  相似文献   

11.
Tm3+ doped zinc silicate glass-ceramics composed of SiO2-Al2O3-ZnO-K2O-Tm2O3 embedded with ZnO nanocrystals were successfully fabricated by melt-quenching method with subsequent heat treatment. Tm3+ ions and ZnO nanocrystals were introduced as blue and yellow luminescence centers, respectively. The effects of heat treatment, excitation wavelength and Tm3+ doping concentration on the photoluminescence behaviors of these glass-ceramics were studied. Short-time (5 minutes) heat treatment was considered as the optimal heat treatment time, which facilitates simultaneously emitting narrow blue peak located at 453 nm and a broad yellow band centered at 580 nm. Blue and yellow emissions could be attributed to the 1D2 → 3F4 transition of Tm3+ and Zni/Oi-related defect emission of ZnO nanocrystals, respectively. The combination of these two emissions allows the realization of white light emitting in the glass-ceramic samples. Furthermore, tunable luminescent color and chromaticity coordinates, including yellow, white and blue, can be realized by varying the pumping wavelengths as well as the content of Tm3+ dopant in the glass matrix. Nearly perfect white light emission with Commission Internationale de l'Eclairage coordinate (x = 0.33, y = 0.32) was achieved for the 0.05 mol% Tm3+ doped glass-ceramic embedding ZnO nanocrystals by heat treatment at 750°C for 5 minutes under the excitation of 360 nm. These luminescent glass-ceramics doped with Tm3+ ion and ZnO nanocrystals could be a promising candidate for white light emitting devices under near-ultraviolet excitation.  相似文献   

12.
During pursuing high color rendering index for full-color-emitting phosphor, low quantum efficiency (QE) is usually accompanying. We intend to elevate the luminescence efficiency when realizing a solar-like spectra distribution, by constructing apatite structure oxynitride, inheriting high covalence and rigidity from oxynitride, and suitable multiple cation sites from oxyapatite compounds. Full-color-emitting apatite structure oxynitride phosphor (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+ has been prepared, and the crystal sites’ occupancies of activators in this host were favorable for white emission. (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+ phosphor shows whole visible light with emission wavelength ranging from 370 to 750 nm, matching the spectra of sunlight quite well. The fabricated white light-emitting diode lamp demonstrated the distinctive overall performance of QE and chromaticity properties (Ra and R9). Furthermore, correlated color temperature is tunable from cool nature to warm white. The obtained lamp possesses the feature of less blue light hazard and high saturation of red degree, compared with the commercial YAG-based lamp.  相似文献   

13.
Single‐phase white‐light‐emitting phosphors NaLa9(1?x?y) (GeO4)6O2: xTm3+, yDy3+ (NLGO: xTm3+, yDy3+) have been synthesized by a traditional solid‐state reaction method. The powder X‐ray diffraction (XRD), photoluminescence (PL), PL excitation (PLE) spectra, fluorescence decay curves, chromaticity coordinates, correlated color temperature (CCT), and the cathodoluminescence (CL) properties of the obtained phosphors are measured and discussed in detail. It is discovered that the series samples could be color‐tunable (from blue to yellow) by tuning the doping content of Dy3+ with a fixed Tm3+ content excited at 357 nm and white light (0.341, 0.324) could be obtained with the CCT of 5079 K. A NLGO: 0.01Tm3+, 0.02Dy3+ is studied carefully as representative. The main emissions of Tm3+ (453 nm, 1D23F4) and Dy3+ (478 nm, 4F9/26H15/2; 572 nm, 4F9/26H13/2) make it emit white light with good thermal stability (67% of the initial till 523 K). The energy transfer from Tm3+ to Dy3+ is noticed and further research has been done to explain the enhancement of Dy3+ emission and the excellent thermal stability. It also keeps stable under continuous electron bombardment with high intensity. All of these indicate that it could be a suitable candidate for white‐emitting phosphor applied for near ultraviolet‐white light‐emitting diode (NUV‐WLED) and field‐emission display (FED).  相似文献   

14.
A green nano-sized ceramic pigment Co0.6Zn0.4Al0.8Cr1.2-xSmxO4 has been successfully prepared by doping ions Zn2+, Cr3+, and Sm3+ into the crystalline CoAl2O4 spinel and using the complex-gel method along with agar as complexing and combustion agent. The Infrared Spectroscopy, X-ray diffraction, Thermo-gravimeter, High resolution transmission electron microscopy, Automatic color reader, and UV Vis diffuse reflectance were applied to characterize the pigment power and its gel precursor. The results reveal that the introduction of Zn2+, Cr3+, and Sm3+ could change the occupation status of ions in the tetrahedral and octahedral framework of CoAl2O4 spinel, leading to the colorant variation of the blue cobalt pigment CoAl2O4, With increasing the content of Sm3+ ion, the reflection peak position of the pigments in visible spectrum appeared a red-shift, ie the color transition from blue green to yellow green, and the average reflectivity in the violet region decreased to 13.31%, and the band gap energy also changed from 3.47 to 3.20 eV. This illustrates the better UV absorption of this green pigment and can be used as UV shielding material. With the hydrochloric acid or sodium hydroxide solution treatment, this pigment was found to be durable in chemical stability.  相似文献   

15.
The Tb3+/Sm3+ codoped Sr2LiSiO4F white emitting phosphors were synthesized by a solid‐state reaction technique at high temperature. The X‐ray diffraction patterns, photoluminescence properties, and decay behaviors have been investigated. The Tb3+ emissions (blue and green) and Sm3+ emissions (orange) are both observed in the codoped samples Sr2LiSiO4F: 0.05Sm3+, xTb3+ by near‐UV light (370 nm) exciting. The white emission has been obtained by adjusting Tb3+ doping concentration at 5% (= 0.05). These luminescent powders are expected to be a potential candidate as white emitting phosphor for near‐ultraviolet InGaN‐based white light‐emitting diodes.  相似文献   

16.

Divalent Mn, Ni, Zn, and trivalent La complexes of H3L ligand [N’,2-bis((Z)-2-oxoindolin-3-ylidene)hydrazine-1 carbohydrazide] were synthesized and characterized via diverse spectroscopic methods (FT-IR, NMR, electronic, PXRD, and GC-MS), molar conductance and magnetic susceptibility measurements. The different ways of binding for the H3L ligand with metal ions were inferred, as the H3L ligand acted in mono-negative N2O tridentate, mono-negative N2O3 pentadentate, bi-negative N2O3 pentadentate, and tri-negative N2O3 pentadentate manners in coordination to Mn2+, Zn2+, La3+, and Ni2+ metal ions, respectively. DFT modeling was performed using the DMOL3/material studio software, and some of the experimental outcomes were interpreted and authenticated. Electrochemical performance of Mn2+ ions in the existence and absence of H3L ligand was considered via cyclic voltammetry. The corrosion effectiveness of the H3L ligand (inhibitor) to aluminum metal was evaluated, and the molecular dynamic (MD) simulations for adsorption of the H3L inhibitor on Al surface were performed via FORCITE quench code. The isolated compounds were inspected for their antimicrobial (against C. albicans fungi, G+ bacteria S. aureus and B. subtilis, and G? bacteria P. aeruginosa and E. coli), cytotoxic, and antioxidant (ABTS, and SOD) activities. A molecular docking study was performed to give the favorable binding sites for the ligand to E. coli, and S. aureus proteins.

  相似文献   

17.
Poly(2‐acrylamido glycolic acid‐co‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) [P(AGA‐co‐APSA)] was synthesized by radical polymerization in an aqueous solution. The water‐soluble polymer, containing secondary amide, hydroxyl, carboxylic, and sulfonic acid groups, was investigated, in view of their metal‐ion‐binding properties, as a polychelatogen with the liquid‐phase polymer‐based retention technique under different experimental conditions. The investigated metal ions were Ag+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, and Cr3+, and these were studied at pHs 3, 5, and 7. P(AGA‐co‐APSA) showed efficient retention of all metal ions at the pHs studied, with a minimum of 60% for Co(II) at pH 3 and a maximum close to 100% at pH 7 for all metal ions. The maximum retention capacity (n metal ion/n polymer) ranged from 0.22 for Cd2+ to 0.34 for Ag+. The antibacterial activity of Ag+, Cu2+, Zn2+, and Cd2+ polymer–metal complexes was studied, and P(AGA‐co‐APSA)–Cd2+ presented selective antibacterial activity for Staphylococcus aureus with a minimum inhibitory concentration of 2 μg/mL. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

18.
A case of phosphor is reported where the cooling rate parameter significantly influences the luminescence property. By quenching the sample after the high‐temperature solid‐state reaction at 1250°C, we successfully prepared the Eu2+‐doped α form Ca3(PO4)2 (α‐TCP:Eu2+) as a new kind of bright cyan‐emitting phosphor. The unusual emission color variation (from cyan to blue) depends on the cooling rate after sintering and Eu2+ doping level as it was observed in the TCP‐based phosphors. By the Rietveld analysis, it is revealed that the cyan‐ and blue‐emitting phosphors are two different TCP forms crystallizing in the monoclinic (space group P21/a, α‐TCP) and the rhombohedral structure (space group R3c, β‐TCP), respectively. Upon 365 nm UV light excitation, α‐TCP:Eu2+ exhibits an asymmetric broad‐band cyan emission peaking at 480 nm, while β‐TCP:Eu2+ displays a relatively narrow‐band blue emission peaking at 416 nm. The Eu2+‐doping in Ca3(PO4)2 shifts the upper temperature limit of the stable structural range of β form from 1125°C to ≥1250°C. Moreover, the crystal structures of α/β‐TCP:Eu2+ were compared in the aspects of compactness and cation site sets. The emission thermal stability of α/β‐TCP:Eu2+ was comparatively characterized and the difference was related to the specific host structural features.  相似文献   

19.
《分离科学与技术》2012,47(7):1002-1009
The synthesis of novel metal-free and magnesium porphyrazines, peripherally substituted with dithia-dioxa (S2O2) and tetrathia (S4) 14-membered macrocycles were performed by cyclotetramerization of (6Z)-1,3,4,9,10,12-hexahydro-2,5,8,11-benzo-dioxadithiacyclotetradecine-6,7-dicarbodinitrile (3) or (6Z)-1,3,4,9,10,12-hexahydro 2,5,8,11-benzotetrathiacyclotetradecine-6,7-dicarbodinitrile (5). The metal-free porphyrazines have been obtained by known route. The structure of compounds were characterized by elemental analysis and 1H, 13C NMR, IR, UV-vis, and MS spectral data. The solvent extraction properties of the synthesized compounds towards some metal cations, such as Ag(I), Hg(II), Cu(II), Mn(II), Cr(III), Ni(II), Pb(II), and Zn(II) have been investigated. The effect of Cu2+, Mn2+, Ni2+, Pb2+, Sr2+, Al3+, Zn2+, Ba2+, Cd2+, Co2+, Hg2+, and Ag+ ions on the absorption spectra of the compounds were investigated by means of spectrophotometric method. Magnesium porphyrazine with S2O2 (6) interacted within Hg2+ ion specifically of all the tested metal ions.  相似文献   

20.
Some aspects of the enol‐imine to keto‐enamine photoisomerism and fluorescent behavior of the new monomer with urethane and anil units in its structure, namely, methacryloyloxyethyl‐2‐carbamoyloxy(m‐methyl, o‐hydroxybenziliden)aniline (UAN), were studied comparatively with the corresponding copolymer poly (methacryloyloxyethyl‐2‐carbamoyloxy(m‐methyl, o‐hydroxybenziliden)aniline)‐co‐methyl methacrylate) (COP‐UAN). The structure, thermal properties, and morphology of the anil compounds were investigated by Fourier transform infrared, proton nuclear magnetic resonance, fluorescence spectroscopies, UV spectrophotometry, thermogravimetric analysis, differential scanning calorimetry, and atomic force microscopy. The photochromic behavior of salicylideneanil units was investigated by UV/laser irradiation, and an inspection of their photophysical properties suggested that such structures could function as fluorescent chemosensors for some transition metals, a fluorescence quenching in the presence of different metal cations (Fe3+, Fe2+, Cu2+, and Ni2+) being evidenced. The direct observation of an enhancement in the fluorescence emission caused of the presence of Zn2+ (solution) or Fe2+, Cu2+, and Zn2+ (thin film) would be rather suitable for the production of turn‐on fluorescent chemosensors. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号