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ABSTRACT: We observe the seldom reported near infrared (NIR) emissions at 870 nm (FWHM = 53 nm) and 1037 nm
(FWHM = 67 nm) which are in the spectral response region of crystalline silicon photovoltaic solar cells.
The emissions are much enhanced with the addition of GeO2, and the possible mechanisms for the photoluminescence
spectra evolution are discussed. The decay curves are monitored at both the visible and
NIR emissions of Pr3+ doped glasses and lifetimes are calculated using a second-order exponential decay
model. Raman spectra are used to characterize some interesting structural evolutions which are responsible
for the GeO2 induced luminescence property changes.
Chemical Physics Letters 03/2013; 568–569:80–83. · 2.34 Impact Factor
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ABSTRACT: The influence of γ-ray irradiation on the optical properties of Bi<sub>2</sub>O<sub>3</sub>-B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> glass has been investigated. Broadband infrared (IR) emission at 1310 nm with a FWHM over 200 nm is observed in the γ-ray irradiated glass. The IR luminescence depends on the γ-ray irradiation dose and the concentration of Bi<sub>2</sub>O<sub>3</sub>. The thermal stability of the γ-ray irradiated IR luminescence center is studied, and the origin of the IR luminescence center has been suggested.
Optics Letters 02/2013; 38(4):516-8. · 3.40 Impact Factor
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ABSTRACT: In the present paper, the effects of GeO2 on properties of GeS2–Ga2S3–CsCl chalcohalide glasses are presented. The
absorption spectra, density, microhardness, DSC and the chemical durability are measured. Results show that the
addition of GeO2 remarkably improves the physical and chemical properties of the chalcohalide glasswhile the visible
transmission spectrumis influenced little. The oxy-chalcohalide glasswas also used asmatrix for dopingTm3+
(0.1 mol%)which shows the similarNIR luminescence spectrumas theGeS2–Ga2S3–CsCl chalcohalide counterpart.
Some interesting structural evolutions are characterized by Raman spectra. The possible mechanism corresponding
to the improved properties is discussed
Journal of Non-Crystalline Solids 01/2013; 362:30–33. · 1.54 Impact Factor
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ABSTRACT: Upon 808 nm excitation, an intense broadband near-infrared emission from Cr<sup>4+</sup> has been observed in 80GeS<sub>2</sub>-20Ga<sub>2</sub>S<sub>3</sub> chalcogenide glass-ceramics (GCs) containing Ga<sub>2</sub>S<sub>3</sub> nanocrystals. The emission band peaking at 1250 nm covers the O, E, S bands (1000-1500 nm). The formation of Ga<sub>2</sub>S<sub>3</sub> nanocrystals (∼20 nm) increases the emission intensity of Cr<sup>4+</sup> by more than three times. The quantum efficiency of the present GCs is as great as 36% at room temperature.
Optics Letters 12/2012; 37(24):5043-5. · 3.40 Impact Factor
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ABSTRACT: The Ag-TCNQ (TCNQ = tetracyanoquinodimethane) nanowires synthesized by a vapor transport reaction exhibit promising field emission properties. Their effective work function at high applied electric field was estimated to be about 1.70 eV according to the Fowler-Nordheim (F-N) theory. In this work, we directly measured the intrinsic work function of Ag-TCNQ nanowires via the ultraviolet photoemission spectroscopy (UPS). According to the threshold binding energy, the work function is obtained to be 5.45 eV, which shows a large discrepancy with the preivous estimation based on F-N theory. The reductive effecitive work function during the field emission is mainly attributed to the morphology-induced enhancement of the nanowire array.
Journal of Nanoscience and Nanotechnology 08/2012; 12(8):6576-8. · 1.56 Impact Factor
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ABSTRACT: We report on near-infrared laser induced luminescence from Bix/Dy3+/Tm3+ triply doped 70GeS2.10Ga2S3.20KBr chalcohalide glasses. Pumping at 808 nm results in three overlapping emissions bands at 1230 nm, 1310 nm and 1470 nm. The intensity of all bands can be enhanced by increasing the concentration of Tm3+ and/or Dy3+ ions. The relevant mechanism of energy transfer and photon emission was investigated in detail and is discussed on the basis of the individual intensity parameters according to the Judd-Ofelt (J-O) model.
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B. 11/2011; 52(6):221-224.
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ABSTRACT: Photoinduced effects of GeSe2 and Ge2Se3 films illuminated in air and in vacuum are investigated by in situ transmission spectra measurements. Both compositions exhibit photobleaching (PB) when exposed to bandgap laser for a prolonged time in air. By comparing with the photoinduced effects in vacuum, we conclude that PB in Ge2Se3 film results from surface photo-oxidation, whereas intrinsic structural changes dominate the PB in GeSe2 film.
10/2011;
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ABSTRACT: The Pr3+–Yb3+ ion codoped 40SiO2–30Al2O3–18Na2O–12LaF3 glasses were synthesized by a conventional melting–quenching method. Near-infrared downconversion emission with 12% quantum yield has been realized. Transparent glass ceramics containing LaF3 nanocrystals were prepared by heat treatment. X-ray diffraction and scanning electron microscopy results show that fluorides favor the formation of small crystals. Comparing the absorption and emission spectra of the glasses with that of the glass ceramics indicates that the Pr3+ ions are incorporated in priority into the LaF3 crystals, due to the similar crystal lattice. Thus, energy transfer efficiency cannot be enhanced in the present glass by crystallization. It is suggested that fluorides from TbF3 to LuF3 (including YF3) having the orthorhombic structure in aluminosilicate glass are suitable for incorporating YbF3 during the crystallization process.
06/2011;
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ABSTRACT: Solid state electric field-assisted diffusion has been widely applied to oxide glasses to make buried waveguides but rarely employed in chalcogenide glasses. We have previously fabricated Ag-doped Ge20Ga5Sb10S65 glasses by electric field-assisted diffusion and studied the Ag+ concentration profiles. However, the optical properties after the silver diffusion were left unexplored. In this article, we use the “scratch method” by atomic force microscopy to investigate the refractive index profile of Dy3+-doped Ge20Ga5Sb10S65 glass after the silver diffusion. The refractive index profile obtained after the diffusion is very symmetric. An enhanced Dy3+ 1.34 μm emission has been found only in the presence of silver. The product of measured lifetime and emission cross-section (τmeaσe) is increased by 12% after the diffusion.
Journal of the American Ceramic Society 05/2011; 94(7):1982 - 1985. · 2.27 Impact Factor
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ABSTRACT: The subbandgap light induced bleaching and/or darkening in (GeS2)x–(SbSI)1−x(x=10,20) glasses were investigated by observing in situ transmission spectra. The light is capable of inducing darkening and/or bleaching depending on the GeS2 content. The self-reversible of metastable darkening occurs in the sample of higher GeS2 content at room temperature. The kinetics of dark decay can be described well by a stretched exponential function. The decay rate is significantly faster than for other chalcogenide glasses. The Raman scattering measurements reveal the origin of photoinduced structural changes.
Journal of the American Ceramic Society 04/2011; 94(6):1657 - 1660. · 2.27 Impact Factor
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ABSTRACT: An ethanol-assisted method is utilized to generate a robust gelated crystalline colloidal array (GCCA) photonic crystal sensor. The functionalized sensor efficiently diffracts the visible light and responds to various stimuli involving solvent, pH, cation, and compressive strain; the related color change can be easily distinguished by the naked eye.
Chemical Communications 04/2011; 47(19):5530-2. · 6.17 Impact Factor
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ABSTRACT: To study the opto/electrical properties of metal organic complex Ag-TCNQ mico/nano structure, they were grown on Si, glass and silver plate substrates by a solution reaction and a vapor-transport reaction, respectively. They were firstly characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. Then Raman observation of single microwire and field emission display of nanowires array were studied experimently.
Journal of Physics Conference Series 03/2011; 276(1):012198.
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ABSTRACT: The intense 1.32, 1.73, and 2.67 μ m near-infrared and midinfrared emissions were observed from the Dy <sup>3+</sup> -doped GeSe <sub>2</sub>– Ga <sub>2</sub> Se <sub>3</sub>– MI ( M = K , Cs, Ag) chalcohalide glasses. These glasses are red light transparent therefore can be pumped by a semiconductor lasers operating at ∼808 nm . The 2.67 μ m emission has not been reported yet which corresponds to an absorption minimum in fluoride fibers and can be very useful for long distance communications. The intensity of emissions is very sensitive to the local chemical environment of Dy <sup>3+</sup> ions embedded in these metal halide modified glasses. A plausible correspondence between the emission intensity and the average oscillator strength was found.
Journal of Applied Physics 03/2011; · 2.17 Impact Factor
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ABSTRACT: W/Mo-oxides of the hexagonal tungsten bronze (HTB) type have been investigated by X-ray absorption spectroscopy to obtain detailed insight into the substitution process of W by Mo that leads to mixed HTB frameworks. Both the morphology of the nanostructured W/Mo-HTBs as well as the oxidation state of Mo are significantly influenced through the incorporation of different alkali cations into the hexagonal channels of this open structure. A variety of complementary analytical methods, including TG, in situ and ex situ XRD, SEM, and solid-state NMR analyses, were applied to determine the thermal stability of the obtained W/Mo-HTB materials with respect to their alkali cation and NH4+ contents. A strong correlation between composition and stability was found with the Rb-W/Mo-HTBs exhibiting the highest structural and morphological resistance among the series (up to 580 °C). The NH3-sensing properties of selected W/Mo-oxides in test atmospheres furthermore point to promising features of the Rb-stabilized hexagonal framework materials.
11/2010;
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ABSTRACT: To investigate the expression and clinical significance of Sonic hedgehog (Shh) in pancreatic adenocarcinoma.
The expression of Shh protein was examined in 34 surgical specimens of primary pancreatic adenocarcinoma, 21 nonmalignant specimens of the pancreas by immunohistochemistry streptavidin-perosidase (SP) method. In addition, semiquantitative reverse transcriptase polymerase chain reaction was carried out to analyze Shh mRNA expression in 22 pairs of freshly resected pancreatic adenocarcinoma tissues and their adjacent nontumorous tissues.
The positive expression rate of Shh protein was 64.7% (22/34) in 34 surgical specimens of primary pancreatic adenocarcinoma and 0% (0/21) in 21 nonmalignant specimens of the pancreas. The expression rate of Shh was higher in pancreatic adenocarcinoma tissues than that of nonmalignant pancreatic tissues (χ2 = 22.647, P = 0.000). Sonic hedgehog protein expression correlated with TNM stages and distant metastasis. Moreover, the expression levels of Shh mRNA were higher in pancreatic adenocarcinoma tissues than that of the matched adjacent nontumorous tissues.
Sonic hedgehog might play a pivotal role during tumorigenesis of pancreatic adenocarcinoma, and high Shh expression might be associated with the malignant potential of pancreatic cancer.
Pancreas 10/2010; 40(2):233-6. · 2.39 Impact Factor
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ABSTRACT: In the present work, barium phosphate glasses codoped with Dy3+–Eu3+ ions are prepared and their photoluminescence properties are studied by the excitation and emission spectra. The dependence of emission spectra on the concentrations of Eu3+ and Dy3+ is discussed with respect to the energy transfer (ET) process from Dy3+ to Eu3+ ions and relevant ET mechanism was proposed.
Journal of the American Ceramic Society 09/2010; 93(10):3064 - 3067. · 2.27 Impact Factor
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ABSTRACT: In this paper, the Bi, Tm3+-doped and Bi/Tm3+ co-doped 70GeS2–10Ga2S3–20KBr chalcohalide glasses are prepared. The near infrared luminescence properties of glass samples are investigated by the absorption and photoluminescence spectra. The enhanced emissions at 1230 and 1470 nm have been observed from Bi/Tm3+ co-doped samples when pumped by an 808 laser diode. The possible energy transfer mechanisms from Bi to Tm3+ ions are proposed.
Journal of the American Ceramic Society 09/2010; 93(11):3539 - 3541. · 2.27 Impact Factor
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ABSTRACT: Eu2+-doped SrCN2 with different Eu2+ contents were prepared by a high-temperature solid-state reaction under NH3 atmosphere. SrCN2 has an energy gap of 4.56 eV by the reflection spectra. The photoluminescence spectra of SrCN2:Eu2+ at different temperatures were measured. The results show that Eu2+-doped SrCN2 shows a broad band emission with a peak at 610 nm when it is excited by 350–520 nm at 77 K. With the temperature increasing, the emission intensity decreases remarkably, indicating that Eu2+-doped SrCN2 has a low quenching temperature.
Journal of the American Ceramic Society 09/2010; 93(10):3052 - 3055. · 2.27 Impact Factor
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ABSTRACT: Eu-doped oxyfluoride aluminosilicate glasses were prepared by melt-quenching method. The glass samples were characterized by photoluminescence (PL) spectroscopy and electron paramagnetic resonance techniques. In the glass samples, the reduction of Eu3+ to Eu2+ ions occurred in the air condition. The PL spectra showed that the intensity of 4f65d→4f7 transition of Eu2+ ions increased and the corresponding peak wavelength decreased with increasing fluorine anion concentration. Meanwhile, the relative emission intensity ratio of Eu2+ to Eu3+ also depended on the content of fluorine anions. A possible reduction mechanism was discussed.
Journal of the American Ceramic Society 09/2010; 93(10):3095 - 3098. · 2.27 Impact Factor
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Small 06/2010; 6(11):1173-9. · 8.35 Impact Factor
