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Pan S.,Ningbo University | Pan S.,Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province | Wang Q.,CAS Shanghai Institute of Ceramics | Li H.,CAS Shanghai Institute of Ceramics | And 3 more authors.
Radiation Measurements | Year: 2016

Eu2+:CeBr3 crystals were grown by vertical Bridgman growth method and slight aliovalent doping of Eu2+ in the CeBr3 crystal did not change the crystal structure. The X-ray stimulated luminescence, photoluminescence, decay kinetics and scintillation properties were investigated at room temperature. The X-ray stimulated luminescence spectra exhibited wide broad emission bands from 3.54 eV to 2.95 eV in the Eu2+:CeBr3 crystal with high content of 620 ppm of Eu2+, which were the overlap of the emission bands ascribed to 5d → 4f transition of Ce3+ and 4f65 d1 → 4f7 transition of Eu2+, respectively. When the content of Eu2+ was decreased to 70 ppm, another emission band centered at 2.29 eV was observed. The photoluminescence spectra showed the energy transfer from Ce3+ to Eu2+. This decreased the Ce3+ emission intensity but enhanced the Eu2+ emission intensity. The photoluminescence decay time of Ce3+ emission decreased from 14 ns to 10 ns when the content of Eu2+ increased from 70 ppm to 620 ppm. The decay time of the emission of 525 nm did not change with the excitation wavelength and Eu2+ content, which could be assigned to the excitons that were bound on Eu2+ related centers. The light output of the Eu:CeBr3 crystal under the excitation of 241Am radioactive source was less than 20.2% of Tl:NaI crystal. © 2016 Elsevier Ltd. All rights reserved. Source


Li G.,Ningbo University | Xu T.,Ningbo University | Xu T.,Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province | Dai S.,Ningbo University | And 5 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2016

Series of GaxSb40-xS60 chalcogenide glasses were synthesized by a melt-quenching method. The thermal and optical properties of sample glasses were determined by the Archimedes principle, X-ray diffraction, thermal expansion, ultra violet-visible-near infrared absorption spectroscopy, and Fourier transform infrared spectroscopy, respectively. The structures of the samples with different compositions were analyzed by Raman spectroscopy. The results show that all of the glasses have good thermal stability and spectral properties. The density decreases slightly, the glass transition temperature improves, and the thermal expansion coefficient reduces with increasing the content of gallium. Besides, there is a slightly augmentation of optic band gap and a regularly blue-shifted of IR absorption cutting-off edge. Since all of the chalcogenide glasses have a high transmittance in a wide spectrum range of 0.8-14.0 μm (covering three main commutation bands and thermal infrared band), they are thus a promising material for mid-infrared application. According to the Raman spectra, the formation of [GaS4] tetrahedral units promote and the [SbS3] pyramid units suppress with the increase of gallium content. The relationship between optical properties and the structure in the chalcogenide glasses was summarized. © 2016, Editorial Department of Journal of the Chinese Ceramic Society. All right reserved. Source


Ma Y.,Ningbo University | Ma Y.,Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province | Lu Y.,Ningbo University | Lu Y.,Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province | And 11 more authors.
ECS Journal of Solid State Science and Technology | Year: 2016

In this paper, the phase change characteristics of Sb-Te-Se films were systematically studied by in-situ resistance-temperature measurement, X-ray diffraction (XRD), Raman scattering spectroscopy, X-ray photoelectron spectra (XPS), and Transmission electron microscopy (TEM). For preferred Sb56Te24Se20 and Sb55Te22Se23 films, the temperature for 10-year data retention can be up to 93.1 and 102.6C, which are higher than that of Ge2Sb2Te5 (GST, 82C). Both amorphous and crystalline resistivities increase with Se content. The resistance ratios between two states maintain almost 4 orders of magnitude. The microstructure of annealed Sb-Te-Se films exhibits uniform distribution of crystallized phases with rhombohedra Sb2SeTe2 and hexagonal Sb. The improvement in thermal stability of Sb-Te-Se films results from the atomic arrangements and consequently the complex cross bond system. © The Author(s) 2015. Source


Jiang C.,Ningbo University | Jiang C.,Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province | Wang X.,Ningbo University | Wang X.,Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province | And 22 more authors.
Optical Engineering | Year: 2016

We developed the extrusion method to prepare arsenic-free chalcogenide glass fibers with glass cladding. By using the double nested extrusion molds and the corresponding isolated stacked extrusion method, the utilization rate of glass materials was greatly improved compared with the conventional extrusion method. Fiber preforms with optimal stability of core/cladding ratio throughout the 160 mm length were prepared using the developed extrusion method. Typical fiber structure defects between the core/cladding interface, such as bubbles, cracks, and core diameter variation, were effectively eliminated. Ge-Sb-Se/S chalcogenide glasses were used to form a core/cladding pair and fibers with core/cladding structure were prepared by thermally drawing the extruded preforms. The transmission loss, fiber bending loss, and other optical characters of the fibers were also investigated. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE). Source


Chen Y.,Ningbo University | Chen Y.,Ningbo Institute of Materials Technology and Engineering | Chen Y.,Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province | Shen X.,Ningbo University | And 11 more authors.
Journal of Applied Physics | Year: 2016

The potentials of Sn, In, or Al doped ZnSb thin film as candidates for phase change materials have been studied in this paper. It was found that the Zn-Sb bonds were broken by the addition of the dopants and homopolar Zn-Zn bonds and other heteropolar bonds, such as Sn-Sb, In-Sb, and Al-Sb, were subsequently formed. The existence of homopolar Sn-Sn and In-In bonds in Zn50Sb36Sn14 and Zn41Sb36In23 films, but no any Al-Al bonds in Zn35Sb30Al35 film, was confirmed. All these three amorphous films crystallize with the appearance of crystalline rhombohedral Sb phase, and Zn35Sb30Al35 film even exhibits a second crystallization process where the crystalline AlSb phase is separated out. The Zn35Sb30Al35 film exhibits a reversible phase change behavior with a larger Ea (∼4.7 eV), higher Tc (∼245 °C), better 10-yr data retention (∼182 °C), less incubation time (20 ns at 70 mW), and faster complete crystallization speed (45 ns at 70 mW). Moreover, Zn35Sb30Al35 film shows the smaller root-mean-square (1.654 nm) and less change of the thickness between amorphous and crystalline state (7.5%), which are in favor of improving the reliability of phase change memory. © 2016 Author(s). Source

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