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1. chinaXiv:201703.00565 [pdf]

Synthesis and luminescence properties of Sm-doped LDPE-Na2SO4 composite material

Jing Zhang; Abu Zayed Mohammad Saliqur Rahman; Yuxiao Li; Jing Yang; Bozhen Zhao; Eryang Lu; Peng Zhang; Xingzhong Cao; Runsheng Yu; Baoyi Wang
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

A series of Sm-doped LDPE-Na2SO4 composites were successfully achieved by melt mixing and hot pressing methods. Their morphology, structure and luminescent properties were characterized by scanning electron microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and photoexcitation (PE), photoluminescence (PL) spectra, respectively. The sizes and concentrations of free volume cavities in composites were studied by positron annihilation lifetime spectroscopy (PALS). SEM micrographs showed that Na2SO4:Sm3+ particles were well-distributed in the polymer matrix. XRD analyses revealed that the addition of Na2SO4:Sm3+ had no effect on the original crystal structure of LDPE. The dominant photoexcitation peak was observed at about 402 nm. The photoluminescence spectra consisted of four main peaks at 563, 598, 644 and 706 nm which could be associated to the transitions 4G5/2→6HJ (J=5/2, 7/2, 9/2 and 11/2, respectively) within the 4f5 electronic configuration of Sm3+. The effect of different doping concentration of Na2SO4:Sm3+ on the luminescent properties of the composites was investigated. The luminescent intensity of the composites increased with phosphor concentration.

submitted time 2017-03-26 Hits1470Downloads839 Comment 0

2. chinaXiv:201703.00563 [pdf]

Vibronic photoexcitation spectra of irradiated spinel MgOAl2O3(n=2) at low temperatures

Abu Zayed Mohammad Saliqur Rahman; Xingzhong Cao; Long Wei; Baoyi Wang; Shuaishuai Sun; Ye Tao; Qiu Xu
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

A vibronic photoexcitation band at approximately 230 nm was found at 13 K in reactor neutron- and electron-irradiated magnesiumaluminate spinel ( MgOAl2O3). Vibronic structure was found to be temperature dependent and became obscure at over 120K. Huang Rhys factor S and Debye Temperature D were estimated from the temperature dependence of the 230 nm band bycurve-fitting method using Debye approximation. Origin of the vibronic photoexcitation band was suggested as F center.

submitted time 2017-03-26 Hits1292Downloads777 Comment 0

3. chinaXiv:201703.00561 [pdf]

Luminescence properties of samarium-doped SiO2-Na2SO4 composite

Abu Zayed Mohammad Saliqur Rahman; Xingzhong Cao; Long Wei; Baoyi Wang; Haichen Wu
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

The comprehensive structural and luminescence study of Sm-doped SiO2-Na2SO4 composite materials are reported. The samples were synthesized by melt-mixing mixture of Na2SO4 and SmF3 into the SiO2 matrix at 1050 C for 30 min. X-ray di raction (XRD) pattern shows the characteristic structure of the SiO2 and addition of 20% Na2SO4:Sm has no e ect on the basic crystal structure of the SiO2. Scanning electron microscopy (SEM) shows the clear di erence in morphological structure between the composite and host SiO2. From photoexcitation (PE) spectra of the as-synthesized composite, the highest excitation e ciency was observed at 402 nm. The photoluminescence (PL) spectra of as-synthesized composite phosphors obtained under 402 nm excitation consist of five narrow emission bands with peaks at 563, 598, 644, 704 and 784 nm. These are assigned to the 4G5=2 ! 6HJ (J=5/2, 7/2, 9/2, 11/2 and 13/2, respectively) transitions within 4f5 electronic configuration of Sm3+. Highest luminescence intensity was observed with SiO2-10%Na2SO4:Sm.

submitted time 2017-03-26 Hits1291Downloads774 Comment 0

4. chinaXiv:201703.00515 [pdf]

Radiation induced modifications on structural and luminescence properties of LDPE–Na2SO4:Sm3+ composites by γ-ray

Jing Zhang; Abu Zayed Mohammad Saliqur Rahman; Yuxiao Li; Jing Yang; Yaru Wu; Daqing Yuan; Xingzhong Cao; Runsheng Yu; Baoyi Wang
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

A comparative study on the morphology, structure and luminescence modifications of LDPE–Na2SO4:Sm3+ composite induced by gamma irradiation was reported for the first time. The composites were irradiated with irradiation doses of 10, 30, and 50 kGy in air at room temperature. Modifications on structural and luminescence properties of LDPE–Na2SO4:Sm3+ composites were investigated by using several analytical methods. The X-ray diffraction (XRD) patterns revealed that the cross-linking improved the crystallinity of the composites. Scanning electron microscope (SEM) images illustrated the surface modifications of composites induced by irradiation. Results of positron annihilation lifetime spectroscopy (PALS) suggested that gamma irradiation affected the free volumes concentrations in the samples. The photoluminescence (PL) spectra of non-irradiated and irradiated composites consisted of four main peaks at 563, 598, 644 and 706 nm which could be assigned to the 4G5/2 6HJ (J =5/2, 7/2, 9/2 and 11/2, respectively) transitions within the electronic configuration of Sm3+. Meanwhile, we observed an additional peak at about 686 nm in the irradiated composites, owing to the conversion of Sm3+ Sm2+. Concentrations of the Sm2+ centers linearly increased with gamma irradiation doses, which partly accounted for the degradation of PL intensity of Sm3+ peaks.

submitted time 2017-03-23 Hits1510Downloads820 Comment 0

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