118 research outputs found
Unexpected luminescence of Cr5+ and Cr3+ ions in ZrSiO4 zircon crystals
Luminescence, decay-times and EPR spectroscopy of Cr-doped ZrSiO4 show the presence of both Cr3+ and Cr5+ active centers, which can be connected with Zr4+ and Si4+ adjacent two-cation replacement. Cr5+ emission occurs within a similar spectral range as for Cr4+ and hence confusion is possible
IR Bismuth active centers in optical fibers: Combined excitation-emission spectroscopy
3D excitation-emission luminescence spectra of Bi-doped optical fibers of
various compositions were measured in a wide wavelength range 450-1700 nm. Such
luminescence spectra were obtained for Bi-doped pure silica and germania
fibers, and for Bi-doped Al- or P-codoped silica fibers (at room and liquid
nitrogen temperatures). The energy level schemes of IR bismuth active centers
in pure silica and germania core fibers were derived from spectra obtained. The
energy level schemes similarity of bismuth active centers in these two types of
fibers was revealed.Comment: 12pages, 7 figures, 5 table
Synthesis and White-Light Emission of ZnO/HfO2: Eu Nanocables
ZnO/HfO2:Eu nanocables were prepared by radio frequency sputtering with electrospun ZnO nanofibers as cores. The well-crystallized ZnO/HfO2:Eu nanocables showed a uniform intact core–shell structure, which consisted of a hexagonal ZnO core and a monoclinic HfO2 shell. The photoluminescence properties of the samples were characterized. A white-light band emission consisted of blue, green, and red emissions was observed in the nanocables. The blue and green emissions can be attributed to the zinc vacancy and oxygen vacancy defects in ZnO/HfO2:Eu nanocables, and the yellow–red emissions are derived from the inner 4f-shell transitions of corresponding Eu3+ ions in HfO2:Eu shells. Enhanced white-light emission was observed in the nanocables. The enhancement of the emission is ascribed to the structural changes after coaxial synthesis
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