Intense green-, red-emitting Tb3+ , Tb3+ /Bi3+ -doped and Sm3+ , Sm3+ /La3+ -doped Ca2 Al2 SiO7 phosphors.

This paper focuses on an optical study of a Tb3+ /Bi3+ -doped and Sm3+ /La3+ - doped Ca2 Al2 SiO7 phosphor synthesized using combustion methods. Here, Ca2 Al2 SiO7 :Sm3+ showed a red emission band under visible light excitation but, when it co-doped with La3+ ions, the emission intensity was further enhanced. Ca2 Al2 SiO7 :Tb3+ shows the characteristic green emission band under near-ultraviolet light excitation wavelengths, co-doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X-ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X-ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light-emitting diodes and energy conversion devices.

Eu(2+) luminescence in SrCaP2 O7 pyrophosphate phosphor.

A series of Eu(2+) activated SrCaP2 O7 pyrophosphate phosphors were synthesized by the modified solid-state reaction method. The X-ray diffraction (XRD) and photoluminescence (PL) properties of these phosphors were investigated at room temperature. The excitation spectra indicate that these phosphors can be effectively excited by Hg-free excitation. The emission spectra exhibit strong blue performance, which is due to the 4f(6) 5d(1) →4f(7) transition of Eu(2+) . The Fourier transform infrared spectrum at room temperature was investigated and surface morphology has been studied by scanning electron microscope. The prepared phosphor exhibited intense blue emission at the 427 nm owing to Eu(2+) ion by Hg-free excitation at 330 nm, that is, solid-state lighting excitation. Hence, the availability of such a phosphor will significantly help in the growth of blue-emitting solid-state lighting applications.

Synthesis and luminescence properties of Eu(2+) activated Ca2P2O7 pyrophosphate phosphor.

In the present study, calcium pyrophosphate activated with Eu(2+) rare earth ions prepared by solid state diffusion and confirmed by XRD. An average crystallite size is found out to be in sub-micrometer range of 2-5 µm from SEM study. FTIR spectra suggest that Ca2P2O7 material belongs to the diphosphate family. The PL spectroscopic characterizations of the prepared phosphors were performed using excitation and emission spectra. Photoluminescence spectra of Ca2P2O7:Eu(2+) pyrophosphate phosphor shows emission at 426 nm when excited at 356 nm.