Luminescence properties of red-emitting Ca2Al2SiO7:Eu3+ nanoparticles prepared by sol-gel method

Abstract

A series of red-emitting Ca 2−x Al 2 SiO 7 :xEu 3+ (x = 1 mol.%-10 mol.%) phosphors were synthesized by the sol-gel method. The effects of annealing temperature and doping concentration on the crystal structure and luminescence properties of Ca 2 Al 2 SiO 7 :Eu 3+ phosphors were investigated. X-ray diffraction (XRD) profiles showed that all peaks could be attributed to the tetragonal Ca 2 Al 2 SiO 7 phase when the sample was annealed at 1000°C. Scanning electron microscopy (SEM) micrographs indicate that the phosphors have an irregularly rounded morphology with particles of about 200 nm. Excitation spectra showed that the strong broad band at around 258 nm and weak sharp lines in 350-490 nm were attributed to the charge transfer band of Eu 3+ −O 2− and f-f transitions within the 4f 6 configuration of Eu 3+ ions, respectively. Emission spectra implied that the red luminescence could be attributed to the transitions from the 5 D 0 excited level to the 7 F J (J = 0, 1, 2, 3, 4) levels of Eu 3+ ions with the main electric dipole transition 5 D 0 → 7 F 2 (618 and 620 nm), and Eu 3+ ions prefer to occupy a lower symmetry site in the crystal lattice. Moreover, the photoluminescence (PL) intensity was strongly dependent on both the sintering temperature and doping concentration, and the highest PL intensity was observed at an Eu 3+ concentration x = 7 mol.% after annealing at 1100°C. The obtained Ca 2 Al 2 SiO 7 :Eu 3+ phosphor may have potential application for the red lamp phosphor.

Enhanced long-persistence of Ca2Al2SiO7:Ce3+ phosphors for mechanoluminescence and thermoluminescence dosimetry

“…ions can be partly replaced by Ce 3? ions without any change of crystal structure [11]. Figure 2 indicates that the crystal structure of Ca 2 Al 2 SiO 7 is mainly tetragonal and matches well to the JCPDS data file no.…”

“…Besides the aluminates, also the stannates, titanates and germanates show some interesting properties. Silicates are an important class of phosphorescence material because of their high quantum efficiency in visible region, long persistence of phosphorescence, color purity, good stability and good thermal, chemical and radiation resistance [10,11]. The benefit of lanthanide ions as activators has now well established in the field of luminescence [12,13].…”

Ca2Al2SiO7:Ce3+ phosphors for mechanoluminescence dosimetry

“…Figure (b) shows the XRD pattern of Ca 2 Al 2 SiO 7 :Ce 3+ phosphors annealed at 1100 °C for 3 h. By annealing the sample at 1100 °C the extra peak of SiO 2 is removed and this results in enhancement of the intensity of the diffraction peak and reduction in the full‐width at half maximum (FWHM), due to the improvement in crystalline and grain growth. XRD analysis revealed that the appropriate introduction of an activator (Ce 3+ ) did not influence the crystal structure of the phosphor matrix, including the fact that that Ca 2+ ions can be partly replaced by Ce 3+ ions without any change in the crystal structure . Figure indicates that the crystal structure of Ca 2 Al 2 SiO 7 is mainly tetragonal and matches well to Joint Committee on Powder Diffraction Standards (JCPDS) data file no.…”

“…Most importantly, these phosphors emit visible light efficiently under near‐UV or blue light irradiation allowing them to be used as down‐conversion luminescent materials for white LEDs . Silicates are an important class of phosphorescence material because of their high quantum efficiency in visible region, long persistence of phosphorescence, color purity, good stability and good thermal, chemical and radiation resistances . The benefit of lanthanide ions as activators has now been well established in the field of luminescence .…”

Effects of Ca Content on Formation and Photoluminescence Properties of CaAlSiN3:Eu2+ Phosphor by Combustion Synthesis

“…As mentioned previously, the XRD measurements (Figure 1) show that at low Ca contents ( i.e ., Y = 0.25 and 0.75), the phases of Ca-α-SiAlON (including Ca-α-SiAlON:Eu 2+ and Ca-α-SiAlON), AlN (including AlN:Eu 2+ and AlN), CaO, Eu 3 N 2 , Ca 2 Al 2 SiO 7 and residual Eu 2 O 3 were detected in addition to the phase of CaAlSiN 3 [21]. Among these, CaAlSiN 3 , Ca-α-SiAlON and AlN have been reported to be possible host lattices forming phosphors activated by Eu 2+ [10,11,12,13,14,15,16,17,18,19,20].…”