Luminescence Performance of Yellow Phosphor Sr_xBa_1−xTiO₃: Eu³⁺, Gd³⁺ for Blue Chip

Abstract

The SrxBa1−xTiO3: Eu3+, Gd3+phosphors are synthesized by high temperature solid-phase method. Multiple techniques including X-ray diffraction (XRD), and scanning electron microscopy (SEM) are used to examine the surface morphology and structural properties of SrxBa1−xTiO3: Eu3+, Gd3+phosphors. The optical properties are presented and discussed in terms of photoluminescence (PL) and photoluminescence excitation (PLE) spectra. The as-obtained SrxBa1−xTiO3: Eu3+, Gd3+phosphors show higher PL emission intensity (at 591, 611 nm). The peaks at 591 and 611 nm are attributed to Eu3+ 5D0-7F1,5D0-7F2. Gd3+has a strong sensitization on Eu3+. A certain amount of Sr2+and Ba2+is contributed to the intensity of light emission. After being irradiated with blue light, the phosphor samples emit yellow light. This suggests its potential applications in many fields.

Semiconductor Physics, Quantum Electronics & Optoelectronics. 2016. V. 19, N 4. P. 343-351. DOI: https://doi.org/10.15407/spqeo19.04.343 SrTiO3:Eu3+ phosphors prepared by sol-gel synthesis: Structural characterization, magnetic properties and luminescence spectroscopy study

“…A possible reason for a small amount of Eu 3+ in SrTiO 3 may be the result of chosen technological conditions including the high temperature ceramic annealing step. However, similar emission is observed in similar phosphors obtained under the high temperature annealing with the temperature exceeding 1200 °С [22,23,25] and, at least in [41] mentioned similar low solid-solubility limit of Eu 3+ in the perovskite matrix. Possible explanation may be related to the low probability process assuming simultaneous exchange substitution of Sr 2+ and Ti 4+ sites by Eu 3+ ions with compensation both electrostatic and spatial distortion within the crystalline structure.…”

“…Indeed, this figure shows that with increasing the Eu concentration within the range 0.2 to 10 mol.% all peaks in the wavelength range λ = 580…710 nm remain the same. A similar dependence was obtained in [23], the optimum doping concentration 5% corresponding to the strongest emission intensity was determined. Authors suggest that it is the result of concentration quenching owing to the nonradiative energy transfer between luminescent centers increased when the doping concentration rises up.…”

“…Indeed, the short overview of the emission properties of europiumdoped materials clearly confirms this statementluminescence of the accommodated Eu 3+ ions strongly depends on both spatial distribution and nature of coordinated ligands [16][17][18][19][20][21]. So, the difference in optical properties of supposedly the same SrTiO 3 :Eu 3+ product obtained by different synthetic procedure clearly indicates the differences of the local environment of emitting ions [16,[22][23][24][25][26]. One of the possible reasons for that is the fact that the most of these materials obtained using the solid phase synthesis, which is peculiar to have spatial heterogeneity in the final material with different phases.…”

“…Similar spectra of the Eu 3+ -doped SrTiO 3 powder were observed F. Fujishiro for the material obtained by the sol-gel based Pechini technique [41], C.R. García et alprepared by pressure-assisted combustion synthesis with powder post-annealing at 1200 °C [22] and L. Dong et al in Sr x Ba 1−x TiO 3 :Eu 3+ phosphors synthesized using the high temperature solid-phase method with calcination at 1100 °C, excited with 466 nm [23]. However, at the same time photoluminescence of europium-doped strontium titanate prepared at lower temperature (microwave hydrothermal method at 140 °C [42], in a molten NaCl flux at 950 °C and dehydrated at 120 °C, excitation 488 nm [26], by the sol-gel process with annealing at 750 °C, excitation 460 nm, 77 K) [24]) demonstrate the dominant band around 620 nm that corresponds to the 5 D 0 → 7 F 2 transition with a low intensity of the 5 D 0 → 7 F 1 band.…”