Enhancing emission intensity and thermal stability by charge compensation in Sr₂Mg₃P₄O₁₅:Eu³⁺

Abstract

Charge compensation was the effective methods to enhance the luminescence properties of phosphors. In this paper, novel single-phased orange light emitting Sr 2 Mg 3 P 4 O 15 :Eu 3+ phosphors were prepared by solid state method. The phase purity and luminous characteristics were examined in detail. Meanwhile, three kinds of charge compensation methods (co-doping the alkali metal R + (R + = Li, Na, and K), substituting Si 4+ for P 5+ and self-compensation) were employed to solve the charge imbalance problem between Sr 2+ and Eu 3+ . The results showed that emission intensity of Eu 3+ was improved by 1.43 (Li + ), 1.58 (Na + ), 1.53 (K + ), 1.61 (Si 4+ ), and 1.30 (self) times than that of Sr 1.6 Mg 3 P 4 O 15 :0.40Eu 3+ , respectively, and there was no change in the emitting color simultaneously. Furthermore, as the temperature reached at 423 K, the emission intensity increased from 41.67% of Sr 1.6 Mg 3 P 4 O 15 :0.40Eu 3+ to 55.69% (Li + ), 61.62% (Na + ), 58.98% (K + ), 71.15% (Si 4+ ), and 80.59% (self) of that at room temperature. The reasons of those phenomena were the reduction in ion vacancies caused by charge imbalance through the charge compensation process. The specific mechanisms were elaborated in detail.Overall, this research validated that the charge compensation strategies could be severed as the key method to improve the luminescence properties, especially the thermal stability of phosphor.

Novel Cyan-Green-Emitting Bi3+-Doped BaScO2F, R+ (R = Na, K, Rb) Perovskite Used for Achieving Full-Visible-Spectrum LED Lighting

“…This substitution produces excess O 2− vacancies to form photon traps and inhibits the luminescence of Bi 3+ , but by incorporating alkali metals R + (such as Na + , K + , or Rb + ), the unbalanced electrical neutrality (Ba 2+ −Sc 3+ −Bi 3+ ) turns into the balanced (R + − Sc 3+ −Bi 3+ = Ba 2+ −Sc 3+ −Ba 2+ ) and removes O 2− vacancies, leading to improvement in the emission of Bi 3+ . 32 Otherwise, the emission intensity of the K + co-doping sample is higher than Na + and Rb + co-doping samples, attributed to the different ion radii, where difference between K + (1.8%) and Ba 2+ is smaller than Na + (13.6%) and Rb + (6.8%). The incorporation of K + cause less distortion of the crystal lattice relative to Na + and Rb + , resulting in the K + co-doping phosphor exhibiting the strongest emission.…”

“…The luminescence center [BiO 12 ] is formed due to Bi 3+ replacing Ba 2+ , which destroys the electrical neutrality of a compound (Ba 2+ –Sc 3+ –Ba 2+ ). This substitution produces excess O 2– vacancies to form photon traps and inhibits the luminescence of Bi 3+ , but by incorporating alkali metals R + (such as Na + , K + , or Rb + ), the unbalanced electrical neutrality (Ba 2+ –Sc 3+ –Bi 3+ ) turns into the balanced (R + –Sc 3+ –Bi 3+ = Ba 2+ –Sc 3+ –Ba 2+ ) and removes O 2– vacancies, leading to improvement in the emission of Bi 3+ . Otherwise, the emission intensity of the K + co-doping sample is higher than Na + and Rb + co-doping samples, attributed to the different ion radii, where difference between K + (1.8%) and Ba 2+ is smaller than Na + (13.6%) and Rb + (6.8%).…”

“…In contrast, as the activator, Bi has been widely researched due to its excitation band in the UV region and nearly no reabsorption in the visible region. − The luminescence of Bi 3+ is very complicated depending on different hosts and coordination environments in the range of 370 to 650 nm because the naked 6s and 6p electrons of Bi 3+ are strongly sensitive to the crystal field. − However, in general, the excitation peak positions of Bi 3+ are located in the UV region shorter than 350 nm, such as Ca 3 Al 2 O 6 :Bi 3+ (λ Ex = 285 nm, λ Em = 305 nm), La 2 LiSbO 6 :Bi 3+ (λ Ex = 313 nm, λ Em = 407 nm), YVO 4 :Bi 3+ (λ Ex = 297 nm, λ Em = 566 nm), and Ca 5 (PO 4 ) 3 F:Bi 3+ (λ Ex = 290 nm, λ Em = 575 nm), which cannot match well with the NUV chips of 360–420 nm. It is necessary to develop a novel Bi 3+ -doped phosphor with NUV excitation and cyan emission for meeting the present lighting requirements of full w-LEDs.…”

Ni2+-Doped Garnet Solid-Solution Phosphor-Converted Broadband Shortwave Infrared Light-Emitting Diodes toward Spectroscopy Application

“…Generally, the thermal quenching behavior of an activator is greatly determined by the structural rigidity of the host lattice, and a stiff host lattice usually leads to smaller thermal quenching. The aliovalent doping of Ni 2+ in this work inevitably causes the lattice distortion, leading to a lower rigidity of the host structure and thus a deteriorated thermal quenching. − The addition of H 3 BO 3 , contributing to the improvement of crystallinity and resulting in less lattice distortion, benefits the enhanced thermal stability. Zr 4+ ions, purposely doped for the charge compensation to avoid the charge imbalance, also reduce the occurrence of structural distortion and lead to the much smaller thermal quenching.…”

Synthesis, structure, and luminescence of Eu3+‐activated La4Ti3O12nanoparticles with layered perovskite structure

“…Eu 3+ is an activator based on its specialties, ie, its emission lines are very simple compared with the other RE ions. Eu 3+ ions substituted for host cations in a host usually exhibit a bright red emission and it can be easily excited by UV‐ and near UV‐radiation which is strongly absorbed by the charge‐transfer (CT) transition of Eu 3+ …”