Combustion assisted spectroscopic investigation of Dy3+ activated SrYAl3O7 phosphor for LED and TLD applications

Luminescence and dosimetry approach in terbium(III)-activated tungstate double perovskite

A series of tungstate double perovskite Ca3 WO6 doped with Tb3+ was prepared by a combustion process using urea as a flux. The crystal structure identification of Ca3 WO6 :Tb3+ phosphors was done using X-ray diffraction patterns, and a monoclinic structure was discovered. The Fourier transform infrared spectrum of Ca3 WO6 :Tb3+ displayed characteristic vibrations of tungstate bonds. Under 278 nm excitation, Ca3 WO6 :Tb3+ exhibited intense downconversion green emission, which corresponded to the 5 D4 -7 FJ (J = 4,5) transitions of Tb3+ . The phosphor exhibited the highest photoluminescence (PL) intensity when it was doped with 1 mol% of Tb3+ ; later intensity quenching appeared to be due to the multipolar interaction at higher dopant concentrations. Moreover, high-quality thermoluminescence (TL) was detected when phosphors were irradiated using beta rays. The effects of Tb3+ concentration and beta dose on TL intensity were the two major aspects studied in detail. The TL intensity demonstrated excellent linear response to the applied range of beta dose. The trap parameters of the studied phosphors were computed by the peak shape approach and glow curve deconvolution. The fading effect on TL intensity was studied by recording the TL glow curves after 1 month of beta irradiation. Obtained results from the PL and TL characterizations showed that the phosphors under study have the potential to be used in lighting displays and in thermoluminescence dosimetry.

Tailored efficient energy transfer Tb3+, Eu3+ activated/co-activated LiAl(PO3)4 phosphor by substitution of alkali metals: the effect of charge compensation

Phosphites are the new emerging candidates in the field of luminescence in the modern era. In the present investigation, Tb3+/Eu3+ activated/co-activated LiAl(PO3)4 phosphor was prepared by a wet chemical method, and the effect of R+ (Na+, K+) ions on photoluminescence (PL) properties of these phosphors are investigated. Phase identification and crystal structure of the prepared phosphor were determined using XRD and Rietveld refinement, respectively. Morphological study and elemental analysis of the proposed phosphor with elemental analysis of the sample were performed using SEM and EDS. The PL properties of the proposed phosphor showed three simultaneous emission peaks in the visible range, giving color-tunable emission. The charge compensation of Na+ and K+ ions make a significant impact on the PL intensity of Tb3+, Eu3+ co-activated LiAl(PO3)4 phosphors. The PL intensity of Tb3+, Eu3+ co-activated LiAl(PO3)4 phosphors was significantly enhanced by factors 1.2 and 1.4 when Na+ and K+ charge compensators, respectively, were introduced. To manifest the charge compensation effect of alkali metals the optimum intense sample in the co-doped sample was used. These results indicate the potential candidacy of the studied phosphor for further improvement in PL properties for application in solid-state lighting.

Intensity enhancement of photoluminescence in Tb3+ /Eu3+ co-doped Ca14 Zn6 Al10 O35 phosphor for WLEDs

This article focuses on the effect of monovalent cation doping on the optical properties of rare earth (RE = Eu³⁺ , Tb³⁺ ) co-doped Ca₁₄ Zn₆ Al₁₀ O₃₅ which has been synthesized by a low temperature combustion method. Crystalline phase of the Ca₁₄ Zn₆ Al₁₀ O₃₅ phosphor was examined and confirmed by X-ray diffraction measurement. Under near-ultraviolet light excitation Eu³⁺ -doped Ca₁₄ Zn₆ Al₁₀ O₃₅ phosphor exhibit characterization of Eu³⁺ emission bands that are located at a maximum wavelength (λ_max ) of approximately 470 nm and other peaks centred at 593 nm and 615 nm, respectively. With Tb³⁺ -doped Ca₁₄ Zn₆ Al₁₀ O₃₅ phosphor showing a green emission band centred at 544 nm under near-ultraviolet range. Furthermore, we studied the energy transfer process in Eu³⁺ /Tb³⁺ pair and enhancement in photoluminescence (PL) intensity with doping different charge compensation. Here we obtained the optimum PL emission intensity of the phosphor in broad and intense visible spectral range which may be significant for the fabrication of white light emitting diodes (WLEDs).

Luminescence investigation of Sm3+ ,Eu2+ -activated/co-activated Ba2 AlB4 O7 Cl phosphors: novel red to blue colour tuning in chloroborates

Borochlorate phosphors have shown their worth in modern day lighting over the last few years. Colour tunability of the phosphor is a modern techniques used to obtain white-light-emitting diodes (WLEDs). In the proposed work, Sm³⁺ ,Eu²⁺ -activated/co-activated Ba₂ AlB₄ O₇ Cl phosphors were investigated for WLED applications as well as display devices. A convectional solid-state diffusion method was used to synthesize the proposed phosphors. X-ray diffraction (XRD) of the proposed phosphors confirmed the crystalline nature of the sample. Morphological studies on the samples were carried out using scanning electron microscopy analysis. A photoluminescence study of the colour tunable phosphor showed the characteristic peak of Sm³⁺ together with one broad peak for Eu²⁺ ions. Red to blue colour tunability was observed in the proposed phosphor with enhancement of Eu²⁺ ions. All these results showed the worth of this sample in WLED applications as well as in display devices.

Combustion assisted Ca8.25 Na1.5 Al6 O18 :Sm3+ phosphors for solid state lighting and WLEDs applications

Aluminate based phosphors are most investigated luminescent phosphors over the decades due to its outstanding optical properties. In the proposed work, a series of Sm³⁺ doped Ca_8.25 Na_1.5 Al₆ O₁₈ (CNAO) phosphor sample wasprepared by employing a simple combustion technique with the help of two fuels i.e., urea-glycine. The purity of phase and structural analysis of the CNAO phosphors were confirmed by XRD analysis. Vibrational features of this phosphors confirmed via FT-IR analysis. Photoluminescence study of this phosphor shows doublet emission at 568 and 576 in yellow region attributable to ⁴ G_5/2 →⁶ H_5/2 transition of Sm³⁺ ions while doublet peak noticed in red part ranges in-between 600-620 nm are attributable to ⁴ G_5/2 →⁶ H_7/2 transition of Sm³⁺ ions. Moreover, CIE colour co-ordinates are also located in yellowish red region which confirms the potential of this phosphor as a yellowish red component for WLEDs and display devices applications.

Luminescence study of Sm3+ ,Eu3+ -doped Y2 Zr2 O7 host: optical investigation of greenish yellow to red colour tunable pyrochlore phosphor

Pyrochlore phosphors have shown their worth in modern day lighting in the last few years. Colour tunability of the phosphor is one of the modern techniques used to obtain white light-emitting diodes (WLEDs). In the proposed work, Y₂ Zr₂ O₇ :Sm³⁺ ,Eu³⁺ phosphors were investigated for WLED applications as well as display devices. A convectional solid-state diffusion method was used to synthesize the proposed phosphors. X-ray diffraction of the proposed phosphors was performed and compared with the standard Inorganic Crystal Structure Database. The crystal structure of the sample was cubic in nature, obtained from Rietveld refinement. Vibrational and morphological studies on the samples were carried out using Fourier transform infrared spectroscopy and scanning electron microscopy analysis. The photoluminescence study of the colour tunable phosphor showed the characteristic peak of Sm³⁺ together with the two sharp peaks of Eu³⁺ ions. Greenish yellow to red colour tunability was observed in the proposed phosphor with enhancement of Eu³⁺ ions. All these results showed the worth of this sample for WLEDs applications as well as in display devices.