Solid state synthesis of CaTiO3:Dy3+/Eu3+ phosphors towards white light emission

Effect of Dopant Concentration on Luminescence Properties of Na3Ca2(SO4)3F: RE (RE = Eu3+, Dy3+) Phosphor for Solid-State Lighting

A fluoride material phosphor doped with rare earth ions Eu3+ and Dy3+ was studied for its photoluminescence (PL) properties. The material was synthesized using a combustion method and characterized using X-ray diffraction (XRD) and PL techniques. The Na3Ca2(SO4)3F: Eu3+ phosphor exhibits two distinct peaks at 593 nm (orange) and 615 nm (red) at an excitation wavelength of 395 nm. The PL excitation spectrum of the Na3Ca2(SO4)3F: Dy3+ phosphor showed series of peaks, corresponding to the 4f → 4f transitions of Dy3+ ions. Under 350-nm excitation, the PL emission spectrum revealed two prominent bands one at 483 nm (blue region) due to the 4F₉/₂ → 6H₁₅/₂ transition, and another at 573 nm (yellow region) resulting from the 4F₉/₂ → 6H₁₃/₂ transition. These blue and yellow emissions suggest potential applications in solid-state lighting, particularly for mercury-free excitation sources. Rare earth-doped Eu3+/Dy3+ materials exhibit highly efficient PL properties, making them suitable candidates for white light-emitting diodes (LEDs) or other solid-state lighting phosphors.

Novel low-temperature synthesis of Y2-x O3 :Eux 3+ nanophosphor using combustion with thioglycerol as fuel for near-UV light-emitting diodes

Luminescent materials used in flat panel displays, compact fluorescent lamps, and light-emitting diodes require high purity, uniform particle size, clean surfaces, spherical shape, and dense morphology to ensure long-term stability. Y2 O3 :Eu3+ is a widely studied red phosphor known for its characteristic photoluminescence (PL) emission at 613 nm with near-UV excitation at 392 nm. Many methods have been explored to synthesize Y2 O3 :Eu3+ nanoparticles with exceptional purity, consistent phases, and uniform particle sizes. The aim is to synthesize particles with pristine surfaces, spherical shape, and compact morphology. This study focuses on the low-temperature synthesis and PL investigation of Y2-x O3 :Eux 3+ nanophosphors using combustion with thioglycerol as fuel. The results are compared with Y2-x O3 :Eux 3+ red nanophosphors synthesized using wet chemical and nitrate combustion methods. The PL characteristics of the Y2-x O3 :Eux 3+ nanophosphors were analyzed using PL emission spectroscopy, X-ray diffraction, and scanning electron microscopy. These findings highlight the advantageous properties of the synthesized nanophosphors, such as their suitability for solid-state lighting applications in the lamp industry as highly efficient red phosphors. The combination of high purity, uniform particle size, clean surfaces, spherical shape, and dense morphology contributes to their potential for long-term stability and reliable performance in lighting devices.

Intense photoluminescence in CaTiO3:Sm3+ phosphors, effect of co-doping singly, doubly and triply ionized elements and their applications in LEDs

In this work, Sm³⁺-doped and Sm³⁺/Li⁺/K⁺/Mg²⁺/Ba²⁺/Gd³⁺/Bi³⁺ co-doped CaTiO₃ phosphors were synthesized by a solid-state reaction method at 1473 K. The phase of phosphors was identified to be orthorhombic with space group Pnma (62) by XRD measurements. The morphological properties of the prepared samples were studied by SEM measurements. The average crystallite and particle sizes were found to increase in the presence of modifiers and they follow the trend Li⁺ > Mg²⁺ > Gd³⁺ > K⁺ > Bi³⁺ > Ba²⁺. EDX measurements were used to verify the presence of Ca, Ti, O, Sm, K, Mg, Ba, Gd and Bi atoms in the prepared phosphor samples. The Sm³⁺ ion shows emission peaks at 564, 599 and 646 nm due to ⁴G_5/2 → ⁶H_5/2, ⁶H_7/2 and ⁶H_9/2 transitions upon 407 nm excitation, among which the peak situated at 599 nm has maximum emission intensity. Concentration quenching was observed above 2 mol% of Sm³⁺ ions in this host. However, the emission intensity of Sm³⁺ peaks can be enhanced using different modifier (Li⁺/K⁺/Mg²⁺/Ba²⁺/Gd³⁺/Bi³⁺) ions. It was found that the size (ionic radii) and charge compensation of the ion together play a dominant role. The enhancement is more after co-doping with smaller radius ions (Li⁺, Mg²⁺ and Gd³⁺), among which Li⁺ shows the largest enhancement. This is because ions of smaller size will be able to go closer to the activator ion and the charge imbalance causes a larger field. The CIE color coordinates, correlated color temperature (CCT) and color purity of the phosphors were calculated and show orange-red color emissions with a maximum color purity of ∼93% in the case of CaTiO₃:2Sm³⁺/1.0Li⁺ phosphor. The lifetime value is increased in the presence of these ions. It is again maximum for the Li⁺ co-doped CaTiO₃:2Sm³⁺ phosphor sample. Thus, the prepared phosphor samples are suitable sources for orange-red light.

Structure, photoluminescence properties, and energy transfer phenomenon in Sm3+/Eu3+ co-doped CaTiO3 phosphors

The energy transfer from Sm3+ and Eu3+ due to dipole–dipole interaction, variation in emission intensity of Sm3+ and Eu3+ peaks with varying concentration of Eu3+ and thermal stability of 2Sm3+, 2.5Eu3+ and 2Sm3+/2.5Eu3+ co-doped CaTiO3 phosphors.

Hydrothermal synthesis and photocatalytic activity of butterfly-like CaTiO3 dendrites with dominant {101} facets

Novel butterfly-like CaTiO₃ dendrites dominantly bounded by {101} facets have been synthesized via a conventional hydrothermal by using tetramethylammonium hydroxide (TMAH) as a mineralizer and surface modifier. The wing-branches of the butterfly-like CaTiO₃ dendrites are composed of primary block tetragonal plates with dominant {101} facets overlapping and ranking around the stem of 〈131〉 directions in the same plane belonging to the group of {101}. With the basis of the experimental results and the lattice structure, a possible formation mechanism of the butterfly-like CaTiO₃ dendrites has been discussed and proposed. The preferential adsorption of the organic [Formula: see text] ions released by the ionization of TMAH on {101} planes suppresses the deposition of the calcium titanate species on {101} planes, which induces the formation of the primary block tetragonal plates and their overlapping as well as ranking around 〈131〉 direction along {101} planes, resulting in the butterfly-like CaTiO₃ dendrites bounded with {101} facets. The investigation on the degradation of rhodamine-B demonstrates, due to the dominant exposition of the {101} facets, the butterfly-like CaTiO₃ dendrites display superior photocatalytic activity of more than four time that of CaTiO₃ microcuboids bounded with smart {101} and (010) facets.

Synthesis and Luminescence Properties of a Novel Green-Yellow-Emitting Phosphor BiOCl:Pr3+ for Blue-Light-Based w-LEDs

The development of white-light-emitting diodes (w-LEDs) makes it meaningful to develop novel high-performance phosphors excited by blue light. Herein, BiOCl:Pr³⁺ green-yellow phosphors were prepared via a high-temperature solid-state reaction method. The crystal structure, luminescent properties, lifetime, thermal quenching behavior, and quantum yield were studied in detail. The BiOCl:Pr³⁺ phosphors presented several emission peaks located in green and red regions, under excitation at 453 nm. The CIE coordinates could be tuned along with the changed doping concentration with fair luminescence efficiency. The results also indicated that the optimized doping concentration of Pr³⁺ ions was at x = 0.0075 because of the concentration quenching behavior resulting from an intense exchange effect. When the temperature reached 150 °C, the intensity of the emission peak at 495 nm could remain at 78% of that at room temperature. The activation energy of 0.20 eV also confirmed that the BiOCl:Pr³⁺ phosphor exhibited good thermal stability. All these results indicate that the prepared products have potential to be used as a high-performance green-yellow-light-emitting phosphor for blue-light-based w-LEDs.