Photoluminescence and electron paramagnetic resonance properties of a potential phototherapic agent: MMgF₄:Gd³⁺ (M = Ba, Sr) sub‐microphosphors

Abstract

Novel narrow band UVB-emitting phosphors, BaMgF :Gd and SrMgF :Gd phosphors, were synthesized using a co-precipitation synthesis method. X-Ray diffraction analysis was carried out to confirm compound formation, phase purity and crystallinity of the phosphor. At 274 nm excitation, phosphors show a sharp narrow band emission at 313 nm that can be assigned to P → S transition of the Gd ion. With increasing dopant concentration, intensity enhances and then decreases after a certain concentration, which is an indication of concentration quenching taking place in the phosphor. Scanning electron microscopy images of the phosphor show agglomerated particles in the sub-micron range. Particles range in size from 600 to 800 nm. Electron paramagnetic resonance studies of the phosphors were carried out to detect radicals present in the prepared phosphor. With narrow band UVB emission, phosphor seems to be a good candidate for UV phototherapy application. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis and characterization of novel Na15(SO4)5F4Cl:Ce3+ halosulfate phosphors

“…Polycrystalline Ce 3+ -doped Na 15 phosphors for white light emission. The 359 nm emission can be utilized to sensitize the Dy 3+ emission and there is the future prospect of energy transfer between Ce 3+ and Dy 3+ ions.…”

“…The optical properties of these phosphors led to the conclusion that they may serve as promising materials for use as lamp phosphors in the UV region, extending from 330 to 390 nm. There is scope to develop single-phase Na15 (SO 4 ) 5 F 4 Cl:Dy 3+ ,Ce 3+ T m ¼ 197:98°C ¼ 471:13 K; T 1 ¼ 143:89°C ¼ 417:04; T 2 ¼ 286:12°C ¼ 559:27 K ω ¼ T 2 -T 1 ¼ 142:23 K; τ ¼ T m -T 1 ¼ 54:09 K; δ ¼ T 2 -T m ¼ 88:14 K…”

Orange light‐emitting Ca3Mg3(PO4)4:Sm3+ phosphors

“…[1] Although the commercially available WLEDs offer a long lifetime, high efficiency, eco-friendliness, etc., they fail to achieve a higher color rendering due to the lack of a red component in the overall blending of different color phosphors. [4] It is of utmost importance that the hosts remain stable to many physical, chemical and thermal conditions. Hence, attempts were made to find an alternative to Eu 3+ ions that could possibly emit in the red region.…”

“…The phase formation and morphology of the prepared phosphors were analysed by X-ray diffraction studies and scanning electron microscopy. [4] It is of utmost importance that the hosts remain stable to many physical, chemical and thermal conditions. The photoluminescence characteristics of the as-prepared phosphors were investigated and their emission spectra showed three peaks due to 4 G 5/2 → 6 H 5/2 , 4 G 5/2 → 6 H 7/2 and 4 G 5/2 → 6 H 9/2 transitions.…”

“…4 has been reported to be a monoclinic crystal structure with space group C12/c1 and lattice constants a = 22.841 Å, b = 9.994 Å and c = 17.088 Å; α = γ = 90°and β = 99.63° [ 8] . The CIE chromaticity coordinates were plotted using Radiant Imaging software.…”