Some Optical Properties of Powder and Crystal Halophosphate Phosphors

Abstract

Diffuse reflectivity and excitation spectra of powder and optical absorption of synthetic single crystal halophosphate phosphors have been determined in the spectral region l100-3000A. Intrinsic optical absorption by the host lattice begins at approximately 1500A in fluoroapatite and 1570A in chloroapatite. Absorption in bands of manganese in fluoroapatite at 1600, 1750, and 2150A results in luminescence in the absence of antimony. Absorption due to antimony lies between 1600 and 2900A. The preparation and some optical properties of synthetic single crystals are described. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.211.208.19 Downloaded on 2015-03-14 to IP

Inverse bottleneck in Eu2+–Mn2+ energy transfer

“…5). There are transitions from the Mn 2+ emitting state resonant with the Eu 2+ emission [18,19] that could have higher oscillator strengths than the parity and spin forbidden transitions from the ground state. Naïvely, one might think that an increase in the Mn 2+ -excited state population would create a bottleneck for Eu 2+ -Mn 2+ energy transfer due to a reduction in the ground state population.…”

“…There are two main assumptions that we have in using these rate equations. First, Mn 2+ excited state absorption of LED radiation is neglected since parity-allowed transitions from the emitting Mn 2+ level are at higher energy than the incident LED radiation [18,19]. Second, after energy transfer to excited Mn 2+ , we assume that Mn 2+ directly returns to the lowest excited state, i.e.…”

“…Second, after energy transfer to excited Mn 2+ , we assume that Mn 2+ directly returns to the lowest excited state, i.e. we exclude loss channels due to photoionization or level crossing based on the high efficiency of halophosphate phosphors under UV excitation [18,19]. The Eu 2+ and Mn 2+ efficiency versus pulse length are calculated with adaptive Runge-Kutta integration of Eqs.…”

Multifrequency Epr Study of Radiation-Induced Defects in Chlorapatite

“…Several authors (Johnson 1961, Swank 1964, Piper et al 1965) noted that center F E(II) in fl uorapatite is closely comparable to the well-known F center in alkali halides. Piper et al (1965) correlated an optical absorption band at ~450 nm in fl uorapatite to center F E(II).…”

Luminescence properties of Eu2+-activated Ca0.13Sr0.87Al2Si2O8: A bluish green phosphor for solid state lighting

“…Eu 2+ -activated phosphors have been widely used in fluorescent, duplication lamps and white light emitting diodes(LEDs) as well as display devices, since the emission of Eu 2+ can vary in a wide range from red to ultraviolet. Eu 2+ -doped aluminates, silicates, alumino-silicates and derivatives are widely used in industry due to their luminescent properties [2]. Luminescence efficiency increases as the size of the phosphor particle is decreased, the preparation processes of phosphors become very important in the technological procedure [3].…”