Rare earth doped CaSO₄ luminescence phosphors for applications in novel displays – new recipes

Abstract

New Recipes for rare earth doped CaSO 4 luminescence phosphors which give high photoluminescence efficiency combined with high thermal stability desired for noval display applications are described. The influence of cooling rate, thermal treatments and water washing as well as crystal size and morphology on the luminescence efficiency are described. While a modified co-precipitation technique was found best suited for preparing thermostimulated luminescence phosphors required for radiation dosimetry, those made by solid state diffusion reactions at high temperatures were found best suited to achieve the high photoluminescence efficiency required for lighting and display applications.www.pss-a.com fect phosphor surface is required. This is optimally achieved with the production of small (2-4 µm) spherical grains at the preparation stage itself without the need to grind larger grains. Another important requirement of display phosphors is the stability of luminescence efficiency against high temperature treatments usually adopted during the baking process of the display panel used for binder burn-off. This paper describes briefly the CaSO 4 phosphors successfully developed by the authors for the first time using different techniques with high fluorescence efficiency, thermal stability and the desired crystal morphology. The potential application of these phosphors for novel display devices such as PDP, fluorescent lamps, liquid crystal display (LCD) backlight and light emitting diodes (LED) will be highlighted A new co-precipitation technique which yields high TSL sensitivity with the desired glow curve structure for applications in radiation dosimetry will also be presented.

A Quantum‐Splitting Phosphor Exploiting the Energy Transfer from Anion Excitons to Tb3+ in CaSO4:Tb,Na

“…This recipe involves high-temperature (750°C, 2 h) sintering of an intimate mixture of CaSO 4 ·2 H 2 O, Tb 4 O 7 , and monovalent chloride or sulfate (NaCl or Na 2 SO 4 ) for the charge compensation, along with an appropriate quantity of (NH 4 ) 2 SO 4 in a closed alumina crucible in air. This method gives better PL efficiency than that obtained by the recipes reported so far [31]. The fluorescence efficiency of CaSO 4 :Tb,Na remained unchanged upon annealing treatment at up to 750°C in air.…”

Recombination luminescence of CaSO4:Tb3+ and CaSO4:Gd3+phosphors

“…A Ca 2+ cation is surrounded by 8 O 2-ions located in two different positions -O1 and O2. X-ray structure analysis and the synthesis procedure of CaSO 4 :Tb 3+ ,Na + phosphors is described in detail in [1,13]. Using this procedure [1] 16] or synchrotron radiation of 4-35 eV at the SU-PERLUMI station of HASYLAB at DESY [for details see 17].…”

Luminescence characteristics of Dy3+activated Na2Sr2Mg (BO3)2F2: Dy3+phosphor

“…The first application of this phenomenon for dosimetric purposes was from Daniel et al (1). Since then, much research has been done for better understanding and improvement of material characteristics as well as to develop new TL materials (2)(3)(4)(5)(6)(7). Now a days, TL dosimetry (TLD) is a wellestablished dosimetry technique with applications in areas such as personel, environmental and clinical dosimetry.…”