S.V. Moharil

Preparation of CaF2:U phosphor by solid-state metathesis reaction

CaF2:RE phosphors have received attention of several research workers. CaF2:Sm2+ is well known as a solid-state laser material. CaF2:Dy and CaF2:Tm phosphors are used as phosphors for dosimetry of ionizing radiations through thermoluminescence. A new route to preparation of CaF2 by solid-state metathesis is reported. The method is very fast and CaF2 could be prepared in 10 min. Intense emission attributable to uranate group was observed in synthesized uranium-doped samples.

Luminescence in Li2BaP2O7

The photo-, thermo- and optically stimulated luminescence in Li2BaP2O7 activated with Eu(2+) /Cu(+) are reported. Strong thermoluminescence, which is about two times greater than LiF-TLD 100 was observed in the Eu(2+) -activated sample. It also exhibited optically stimulated luminescence sensitivity of ~20% that of commercial Al2O3:C phosphor.

Modification of luminescence spectra of CaF2: Eu2+

CaF2:Eu(2+) is a well known phosphor having efficient excitation in the near ultraviolet (NUV) range. Phosphors with NUV excitation are required in newly emerging applications such as photoluminescence liquid crystal displays (PLLCD), solid-state lighting (SSL), and down-conversion for solar cells. However, emission of CaF2:Eu(2+) is around 424 nm. Eye sensitivity drops considerably at these wavelengths. It is thus not useful for display applications for which emission in one of the primary colours (blue - 450 nm, green - 540 nm or red - 610 nm) is required. Efforts were made to modify the Photoluminescence (PL) spectra of CaF2:Eu(2+) to meet these requirements using co-dopants. A Ca0.49 Sr0.50 Eu0.01 F2 phosphor showing better colour coordinates and having an emission maximum around 440 nm was discovered during these studies.