Fluorescence properties and synthesis of green-emitting Tb 3+-activated amorphous calcium silicate phosphor by ultraviolet irradiation of 378nm

Abstract

The excitation wavelength of conventional Tb3+-activated phosphor is near 270nm. This study describes novel green-emitting Tb 3+-activated amorphous calcium silicate by ultraviolet excitation at 378 nm. The Tb3+-activated amorphous calcium silicate was prepared by heating a sample of Tb3+-activated calcium silicate hydrate (CSH) at 900C for 30 minutes. The emission wavelength of the resulting phosphor was 544nm. The optimum excitation wavelength within the range 300-400nm was 378nm. The Tb3+-activated amorphous calcium silicate emitted green by ultraviolet irradiation. The optimum initial Tb/Ca atomic ratio of this phosphor was about 0.5. A mechanism for the action of the phosphor is proposed, in which Tb3+ ions existing in the layer of the CSH lead to loss of water molecules and OH groups. Copyright © 2012 Yoshiyuki Kojima et al.