Calcium and strontium aluminates composite for long-afterglow applications

Abstract

Phosphors emission of white light-emitting device (WLED) is typically light off after electrical power turned off. Innovative white light long-afterglow phosphors in this study can provide several hours' continuously illumination for visible environment without electrical power supply and for energy savings. A modified synthesis method named as the sol-gelatinization (SG) was employed to form doped aluminates of SrAl2O4:Eu2+,Dy3+(SAO) and CaAl2O4:Eu2+,Dy3+(CAO) phosphors. The SAO was found a mixture of two phases of green light SrAl2O4 (SAOG) emitted at 520 nm and red light Sr3Al2O6 (SAOR) emitted at 610 nm after calcined at 600 degrees C in air further 1100 degrees C in carbon monoxide (CO) reduction atmosphere. The SG-prepared CAO could emit blue light of 440 nm by 330 nm excitation. The SG-prepared CAO and SAO behaved long-afterglow without B2O3 flux addition. The composite of the thin layer of SAOG on CAO substrate co-fired at 1100 degrees C could achieve red-green- blue (RGB) broad-band white light luminescence under 430 nm excitation. This study creates a new era of low luminescent intensity with white light long-afterglow for applications in automobiles/ships/aviation and navigational instruments, escape routes, road markings, life sciences, optical information storage, counterfeiting, surveillance and so on