Effect of Heating Temperature on Luminescent Color of Bismuth (III) Doped Calcium Sulfide Incorporated Na+ Ion Phosphor

Abstract

This paper reports the effect of heating temperature on luminescent color of bismuth (III) doped calcium sulfide (CaS) incorporated Na⁺ ion phosphor. When the CaS : Bi³⁺ incorporated Na⁺ phosphor was heated in the electric furnace while irradiating black light, emission wavelength of the phosphor measured with luminance meter increased linearly to near 460 °C. This originates for using the energy excited by the lattice vibration. The change of luminescent color from the blue to the green was observed over 380 °C in the human eye. The luminescent color charged from Blue to Greenish blue, when chromaticity diagram was used. This reproducibility by the repetition of the heating was good. However, the emission intensity of the phosphor, which repeated 5 times, decreased to 50% compared with that of the original sample.