Synthesis of $CaS:Eu^{2+}$ phosphor by using a sealing vessel and its photoluminescence properties

밀폐 용기를 이용한 $CaS:Eu^{2+}$ 형광체의 합성 및 발광특성

We have synthesized $CaS:Eu^{2+}$ phosphor by using a sealing vessel and evaluated its photoluminescence properties. The method using a sealing vessel is simple and economical in comparison with other methods reported up to date, As an activator concentration was increased from 0.1 mol to 4 mol, the main emission wavelength of the phosphor was increased from 642 nm to 651 nm due to crystal field splitting of 5d level of $Eu^{2+}$ ions. Although the same amount of $Eu_2O_3$ was used, the concentration of the activator ions which were reduced from $Eu^{3+}$ to $Eu^{2+}$ and substituting $Ca^{2+}$ ions was increased with increase of firing temperature. Therefore, the main emission wavelength was also increased from 645 nm to 651 nm with increase of firing temperature from $1100^{\circ}C$ to $1300^{\circ}C$.