Red phosphor is one of rare earth elements (REEs) that is important in white light emitting diodes (WLEDs) applications. However, the process of mining on the REEs is harmful to environment and it makes the prices of REEs to be expensive. Europium (III( (also known as Eu3+) is one of the REEs which has big potential to be used as a red phosphor due to their great luminescence properties. However, the price of Eu3+ is very high, therefore an effort to minimising the use of Eu3+ is essential. On the other hand, Samarium (III) (Sm3+) is also known to enhance photoluminescence properties of several phosphors. This project is conducted to investigate the possibility of minimizing the use of Eu3+ by replacing the rare earth cations with co-activator Sm3+ in tungstate/ molybdate compound. This aim can be achieved by the following objectives; to evaluate the spectral properties and investigate the optimum amount of Sm3+ can be employed in n LiEu(0.55-x)Y0.45(MoO4)2Smx, LiEu(0.45- x)Gd0.55(MoO4)2Smx, LiEu(0.55-x)Y0.45(WO4)2Smx and LiEu(0.50-x)Gd0.50(WO4)2Smx phosphors. Therefore, the crystal structure in tungstate/ molybdate compound as Sm3+ increases in replacing Eu3+ also had been evaluated. These phosphors were prepared by using solid-state reaction technique with different concentration between Eu3+ and Sm3+ in the host lattice with concentration (x) in range of 0 to 0.55 mol. The experiments conducted were X-ray powder diffraction (XRPD), scanning electron microscope (SEM) and photoluminescence study (PL). It was found that incorporation of Sm3+ into the host lattice offered the better intensity when the intensities of the phosphors increase until 288% compared to the parent compound. For the PL results, the emission intensity was observed at 615 nm, and the optimum amount of Sm3+ recorded in the range of 0.10 to 0.20 mol where resulted in the highest intensity of each phosphor. It also found that the compound LiEu(0.55x)Y0.45(MoO4)2Smx with concentration (x) = 0.20 mol offers the highest intensity compared the other compound. These findings proved that the use of Eu3+ can still be reduced in this red phosphor which helps to reduce the cost of manufacturing WLEDs since the price Eu3+ is very high. This finding is significant in giving an indication that there are rooms for the red tungstate/ molybdate phosphors to be optimised and indirectly can minimise the use of REEs.
