###### Abstract  
We present a series of Sm\({}^{3+}\)/Tb\({}^{3+}\) co-doped CaMoO\({}_{4}\) phosphors synthesized by an efficient method of microwave-assisted heating. The prepared CaMoO\({}_{4}\) samples were characterized by X-ray diffraction, photoluminescence, and Commission Internationale de l'Elcariage (CIE) chromaticity diagram. The X-ray diffraction results confirmed that all synthesized CaMoO\({}_{4}\) samples are crystallized in a pure tetragonal phase. The photoluminescence spectra significantly show both red- and green emissions in the synthesized Sm\({}^{3+}\)/Tb\({}^{3+}\) co-doped CaMoO\({}_{4}\) phosphors. It is obvious that the variations in the intensity ratio of red/green emissions depend on the molar ratio of Sm\({}^{3+}\)/Tb\({}^{3+}\) co-doping and dominate the CIE color coordinates on the chromaticity diagram. The investigations showed the functionality of the material system as advanced color-tunable phosphors for white-LEDs as evidenced by the controllability of the light-emitting region of Sm\({}^{3+}\)/Tb\({}^{3+}\) co-doped CaMoO\({}_{4}\) phosphors through the adjustment of the molar ratio of Sm\({}^{3+}\)/Tb\({}^{3+}\) ions.  
CaMoO\({}_{4}\) microwave-assisted synthesis; X-ray diffraction; photoluminescence +
Footnote †: journal: Applied Sciences  
**Competition**  
**Tunable Luminescence of Sm\({}^{3+}\)/Tb\({}^{3+}\) Co-Doped CaMoO\({}_{4}\) Phosphors Synthesized by Microwave-Assisted Heating.**  
**Tunable Luminescence of Sm\({}^{3+}\)/Tb\({}^{3+}\) Co-Doped CaMoO\({}_{4}\) Phosphors Synthesized by Microwave-Assisted Heating.  
(Sm3+) and red (Eu3+) emission [8; 9]. Based on energy transfer mechanism, co-doped phosphors have been extensively studied because of their enhanced luminescent properties. It can be expected that the RE3+ (Sm3+/Tb3+) co-doped CaMoO4 phosphors should have the advantage of tunable multicolor emissions, which can be exploited and developed as an advanced phosphor applied in white-LEDs [10; 11].  
Several methods, such as a microwave-assisted heating method [9], precipitation [10; 11], hydrothermal process [12; 13], ionic liquid-assisted process [14], and sol-gel [15] have been developed to synthesize the CaMoO4 phosphors. Among the different techniques, the microwave-assisted synthesis is the most viable method because it is a relatively fast and easy to operate process. The inherent character of the method also makes it fairly energy efficient, leading to low fabrication costs so that high yield for large scale industrial production may be realized. Moreover, the polar solvent-free system is eco-friendly so that environmental pollution may be avoided. In addition, compared to the numerous research focusing on Tb3+ ion as a sensitizer for enhancing the emission intensity of Eu3+ ion [16; 17], there are only few results on the co-doping of the Tb3+ ion and Sm3+ ion. Based on the few available experimental results, the ability to tune the intensity ratio of the red/green emissions of the Sm3+/Tb3+ co-doped CaMoO4 had been demonstrated. Nevertheless, more exploratory experimental works are warranted in this area so that a better controllability of the tuning process may be attained and a better understanding of the process can be realized. Therefore, in this paper, we present the Sm3+-doped, Tb3+-doped, and Sm3+/Tb3+ co-doped CaMoO4 phosphors prepared by microwave-assisted heating method. The structural characteristic, luminescence property, and optical performance of the synthesized CaMoO4 phosphors were investigated by X-ray diffraction (XRD), photoluminescence (PL), and Commission Internationale de l'Elcairage (CIE) chromaticity diagram, respectively. The variations in the measured data with the controlled molar ratio of Sm3+/Tb3+ co-doped CaMoO4 phosphors were analyzed and discussed.