| Summary: | A precursor was prepared using a co-precipitation method to synthesize crystalline calcium tungstate. The prepared precursor was dried in an oven at 80 °C for 18 h. The dried powders, prepared without a heat treatment process, were observed in XRD analysis to be a crystalline CaWO<sub>4</sub> phase, confirming that the synthesis of crystalline CaWO<sub>4</sub> is possible even at low temperature. To use this crystalline CaWO<sub>4</sub> as a light emitting material, rare earth ions were added when preparing the precursor. The CaWO<sub>4</sub> powders doped with terbium (Tb<sup>3+</sup>) and europium (Eu<sup>3+</sup>) ions, respectively, were also observed to be crystalline in XRD analysis. The luminescence of the undoped CaWO<sub>4</sub> sample exhibited a wide range of 300~600 nm and blue emission with a central peak of 420 nm. The Tb<sup>3+</sup>-doped sample showed green light emission at 488, 545, 585, and 620 nm, and the Eu<sup>3+</sup>-doped sample showed red light emission at 592, 614, 651, and 699 nm. Blue, green, and red CaWO<sub>4</sub> powders with various luminescence properties were mixed with glass powder and heat-treated at 600 °C to fabricate a blue luminescent PiG disk. In addition, a flexible green and red light-emitting composite was prepared by mixing it with a silicone-based polymer. An anti-counterfeiting application was prepared by using the phosphor in an ink, which could not be identified with the naked eye but can be identified under UV light.
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