Novel pure Ca₂ ZnMoO₆ composition with white-light luminescence

Phosphors with composition Ca₂ ZnMoO₆ were synthesized at temperatures of 800-1200°C using the solid-state method. Analysis of X-ray diffraction patterns of the Ca₂ ZnMoO₆ powders did not reveal a double perovskite structure. When the synthesis temperature was equal to or higher than 800°C, the synthesized Ca₂ ZnMoO₆ powders revealed a tetragonal structure (CaMoO₄ ) rather than an orthorhombic structure (Ca₂ ZnMoO₆ ) and the cubic structure (Sr₂ ZnMoO₆ ) of a double perovskite. The ZnO phase was still observed at a synthesis temperature of 1200°C. The compositions of synthesized Ca₂ ZnMoO₆ powders differed from the prepared powder, and the Ca₂ ZnMoO₆ phosphors exhibited some important novel features. First, synthesized Ca₂ ZnMoO₆ compositions could emit light as a phosphor no activators, called Ca₂ ZnMoO₆ phosphors. Effect of synthesis temperature on luminescence properties of these Ca₂ ZnMoO₆ phosphors was readily observed, and some important novel features and properties were noted. Second, the phosphors presented only one broad characteristic emission peak in the visible light region. Third, measurement of the chromaticity diagram of the Ca₂ ZnMoO₆ phosphors revealed a white-light source. Through analysis, we determined why the synthesized Ca₂ ZnMoO₆ phosphors had just one broad characteristic emission peak.