Controlled synthesis of calcite/vaterite/aragonite and their applications as red phosphors doped with Eu3+ ions
Calcium carbonate (CaCO3) particles including three anhydrous polymorphs (calcite/vaterite/aragonite) have been prepared in the absence and presence of sodium carboxyl methylcellulose (NaCMC), which further serve as hosts to prepare the phosphors doped with Eu3+. The as-obtained samples were characterized by means of XRD, SEM, and PL techniques. The experimental results reveal that vaterite, as a less stable polymorph, will transform into calcite in aqueous solution without any additive. In contrast, NaCMC can induce the formation of vaterite phase at 50 oC and the formation of aragonite phase at 90 oC in aqueous solution. In addition, polymorph dependent luminescence properties of CaCO3:Eu3+ have been briefly studied by excitation spectra, emission spectra and PL decay curves.