Facile surfactant- and template-free synthesis and luminescence properties of needle-like calcite CaCO3:Eu3+ phosphors

Needle-like CaCO3:Eu3+ calcite phosphors have been successfully synthesized by a simple carbonization method in an ethylene glycol-H2O system without using any surfactant, catalyst, or template. The as-obtained samples were characterized by means of XRD, FT-IR, SEM, TEM, HRTEM, SAED, and PL techniques. The XRD and FT-IR results demonstrate that the product is a pure calcite phase. The SEM and TEM images indicate that the morphology of the as-prepared calcite CaCO3:Eu3+ nanoparticles is needle-like. The possible formation mechanism of the needle-like CaCO3:Eu3+ calcite has been proposed based on a series of pH-dependent experiments. The needle-like CaCO3:Eu3+ calcite nanoparticles exhibit much stronger red emission under UV light excitation than cubic and spindle-like CaCO3:Eu3+ calcite nanoparticles.