Color tracing in the hydration process of α-Ca3(PO4)2:Eu

Eu-doped tricalcium phosphate (α-TCP:Eu) powders were obtained via solid-state reaction under air. The phase and microstructures of as-recieved samples and the hydration products soaked in 0.25 M K2HPO4 solution for different time was investigated using X-ray diffraction, SEM and Rietveld refinement method. The photoluminescence results of powders were changed with prolonged hydration time, not only the luminescence intensity of the products gradually depressed, but also the CIE chromaticity coordinates moved from bluish-green region of α-TCP phase to orange region of hydroxyapatite phase. The light emission change was confirmed by the color under the UV lamp. Therefore, results of this study suggested that the photoluminescence color of hydration products can be used as an obvious qualitative feature to trace the hydration process of α-TCP: Eu.