Hydrothermal synthesis and properties of a red-emitting phosphor of fully concentrated Eu3+ based oxalate Eu2(C2O4)3·10H2O

Fully concentrated Eu3+ based oxalate Eu2(C2O4)3·10H2O phosphor has been successfully synthesized by an efficient surfactant-free hydrothermal method directly without further sintering treatment. The techniques of XRD, TG–DTA, FT-IR, SEM, EDS and PL were employed to characterize the as-obtained products. It was found that in the temperature range of 100–150 °C, all samples were well crystallized with monoclinic structures. And the best purity of the samples produced was achieved when the temperature is 150 °C. The possible formation mechanisms for Eu2(C2O4)3·10H2O with different structures were put forward. The Eu2(C2O4)3·10H2O phosphors can be effectively excited by 396 nm light, and exhibit strong red emission around 619 nm, attributed to the Eu3+ 5D0 → 7F2 transition. A detailed investigation on the fluorescence of products revealed that the luminescence properties are strongly correlated with the crystallinities, morphologies and sizes.