Upconversion/Downconversion luminescence and preparation of NIR-to-UV-excited Gd2O2S:Er phosphor

Efficient conversion of ultraviolet (UV) and near-infrared (NIR) radiations to visible emissions were carried out through Gd2O2S: Er phosphor synthesized by solid-state reaction method in vacuum. The spectra study of Gd2O2S: Er phosphor was performed as a function of firing temperature under the excitation wavelengths of 379 and 980 nm, respectively. The emission bands in visible light region corresponding to the transitions between H-2(9/2) -> I-4(15/2) (412 nm), F-4(7/2) -> I-4(15/2) (488 nm), H-2(11/2) -> I-4(15/2) (531 nm), S-4(3/2) -> I-4(15/2) (554 nm) and F-4(9/2) -> I-4(15/2) (670 nm) were demonstrated. Color emission can be tuned from red to green due to Er3+ ions doping by varying the firing temperature under 379 nm UV light excitation. First principles calculation results indicated that crystallographic plane of (101) has higher absorption efficiency than the crystallographic plane of (100) thus to result in higher luminescent intensity.