Laser induced thermal effect on upconversion luminescence and temperature-dependent upconversion mechanism in Ho3+/Yb3+-codoped Gd2(WO4)3 phosphor

Abstract

Sub-micro sized Gd2(WO4)3:Yb3+/Ho3+ phosphor was synthesized via a co-precipitation reaction. The crystal structure and morphology of the phosphor were characterized by XRD and SEM. The time scanning of green and red upconversion emissions displayed that the upconversion luminescent intensities were dependent on the irradiation time and the excitation powder, which was resulted from the thermal effect induced by LD (laser diode) irradiation. The upconversion luminescence of Gd2(WO4)3:Yb3+/Ho3+ phosphor at different sample temperatures was studied. It was found that at room temperature the red and green upconversion emissions were 1.5- and 2-photon processes, respectively. With increasing sample temperature the 2-photon process for the red upconversion emission and 3-photon process for green upconversion emission occurred.