Infrared-to-Ultraviolet upconversion luminescence of La0.95Yb0.49Tm0.01F3 nanostructures

In this work, we used the hydrothermal method to synthesize Yb³⁺ and Tm³⁺ doped LaF₃ nanostructures, which is an ultraviolet upconversion luminescent material. Two distinct shapes such as nanosheets, nanoparticles and bulk samples formed in the products by adjusting the concentrations of the surfactant of the reaction solution. Powder X-ray diffraction analysis showed that the products were pure hexagonal phase, while electron microscopy measurements confirm the formation of different morphologies. These nanostructures exhibit strong ultraviolet upconversion luminescence under the excitation of a 978-nm diode laser. In Yb³⁺ and Tm³⁺ codoped LaF₃ materials, the relative intensity of ultraviolet and blue upconversion emissions became stronger as the size and morphology of sample changed from bulk to sheets.