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A series of Yb∶Tm∶LiNbO3 crystals doped with x mol% Hf4+ ions (x =2,4,and 6) were grown by the Czochralski method.The dopant occupancy and defect structure of Hf∶Yb∶Tm∶LiNbO3 crystals were investigated by x-ray diffraction and infrared transmission spectra.The influence of Hf4+ ions concentration on UV-VIS-NIR absorption spectra of Hf∶Yb∶Tm∶LiNbO3 crystals was discussed.The upconversion luminescence of Hf∶Yb∶Tm∶LiNbO3 crystals was obtained under 980 nm excitation.Strong emissions were observed at 475 nm in the blue wavelength range and 651 nm in the red wavelength range.Remarkably,enhancement of the red and blue upconversion luminescence was achieved by tridoping Hf4+ ions.