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In this work, Tb3+ or Eu3+ single doped and co-doped La 2 W 3 O 12 were synthesized via a solid-state reaction at 900 °C. The crystal structure and photoluminescence properties were systematically investigated in detail. It was found that the La 2 W 3 O 12 based on the advantages of WO 4 groups exhibits a broad absorption cross-section in the ultraviolet area, which can effectively enhance the emission intensity of Tb3+ and Eu3+. The energy transfer from Tb3+ to Eu3+ is determined by the dipole-dipole mechanism, and the energy transfer efficiency from Tb3+ to Eu3+ is as high as 36%. Based on efficient energy transfer effect, multicolor tunable emission from green to yellow and eventually toward red is realized. In addition, the temperature-dependent luminescence of La 2 W 3 O 12 : Tb3+, Eu3+ are carefully investigated, which suggested that as-prepared La 2 W 3 O 12 : Tb3+, Eu3+ phosphors are excellent candidates for solid-state laser, panel display, WLEDs and LED plant lights. [Display omitted] • A prepared novel tungstate Tb3+/Eu3+ co-doped LWO phosphors have good thermal stability and luminescence performance. • The energy transfer mechanism from Tb3+ to Eu3+ was determined to be a dipole-dipole mechanism. • Multicolor tunable emission from green through yellow and eventually to red is realized under UV light excitation. [ABSTRACT FROM AUTHOR]

As the most common up-conversion (UC) activation center now, Er3+ can emit the blue, green and red light under the excitation of 980 nm. It has important meaning how to manipulate the emission wavelength in practical application. In our work, a series of excellent UC luminescence materials Y 6 O 5 F 8 : M3+ (M = Yb, Er, and Fe) are synthesized by the hydrothermal method. Under the condition of different pH, the prepared precursors exhibited different phases of YF 3 and Y(OH) 1 · 63 F 1.37 and various morphologies. The hydrogen bond guides a regular crystal growth process. With the change of pH, OH group could be selectively introduced into the host during this different crystal growth process. The structure change is likely to decrease the rigidity of this lattice and adjusted the cut-off phonon energies, and further influence the f - f transition of Er3+, selectively forming red emission in Y 6 O 5 F 8 : Yb3+, Er3+. The intensity of red UC luminescence is enhanced by 22 times via Fe3+ co-doping into the Y 6 O 5 F 8 : Yb3+, Er3+ crystalline lattice. The introduction of transition metal ions Fe3+, produces an excellent energy transfer from <2F 7/2 , 4T 1g > (Yb3+-Fe3+ dimer) to energy levels of Er3+ as well as the distortion of the crystalline field symmetry. In addition to the enhancing luminescence effect, Fe ions also introduce magnetism from the hysteresis loop curve. The temperature-dependent UC emission of Y 6 O 5 F 8 : Yb3+, Er3+, Fe3+ display significant thermal coupling occurs with a higher absolute sensitivity. Based on this, the anti-fake and temperature-sensitive luminescent applications of this material are investigated in detail. • The appropriate CPB in Y 6 O 5 F 8 is benefit for the red transtiton of Er3+. • The internal OH− groups can adjust the CPB. • The red UC luminescence is enhanced by 22 times via Fe3+ co-doping. • Significant thermal coupling occurs with a higher absolute sensitivity. • Bright red emission patterns on the printed A4 papers can be observed. [ABSTRACT FROM AUTHOR]