Ho³⁺/Yb³⁺: BaMoO₄ phosphors with different concentrations were fabricated by a gel combustion method. The upconversion (UC) luminescence, intrinsic optical bistability, and the corresponding mechanisms were reported for the present system. The optical thermometric properties based on red (⁵F₅→⁵I₈) and green (⁵F₄/⁵S₂→⁵I₈) emissions were studied. The sensing sensitivities could be tuned by manipulating the cooperative energy transfer process. The highest absolute sensitivity was 99 × 10 ⁴ K ¹ at 573 K, which is larger than that of many previous UC materials.

In this work, we investigate a new type of fluoride glasses modified by Al(PO3)3 with various Tm3+/Ho3+ doping concentrations. The introduced PO3 plays an effective role in improving the glass-forming ability and thermal stability. Besides, 1.47, 1.8, and 2.0 μm emissions originating from Tm3+ and Ho3+, respectively, are observed. The spectroscopic properties and energy transfer mechanisms between Tm3+ and Ho3+ are analyzed as well. It is noted that the higher predicted spontaneous transition probability (118.74 s 1) along with the larger product of measured decay lifetime and the emission cross section (σemi×τ) give evidence of intense 2.0 μm fluorescence.

Infrared-to-visible upconverted luminescent spectra of Er3+ and La3+ codoped Y2O3 powders are investigated. By introducing La3+ ions, the upconversion green radiation is found to be greatly enhanced when compared with the powders with La3+ absent. Such enhancement can be attributed to the modification of the local symmetry surrounding the Er3+ ion, which benefits the intra-4f transitions of Er3+ ion, and the decreasing interaction between Er3+ ions, which suppresses the energy transfer process F7/24+I411/2→F49/2+F49/2160.0160 Materials 230.0230 Optical devices 300.0300 Spectroscopy