This article reports luminescence studies on wet-chemical route prepared YVO 4 :Er 3 ∕Yb 3 microdisc phosphor. The 980 nm laser excited upconversion (UC) emission intensity ratio of green to red bands is found too high to neglect the contribution from the red emission band, which is not observed normally in Er 3 ∕Yb 3 -doped materials. The red emission is also found absent in the downconversion emission under excitation at 316 nm. The variation of UC intensities with external temperature exhibits a well-fashioned pattern, which suggests that the 2 H 11∕2 and 4 S 3∕2 levels of Er 3 ion are thermally coupled. The YVO 4 :Er 3 ∕Yb 3 phosphor has shown outstanding temperature-sensing behavior with maximum sensitivity of 0.0117 K −1 at 400 K. This material is also employed to develop a latent fingerprint in green color. Furthermore, the present phosphor could be useful for solar cell concentrators, drug delivery, and disease therapy applications.

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Rare earth doped/codoped phosphors have been extensively studied for different types of applications based on their intense luminescence features. For this, researchers have tried to choose the inorganic host matrices having both a low phonon cut-off frequency and a high refractive index. Many articles have been published on oxide based phosphor materials, but due to their high cut-off phonon frequency, use of these materials is restricted for optical based applications. This is why additional research has been carried out on fluoride based host materials because of their low phonon frequencies, low composition degradation, and high quantum efficiency. In this paper, the authors review the rare earth fluoride based host nano-and micromaterials for different applications and discuss possible mechanisms.

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The authors in this manuscript present the results on synthesis of Er3+/Yb3+ codoped La2O3 upconverting phosphor and its demonstration on the development of latent fingermarks on the surfaces of semi-porous and non-porous objects. The samples were synthesized via combustion using urea as a reducing agent and chemical precipitation methods. The annealed samples showed enough intense green emission in the 520–550 nm range on 980 nm excitation. Excellent emission property of the samples in the green region showed an advantage to use it in latent fingermarks detection. A dry powder dusting technique is used to develop latent fingermarks and the results are compared. The studies reflected the superiority of upconversion phosphor materials for the detection of latent fingermarks over the traditional downconversion luminescence methods.