This work presents the structural, morphological and luminescent properties of Y3Al5O12:Ce3+(0.1%)-Pr3+(0.1%)
nanophosphors synthesized by a hydrothermal precipitation method. It was observed that the incorporation of Amonium
hydroxide (NH4OH, Ammonia) increases the YAG (%)/YAM(%) ratio, leading to an increase of 83% in the overall
emission under 460 nm excitation. The nanophosphor with the highest content of YAM, presented the best broad green-yellow-
red emission band corresponding to Ce3+ and Pr3+ emissions under 340 nm excitation. The average
nanocrystallite size was 50 and 55 nm for the samples with and without Ammonia respectively. Quenching of the overall
emission after an annealing treatment at 1100°C is observed in spite of reaching single YAG crystalline phase. That
suggests Pr4+ and/or color centers formation due to the estequiometric unbalance as a consequence of the YAM to YAG
transformation. By taking advantage of the broad emission under 340 nm and using a blue dye, we produced white light
with CIE coordinates of (0.30, 0.36).
Er doped and Yb-Er-Tm codoped ZrO2 nanocrystals of average 80 nm in size were prepared by a sol-gel
process with the presence of nonionic (PLURONIC F-127) surfactant, and the up-conversion emission
was characterized under IR (980 nm) excitation. The effect of the codoped conditions on the crystalline
structure and photoluminescence properties were studied. A strong green emission was produced with 5
mol %, 0.2 mol %, 0.01 mol % of Yb3+-Er3+-Tm3+ codoped ZrO2 respectively. It was prepared Er doped
ZrO2 -SiO2 core-shell and SiO2 coated Er doped ZrO2 in 2-propanol and water, respectively. The presence
of the silica shell of average of 15 nm in thickness has been confirmed by transmition electron
microscopy. Photolumineiscence studies show that the silica shell does not affect the emission when the
nanoparticles are excited with 980 nm. The up-converting Yb3+-Er3+-Tm3+ codoped ZrO2 nanocrystal has
showed to be a powerful tool to future detection techniques. The viability of the nanoparticles of codoped
ZrO2 for biological imaging was confirmed by multiphotonic microscope imaging of cervix tissue with inserted codoped ZrO2 nanoparticles. The cervix tissue has a moderate dysplasia. The nanoparticles were
introduced at 80 % of the tissue depth (5 μm) without being functionalized.
Although the general properties of the rare earths' electronic states and transitions are well understood, much less is
known regarding the relationships between them and the electronic band states of a crystal lattice. These interactions can
enhance or inhibit performance and provide mechanisms for manipulating the material's optical properties. Up-conversion
ZrO2:Tm3+, Yb3+, Er3+, Ho3+ nano-crystalline samples were synthesized by sol-gel method and emission
properties were analyzed as function of different concentrations of rare earth ions. The samples were pumped at 970 nm
with a semiconductor laser source. The introduction of different ion concentrations affects the shape and peak intensities
of the measured blue, green and red bands. Results showed in this work tend to demonstrate a feasible control of the
chromaticity coordinates of emission and present an approximation to the equipotential white chromaticity coordinates.
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