The effect of Eu³⁺and Gd³⁺co-doping on the morphology and luminescence of NaYF₄:Eu³⁺, Gd³⁺phosphors

Abstract

β-NaYF4: Eu3+ microparticles co-doped with Gd3+ ions were obtained by hydrothermal synthesis at 180 0C using citric acid as a stabilizing agent. All synthesized materials have β-NaYF4 crystalline phase, where...

Effect of Gd3+, La3+, Lu3+ Co-Doping on the Morphology and Luminescent Properties of NaYF4:Sm3+ Phosphors

“…Therefore, one can conclude, that doping by Ln 3+ ions results in changing only extinction coefficients due to the changing probability of symmetry forbidden 6 H 5/2 → 4 K 11/2 transition. Luminescence intensity enhancement resulted from co-doping of Eu 3+ -containing materials by non-luminescent ions such as Bi 3+ , Gd 3+ , alkali, and alkali earth metal ions was reported previously [ 11 , 26 , 27 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. The observed effect was explained by structure distortion due to the difference between radii of substituted and doping ions resulting in the increase in the emission and absorption probabilities.…”

“…Microcrystalline β-NaYF 4 samples co-doped with Sm 3+ , La 3+ , Gd 3+ , and Lu 3+ were synthesized using the hydrothermal method using citric acid as a stabilizing agent, described previously [ 11 , 16 ]. Rare earth chlorides taken in stoichiometric amounts (total amount of rare earth chlorides was 0.75 mmol) with 3 mmol of citric acid were dissolved in distilled water to obtain 5 mL solution in total.…”

“…The optical properties of these materials depend on the particles’ size and morphology, crystal symmetry, type, and concentration of rare earth ions in the host matrix [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Sodium yttrium fluoride is one of the best host matrices for luminescent rare earth-doped inorganic materials because this matrix has only low-frequency vibrational modes, and therefore does not quench the luminescence.…”

“…As a co-dopant, lanthanide ions play several key roles in photoluminescent materials: they may absorb light as sensitizers or emit photons as luminescence activators as well as transfer energy from the sensitizer to activator [ 13 , 14 , 23 , 24 , 25 ]. At the same time, the addition of non-luminescent dopants (e.g., alkali, alkali earth, some p -, d - and f -metal ions) in host matrix doped with luminescent ions is known to enhance the luminescence intensity [ 11 , 26 , 27 , 28 ]. This effect is assumed to be caused by several factors: structural changes in the crystal lattice upon doping (e.g., formation of ionic vacancies) and modification of the crystal field surrounding Ln 3+ activators [ 28 , 29 , 30 ].…”

“…We found that the average diameter of particles reaches the least value for Sm 3+ , Eu 3+ , and Gd 3+ doped materials. We have studied NaYF 4 :Eu 3+ particles co-doped with Gd 3+ ions [ 11 ] and revealed that Gd 3+ doping results in particle size reduction as well as the increase in emission intensity and 5 D 0 lifetime of europium (III). We have obtained a similar effect of simultaneous size reduction and luminescence intensity enhancement for gadolinium ion-doped materials for NaYF 4 :Yb 3+ , Tm 3+ /Er 3+ up-conversion microcrystalline materials [ 16 ].…”