Upconversion luminescence enhancement of β-NaYF4: Er3+/Ho3+ by introducing Ca2+ and multicolor tuning by 980 nm pulse excited

Water-soluble Cit-NaYbF4:Tm3+with enhanced 802 nm emission by Sr2+ion doping forin vivofluorescence molecular tomography

“…Except for the valence state, the radius of Fe 3+ is smaller than that of Mn 2+ and Fe 2+ , which is another reason for the slightly larger size. 41,42 These results are similar to previous studies, 44 but the size reduction effect is not as good as that of Sr 2+ ion doping.…”

“…It is well known that lanthanide (Ln 3+ ) or non-lanthanide Ln 3+ ion doping is a more direct and common method for enhancing fluorescence. 24,[38][39][40][41][42][43][44][45] Appropriate doping ions can not only tune the size and morphology of NaYbF 4 , but also effectively tune the host lattice and local crystal field of the activator ions, thereby significantly improving the luminescence properties of the activator. [38][39][40][41][42][43][44][45][46][47] Previously, researchers mainly explored the regulation of Mn 2+ , Fe 3+ , and Bi 3+ ion doping on the luminescence properties of the activator Tm 3+ , while the studies on other ions were relatively few, and the substrates were mostly NaYF 4 or NaGdF 4 .…”

“…24,[38][39][40][41][42][43][44][45] Appropriate doping ions can not only tune the size and morphology of NaYbF 4 , but also effectively tune the host lattice and local crystal field of the activator ions, thereby significantly improving the luminescence properties of the activator. [38][39][40][41][42][43][44][45][46][47] Previously, researchers mainly explored the regulation of Mn 2+ , Fe 3+ , and Bi 3+ ion doping on the luminescence properties of the activator Tm 3+ , while the studies on other ions were relatively few, and the substrates were mostly NaYF 4 or NaGdF 4 . [38][39][40]48,49 Therefore, there is an urgent need to explore suitable doping ions that can reduce the size of NaYbF 4 to reduce biotoxicity and enhance near-infrared emission.…”

Local Disorder Affecting NIR-Upconverting White Light Emission Manifests in Lattice Strain

“…Since the success of these UC nanomaterials in their respective fields of application is critically dependent on the intensities of the corresponding white emission through NIR triggered upconversion luminescence (UCL), there is a current need to develop systematic approaches to intensify the white light emission through rational manipulation of the concerned crystal lattice. Most of the approaches reported to date for enhancing the PL in upconverting nanocrystals either involve an epitaxial shell growth on the core upconversion nanoparticle (UCNP) or doping nonlanthanide ions within a single-phase UC host lattice. − Based on the current literature so far, the enhancement of the UCL intensity in a core–shell-based NP has been attributed to the surface passivation of core particles to minimize the nonradiative loss. − Interestingly, in the context of core–shell-based quantum dots, Smith et al first reported a mismatch of respective lattices at the core–shell interface, which resulted in lattice strains tuning the optical and electronic properties of the materials . Such lattice mismatch at the core–shell interface was similarly recognized by Lay et al in heteroepitaxial UC nanocrystals, where the concerned mismatch-derived lattice strains had been shown to modify the associated optical and mechanical sensing properties of the nanomaterials …”

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

“…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 ]. Yet, generally, it is still early to believe that the mechanism of the co-doping effect on luminescence is fully explained because there is no model to predict the impact of any dopant ions on the optical properties of such doped materials.…”