Exploring the intra-4f and the bright white light upconversion emissions of Gd₂O₃:Yb³⁺,Er³⁺-based materials for thermometry

Abstract

Upconversion broadband white light emission driven by low-power near-infrared lasers has been reported for many materials, but the mechanisms and effects related to this phenomenon remain unclear.

Thermal properties of nanofluids using hydrophilic and hydrophobic LiYF4:Yb/Er upconverting nanoparticles

“…3,8,9 For this reason, thermometers working at the nanoscale have been investigated in recent years, 9 with special attention to luminescent nanothermometers. 3,[8][9][10][11][12] Luminescence nanothermometers exploit the temperaturedependent luminescence of a thermally imaged object, yielding high relative thermal sensitivity (>1% K −1 ) and spatial resolution (<10 mm). 3 Several types of luminescent nanothermometers have been recently developed for this specic purpose such as green uorescent protein, 13,14 small organic molecules, 15 quantum dots, 16 polymers, 17,18 polymer dots 19 and lanthanide-doped nanoparticles.…”

“…3,8,9 For this reason, thermometers working at the nanoscale have been investigated in recent years, 9 with special attention to luminescent nanothermometers. 3,8–12…”

“…3 Several types of luminescent nanothermometers have been recently developed for this specic purpose such as green uorescent protein, 13,14 small organic molecules, 15 quantum dots, 16 polymers, 17,18 polymer dots 19 and lanthanide-doped nanoparticles. 8,20,21 Amongst these promising materials, lanthanide ion (Ln 3+ ) based nanomaterials show several unique features and advantages, such as absence of photodegradation, high thermal and chemical stability, and due to the shielding of 4f-electrons and forbidden nature of their 4f-4f transitions, 10,22,23 Ln 3+ show very narrow emission bands (∼100 cm −1 ) and long luminescent lifetimes (in the order of ms). 24 Such materials are also widely employed in energy conversion processes, particularly, upconversion (UC) emission, which converts photons in the near infrared region into visible radiation.…”