Thermal sensing in NIR to visible upconversion of Ho3+ and Yb3+ doped yttrium oxyfluoride phosphor

Assessment of NIR-triggered PEG-coated NaGdF4:Tm3+/Yb3+ bio-compatible upconversion nanoparticles for contrast enhancement in OCT imaging and optical thermometry

“…The two major parameters called absolute and relative sensitivity are calculated using the relations given in equations ( 8) and ( 9) respectively [37,45,46]:…”

Synthesis and upconversion emission studies of CaYF5:Ho3+/Yb3+ phosphor and its applications in optical thermometry, fingerprint detection, and security ink

“…The Ho 3+ -Yb 3+ pair is also used to achieve intense green emission. 17,18 Contrary to the Er 3+ ion emission the Ho 3+ ion gives only one emission in visible region and hence green colour purity of Ho 3+ is found better than the Er 3+ ion. Another benet of using Ho 3+ -Yb 3+ pair over Er 3+ /Yb 3+ and Tm 3+ /Yb 3+ pairs is that latter pairs contain thermally coupled levels which limit its applicability when used for optical thermometric application but due to the absence of thermally coupled levels in Ho 3+ ions, the doping of Ho 3+ ions provide relatively much better sensitivity using non-thermally coupled level method.…”

High-contrast multi-surface imaging of latent fingerprints using color-tunable YOF:Tb3+,Eu3+ ultrafine nanophosphors with high quantum yield

“…YOF has a wide energy band gap (4.92 eV) (Data retrieved from the Materials Project for YOF (mp-3637) from database version v2023.11.1. ), 30 high chemical and thermal durability, 31 and can be synthesized in various morphologies by adopting different synthesis routes such as the hydrothermal method, 32 sol–gel method, 33 precipitation synthesis, 34 pyrolysis, 35 vacuum hot-press sintering method, 36 etc . However, most of the synthesis methods previously reported followed a long reaction time, non-uniform heating of the precursor solution, or a complicated synthesis process, which in turn, provided difficulty in controlling the particle size, a low yield of the phosphor, and non-uniformity in its morphology.…”