Primary thermometers based on sol–gel upconverting Er3+/Yb3+ co-doped yttrium tantalates with high upconversion quantum yield and emission color tunability

Refined structural studies on the fluorite-related polymorphs of sol–gel undoped and Eu3+-doped yttrium tantalates

“…46 Similarly, doping with distinct RE 3+ , such as Pr 3+ or Er 3+ , causes M′-YTaO 4 to emerge as the preferential phase at low RE 3+ content (0.1 and 0.5 mol% RE 3+ ), while increasing RE 3+ concentrations up to 5.0 mol% stabilize the Y 3 TaO 7 phase, delaying M′-YTaO 4 formation. 36,39 For the second Eu 3+ concentration range, the Y 3 TaO 7 phase stabilizes because a solid solution arises. 9…”

“…However, these authors did not offer a quantitative refined analysis of the structure. These differences have been observed even recently, 29,36 proving that assigning the Y 3 TaO 7 crystalline structure is still a point of contention.…”

“…In previous works, we have shown that lanthanide ions are highly soluble within the Y 3 TaO 7 structure and homogeneously distributed in the lattice, and that doping with RE 3+ affects Y 3 TaO 7 crystallization and phase stabilization. 8,9,36,39–41 Indeed, Eu 3+ present in this host affects Y 3 TaO 7 phase decomposition and delays M′-YTaO 4 formation. 8 The Eu 3+ -doped yttrium tantalates afforded a high concentration luminescence quenching (∼30 mol% Eu 3+ ) and an absolute quantum yield value up to 30%.…”

Influence of excitation and detection geometry on optical temperature readouts – reabsorption effects in luminescence thermometry

“…Inaccessible systems (such as the interior of biological tissue, or closed systems under pressure) can be explored by optical thermometry using diverse temperature-dependent (thermometric) properties of Ln 3+ ions and remote detection of light emission. 1,5,13,30,33–42 An increasing number of research studies on thermometry is related to the development and analysis of primary thermometers. 24,25,28,30,38,43,44 Primary thermometers are characterized by a well-established equation of state that directly relates a given measurement value to absolute temperature without the need for calibration.…”

Upconverting nanoparticles as primary thermometers and power sensors

“…The most common approach to infer absolute temperature is based on the intensity ratio of two distinct transitionsratiometric luminescence thermometry (Brites et al, 2016). In the last few years, primary thermometers based on luminescent nanoprobes have been studied which take advantage of the temperature-dependent intensity ratio of the two thermally coupled Er 3+ levels, 2 H 11/2 and 4 S 3/2 (Balabhadra et al, 2017;Bastos et al, 2019;Brites et al, 2019b;Martínez et al, 2019;Borges et al, 2021;Martins et al, 2021;Dos Santos et al, 2022). A primary thermometer is characterized by a well-established emitting state population equation that follows Boltzmann statistics.…”