Luminescence and temperature‐sensing properties of Y₄GeO₈:Bi³⁺,Eu³⁺ phosphor

Abstract

In this paper, Y4GeO8:Bi3+,Eu3+ phosphor with dual emission centers was elaborated via conventional solid‐state reaction technology. Thorough research on the structure, morphology, and luminous properties of Y4GeO8:Bi3+,Eu3+ phosphor, the potential applications in optical thermometry were investigated by means of fluorescence intensity ratio and thermochromic techniques. Under 290 and 347 nm excitation, Y4GeO8:Bi3+,Eu3+ phosphor presents broadband emission from 3P1 → 1S0 transition of Bi3+ ions and characteristic emission peaks from 4f–4f transition of Eu3+ ions. Outstanding temperature‐sensing capabilities are acquired from Y4GeO8:Bi3+,Eu3+ phosphor. The maximum relative sensitivity (Sr) can attain 1.51% K−1 (λex = 290 nm). With temperature raising (303–513 K), the emitted color of Y4GeO8:Bi3+,Eu3+ phosphor (λex = 290 nm) shifts from faint yellow to red with a high chromaticity shift (0.180), which can be distinguished by the unaided eye clearly. Our results indicate that Y4GeO8:Bi3+,Eu3+ phosphor has potential applications in optical temperature measurement and high‐temperature safety marker.

Stimuli-Responsive Photoluminescence of Eu(III) Complexes with Triazine-Based Luminophores

“…Luminescent lanthanide complexes find widespread use in developing technologies. − The light converting molecular devices (LCMD) in which light is absorbed by coordinated ligands and then transferred to the emitting metal ion, ultimately increasing the overall photoluminescence (PL) properties, solid-state lighting (SSL) electronic devices, organic light-emitting diodes (OLEDs), and biological probes are among the most intriguing applications of lanthanide emissive complexes. − Eu­(III)-based systems are of particular interest due to their long lifetimes and high quantum efficiencies. − These photophysical features have been extensively explored in materials science, in light-converting devices, security inks, − luminescent probes in biomedical assays, , sensors, − and luminescence thermometers. − In particular, temperature-dependent luminescence intensity was first observed for Eu­(III)-β-diketonate chelates and associated with the thermal activation of competitive nonradiative deactivation pathways resulting in high temperature quenching of the emission. This observation motivated extensive further research in this field based on the enormous potential of luminescence thermometry in nanotechnology and nanomedicine, where a new generation of nanoscale thermometers is demanded.…”

“…In fact, conventional methods fail in giving accurate measurements of temperature distributions down to the nanoscale regime, e.g., intracellular temperature fluctuations, temperature at the molecular scale, or in microcircuits and microfluids. The examples of Eu­(III)-based luminescent molecular thermometers so far reported include isolated complexes as themselves or embedded into polymeric thin films, Eu­(III)-doped inorganic and organic–inorganic hybrid materials, coordination polymers, and MOFs. − Besides, Eu­(III)-containing materials characterized by intense, sharp emissions with suitable sensitization have attracted considerable interest and have been effectively used in designing white-emitting nanoparticles. − Red Eu­(III) ions doped into a judiciously chosen suitable host provided phosphors with emission covering the entire visible spectrum with high color purity. Since the Eu­(III) (4f–4f) transitions are rather sensitive to the coordination modes of the organic ligands, a great diversity of organic ligands can be used in the synthesis of new europium complexes to provide an antenna effect. − ,,− ,,,, Some of us recently reported the intriguing photophysical behavior of triimidazo­[1,2- a :1′,2′- c :1″,2′′- e ]­[1,3,5]­triazine ( L , Scheme ) and its derivatives. − For instance, L revealed aggregation-induced emission (AIE) behavior, displaying, in particular, room-temperature ultralong phosphorescence (RTUP) under ambient conditions associated with the presence of H-aggregates in its crystal structure.…”