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Temperature sensitive properties of Eu2+/Eu3+ dual-emitting LaAlO3 phosphors
摘要： In this study, Eu2+/Eu3+ coexisting perovskite LaAlO3 phosphors were synthesized by a traditional high-temperature solid-phase reaction method and investigated via X-ray diffraction data, X-ray photoelectron spectroscopy and temperature-dependent photoluminescence spectra. The Eu2+/Eu3+ coexisting LaAlO3 phosphors exhibit excellent optical temperature sensing characteristics and are potential inorganic materials for temperature detection. The measured maximal absolute temperature sensitivity reaches 0.014 K-1, and the corresponding largest relative temperature sensitivity is 1.193% K-1, which are superior to most of previous reports of that. Meanwhile, the monitored signal peaks are well separated, providing a good signal discriminability. The energy level crossover relaxation of Eu2+ and Struck-Fonger crossover process involving O2–-Eu3+ charge transfer band were used to explain the different temperature-dependent responses of Eu2+ and Eu3+. This work may give new ideas for the future research of optical thermometric materials with high sensitivity and high discriminability.
关键词： Fluorescence intensity ratio,Charge transfer band,Thermometry phosphor,LaAlO3
更新于2025-11-14 15:13:28
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Excellent photoluminescence and temperature sensing properties in Ho3+/Yb3+ codoped (Y0.88La0.09Zr0.03)2O3 transparent ceramics
摘要： Ho3+/Yb3+ codoped (Y0.88La0.09Zr0.03)2O3 transparent ceramics were prepared by a high temperature solid-state reaction method. SEM observation confirms that there are no obvious impurities or pores existed in the grain boundaries of the samples. Accordingly, all the samples show excellent transparency in the visible and near-infrared range. Upon 980 nm excitation, strong green emission peaked at 549 nm, red emissions centered at 667 and 756 nm, as well as near infrared emission located at 2 μm respectively from Ho3+ ions are observed. By utilizing the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors of the optimal sample (Yb0.03Ho0.01Y0.84La0.09Zr0.03)2O3 are investigated at different excitation power densities based on the non-thermally coupled levels of 5F4/5S2 and 5F5. The thermometry is found to be immune to the excitation power density, leading to the consistent calibration curves and sensing sensitivities at the different power densities. The maximal sensing sensitivity is about 71.28×10?4 K?1 at 563 K. The results indicate that the Ho3+/Yb3+ codoped (Y0.88La0.09Zr0.03)2O3 transparent ceramics are promising for the temperature sensors, display devices and 2 μm solid-state lasers.
关键词： Upconversion luminescence,Rare earth,Optical thermometry,Transparent ceramics
更新于2025-09-23 15:23:52
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Pressure effect on phosphor thermometry using Mg <sub/>4</sub> FGeO <sub/>6</sub> :Mn
摘要： This study examined the effect of ambient pressure on the luminescent lifetime of Mg4FGeO6:Mn phosphors in different morphologies. To evaluate the pressure sensitivity of phosphor in the form of particle, agglomerated particle and chemically bonded coating, samples including phosphor powder, pressed phosphor disc, and chemically bonded phosphor coating were fabricated and calibrated using a PMT-based measurement system for a pressure range of 20-200 kPa and a temperature range of 298-873 K. The results showed no obvious pressure effect on the lifetime of the chemically bonded Mg4FGeO6:Mn coating. However, the lifetime of the phosphor powder and pressed phosphor disc decreased as pressure increased. This pressure effect was most obvious for the pressed phosphor disc, which was further aggravated at higher temperatures. The atomic distance between manganese ion and other atomics reduced as pressure increased, which induced the movement of excited state in the configuration coordinate. Considering this dependency of pressure sensitivity on phosphor morphology, it is important to adopt the same fabrication procedure for calibration and temperature measurement using Mg4FGeO6:Mn. In addition, for in-flow measurement using Mg4FGeO6:Mn tracer particles, the influence of environmental pressure must be considered.
关键词： Phosphor thermometry,Lifetime,Mg4FGeO6:Mn,Pressure effect
更新于2025-09-23 15:23:52
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Enhanced photoluminescence and ultrahigh temperature sensitivity from NaF flux assisted CaTiO3: Pr3+ red emitting phosphor
摘要： The Pr3+ doped CaTiO3 red emitting phosphor with enhanced PL and ultrahigh temperature sensing was prepared via NaF flux assisted solid-state reaction. All samples had the orthorhombic perovskite phase and no impurity was found. The typical sample mainly had sphere-like morphology with particle size of ~670 nm. The optical bandgap values were ~3.62-3.63eV. The Pr3+ quenching content was 0.6 mol% and the ET mechanism for quenching was the d-d interaction with the critical distance of 26.09 ?. A certain amount of NaF flux could enhance red emission attributed to 1D2→3H4 transition owing to improving the crystallinity of phosphors and reducing point defects near Pr3+ through the substitution of O2- by F- and Ca2+ by Na+. The energy storage trap (oxygen vacancy) near IVCT state played the key role for trapping electrons, accounting for the LAG emission and the average depth of trap was 0.39 eV. The CIE chromaticity coordinates were very close to that of the ideal red light and the CP was as high as 99.98%. The maximal Sa and Sr was as high as ~0.015 K-1 and~ 5.2% K-1, respectively. The thermal induced relaxation between the 3Pj levels and 1D2 level through the IVCT state was supposed to account for the excellent optical temperature sensing. Our work may provide a useful inspiration for developing ultrahigh sensitive optical temperature sensors.
关键词： Praseodymium,Calcium titanate,Optical thermometry,Intervalence charge transfer state
更新于2025-09-23 15:23:52
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Lanthanide complexes with 2-(tosylamino)-benzylidene-N-(aryloyl)hydrazones - universal luminescent materials
摘要： Lanthanide complexes Ln(L1)(HL1) (Ln = Lu, Yb, Er, Gd, Eu, Sm) and Ln(L2)(HL2) (Ln = Lu, Yb, Gd, Eu) with 2-(tosylamino)-benzylidene-N-(aryloyl)hydrazones (H2L1, aryloyl = 2-hydroxybenzoyl; H2L2, aryloyl = Isonicotinoyl) were obtained with the aim to explore them as new luminescent materials. They were found to form monomeric species independently on the aryloyl nature, their crystal structures were determined from single crystal X-ray data (Yb(L2)(HL2)·0.5(C2H5OH)), as well as from powder X-ray data by Rietveld refinement (Eu(L1)(HL1)). Ytterbium complexes exhibited intense luminescence, which allowed using them in host-free OLEDs, which demonstrated remarkable efficiency of NIR electroluminescence (50 μW/W) at low voltage (5V). Special mechanism of europium luminescence quenching allowed using europium complexes as luminescent thermometers, which demonstrated very high sensitivity up to 12%/K. The theory of luminescence thermometry based on three-level system was proposed which allowed predicting sensitivity with high accuracy (error within 20%).
关键词： lanthanide complexes,OLEDs,luminescent thermometry,NIR emission,luminescent materials
更新于2025-09-23 15:23:52
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Bi-functional heater-thermometer Nd3+-doped nanoparticles with multiple temperature sensing parameters
摘要： Achieving a combination of real-time diagnosis and therapy in a single platform with sensitive thermometry and efficient heat production is a crucial step towards controllable photo-thermal therapy. Here, Nd3+-doped Y2O3 nanoparticles prepared by combined Pechini-foaming technique operating in first and second biological windows were demonstrated as thermal sensors within wide temperature range of 123–873 K and heaters with temperature increase by 100 K. Thermal sensing was performed based on various approaches: luminescence intensity ratio (electronic levels; Stark sublevels), spectral line position and line bandwidth were used as temperature dependent parameters. Applicability of regarded sensing parameters along with relative thermal sensitivity and temperature resolution were discussed and compared. Influence of Nd3+ doping concentration on thermometer and heater efficiency was also investigated.
关键词： Nanosensor,Biological window,Hyperthermia,Luminescence,Thermometry,Nd3+
更新于2025-09-23 15:23:52
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Colloidal Rare Earth Vanadate Single Crystalline Particles as Ratiometric Luminescent Thermometers
摘要： Thulium/ytterbium-doped yttrium vanadate particles provide ratiometric thermal response as both colloids and powders via downshift or upconversion emissions. Here, we synthesized yttrium vanadates by controlled colloidal conversion of hydroxycarbonate precursors. A protected annealing process yielded single crystalline and readily dispersible particles that were manipulated individually by optical tweezers in water. Because individual particles displayed detectable emissions, this system has potential applications as a single-particle luminescent temperature sensor. Excitation on Yb3+ sensitizers (λexc=980 nm) or at vanadate groups (λexc=300 nm) resulted in Tm3+ emissions that effectively correlated with the temperature of the sample from 288 to 473 K with high relative thermal sensitivity (0.8-2.2% K-1), one of the highest reported for vanadate nanocrystals so far. Different pairs of Tm3+ transitions afford a ratiometric thermal response, which fitted common sensing requirements such as large [3F2,3→3H6 (λ=700 nm)/1G4→3H6 (λ=475 nm)] or small [3F2,3→3H6 (λ=700 nm)/1G4→3F4 (λ=650 nm)] spectral gaps, and emission wavelengths at the first near infrared biological window [3F2,3→3F4 (λ=700 nm)/3H4→3H6 (λ=800 nm)]. Our findings open new perspectives for the use of luminescent nanothermometers with controllable spatial localization, which is a remarkably interesting prospect to investigate microscopically-localized events related to changes in temperature.
关键词： Luminescence,Thermometry,Nanoparticles,Thermal Sensors,Vanadates,Optical Trapping,Rare Earth
更新于2025-09-23 15:23:52
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Enhanced NIR-NIR luminescence from CaWO4: Nd3+/Yb3+ phosphors by Li+ codoping for thermometry and optical heating
摘要： Rare earth ions doped luminescent materials have demonstrated their potentiality as sensitive thermometers with good accuracy and high spatial resolution. Nevertheless, low luminescence efficiency, especially at high temperature, still limits the development of this thermometry technique. Here, Nd3+/Yb3+ codoped CaWO4 phosphors were synthesized using high temperature solid-state method, and Li+ ions were introduced aiming to improve the near-infrared (NIR) emissions from Nd3+ in the spectral range of 725-950 nm. The influence of Li+ codoping on the structure and NIR luminescence in CaWO4: Nd3+/Yb3+ when excited by a 980 nm laser diode was investigated. NIR-NIR emissions from Li+ codoped samples are successfully strengthened compared with that without Li+ ions, which is mainly attributed to the distortion of the crystal structure and the increase of crystalline size by Li+. The optical temperature sensing behavior of NIR luminescence from Nd3+ was studied based on fluorescence intensity ratio (FIR). Assisted by Li+ ions, the NIR-NIR emissions are observed to be effectively enhanced with the increment of temperature. And a new pair of thermally coupled levels in Nd3+ ions with excellent thermometry characteristics is explored, through which superior measurement sensitivity as well as accuracy could be achieved. In addition, light-induced temperature rise was realized in the phosphors, which makes CaWO4: Nd3+/Yb3+/Li+ excellent candidate for luminescence thermometry and optical heaters.
关键词： Li+ codoping,thermometry,Nd3+ ions,NIR luminescence
更新于2025-09-23 15:22:29
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The influence of Eu3+ concentration on the spectroscopic properties of YAG:Ti, Eu3+ nanocrystalline luminescent thermometer
摘要： The influence of Eu3+ co-dopant on the luminescent properties of an yttrium aluminum garnet co-doped with titanium and europium ions (YAG: Ti, Eu) nanocrystals has been investigated. This is a continuation of the search for novel materials suitable for luminescence thermometry using an approach based on inorganic nanocrystals co-doped with transition metal ions and lanthanides. The optical response of Ti3+, Ti4+ and Eu3+ ions present in the examined structures was analyzed in a wide range of temperatures. A model of distribution of energy levels of these ions explaining the observed spectra and their dependence on the Eu concentration was proposed. Moreover, the possibility of energy transfers between these ions and their dependence on the concentration of Eu ions and on the temperature was indicated. On this basis, a model was proposed, allowing for the optimization of the maximum sensitivity and the corresponding temperature.
关键词： Titanium,Luminescent thermometry,Europium,Eu3+,Nanocrystals
更新于2025-09-23 15:22:29
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MR temperature imaging using PRF phase difference and a geometric model-based fat suppression method
摘要： BACKGROUND: Because protons in fat do not exhibit a temperature-dependent frequency shift, proton resonance frequency shift (PRFS)-based MR thermometry always suffers from disturbances due to the presence of fats or lipids. OBJECTIVE: A new fat suppression method for PRFS-based MR thermometry is proposed to obtain accurate variation of phase angle. METHODS: Similar to the approach of separating fat and water with the two-point Dixon technique, we first scan a complex MR image for reference and then scan another complex image varying with temperature at the same TE point. Based on the conventional PRFS method, we use geometric relationships to remove the effect of fat on the variation of the phase angle. RESULTS: Two phantoms with different water-to-fat ratios are involved in the temperature mapping test. Experimental results show that the temperature images of two phantoms are approximated under the same conditions. CONCLUSIONS: The proposed fat suppression method is simple and effective for PRFS-based MR thermometry.
关键词： geometric model,MR thermometry,fat suppression,PRFS
更新于2025-09-23 15:22:29