1,721,071 research outputs found
Enhancing the upconversion luminescence properties of Er 3+ –Yb 3+ doped yttrium molybdate through Mg 2+ incorporation: effect of laser excitation power on temperature sensing and heat generation
No full textSynthesis and Upconversion Emission Properties of Green Emitting Y<SUB>4</SUB>MoO<SUB>9</SUB>: Er<SUP>3</SUP><SUP>+</SUP>/Yb<SUP>3</SUP><SUP>+</SUP> Phosphor
No full textUp/down-converted green luminescence of Er3+-Yb3+ doped paramagnetic gadolinium molybdate: a highly sensitive thermographic phosphor for multifunctional applications
No full textA series of Er3+-Yb3+ doped gadolinium molybdate phosphors were synthesized via hydrothermal method with varying Er3+ and Yb3+ concentrations and their thermal stability, crystal phase formation, particle morphology and photoluminescence properties were explored. The effects of rare earth doping concentration and annealing temperature on upconversion and downconversion properties have been investigated upon 980 nm and 380 nm light excitation and explained with the variation in lifetime of the S-4(3/2) level of Er3+. The materials were further investigated to look into the effect of Er3+-concentration on optical temperature sensing and nano-heating behavior. Temperature sensing measurements were performed by the fluorescence intensity ratio technique using the transitions from the two thermally coupled energy levels (H-2(11/2)/S-4(3/2) -> I-4(15/2)) of Er3+. The maximum temperature sensitivity was obtained as 0.0105 K-1 (at 450 K), which is among the highest measured sensitivities for luminescence based thermometers. Moreover, the material shows very high thermal gain due to laser irradiation, resulting in a temperature rise from 364 K to 683 K as the excitation power changes from 7.0 to 65 W cm(-2) and defines the present material as a highly sensitive thermographic phosphor. Additionally, the paramagnetic nature and effect of the magnetic field on upconversion properties of this phosphor have also been explored. The thermally-stable, paramagnetic Gd2Mo3O9:Er3+/Yb3+ phosphor particles seem to be potential candidates for displays, remote temperature sensing, optical heaters, magneto-optic modulators and bio-imaging applications
Comparative thermometric properties of bi-functional Er<sup>3+</sup>–Yb<sup>3+</sup> doped rare earth (RE = Y, Gd and La) molybdates
No full textEr3+-Yb3+ doped vanadate nanocrystals: A highly sensitive thermographic phosphor and its optical nanoheater behavior
No full textOptical temperature sensors play a vital role in biomedical and therapeutic applications due to their reliable and unique detection sensitivity. Internal self-heating in Er3+/Yb3+ doped yttrium vanadate particles is observed on optical excitation at 980 nm wavelength of a diode laser. Temperature sensing performance is investigated by exploiting the temperature dependent fluorescence intensity ratio (FIR) of two emission bands (H-2(11/2)/S-4(3/2)-> I-4(15/2)) of Er3+ ion. The calculated sensor sensitivity, 0.01169 K-1 at 380 K, is found the highest among the reported results for inorganic nanosensors. The temperature of the nanocrystalline sample particles is found to increase by a large value (315-460 K) within a short interval of excitation pump power (13.18-50.45W cm(-2)). This achievement suggests potential use of the present material as an optical nanoheater for hyper-thermal treatment. (C) 2014 Elsevier B.V. All rights reserved
Upconversion photoluminescence of Ho3+-Yb3+ doped barium titanate nanocrystallites: Optical tools for structural phase detection and temperature probing
No full textOpen-Access-Publikationsfonds 202
YVO4:Er3+/Yb3+ phosphor for multifunctional applications
No full textThis article reports luminescence studies on wet-chemical route prepared YVO4:Er3+/Yb3+ microdisc phosphor. The 980 nm laser excited upconversion (UC) emission intensity ratio of green to red bands is found too high to neglect the contribution from the red emission band, which is not observed normally in Er3+/Yb3+-doped materials. The red emission is also found absent in the downconversion emission under excitation at 316 nm. The variation of UC intensities with external temperature exhibits a well-fashioned pattern, which suggests that the H-2(11/2) and S-4(3/2) levels of Er3+ ion are thermally coupled. The YVO4:Er3+/Yb3+ phosphor has shown outstanding temperature-sensing behavior with maximum sensitivity of 0.0117 K-1 at 400 K. This material is also employed to develop a latent fingerprint in green color. Furthermore, the present phosphor could be useful for solar cell concentrators, drug delivery, and disease therapy applications. (C) 2014 Optical Society of Americ
Dualistic temperature sensing in Er3+/Yb3+ doped CaMoO4 upconversion phosphor
No full textTemperature sensing performance of Er3+/Yb3+ doped CaMoO4 phosphor prepared via polyol method is reported herein. The X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy are done to confirm the phase, structure and purity of the synthesized phosphor. The infrared to green upconversion emission is investigated using 980 nm diode laser excitation along with its dependence on input pump power and external temperature. The temperature dependent fluorescence intensity ratio of two upconversion emission bands assigned to H-2(11/2) -> I-4(15/2) (530 nm) and S-4(3/2) -> I-4(15/2) (552 nm) transitions has shown two distinct slopes in the studied temperature range - 300 to 760 I< and therefore, dual nature of temperature sensitivity is observed in this phosphor. This phenomenon in rare earth doped materials is either scarcely reported or overlooked. The material has shown higher sensitivity in the high temperature region (535 K < T< 760 K) with a maximum of 721 x 10(-3) K-1 at 535 K. The results indicate potential of CaMoO4: Er3+/Yb3+ phosphor in high temperature thermometry. (C) 2016 Elsevier B.V. All rights reserved
Demonstration of Temperature Dependent Energy Migration in Dual-Mode YVO4: Ho3+/Yb3+ Nanocrystals for Low Temperature Thermometry
No full textA dual mode rare-earth based vanadate material (YVO4: Ho3+/Yb3+), prepared through ethylene glycol assisted hydrothermal method, demonstrating both downconversion and upconversion, along with systematic investigation of the luminescence spectroscopy within 12-300 K is presented herein. The energy transfer processes have been explored via steady-state and time-resolved spectroscopic measurements and explained in terms of rate equation description and temporal evolution below room temperature. The maximum time for energy migration from host to rare earth (Ho3+) increases (0.157 mu s to 0.514 mu s) with the material's temperature decreasing from 300 K to 12 K. The mechanism responsible for variation of the transients' character is discussed through thermalization and non-radiative transitions in the system. More significantly, the temperature of the nanocrystals was determined using not only the thermally equilibrated radiative intra-4f transitions of Ho3+ but also the decay time and rise time of vanadate and Ho3+ energy levels. Our studies show that the material is highly suitable for temperature sensing below room temperature. The maximum relative sensor sensitivity using the rise time of Ho3+ energy level (F-5(4)/S-5(2)) is 1.35% K-1, which is the highest among the known sensitivities for luminescence based thermal probes.European Commission; Department of Science and Technology, New DelhiOpen-Access-Publikationsfonds 201
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