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980-nm-upconverted 530 and 550 nm Er 3+ green fluorescence spectra of Er 3+ /Yb 3+ -codoped NaGd(WO 4 ) 2 submicron crystals were measured in the temperature range of 298-383 K. A sextuple ratiometric thermometry is proposed. It is established on the basis of six schemes of fluorescence intensity ratio (FIR) that considers three component peaks of the 530 nm emission band and two component peaks of the 550 nm emission band, which involve electronic transitions between two Stark sublevels of Er 3+ . The study shows that the phosphor shows strong green fluorescence, which is verified by measured quantum yield, and thermally stable spectral structure desired for the sextuple ratiometric thermometry. All of the six FIR schemes display highly efficient sensing performances with slightly different thermal sensitivities. Each scheme gives a temperature value and the six schemes give an averaged result. In parallel, we have also carried out an ex vivo experimental study on the temperature characteristics of the green fluorescence of the phosphor. Almost same results have been obtained, verifying biological applicability of the phosphor. The ex vivo experimental results also show that the sextuple thermometry increases considerably the accuracy and reliability of temperature measurement in comparison with the conventional intensity integration method., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Fluorescence and absorption spectra at 530 nm (2H11/2→4I15/2), 560 nm (4S3/2→4I15/2), 660 nm (4F9/2→4I15/2), 980 nm (4I11/2→4I15/2), 1530 nm (4I13/2→4I15/2), and 2710 nm (4I11/2→4I13/2) of Er3+ in Gd3Ga5O12 single‐crystal codoped with Pr3+ have been measured. Judd‐Ofelt analysis yields the intensity parameters Ω2 = (0.68 ± 0.03) × 10−20 cm2, Ω4 = (0.60 ± 0.07) × 10−20 cm2, and Ω6 = (0.90 ± 0.17) × 10−20 cm2. A comparison with previously reported values of Er3+‐only doping case shows that Pr3+‐codoping causes slight change of both Ω2 and Ω4, while onefold increase of Ω6. From calculated radiative rates and measured fluorescence spectra, Er3+ emission cross‐section spectra were calibrated at first. Then, the absorption cross‐section spectra were calculated using McCumber relation. In parallel, the absorption cross‐section spectra were also obtained from the measured absorption spectrum, and compared with those obtained from the McCumber relation. The comparison shows that both methods give consistent result of absorption cross‐section spectrum. Further comparison with Er3+‐only doping case shows that Pr3+‐codoping causes considerable change of Er3+ cross‐section value. In spectrally mixing regions of Er3+ and Pr3+, Pr3+ emission affects little the determination of Er3+ emission cross‐section as Pr3+ fluorescence is much weaker than Er3+ fluorescence due to low Pr3+ concentration. [ABSTRACT FROM AUTHOR]

Some Er 3+ -doped LiTaO 3 plates were prepared by in-diffusion of Er-metal film locally coated onto congruent Z -cut substrate in air at a wide temperature range from 1000 to 1500 °C. After diffusion, Er 3+ -doping effect on LiTaO 3 refractive index and Li 2 O out-diffusion arising from Er 3+ in-diffusion were studied at first. Refractive indices at the doped and undoped surface parts were measured by prism coupling technique and the surface composition was estimated. The results show that Er 3+ dopant has small contribution to the LiTaO 3 index. Li 2 O out-diffusion is slight (Li 2 O content loss <0.3 mol%) for the temperature below 1300 °C while is moderate (Li 2 O content loss <0.6 mol%) for the temperature above 1400 °C. The Er 3+ profile was studied by secondary ion mass spectrometry. The study shows that the diffused Er 3+ ions follow either a complementary error function or a Gaussian profile. Characteristic parameters including diffusivity, diffusion constant, activation energy, solubility, solubility constant and heat of solution were obtained and compared with the LiNbO 3 case. The comparison shows that the diffusivity and solubility in LiTaO 3 are considerably smaller than in LiNbO 3 because of the difference of Ta and Nb in atomic weight. [ABSTRACT FROM AUTHOR]

We have developed a simple, low-cost and highly efficient optical temperature sensor based on intensity ratio of down-conversion green fluorescence of Er 3+ ions doped in SrGdGa 3 O 7 single crystal. The sensor consists simply of a 384 nm light emitting diode, two narrow-band interference filters, two Si-photocells and two multimeters, without use of a monochromator or spectrometer or focusing lens. It has a simple, compact structure and is low-cost. The experimental results show that the device displays highly efficient sensing performance with good signal-to-noise ratio and high thermal resolution and temperature sensitivity, which has a value of (5.5-102.1) × 10 −3 K −1 in the considered temperature range of 100–430 K. In addition, the experiments were repeated using a spectrometer and consistent results are obtained. [ABSTRACT FROM AUTHOR]

Judd-Ofelt (J-O) spectroscopic knowledge of a rare-earth-doped luminescent material is crucial to its application. Although a large number of papers with regard to the J-O study of various rare-earth-doped luminescent materials have been reported each year, few papers presented the errors of the J-O intensity parameters Ω i (i = 2, 4, 6) and radiative probabilities evaluated from them. Present study focuses on the error evaluation of the J-O parameters and radiative probabilities. An error theory is established for the J-O analysis and radiative probability. Two error analysis methods based on root mean square of the difference either between measured and calculated oscillator strengths (δf rms) or between measured and calculated line strengths (δS rms) are studied. Explicit error expressions are presented for the J-O parameters and radiative probability. The validity of the theory is verified by applying it to widely studied Er3+, Tm3+, Ho3+ and Nd3+ ions that are doped into four single-crystals (LiNbO 3 , SrGdGa 3 O 7 , LiYF 4 and YVO 4) and a glass. The two methods are identical in nature and give similar results of errors of Ω i. [ABSTRACT FROM AUTHOR]