Temperature Dependence Of Upconversion Luminescence Research Articles

A novel upconversion luminescence temperature sensing material: Negative thermal expansion Y2Mo3O12:Yb3+, Er3+ and positive thermal expansion Y2Ti2O7:Yb3+, Er3+ mixed phosphor

Thermal enhancement and quenching of upconversion luminescence of rare earth ions can be realized in the negative expansion and positive expansion hosts, respectively, which is advantage of temperature sensing applications. In this work, the negative expansion Y2Mo3O12:Yb3+, Er3+ and positive thermal expansion Y2Ti2O7:Yb3+, Er3+ phosphors were prepared, respectively. The temperature dependence of upconversion luminescence demonstrated that the green, red and near infrared upconversion luminescence of Y2Mo3O12:Yb3+, Er3+ phosphor increases with the increasing of temperature, while the upconversion luminescence of Y2Ti2O7:Yb3+, Er3+ phosphor decreases upon the 980 nm laser excitation. A novel upconversion luminescence temperature sensor was obtained by the intensity ratio of the upconversion luminescence of negative thermal expansion Y2Mo3O12:Yb3+, Er3+ to the upconversion luminescence of positive thermal expansion Y2Ti2O7:Yb3+, Er3+. The near infrared-red fluorescence intensity ratio (FIR) (I860/I675) was researched in the range from 293 K to 574 K, which suggests that FIR increases with rising temperature. The maximum relative sensitivity (Sr) was 1.61% K−1 in near infrared-red FIR (I860/I675) at 293 K. The result suggests that the mixed phosphor exhibits potential application as a new temperature sensing device.

Temperature dependence of up-conversion luminescence and sensing properties of LaNbO4: Nd3+/Yb3+/Ho3+ phosphor under 808nm excitation.

LaNbO4: Nd3+/Yb3+/Ho3+ phosphor was prepared by a conventional high temperature solid-state reaction method. The temperature dependence of up-conversion (UC) luminescence property of LaNbO4: Nd3+/Yb3+/Ho3+ phosphor under 808nm excitation and the potential application of exploiting the red-to-green UC emission intensity ratio (IR/IG) of Ho3+ in temperature sensing were studied. Two-photon processes were confirmed to be responsible for both the green and the red UC emissions at different temperatures by analyzing the excitation power density dependent UC luminescence spectra measured at different temperatures. The energy level diagram was drawn to analyze the UC luminescence mechanism of Ho3+. In addition, it was found that the ratio IR/IG of Ho3+ was independent of the excitation power density of 808nm laser under the current experimental condition, but it was sensitive to the temperature. And the temperature dependent UC luminescence spectra displayed that the ratio IR/IG exhibited a good linear increasing tendency with temperature rising. The obtained temperature sensing sensitivity was 2.04×10-3K-1 in the temperature range of 303-693K. The results suggest that LaNbO4: Nd3+/Yb3+/Ho3+ phosphor may be a good candidate for application in optical temperature sensors.

Simultaneous Enhancement and Modulation of Upconversion by Thermal Stimulation in Sc2Mo3O12 Crystals.

Rational control of photoluminescence against a change in temperature is important for fundamental research and technological applications. Herein, we report an anomalous temperature dependence of upconversion luminescence in Yb/Ho co-doped Sc2Mo3O12 crystals. By leveraging negative thermal expansion of the crystal lattice, energy transfer between the lanthanide dopants is promoted as the temperature is increased from 303 to 573 K, resulting in an ∼5-fold enhancement of the emission. Meanwhile, the emission profile is also substantially altered due to the concurrent thermal quenching of selective energy states, corresponding to a clear shift in color from green to red. Via correlation of the red-to-green emission intensity ratio of Ho3+ dopant ions with temperature, a ratiometric luminescence thermometer is constructed with a maximum sensitivity of 2.75% K-1 at 543 K. As the Sc2Mo3O12 crystals are thermally stable and nonhygroscopic, our findings highlight a general approach for highly reversible control of upconversion by temperature in ambient air.

Temperature dependence of upconversion luminescence and sensing sensitivity of Ho3+/Yb3+ modified PSN-PMN-PT crystals

In view of the vital role of temperature in actural applications of materials, a detailed investigation was conducted for Ho3+/Yb3+-modified Pb(Sc1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PSN-PMN-PT) crystals focusing on their temperature dependence of upconversion luminescence and sensing abilities. The results indicated that the luminescence intensity of grown crystals weakened with elevating temperature, and the fastest decrease rate occurred in green emission. The absolute and relative sensitivities calculated by S755/S767 (SA2 and SR2) were higher than that based on I665/I554 (SA1 and SR1) at low temperature, and the maximum of 0.0112 K-1 and 0.0373 K-1 were obtained at 93 K, comparable to that of some rare earth (RE) doped host materials reported. The study on chromaticity coordinate revealed the high colour purity of crystals, nearly up to 99%. Furthermore, the decay dynamics of crystals were investigated. The longest average decay time (157.44 μs ) of 554 nm emission was obtained at 293 K. These results manifest the promising applications of Ho3+/Yb3+-modified PSN-PMN-PT crystals as luminescent and optical thermometric materials at low and room temperature. It is also of significance for further investigation of photoelectric coupling performance of ferroelectric crystals.1

Ho,3+ (or Tm3+ )-Activated Upconversion Nanomaterials: Anomalous Temperature Dependence of Upconversion Luminescence and Applications in Multicolor Temperature Indicating and Security

Ho,³⁺ (or Tm³⁺ )-Activated Upconversion Nanomaterials: Anomalous Temperature Dependence of Upconversion Luminescence and Applications in Multicolor Temperature Indicating and Security

Three-dimensional micro-printing of temperature sensors based on up-conversion luminescence

The pronounced temperature dependence of up-conversion luminescence from nanoparticles doped with rare-earth elements enables local temperature measurements. By mixing these nanoparticles into a commercially available photoresist containing the low-fluorescence photo-initiator Irgacure 369, and by using three-dimensional direct laser writing, we show that micrometer sized local temperature sensors can be positioned lithographically as desired. Positioning is possible in pre-structured environments, e.g., within buried microfluidic channels or on optical or electronic chips. We use the latter as an example and demonstrate the measurement for both free space and waveguide-coupled excitation and detection. For the free space setting, we achieve a temperature standard deviation of 0.5 K at a time resolution of 1 s.

Influence of temperature on upconversion multicolor luminescence in Ho^3+/Yb^3+/Tm^3+-doped LiNbO_3 single crystal

The temperature dependence of upconversion luminescence in Ho3+/Yb3+/Tm3+ tri-doped LiNbO3 single crystal was studied at different temperatures from 289 to 773 K under 980 nm excitation. The tri-doped LiNbO3 single crystal offers temperature-dependent color tuning properties, and the white-light emission can be obtained by simply tuning the temperature. In addition, the competition between nonradiative transition and thermal population plays an important role in the upconversion process with temperature increase. This research has implications in the extension of research for optical temperature sensors and multicolor variable temperature display materials.

Temperature dependence of upconversion luminescence in erbium-doped tellurite glasses

Temperature quenching characteristics of infrared-to-visible frequency upconversion in ytterbium-sensitized erbium-doped tellurite glasses under 970 nm excitation were reported. Intense upconversion emissions around 530, 545 and 657 nm corresponding to the 2H 11/2, 4S 3/2 and 4F 9/2 transitions to the 4I 15/2 ground state were observed. The green emission around 530 nm presents continuous increase with increase of temperature. While the emission around 545 nm increases from 20 to 80 K and reaches the largest value around 80 K, then decreases from 80 to 300 K. The dependence of intensity characteristics on temperature was systematically analyzed by rate equations and a simple three-level system. In addition, the temperature dependence on the multiphonon relaxation rates ( 2H 11/2, 4S 3/2→ 4F 9/2) fitted with 4 phonons of the 760 cm −1 was presented.

Temperature dependence of upconversion luminescence from Pr 3+ and Yb 3+ codoped ZBLAN glass pumped by 960 nm laser diode

In this paper, the temperature dependence of upconversion luminescence from Pr 3+ and Yb 3+ codoped ZBLAN glass pumped by 960 nm laser diode was studied. In our experiments the temperature was changed from room temperature (24°C) to 300°C. The results show that not only luminescence intensity but also upconversion spectrum configuration changes with the increase of temperature. In the range of temperatures we were interested in, the intensity of upconversion luminescence first increases with temperature, and arrives at its maximum, then decreases.