Fluorescence Intensity Ratio Technology Research Articles

Energy-Transfer-Enhanced Cr3+/Ni2+ Co-doped Broadband Near-Infrared Phosphor for Fluorescence Thermometers and Near-Infrared Window Imaging.

Here, near-infrared broad dual-band emission phosphors were achieved through energy transfer between Cr3+ and Ni2+ ions in the β-Ga2O3 host. All samples co-doped with Cr3+ and Ni2+ exhibit dual-band emission covering 600-1700 nm under 430 nm excitation. Thanks to the doping of Cr3+ ions, the emission intensity of Ga2O3:Cr3+, Ni2+ phosphors has increased by about 2.4 times and the internal quantum efficiency has increased by 83.2% compared to Ga2O3:Ni2+ phosphors. Meanwhile, when the fluorescence lifetime was monitored at 745 nm, an efficient energy transfer between Cr3+ and Ni2+ ions in the β-Ga2O3 host was verified. Due to the significant differences in the emission temperature-sensitive properties of Cr3+ and Ni2+ ions, a thermometer was designed utilizing fluorescence intensity ratio technology, achieving a maximum relative sensitivity of 5.26% K-1, which surpasses most optical temperature measurement phosphors. This suggests that Ga2O3:Cr3+, Ni2+ samples hold promise as potential candidates for optical thermometer materials. Additionally, the broadband near-infrared emission of the Ga2O3:Cr3+, Ni2+ sample has been investigated for potential applications in component analysis and night vision, demonstrating its versatility for multifunctional applications.

Photoluminescence properties and Mn4+ → Tm3+ energy transfer of La0.557Li0.33TiO3: Mn4+, Tm3+ for thermometry and NIR-LED applications

Over the span of years, Mn4+-doped red phosphors have been utilized to meaningful optoelectronic devices due to their outstanding optical properties, and Tm3+ usually is used for activator ion because of its efficient up-conversion emission, but the down-conversion processes are rarely used. Herein, we have successfully synthesized a series of novel La0.557Li0.33Ti1-xO3:xMn4+ (x = 0.1–7 %) phosphors. The photoluminescence properties have been analysis in detailed. Using Mn4+-Tm3+ co-doped strategy, we successfully synthesis La0.557-yLi0.33Ti0.993O3:0.7 %Mn4+, yTm3+ phosphors. Upon excitation with 360 nm light, this phosphor exhibits two distinct emission peaks at 729 nm and 806 nm. The emission intensity of Tm3+ is greatly improved after Mn4+ doping, which is attributed to the energy transfer of Mn4+ to Tm3+. In terms of potential applications, utilizing fluorescence intensity ratio technology, La0.551Li0.33Ti0.993O3:0.7 %Mn4+, 0.6 %Tm3+ exhibits maximum absolute and relative sensitivities of 3.25 % K−1 at 523 K and 3.49 % K−1 at 298 K, which demonstrating its potential for application in optical thermometry. Furthermore, The NIR-LED using phosphor and 365 nm chips reveals potential applications of the La0.551Li0.33Ti0.993O3:Mn4+, Tm3+ phosphor in NIR night vision and biosensing.

Few-mode optical fiber-based flexible pressure feedback tentacle doped with fluorescence temperature pointer

Abstract In this paper, a flexible fiber pressure feedback whisker is proposed, which consists of a water droplet shaped polydimethylsiloxane (PDMS) elastomer with an embedded balloon shaped few mode fiber. The mechanical sensing performance of the device was analyzed and optimized using a combination of finite element method and beam propagation method (BPM). The built-in cladding corroded few-mode fiber increases pressure sensitivity by more than four times. The collection efficiency of fluorescence signal is improved by cladding corrosion. The PDMS elastomer was doped with upconversion nanoparticles NaYF4:Yb, Er@NaYF4 in order to achieve temperature measurement by fluorescence intensity ratio technology. The combination of fluorescence signal and interference spectrum can not only achieve real-time and accurate pressure detection at different temperatures, but also incorporate fluorescent materials into flexible bionic skin for temperature self-compensation, which has potential application value for the development of bionic fiber micro-nano sensing and control devices.

Charge compensation improves energy transfer to realize anti-thermal-quenching and enhances the CaMoO4: Sm3+ phosphors optical temperature measurement sensitivity base on the FIR model

Luminescent materials are the main focus of non-contact thermometers due to their high detection sensitivity, non-invasiveness, quick reaction, exceptional stability. It is still difficult to design high sensitivity optical temperature sensors using fluorescence intensity ratio technology. This article increases fluorescence intensity ratio value and obtains high sensitivity temperature sensitive phosphors by utilizing the anti-thermal-quenching effect of rare earth luminous centers. Sm3+ and alkali metal co-doped CaMoO4 phosphors have been prepared by high-temperature solid-state method. Rietveld refinement results showed that the co-doping of Sm3+ and K+ can significantly improve the energy transfer from the host to Sm3+ and significantly increase the luminous intensity of Sm3+. We found that co-doping of Sm3+ and K+ not only effectively enhanced the luminescence intensity, but also regulated the lifetime of this phosphors. When K+ is introduced into the CaMoO4: 0.02Sm3+, the τ value decreased from 4.12 to 3.54 ms, which proves to be effective in light-emitting diode. The optical temperature measurement of CaMoO4: 0.001Sm3+, 0.001 K+ was studied using fluorescence intensity ratio technology. The maximum SaMAX and SrMAX values are 0.27 K−1 at 483 K and 2.25 % K−1 at 363 K, respectively. Moreover, the CaMoO4: 0.02Sm3+, 0.02 K+ also has a certain absorption capacity in visible optical drive, which proved by ultraviolet visible diffused reflectance spectra. The electronic density of states of phosphors are drawn via first-principles to understand the effect of Sm3+ and alkali metals co-doped on luminescence. The above results demonstrate that the Sm3+ and K+ co-doping CaMoO4 might be an attractive material for the application of temperature measurement and light-emitting diode.

Er3+/Yb3+/Ho3+ tri-doped no-core fiber temperature sensor based on fluorescence intensity ratio technology: towards high stability and accurate measurements.

In this paper, the green upconversion (UC) fluorescence emission from E r 3+/Y b 3+/H o 3+ tri-doped tellurite glass is investigated for temperature sensing. The doping of H o 3+ ions not only enhances the chance of energy level transition but also avoids the influence of the thermal effect caused by the proximity of 2 H 11/2 and 4 S 3/2 energy levels. The luminescence characteristics at different Y b 3+ and H o 3+ ion concentration doping molar ratios were investigated, and the strongest luminescence characteristics were exhibited when the Y b 3+ ion concentration was at 5mol% and H o 3+ at 0.2mol%. Based on this, a tri-doped T e O 2-Z n O-B i 2 O 3 (TZB) no-core fiber was fabricated and connected with multimode fibers (MMFs) to form a temperature sensor. The temperature sensing performance of the tri-doped TZB temperature sensor was evaluated in detail over the temperature range of 255-365K. The repeatability and stability of the temperature sensor was experimentally verified. The E r 3+/Y b 3+/H o 3+ tri-doped sensor can be used for noninvasive optical temperature sensing in the fields of environmental monitoring, biological sensing, and industrial process temperature control, etc.

Excitation wavelength and pumping power dependent temperature sensing property of Nd3+/Yb3+/Er3+ triply-doped LaNbO4 phosphor

Optical thermometry based on the fluorescence intensity ratio technology between the thermally coupled energy levels of Er3+ has become a research hotspot, but it is often limited by excitation conditions, which reduces its universality and reliability. In this work, Nd3+/Yb3+/Er3+ triply-doped LaNbO4 phosphor with excellent up-conversion (UC) luminescence characteristic and reliable temperature sensing sensitivity has been prepared by solid-state reaction method. Intense green and weak red UC emissions were gained under 808 nm and 980 nm excitations. The temperature dependent UC luminescence property and temperature sensing behavior of the sample has been investigated. The results demonstrated that the intensity ratio of the two green emissions was insensitive to the excitation wavelength and pumping power of the lasers, and the maximum absolute sensitivity was derived to be 0.91 % K−1 at 481 K. This work provides a new material with reliable and high temperature sensing sensitivity for optical thermometers.

An Er3+/Yb3+ Co-Doped Tellurite Temperature Sensor Based on Fluorescence Intensity Ratio Technology for Real-Time Thermal Monitoring of Automotive 3-D LiDAR

An Er³⁺/Yb³⁺ Co-Doped Tellurite Temperature Sensor Based on Fluorescence Intensity Ratio Technology for Real-Time Thermal Monitoring of Automotive 3-D LiDAR

Integrated photothermal agents with fluorescence intensity ratio/lifetime dual-mode temperature sensing

Non-invasive photo-thermal therapy (PTT) has been proposed as a powerful method for cancer treatment, in which accurate temperature monitoring is necessary to prevent ineffective therapy or damage to normal cells during the process of PTT. This promotes the design and development of photothermal agents (PTAs) with real-time temperature control and excellent photothermal conversion. Here, the designed dual-function photothermal agents YVO4: Nd3+, Yb3+@IR-780 were obtained, while the temperature detection behavior based on the fluorescence intensity ratio (FIR) of Nd3+ (4F3/2 → 4I11/2) to Yb3+ (2F5/2 → 2F7/2) and the temperature-dependent Yb3+ lifetime were investigated in detail. The advantages of fluorescence lifetime thermometry in the biological field were confirmed by the internal temperature detection of pork tissue through comparison with fluorescence intensity ratio technology. The photo-thermal conversion efficiency of samples YVO4: Nd3+, Yb3+@IR-780 reached about 34.3% and its potential application was also evaluated by the sterilization of E. coli and S. aureus, which shows that IR-780 coated nano-materials have excellent photo-thermal conversion performance. Results illuminated that the present photothermal agents with temperature self-monitoring had a bright future in the process of photothermal therapy.

Fluorescent sensing probe based on heterovalent doped Lu2W2.5Mo0.5O12:Er3+/Yb3+ phosphor for real-time chip temperature monitoring

The influence of Li+/Zn2+ heterovalent doping on the structural change and upconversion luminescence properties of Lu2W2.5Mo0.5O12:Er3+/Yb3+ phosphors was investigated in details. The gradual substitution of Li+/Zn2+ ions for Lu3+ ions result in the evolution from orthorhombic Lu2W2.5Mo0.5O12 to monoclinic (LiZn)2W2.5Mo0.5O12, which bring the structural distortion, the reduction of local symmetry and the crystallite growth. The green upconversion intensity of Er3+ ions at 536 nm and 550 nm were enhanced significantly by a factor of 8000 and 4000. The temperature sensing characteristics of a single (LiZn)2W2.5Mo0.5O12:Er3+/Yb3+ particle in all-fiber structure was explored and the unusual thermally-enhanced upconversion luminescence was observed, which is beneficial for achieving high-precision temperature measurement based on the fluorescence intensity ratio technology. The absolute temperature sensitivity reached a maximum of 0.0095 K−1 at 423 K and the temperature deviation was less than 0.6 K. The as-built all-fiber temperature sensor was successfully applied in the on-line monitoring of CPU temperature.

ZnS:Er3+/Yb3+ phosphor for optical temperature sensing and dual-mode anti-counterfeiting

Optical temperature sensors have become a research hotspot in recent years due to their non-contact feature. In this study, Er3+/Yb3+ co-doped ZnS phosphors (1:3, 1:6, 1:9, 1:12, 1:15, 1:19) were prepared by co-precipitation method. The up-conversion and down-conversion luminescence performance of the phosphors was studied. It was found that the luminescence performance is optimized when the doping molar ratio is 1:9. Based on the fluorescence intensity ratio technology of non-thermal coupling energy level, the temperature sensing characteristics of ZnS:Er3+/Yb3+ (1:9) phosphors were studied in the temperature range of 313–533 K. The results show a maximum absolute sensitivity of 1.9 % K−1 and a maximum relative sensitivity of 2.7 % K−1. In terms of multifunctionality, this work also designed a flexible film based on thermoplastic polyurethane (TPU) to explore its anti-counterfeiting properties. The results of this work demonstrate the great potential of ZnS:Er3+/Yb3+ phosphors for optical temperature measurements and anti-counterfeiting.

A ratiometric optical thermometer with dual-color emission based on Eu2+-doped CsCu2I3 microcrystals

With the increasing demand for non-contact fluorescence intensity ratio-based optical thermometry, novel phosphor materials with high-efficiency, dual-emitting centers, and differentiable temperature sensitivity are highly desired. In this work, rare earth Eu2+ ions were incorporated into CsCu2I3 microcrystals by solid-state reaction. Under a single UV excitation, the as-synthesized samples exhibit two emissions: 452 nm blue emission from the 5d→4f transition of Eu2+ and 582 nm yellow emission from self-trapped exciton emission of CsCu2I3. The photoluminescence quantum yield reaches to 50%. The dual-band emission of Eu2+-doped CsCu2I3 shows different temperature responses in the range of 260–360 K. Based on fluorescence intensity ratio technology, the maximum absolute sensitivity and relative sensitivity are 0.091 K–1 (at 360 K) and 2.60%/K (at 260 K), respectively. These results suggest that Eu2+-doped CsCu2I3 could be a good candidate for highly sensitive optical thermometer.

Negative lattice expansion-induced upconversion luminescence thermal enhancement in novel Na2MoO4:Yb3+, Er3+ transparent glass ceramics for temperature sensing applications

Negative lattice expansion-induced upconversion luminescence (UCL) thermal enhancement can efficiently solve thermal quenching of lanthanide ions, and the temperature sensing characteristics can be obtained by combining with fluorescence intensity ratio technology.

White up-conversion La2Mo2O9:Yb3+, Ho3+, Tm3+ phosphors based on dual luminescence centers for high-sensitive optical thermometry

In this paper, the La2Mo2O9:Yb3+, Ho3+, Tm3+ phosphors are successfully synthesized through simple solid-state method. The white up-conversion luminescence is realized by appropriately varying the co-doped concentrations of Ho3+, Tm3+. The up-conversion luminescence characteristics and energy transfer processes of La2Mo2O9:Yb3+, Ho3+, Tm3+ are specifically analyzed upon 980 nm laser excitation. A strategy to enhance the optical temperature sensing performance is demonstrated via flexibly selecting diverse non-thermally coupled energy levels of dual luminescence centers with the fluorescence intensity ratio technology. The maximum values of absolute and relative sensitivity for the thermometer reach 0.2478 K−1 and 1.38% K−1 based on the non-thermally coupled energy levels of 3F2,3 (Tm3+)/5S2,5F4 (Ho3+). The luminescence color of La2Mo2O9:Yb3+, Ho3+, Tm3+ phosphors can maintain in the white region over the whole measured temperature range. These results indicate that the phosphors possess great potential in broad application prospects in the aspects of anti-counterfeiting, displays and non-contact temperature sensing.

Enhanced upconversion emission in Er3+/Yb3+-codoped Al2Mo3O12 microparticles via doping strategy: Towards multimode visual optical thermometer

To explore highly sensitive luminescent materials, a series of Er3+/Yb3+-codoped Al2Mo3O12 microparticles were prepared through a high-temperature solid-state reaction method. The phase structure, light harvest ability, morphology, and upconversion (UC) emission characteristics of these synthesized microparticles were investigated systematically. Excited at 980 nm, glaring visible UC emissions are gained in the developed specimens, in which the optimal doping content for Yb3+ is 7 mol% and the two-photon absorption process contributes to the UC emission mechanism. Based on the fluorescence intensity ratio technology, the thermometric properties of resultant microparticles are studied by analyzing the temperature-dependent green UC emissions of Er3+ arising from the thermal coupling energy levels. The maximum absolute and relative sensitivities of final products are 0.011 K-1 and 1.09% K−1, respectively, and they are barely influenced by Yb3+ contents. Besides, via exploring the lifetimes of 2H11/2 and 4S3/2 levels of Er3+ at various temperatures, the relative sensitivities of resultant microparticles are determined to be 0.27% and 0.26% K−1, respectively. Furthermore, the newly developed microparticles can be adopted to fabricate fluorescent ink to realize optical anti-counterfeiting and visual temperature monitoring. Our studies demonstrate that Er3+/Yb3+-codoped Al2Mo3O12 microparticles with strong UC emissions possess great potential for multimode visual optical thermometry applications.

Achieving power-dependent fluorescence intensity ratio via enhanced photothermal effect in rare-earth and CaCu3TiO12 co-doped alkali niobate ceramics

Controlling the laser power density is one of the major means to bring photothermal conversion phenomenon. However, only a slight temperature enhancement was achieved by exposure to the laser. How to enhance photothermal conversion to develop power-sensitive fluorescence intensity ratio technology becomes a problem. Here, we report an eco-friendly niobate-based ceramic (K 0.25 Na 0.25 NbO 3 ) doped with rare earth ions (Er 3+ , Yb 3+ ) and simultaneously modified with CaCu 3 TiO 4 , exhibiting superior photothermal effect (PTE) and fluorescence intensity ratio (FIR). Thereinto, PTE originating from the up-conversion luminescence of Er 3+ greatly elevates due to the Cu 2+ quenching and Yb 3+ sensitization. Meanwhile, the defects formed by the volatilization of potassium and sodium at high temperature can enhance PTE (70 °C, 0.4 W) and power sensitivity ( S p = 0.61 W -1 ). Under multiple power cycles, stable FIR of the ceramic shows outstanding resistance to temperature in long-term power-dependent tests. Furthermore, this strategy can open opportunities for preparing efficient photothermal conversion ceramics and exploiting PTE for vision-to-tactile sensory conversion.

Upconversion luminescence and optical temperature sensing of Er3+-doped La2Mo2O9 phosphors under 980 and 1550 nm excitation

A series of Er3+-doped La2Mo2O9 phosphors are prepared by the solid-state method. Up-conversion luminescence properties of La2Mo2O9:Er3+ are studied in detail under 980 and 1550 nm excitation. By inspecting the power dependent up-conversion intensity, indicating the two- and three-photon up-conversion population processes for 980 and 1550 nm excitation, respectively. The thermally coupled energy levels of 2H11/2 and 4S3/2 exhibit strong temperature dependence in the range of 293–533 K. Based on fluorescence intensity ratio technology, the La2Mo2O9:Er3+ phosphors present the maximum absolute sensitivity of 78.95 × 10−4 K−1 at 493 K and high relative sensitivity of 1.16% K−1 at 293 K under relatively safe wavelength of 1550 nm excitation. The results suggest that La2Mo2O9:Er3+ phosphor can be used as excellent optical temperature sensor.

Up-conversion luminescence, temperature sensitive and energy storage performance of lead-free transparent Yb3+/Er3+ co-doped Ba2NaNb5O15 glass-ceramics

In this work, a new type of Yb 3+ /Er 3+ co-doped lead-free glass-ceramics (GCs) containing Ba 2 NaNb 5 O 15 nanocrystals was synthesized via traditional melt-quenching and controlled crystallization. The research results illustrate that a transparency of GCs can reach 50% at wavelength of 600 nm and the up-conversion (UC) luminous performance of GCs has been improved obviously compared with precursor glass (PG). And the dual-mode temperature measurement was carried out by fluorescence intensity ratio technology. Using thermally/non-thermally coupled energy levels (TCELs/non-TCELs), the maximum absolute sensitivities of S a-max (TCELs) and S a-max (non-TCELs) are 0.65% K −1 and 0.68% K −1 , and the maximal relative sensitivities of S r-max (TCELs) and S r-max (non-TCELs) are 1.19% K −1 and 0.90% K −1 , respectively. Furthermore, the discharge energy density (W d ) of 1.53 J cm −3 and the instantaneous discharge power density of 370 MW cm −3 with ultra-fast discharge time of 7 ns are simultaneously achieved in the GCs. These findings reveal the potential applications of new lead-free transparent Yb 3+ /Er 3+ co-doped Ba 2 NaNb 5 O 15 GCs for optical temperature measurement and energy storage. • Multi-function RE-doped Ba 2 NaNb 5 O 15 transparent glass ceramics were first fabricated. • Realizing dual-mode Up-conversion optical thermometry in the glass ceramics. • The maximum S r-max and S a-max can reach 1.19% K −1 and 0.68% K −1 . • Achieving high W d of 1.53 J cm − 3 and high P d of 370 MW cm − 3 at 600 kV/cm.

Temperature-dependent luminescence of Bi3+, Eu3+ co-activated La2MgGeO6 phosphor for dual-mode optical thermometry

Using a high-temperature solid-phase method, a series of La2MgGeO6: Bi3+, Eu3+ samples with different doping amounts of Bi3+ and Eu3+ were obtained. The crystal structure, morphology, luminescence characteristics, temperature-varying luminescence spectrum, fluorescence attenuation curve, and energy transfer mechanism of the samples were explored. In La2MgGeO6: Bi3+, Eu3+ phosphors, Bi3+ and Eu3+ ions occupy the La3+ ion position. Under ultraviolet (UV) excitation, the emission spectra of LMGO: Bi3+ and the excitation spectra of LMGO: Eu3+ have significant spectral overlap, indicating that there is energy transfer between Bi3+ and Eu3+. By adjusting the doping amounts of Eu3+, adjustable luminescence can be obtained in the co-doped samples. According to the varying temperature-dependence trends of Bi3+ and Eu3+ ions, fluorescence intensity ratio technology was used to explore the temperature-sensing characteristics of Bi3+ and Eu3+ ions. The maximum absolute sensitivity and relative sensitivity were 0.074%·K−1 and 2.389%·K−1, respectively. In addition, by monitoring the lifetime decay time of Bi3+ with temperature, the maximum temperature sensitivity of the La2MgGeO6: Bi3+ samples was 4.09%·K−1. The above results indicate that La2MgGeO6: Bi3+, Eu3+ samples can be used as potential luminescent materials for temperature detection.

Sensitive optical thermometer via efficient energy transfer in dual-emitting thermochromic YNbO4:Bi3+, Eu3+ phosphor

The remote and non-invasive optical thermometer exploiting fluorescence intensity ratio technology is of great importance in various intelligent optoelectronic sensors. Dual-emitting YNbO4:Bi3+, Eu3+ phosphor is synthesized and investigated for the development of temperature sensing materials. The phosphor excited at 318 nm shows a blue broad band emission and several red sharp peaks. The value of Bi3+→Eu3+ energy transfer can reach 98.2% when Eu3+ doping content is 0.14. Benefiting from diverse thermal response behaviors due to Bi3+ and Eu3+ ions completely different electronic configurations, a dual-emitting optical thermometer is designed. The maximum values of absolute and relative sensitivities are as high as 2.51% K−1 at 473 K and 1.43% K−1 at 423 K, respectively. The thermochromic phosphor possesses a great chromaticity shift (ΔE = 317×10−3) with temperature. Based on superior color discriminability, visual colorimetry temperature measurement relied on thermal characteristic is proposed. All the results demonstrate that YNbO4:0.01Bi3+, 0.005Eu3+ phosphor as a sensitive and reliable optical thermometer has great potentials in temperature measurement.

Structure, up-conversion luminescence and optical temperature sensitive properties of glass ceramics containing Ca5(PO4)3F with double luminescence centers

In this study, CaF 2 –ZnO–P 2 O 5 –CaO–SiO 2 system glass ceramics containing Ca 5 (PO 4 ) 3 F nanocrystals were prepared via melting and crystallization, and their structure, up-conversion luminescence properties and energy transfer were investigated. Owing to the different temperature dependences of the three emitting bands at 523, 547 and 659 nm, dual-mode temperature measurement can be realized according to the employed fluorescence intensity ratio technology. Using thermal-coupled energy levels, the maximum relative sensitivity ( S r-max ) and absolute sensitivity ( S a-max ) were found to be 1.71% K -1 and 0.69% K -1 , respectively. Moreover, the maximum relative sensitivity (S r-max ) and absolute sensitivity (Sa-max) were found to be 2.19% K -1 and 0.11% K -1 , respectively, based on the nonthermal coupled energy levels. This shows that fluoroapatite transparent glass ceramics have latent application prospects in the optical temperature measurement field.