RÉSUMÉ
Remote thermal sensing has emerged as a temperature detection technique for tasks in which standard contact thermometers cannot be used due to environment or dimension limitations. One of such challenging tasks is the measurement of temperature in microelectronics. Here, optical thermometry using co-doped and mixed dual-center Gd2O3:Tb3+/Eu3+samples were realized. Ratiometric approach based on monitoring emission intensities of Tb3+(5D4-7F5) and Eu3+(5D0-7F2) transition provided sensing in the range of 30 °C-80 °C. Dispersion system type only slightly affected relative sensitivity, accuracy and precision. The applicability of phosphors synthesized to be utilized as remote optical thermometers for microelectronics has been proved with an example on a surface mount resistor and microcontroller.
RÉSUMÉ
In the last decade much attention has been paid to the development of novel approaches in luminescence thermometry, which could allow contactless and noninvasive temperature sensing when traditional thermometers are useless. Typically, an optical thermometer exploits a distinct luminescence parameter to define temperature. However, the use of multimode sensors can significantly broaden the working range and improve the reliability of the temperature measurements. In this work, a Eu3+-doped LaVO4 sample was successfully utilized as a thermal sensor within a wide temperature range of 98-723 K based on monitoring various temperature-sensitive luminescence features. Different thermal sensing strategies were assessed and compared in terms of thermal sensitivity and temperature resolution. The best thermometric performances of the Eu3+-doped LaVO4 sensor reached an Sr = 1.49% K-1 and a ΔT = 0.6 K at room temperature. All the studies performed showed that the LaVO4:Eu3+ phosphor is a prospective multimode optical thermometer.
RÉSUMÉ
Single doped CaWO4:Er3+phosphors were synthesized and studied for application of optical thermal sensing within a wide range of 98-773 K. Ratiometric strategy utilizing two luminescence intensity ratios, one between host and Er3+band (LIR1) and second between different Er3+transitions (LIR2), results in self-referencing temperature readouts. The presence of two temperature-dependent parameters could improve thermometric characteristics and broaden the working temperature range compared to a usual single-parameter thermometer. Thermometric performances of prepared samples were evaluated in terms of thermal sensitivities, temperature resolution and repeatability. The highest sensitivity of 2.09% K-1@300 K was found for LIR1, whereas LIR2provided more accurate thermal sensing with a temperature resolution of 0.06-0.1 K. Effect of Er3+doping concentration on sensing properties were studied. The presented findings indicate that CaWO4:Er3+phosphors are perspective in dual-mode thermal sensing with high sensitivity and sub-degree resolution.
RÉSUMÉ
Crystalline inorganic nanoparticles doped with rare earth ions are widely used in a variety of scientific and industry applications due to the unique spectroscopic properties. The temperature dependence of their luminescence parameters makes them promising candidates for self-referencing thermal sensing. Here we report single phase YVO4 nanoparticles doped with different pairs of rare earth ions (Nd3+/Er3+, Tm3+/Er3+ and Nd3+/Tm3+) for contactless ratiometric thermometry within a wide temperature range of 298-573 K. The presence of dual luminescence centers in the optical thermometer allows one to circumvent the fundamental limitation of sensitivity inherent to thermometers based on thermally coupled levels. Important parameters for temperature sensing, such as relative thermal sensitivity and temperature resolution, were calculated for all synthesized samples and compared with the literature data. The YVO4:Tm3+,Er3+ sample displayed a relative sensitivity of 0.28% K-1 at room temperature, and the YVO4:Nd3+,Er3+ phosphor exhibited a high sensitivity of 0.56% K-1 at 573 K, while YVO4:Nd3+,Tm3+ demonstrated sub-degree thermal resolution. These findings demonstrate the good potential of dual-center ratiometric YVO4 thermometers and open the way toward future enhancement of their thermometric performances through variation of the doping concentration.
RÉSUMÉ
During last decade luminescence thermometry has become a widely studied research field due to its potential applications for real time contactless temperature sensing where usual thermometers cannot be used. Special attention is paid to the development of accurate and reliable thermal sensors with simple reading. To address existing problems of ratiometric thermometers based on thermally-coupled levels, LuVO4:Nd3+/Yb3+thermal sensors were studied as a proof-of-concept of dual-center thermometer obtained by co-doping or mixture. Both approaches to create a dual-center sensor were compared in terms of energy transfer efficiency, relative sensitivity, and temperature resolution. Effect of excitation mechanism and Yb3+doping concentration on thermometric performances was also investigated. The best characteristics ofSr = 0.34% K-1@298 K and ΔT = 0.2 K were obtained for mixed phosphors upon host excitation.
RÉSUMÉ
Accurate contactless thermometry is required in many rapidly developing modern applications such as biomedicine, micro- and nanoelectronics, and integrated optics. Ratiometric luminescence thermal sensing attracts a lot of attention due to its robustness toward systematic errors. Herein, a phonon-assisted upconversion in LuVO4:Nd3+/Yb3+ nanophosphors was successfully applied for temperature measurements within the 323-873 K range via the luminescence intensity ratio technique. Dual-activating samples were obtained by codoping and mixing single-doped nanopowders. The effect of the type of dispersion system and the Yb3+ doping concentration was studied in terms of thermometric performances. The relative thermal sensitivity reached a value of 2.6% K-1, while the best temperature resolution was 0.2 K. The presented findings show the way to enhance the thermometric characteristics of contactless optical sensors.
RÉSUMÉ
The development of new contactless thermal nanosensors based on a ratiometric approach is of significant interest. To overcome the intrinsic limitations of thermally coupled levels, a dual activation strategy was applied. Dual activation was performed using co-doped single nanoparticles and a binary mixture of single-doped nanoparticles. Co-doped and mixed YVO4:Nd3+/Eu3+ nanoparticles were successfully demonstrated as luminescent nanothermometers and their thermometric performance, in terms of thermal sensitivity, temperature resolution and repeatability, was studied and compared.