Potential Application In Temperature Research Articles

Optical temperature sensing using upconversion luminescence in rare-earth ions doped Ca2Gd8(SiO4)6O2 phosphors

A series of Yb3+-Er3+, Yb3+-Ho3+, and Yb3+-Tm3+ doped Ca2Gd8(SiO4)6O2 (CGS) phosphors were synthesized by solid-state reaction method, and their upconversion (UC) luminescence properties for temperature sensing were studied. Upon 980 nm excitation, the green and red emissions of Er3+ were observed, and the optimal Er3+ concentration was determined to be 3 mol%. For the CGS:10%Yb3+,yHo3+ phosphors, three emission peaks in the green, red and near-infrared region appear. It was found that the relative intensities of Ho3+ different emissions change with Ho3+ concentration, which has been explained by the cross-relaxation process. The strongest Tm3+ emission appeared at 790 nm, attributed to the 3H4-3H6 transition. The optimal Tm3+ concentration was determined to be 0.5 mol%. The temperature sensing behavior was evaluated by employing the thermally-coupled or non-thermally coupled levels of Er3+, Ho3+ and Tm3+. The maximum sensitivities obtained are 3.71×10−3 and 1.12 K-1 for CGS:10%Yb3+,3%Er3+, 0.111 K-1 for CGS:10%Yb3+,3%Ho3+ and 3.3×10−4 K−1 for CGS:10%Yb3+,0.5%Tm3+, respectively. The high sensitivities indicate the present phosphors could have potential application in temperature sensing.

Eu3+ activated LiSrVO4 phosphors: Emission color tuning and potential application in temperature sensing

A series of color-tunable emitting LiSrVO4:Eu3+ phosphors were synthesized by solid state reaction. The Luminescence properties and temperature sensing performance were investigated. Under near ultraviolet (NUV) excitation, LiSrVO4: Eu3+ exhibited both the green broad band luminescence due to (VO4)3−groups and red sharp emission peaks of sensitized Eu3+ ions. The tunable color of high-brightness emission from green to red is realized by controlling the Eu3+ doping content. The optical thermometry of LiSrVO4: Eu3+ was studied via excitation intensity ratio between V-O charge transfer band and Eu3+ f-f transition at low temperature (10–323 K). The highest absolute sensitivity SA is found to be 8.6%. The red emission intensity of Eu3+ shows a linear relationship in high temperature range of 298–573 K. The maximum value of relative sensitivity SR is established as 2.2%K−1 @573 K. The LiSrVO4:Eu3+ phosphors might be a promising candidate for NUV based phosphor and temperature sensing in a wide temperature range.

Multifunctional broad-band excited Eu3+-activated fluorescent materials for potential warm white light-emitting diodes (w-LEDs) and temperature sensor applications

Discovery of novel multifunctional fluorescent materials are of great concern to the development of disciplinary crossing and integration. In this work, we prepared a broad-band Eu3+-activated Lu2MoO6 multifunctional material for potential warm white light-emitting diodes (w-LEDs) and temperature sensor applications. Lu1.9MoO6:0.1Eu3+ phosphor was synthesized by high-temperature solid-state reaction method, and the structure characterization was investigated for the first time. The excitation spectrum of this phosphor exhibits the intense broad band ranging from 250 nm to 440 nm assigned to the O2−-Mo6+ charge transfer band (CTB) transition, and a strong red emission centered at 610 nm corresponding to the 5D0 → 7F2 transition of Eu3+ ions were detected under 365 nm excitation. Importantly, warm white light composite material was hybridized via blending commercial green, blue and the present red phosphors, which under 365 nm excitation exhibited a high color rendering index (CRI) of 78 at a correlated color temperature of 4271 K with CIE coordinates of x = 0.351, y = 0.308. Furthermore, a strong temperature sensitization phenomenon was found, where the results show that the emission intensities and chromaticity coordinates are sensitive to the temperature, which can provide guidance for the potential application in temperature sensing.

Temperature induced color change in gold nanoparticle arrays: Investigating the annealing effect on the localized surface plasmon resonance

The localized surface plasmon resonance (LSPR) effect in metal nanoparticles is important for a range of applications, including photovoltaics and sensors. The actual LSPR effect is difficult to predict, because it can vary strongly with the size, shape, surface structure, and surrounding media of the nanoparticles. In order to understand this better, more experimental data are needed. Here, the authors present a study of the LSPR effect in macroscopic two-dimensional square arrays of gold nanoparticles, 50–80 nm in diameter with a pitch of approximately 160 nm, fabricated on borosilicate substrates. The arrays were exposed to different annealing temperatures in steps of 50 up to 600 °C. The authors observe an irreversible blue-shift of the LSPR extinction peak, from around 580 to around 520 nm at annealing temperatures of only 450 °C, an effect clearly visible to the naked eye. The authors also present measurements of the shape of the nanoparticles at the different annealing steps. These measurements were obtained using a combination of scanning electron microscopy (SEM) and atomic force microscopy (AFM). A carefully indexed pattern allowed us to measure the exact same nanoparticles with separate AFM and SEM instruments. The only clear effect that can be observed is that the nanoparticles appear to get smoother with annealing. Our results demonstrate that seemingly minor changes in the metal nanoparticle appearance can lead to a strong change in the LSPR effect. Our results also open up for potential applications in temperature sensing. The fact that the effect of temperature exposure can be observed with the naked eye without any need of electronic readout or power supply is particularly advantageous.

One-dimensional nano layered SiC/TiO2 based photonic band gap materials as temperature sensor

In this present paper, we have proposed a novel design of temperature sensor using 1-dimensional photonic band gap materials, which is made by alternate layers of TiO2 and silicon carbide (4H–SiC) with periodic variation of their respective thickness and refractive indices. We have investigated the reflection properties, relative band width behaviour and group velocity of the proposed photonic band gap materials at different temperature. The refractive index of SiC is temperature dependent, so by increasing the temperature the number of forbidden bands as well as width of the forbidden bands increases and the value of group velocity decreases. Thus, by analysing the band gap width, number of forbidden bands, and group velocity, it is easy to calculate the value of temperature of the given environment. This paper is focused on what we regard the latest development in the use of photonic band gap materials in photonic devices, a strong importance with the application in communication. It may be used as a temperature sensor. Our results show the potential application in temperature controlled optoelectronic devices.

Yttrium hydroxide fluoride based monodisperse mesocrystals: additive-free synthesis, enhanced fluorescence properties, and potential applications in temperature sensing

Fluorine-containing monodisperse mesocrystals constructed by nanorods were synthesized via an additive-free hydrothermal route and Eu3+ was successfully incorporated into the yttrium hydroxide fluoride host lattice.

The thermal dependence of the luminescent properties of Eu3+ doped Y2MoO6 phosphor and its potential application in temperature sensing

The temperature dependence of luminescence performance is crucial for most applications of the luminescent materials. Temperature dependent emission spectra of Y2MoO6: 20% Eu3+ phosphor were investigated over a very large temperature range from 20 to 500K, and the experimental result shows that the emission intensity decreases dramatically with the temperature increasing. With the help of the decay curves of the emission, the possible mechanisms for the thermal quenching behavior of the Eu3+ luminescence were discussed. Considering the acute change of the emission intensity with temperature, Eu3+ doped Y2MoO6 could be a promising candidate for temperature sensors.