Thermoluminescent microparticle thermal history sensors

Abstract

While there are innumerable devices that measure temperature, the nonvolatile measurement of thermal history is far more difficult, particularly for sensors embedded in extreme environments such as fires and explosions. In this review, an extensive analysis is given of one such technology: thermoluminescent microparticles. These are transparent dielectrics with a large distribution of trap states that can store charge carriers over very long periods of time. In their simplest form, the population of these traps is dictated by an Arrhenius expression, which is highly dependent on temperature. A particle with filled traps that is exposed to high temperatures over a short period of time will preferentially lose carriers in shallow traps. This depopulation leaves a signature on the particle luminescence, which can be used to determine the temperature and time of the thermal event. Particles are prepared-many months in advance of a test, if desired-by exposure to deep ultraviolet, X-ray, beta, or gamma radiation, which fills the traps with charge carriers. Luminescence can be extracted from one or more particles regardless of whether or not they are embedded in debris or other inert materials. Testing and analysis of the method is demonstrated using laboratory experiments with microheaters and high energy explosives in the field. It is shown that the thermoluminescent materials LiF:Mg,Ti, MgB 4 O 7 :Dy,Li, and CaSO 4 :Ce,Tb, among others, provide accurate measurements of temperature in the 200 to 500°C range in a variety of high-explosive environments.

Correlated Na+ Ion Migration Invokes Zero Thermal Quenching in a Sodium Superionic Conductor-type Phosphor

“…Therefore, we measured thermoluminescence (TL) as a function of the Lu 3+ concentration (Figure e), which reduced the TL intensity, implying that the trap concentration decreased upon Lu 3+ doping in NSPO:Eu 2+ (Figure S9). However, these results strongly support that the local environment around the Na + ions is a prerequisite for their ionic conduction, which severely affects the Na + ionic mobility and, consequently, the trap concentration and the PLTQ behavior of NSPO:Eu 2+ .…”

Heat transfer coefficient: a review of measurement techniques

“…This type of temperature sensor is widely used as a mechanical switch for temperature control, usually, know as thermostats. [10] Few millimeters/minutes 0.1 °C Biomaterial [11,12] Few millimeters/seconds 0.1 °C Gas thermometers [13] Centimeters/minutes 0.001 K Acoustic [14][15][16][17][18] Centimeters/milliseconds 0.1 °C Electrical Thermocouple [19,20] 0.02-5 mm/50 ms-1 min 0.1 °C RTD [20,21] Few millimeters/minutes 0.001 °C Thermistor [13,21] 1-10 mm/20-300 s 0.01 °C (low span, 50 °C) Semiconductor junction [22] Few millimeters/minutes 0.5 °C Optical Optical fiber [23,24] millimeters 1D/millisecond 0.05-0.1 °C Thermoreflectance [25][26][27] 10 μm/down to ms 0.1-1.1 °C Liquid crystal [28][29][30][31] 2D/less than 1 s 0.5-0.9 °C Thermo-and photoluminescence [32][33][34][35] 2D observed temperature fields 1-31 °C Interferometry [36][37][38] 2D/milliseconds or less 2% (temperature in K) IR thermography [39][40][41] 40 μm-1 mm (2D)/down to ms 18 mK Temperature-sensitive paints (TSP) [41] 5 μm-1 mm (2D)/down to ms 0.4 °C 2.1.1.3 Gas thermometers Such mechanical thermometers are based on the variation in the pressure or volume when a fluid changes the temperature [13]. Basically, two types of fluid states are used, gas state or saturated state.…”

“…Optical techniques for temperature measurement are a set of emerging techniques that potentialize new applications hardly solved by mechanical or electrical temperature sensors. Their main advantages are noncontact temperature measurements, easy integration for obtaining high-resolution 2D temperature fields, fast response time and high immunity to electromagnetic interference [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”

“…The thermo-and photoluminescence technique for temperature measurements is based on the temperature dependence of the visible luminescence intensity of some rare-earth ions. Such a dependence is due to the presence of closely spaced energy levels in those special ions [32][33][34][35]. A temperature measurement apparatus involves first the charging of particles with energy from an irradiation source in a specific spectral range (UV, visible or infrared) and registration of the intensity of emitted light radiated by the temperature-dependent thermoluminescence particles.…”

Thermochromic Polymer Film Sensors for Detection of Incipient Thermal Damage in Carbon Fiber–Epoxy Composites

“…Thermochromic fluorescence has been used as the basis for reversible “fluorescence thermometers” which cannot retain the necessary time information [ 21 , 29 ]. Irreversible thermal history sensors based on thermochromic fluorescence of lanthanide metals have inappropriate dynamic time and temperature ranges for aerospace composite applications [ 30 , 31 ]. With these challenges in mind, we developed a thermochromic fluorescent probe in which a highly fluorescent molecule, 9,10-Bis(p-dimethylaminostyryl)-anthracene ( M2 ) is rendered non-fluorescent by the addition of N-phenyl maleimide ( M3 ) to its anthracene core to form the initial molecule ( M1 ) via the well-known [4+2] Diels–Alder reaction.…”