Investigation Of The Temperature Dependence Of Europium Doped Barium Magnesium Aluminate Thermographic Phosphor

Laser induced fluorescence thermometry using thermographic phosphors is anremote and semi-intrusive temperature measurement technique, and has been widelyused in practical temperature measurements. Thermographic phosphors are typicallyceramic materials doped with rare earth or transition metal ions. When a surface iscoated with a thin film of thermographic phosphor and excited by optical sources, thesubsequent emission exhibit temperature dependent properties in the time domain orfrequency domain, which are exploited for temperature determination. For a given task,there is usually more than one thermographic phosphor to meet the requirements. Ourpurpose is to explore the feasibility of using laser induced fluorescence thermometryfor the transient temperature measurements during shock loading. Considering the keyfactors of shock loading, we choose europium doped barium magnesium aluminate(BaMg2Al16O27:Eu2+, BAM) as temperature sensor for laser induced fluorescencethermometry.The temperature response of thermographic phosphor is a key feature forthermometry. Therefore, the characterization of the temperature response of BAM hasbeen done, the excitation wavelength are800nm,400nm,266nm, respectively. Wehave confirmed the mechanism of temperature dependence of BAM. We observed theup conversion fluorescence of BAM when we used800nm femtosecond laser asexcitation source and the spectral characteristics are totally the same as single photonexcitation.The time integrated spectra study of BAM shows that the fluorescence of BAMare sensitive to the environment temperature, especially for the intensity ratio ofdifferent spectral range. According to the spectral response of BAM, we carried out theintensity ratio calibration by two band pass filters, one is440±10nm and the other is495±25nm. We also calculated the relative sensitivity of intensity ratio. The resultsshow that the fluorescence intensity of BAM shows good sensitivity between300and700K. The temporal results show that the radiative and non-radiative relaxationlifetime of BAM in the order of10-6s and10-11s magnitudes, which indicates that the fluorescence of BAM phosphor can response transient temperature in real time and theintensity ratio method combined with a time gate detector can obtain a higher temporalresolution than the lifetime method.Then we compared the temperature response of BAM under three differentexcitation wavelength, the results indicate that the temperature dependence propertiesof BAM does not change with excitation wavelength. Thus it is convenient to choosethe excitation wavelength and this can obtain great flexibility for intensity ratiothermometry.