The influence of morphology and Eu3+ concentration on luminescence and temperature sensing behavior of Ba2MgWO6 double perovskite as a potential optical thermometer

The paper presents the temperature sensing potential of Ba2Mg1-2xEuxLixWO6 as a self-calibrating luminescent thermometer based on the temperature-dependent emission intensity of two independent emission centers. The luminescent thermometer based on the spin-allowed emission of host and the spin-forbidden emission of rare earth ions can be a promising direction for non-contact temperature sensing and a highly interesting extension to this field. The experimental results show that the high probability of the energy transfer from the tungstate group to Eu3+ is the reason why the spin-allowed emission of [WO6](6-) group was observed only for the samples with the lowest dopant concentration. The mechanism responsible for the thermal depopulation of D-5(0) luminescence of Eu3+ ions is mainly induced by the charge transfer (CT) states of tungstate groups. The study of the temperature sensing showed that the sample exhibits the best temperature sensing ability in the low-temperature region (77-200 K) with the maximum of the relative sensitivity 1.5% K-1 at 120 K and that potentially it can be applied it as a low-temperature sensor. (C) 2020 Elsevier B.V. All rights reserved.