Eu3+-doped manganese tungstate for multiparametric and colorimetric luminescence thermometry

Abstract

Improvement of luminescent thermometers requires not only the search for high-sensitivity thermometric outputs, but also availability of multiple thermometric parameters affording a combined and reliable response. We hereby detail for the first time the luminescence of Eu³⁺ in manganese tungstate (Eu³⁺:MnWO₄) solids obtained by coprecipitation under ultraviolet excitation and how this material provided an optical thermometric response from 77 K to 373 K via excitation and emission spectra. Processing of up to five thermometric parameters, namely bandwidths, band positions, band shifts and luminescence intensity ratios, resulted in relative thermal sensitivities as high as 1.56% K⁻¹ and temperature uncertainties between 0.01 and 2 K depending on the choice of the spectral parameter. In addition, we demonstrate that Eu³⁺:MnWO₄ also act as a qualitative colorimetric thermosensor because of progressive change of emission color to greenish-yellow to bluish-green upon heating under UV excitation. Therefore, our results show that the combination of broadband tungstate emissions with the 4f-4f narrow emissions of Eu³⁺ is an effective approach to achieve a multiparametric luminescent thermal response via emission, excitation and visual observation, which makes Eu³⁺:MnWO₄ a promising candidate for advanced thermometry applications.