Temperature dependence of the Cr3+-DOPED Mg2TiO4 near-infrared emission

Abstract

This paper presents the Cr 3+ -activated Mg 2 TiO 4 phosphor temperature dependance of its near infrared luminescence and its potential in the optical thermometry applications. In this respect, temperature dependences of three emission features were tested over the broad temperature range (10–500 K): (i) the luminescence intensity ratio (LIR) between emissions from 4 T 2 → 4 A 2 and 2 E→ 4 A 2 transitions, (ii) the emission lifetime, and (iii) the shift of the 2 E→ 4 A 2 emission band. We observed that LIR follows the Boltzmann equation for T > 300 K with the maximal value of relative sensitivity of 1.73 %K −1 . The lifetime value of the 2 E→ 4 A 2 transition strongly decreases with temperature with a maximal relative sensitivity of about 0.75 %K −1 at around 430K. Finally, the shift of the emission band is about 65 cm −1 over the complete temperature range. • Synthesis of single phase Mg 2 TiO 4 :Cr 3+ phosphor. • Multi readout approach to temperature sensing in first biological NIR window. • The maximum relative sensitivity of 1.73 %K −1 in the LIR mode at physiological temperatures. • The maximum relative sensitivity 0.75 %K −1 in the lifetime mode in broad temperature range from 100 K to 400 K. • Significant red shift of the Cr 3+ R line with temperature increase.