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

This paper presents the Cr³⁺-activated Mg₂TiO₄ 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 ⁴T₂→⁴A₂ and ²E→⁴A₂ transitions, (ii) the emission lifetime, and (iii) the shift of the ²E→⁴A₂ 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 ²E→⁴A₂ 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.