Investigation of spectroscopic properties of LaAlO₃:Ti³⁺ for lifetime-based thermometry

Inorganic nanocrystals doped with transition metal ions combine several advantageous features: (1) high chemical and photochemical stability with (2) efficient luminescence resulting from the high absorption cross-section and (3) tunabile spectral positions of the absorption and emission bands depending on the chosen host material. The most extensively studied transition metal ions in optical spectroscopy are Cr³⁺ and Mn⁴⁺ ions, which seems promising for many applications related to their red or infrared emission [1,2]. However, their properties have already been determined in many host materials, making it possible to roughly predict their behavior in others and thus assume certain limitations. This issue does not apply to Ti³⁺ ions, the stabilization of which beyond the well-known sapphire has only been confirmed in a few host materials. Meanwhile, it has already been presented that the emission and excited state lifetimes of Ti³⁺ ions are characterized by a significant dependence on temperature changes, which may be beneficial for luminescent thermometry [3]. Moreover, Ti³⁺ ions can be characterized by relatively long excited state lifetimes of the order of several tens of milliseconds. Therefore, step-by-step optimization of the synthesis condition and dopant concentration of LaAlO₃ doped with Ti³⁺ ions will be presented in order to understand the influence of dopant concentration on spectroscopic properties and the thermal quenching process. Finally, the influence of non-stoichiometric ion distribution on the above properties will be analyzed.

Acknowledgments:

This work was supported by the National Science Center Poland (NCN) under project no. 2022/45/N/ST5/01457.

References:

[1] W. E. Cohen et al., ECS J. Solid State Sci. Technol. 12, (2023), 76004.

[2] Z. Pan et al., Nat. Mater. 11 (2012) 58–63.

[3] W. M. Piotrowski et al., Chem. Eng. J. 428, (2022), 131165.