Lanthanide dopant stabilized Ti3+ state and supersensitive Ti3+ -based multiparametric luminescent thermometer in SrTiO3:Ln3+ (Ln3+ = Lu3+, La3+, Tb3+) nanocrystals
Wojciech Piotrowski, M. Kuchowicz, Miroslav D. Dramićanin, Ł. Marciniak
Abstract
Herein, we show that the substitution of Sr2+ by trivalent lanthanide ions (Lu3+, La3+, Tb3+) in SrTiO3 nanocrystals stabilizes and enhances Ti3+ near-infrared emission (around 800 nm). This emission occurs from the 6-fold coordinated Ti3+ luminescent centers that appear in the vacancy–Ti3+–O form after lanthanide doping into the Sr2+ site. The strong dependence of the Ti3+ emission on temperature provided means for the tailored chemical engineering of luminescent nanonthermometers able to read the temperature in three ways: from the changes in Ti3+ emission intensity, excited-state lifetime, and from the ratio of Tb3+ and Ti3+ emission intensities. We demonstrated the unprecedented temperature sensitivity of the lifetime-based luminescent thermometer (8.83% K−1) with SrTiO3:Tb3+, along with exceptional repeatability in measurements.