Nd:YAG Near‐Infrared Luminescent Nanothermometers

In this work, the thermal sensing capability of Nd 3+ ‐doped Y 3 Al 5 O 12 nanoparticles fabricated by combustion synthesis is reported. Under excitation at 808 nm, the relative intensity of the two spectrally isolated luminescence peaks located at around 940 nm (corresponding to a 4 F 3/2 → 4 I 9/2 transition of the Nd 3+ ions) is found to be markedly temperature‐dependent allowing for ratiometric luminescence nanothermometry. The potential use of neodymium‐doped yttrium aluminum garnet nanoparticles in nanothermometry has been successfully tested in a variety of systems including integrated microelectronics, optofluidic devices, and subtissue ex vivo experiments.